No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Comparison of global warming potential between conventionally produced and CO2-based natural gas used in transport versus chemical production
Abstract
In the future, the capacities of renewable SNG (synthetic natural gas) will expand significantly. Pilot plants are underway to use surplus renewable power, mainly from wind, for electrolysis and the production of hydrogen, which is methanated and fed into the existing gas pipeline grid. Pilot projects aim at the energetic use of SNG for households and transport in particular for gas fueled cars. Another option could be the use of SNG as feedstock in chemical industry.The early stage of development raises the question of whether SNG should be better used for mobility or the production of chemicals. This study compares the global warming potential (GWP) of the production of fossil natural gas (NG) and carbon-dioxide (CO2)-based SNG and its use for car transport versus chemical use in the form of synthesis gas. Since the potential of wind energy for SNG production is mainly located in northern Germany, the consequences by a growing distance between production in the North and transport to the South of Germany are also examined.The results indicate that CO2-based SNG produced with wind power would lead to lower GWP when substituting NG for both uses in either transport or chemical production. Differences of the savings potential occur in short-distance pipeline transport. The critical factor is the energy required for compression along the process chain.
... Most LCA studies 173,281,282,615,616 have focused on the process simulation for Ni-catalyzed production of synthetic natural gas without recycle as proposed by Muller et al. 617 This process simulation is based on a pilot plant reported by Sterner 618 and achieves a conversion of 95% at a reaction temperature of 280°C and 8 bar of operating pressure, which are common operating conditions for the Sabatier reaction (see section 2.2). ...
... To make the results comparable, the emissions of combustion are eliminated from all studies, and the results are harmonized to 1 MJ of methane using the lower heating value. The studies presented by Hoppe et al. (2016) 616 and Parra et al. 620 are not included in Figure 17, since the results are identical to those of Hoppe et al. (2017) 173 and Zhang et al., 621 respectively. The results from the LCA by Meylan et al. 625 are excluded from the comparison since it treated the indirect emissions caused by operating the process (e.g., purge, heat, electricity) only with an estimate of 10% of the incorporated CO 2 without further analysis. ...
... To make the results comparable, the emissions of combustion are eliminated from all studies, and the results are harmonized to 1 MJ of methane using the lower heating value. The studies presented by Hoppe et al. (2016) 616 and Parra et al. 620 are not included in Figure 17, since the results are identical to those of Hoppe et al. (2017) 173 and Zhang et al., 621 respectively. The results from the LCA by Meylan et al. 625 are excluded from the comparison since it treated the indirect emissions caused by operating the process (e.g., purge, heat, electricity) only with an estimate of 10% of the incorporated CO 2 without further analysis. ...
CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does not depend primarily on the absolute amount of CO2 emissions that can be remediated by a single technology. Rather, CO2-based chemistry is stimulated by the significance of the relative improvement in carbon balance and other critical factors defining the environmental impact of chemical production in all relevant sectors in accord with the principles of green chemistry.
... Indeed, the optimal methane utilisation route will depend on its end-use phase and the environmental impact of its supply chain. 77 Thus, it might be regarded as a short-term interim solution in the transition of the chemical industry. Notably, optimization-based assessments suggested that hybrid plants consuming biomass and natural or shale gas feedstock reduce the environmental footprint and the dependency on fossil sources. ...
... Furthermore, studies often restrict the scope to environmental impact(s) tightly linked to the use of biomass and CO 2 as feedstock, focusing on global warming and fossil depletion metrics. 38,42,48,77,78,109,120,126,[159][160][161][162][163] However, the large-scale adoption of emerging technologies could unintendedly shift burdens across environmental categories or echelons in the product's supply chain. It was stressed that LCA studies on CCU products are not harmonized in terms of assumptions, scope, system boundaries and impact metrics, which makes comparisons challenging. ...
Meeting the Sustainable Development Goals and carbon neutrality targets requires transitioning to cleaner products, which poses significant challenges to the future chemical industry. Identifying alternative pathways to cover the growing demand for chemicals and fuels in a more sustainable manner calls for tight collaborative programs between experimental and computational groups as well as new tools to support these joint endeavours. In this broad context, we here review the role of Process Systems Engineering tools (PSE) in assessing and optimising alternative chemical production patterns based on renewable resources, including renewable carbon and energy. The focus is on the use of process modelling and optimisation combined with life cycle assessment methodologies and network analysis to underpin experiments and generate insight into how the chemical industry could optimally deliver chemicals and fuels with a lower environmental footprint. We identify the main gaps in the literature and provide directions for future work, highlighting the role of PSE concepts and tools in guiding the future transition and complementing experimental studies more effectively.
... 47 The increase of raw material input for the production of methanol from CO 2 due to the high material demand of renewable energy infrastructure is already identified as a trade-off on a cradle-to-gate basis. 37,48 This trade-off may affect material efficiency 49 and sustainable resource use negatively. 50 Cradle-to-gate assessments are the current paradigm in life cycle assessment (LCA) on CCU technologies. ...
... In contrast to the scope of the funding and research focus of CCU, the energetic use of carbon may not be preferable compared to material use, as already identified on a cradle-to-gate basis for CO 2 based synthetic natural gas. 48 This study compares different technology options to substitute fossil-based products, such as polymers for material use and fuels for energetic use, with products based on methanol produced from recycled CO 2 . The potential to reduce GHG emissions and the change in material demand is assessed based on the life cycle wide product climate and material footprint. ...
The European Commission as well as the German government favor an energetic use of methanol from CO 2 recycling with their legislation and funding mechanisms. This study uses the product climate footprint and the product material footprint to assess the complete life cycle of fossil-based polypropylene, polyoxymethylene, heavy fuel oil, petrol and diesel compared to a functional equivalent product manufactured with methanol from recycled CO 2. Assuming that renewable electricity from wind power feeds the electrolysis for the hydrogen production, the results confirm that the use of recycled CO 2 reduces the climate footprint, but increases the material footprint as a trade-off. The substitution of polyoxy-methylene provides the highest climate footprint reduction closely followed by the substitution of petrol, followed by polypropylene, heavy fuel oil and diesel. Solely for polyoxymethylene, petrol and heavy fuel oil the greenhouse gas emission savings are relatively higher than the additional material demand. Material recycling and energy substitution from plastics waste incineration provide a benefit to the footprints that is by a factor of three higher than for the substitution of fossil-based polymers alone. The analysis until 2050 reveals that the additional material demand is reduced due to the defossilization of the German electricity grid.
... 2 However, previous studies have questioned whether CCU provides an environmental benefit, from a life cycle perspective. [2][3][4] Existing life cycle assessments (LCA) of CCU investigate the environmental impacts of the production of a chemical, for example, C 1 -basic chemicals like carbon monoxide 5 , syngas 6,7 , formic acid 5,8,9 , methane 6,7,10-16 and methanol 5,6,[12][13][14]17,18,19 . Other LCAs focused on the assessment of more complex molecules produced via CCU, like methyl propionate 20 , DME 11,19,21 , DMC 17,22 , OME 23 , (jet) fuels 24,25 , polymers 4,14,21,26,27 . ...
... As given in the LCA literature, supply of electricity and heat is a significant contributor to the total impact of CCU. 5,7,10,13,14,16,[22][23][24][25]75 For the electricity supply, we assumed the marginal German market mix as default provider and tested how results changed when assuming that the provision of electricity is solely from lignite (as a worst case) and solely from wind (as a best case). For the heat supply, we assumed the provision of heat within the chemical industry as a default provider. ...
Carbon capture and utilization is a promising approach to reduce greenhouse gas emissions and fossil resource depletion in the chemical industry. However, since carbon capture and utilization is an energy and material intensive process, it is unclear whether it allows for a net reduction of environmental impacts on a life cycle perspective. Previous life cycle assessment studies on carbon capture and utilization-focused on the production of one specific chemical or the comparison of C1-basic chemicals and applied an attributional approach. This study assesses twelve CO2-conversion technologies to provide decision support on the potential life-cycle environmental impacts of each technology. Consequential life cycle assessment was chosen as modeling approach to better understand the system-wide environmental consequences of introducing carbon capture and utilization technologies in the chemical industry. This study has identified that in a near- and a long-term scenario the global warming impact for all CO2 conversions technologies, besides dimethoxymethane, electrochemical produced formic acid, and Fischer-Tropsch production, is negative. Formic acid produced via hydrogenation and polyol production are the conversion technologies with the highest potential for reducing the global warming impact on a life cycle perspective. Holistically the polyol production is the conversion technology with the highest potential for reducing environmental impacts. In general, it seems recommendable to introduce carbon capture and utilization within the chemical industry from an environmental perspective.
... Recently published LCA studies on the production of CO 2based chemicals like methane or methanol indicate that the GWI could be lowered compared to fossil-based production (von der Assen et al. 2013;Sternberg and Bardow 2015;Hoppe et al. 2016). The result, however, strongly depends on the energy source for electrolysis and the chosen CO 2 input. ...
... Last, but not least, cross-sectoral analysis should clarify whether CO 2 -based methanol produced with renewable energy could be better used as feedstock for chemical syntheses or as fuel for energetic purposes (for methane, Hoppe et al. [2016] got first insights). For that purpose, the both environmental and economic performance of production routes will have to be studied. ...
Previous studies showed that using carbon dioxide (CO2) as a raw material for chemical syntheses may provide an opportunity for achieving greenhouse gas (GHG) savings and a low-carbon economy. Nevertheless, it is not clear whether carbon capture and utilization benefits the environment in terms of resource efficiency. We analyzed the production of methane, methanol, and synthesis gas as basic chemicals and derived polyoxymethylene, polyethylene, and polypropylene as polymers by calculating the output-oriented indicator global warming impact (GWI) and the resource-based indicators raw material input (RMI) and total material requirement (TMR) on a cradle-to-gate basis. As carbon source, we analyzed the capturing of CO2 from air, raw biogas, cement plants, lignite-fired power, and municipal waste incineration plants. Wind power serves as an energy source for hydrogen production. Our data were derived from both industrial processes and process simulations. The results demonstrate that the analyzed CO2-based process chains reduce the amount of GHG emissions in comparison to the conventional ones. At the same time, the CO2-based process chains require an increased amount of (abiotic) resources. This trade-off between decreased GHG emissions and increased resource use is assessed. The decision about whether or not to recycle CO2 into hydrocarbons depends largely on the source and amount of energy used to produce hydrogen.
... If this development continues, the world will be threatened with an energy crisis, as the worldwide fossil oil reserves will be exhausted in shorter than 30 years. In addition to the fact of limited oil resources, extensive use of fossil fuel contributes to increase the atmospheric CO 2 that results in global warming [2,3]. This phenomenon may lead to catastrophic changes in earth's climate, as some of the available evidence suggests that scientists have been conservative in their predictions of the impacts on climate change [4,5]. ...
... In addition to the fact that it is a renewable fuel that could be sustainably supplied, adopting biodiesel has a number of advantages; (1) substituting biodiesel for petroleum diesel results in substantial reductions of soot, sulphur and unburned hydrocarbon emissions. In addition, because biofuel is derived from biomass, it does not contribute to atmospheric CO 2 emissions [11]; (2) biodiesel can be used in existing diesel engines, blended with petroleum diesel or can be used unblended in slightly modified engines with better engine performance [12]; (3) biodiesel has lubrication properties that can actually improve engine life because it has twice the viscosity of petroleum diesel [13]; (4) it is highly biodegradable and, therefore, has minimal toxicity [14,15]; and (5) biodiesel investment will has significant improvement of rural economic potential. The primary biodiesel feedstocks for different producing countries are provided in Table 1. ...
... Carbon dioxide (CO 2 ), as of the greenhouse gases, is closely monitored in the context of global climate change (Florides and Christodoulides 2009;Ghommem et al. 2012;Lee et al. 2013;Hoppe et al. 2016;Szulejko et al. 2017;Liu and Chen 2017;Ishikura et al. 2018; Al-Ghussain 2019; Binet et al. 2020;Bhattacharyya et al. 2021;Mitevski et al. 2022). One of the most important natural components of the global carbon cycle is soil respiration (Zhao et al. 2017;Jian et al. 2018Jian et al. , 2021. ...
Part of the gaseous carbon dioxide (CO2) produced in karst soils / epikarst is transported into underground cavities / caves during the growing season by advective flux, diffusive flux, and flux associated with degassing of seeping water. In dynamic caves, accumulated CO2 is released into the outside atmosphere during the autumn-winter period through advective flux associated with ventilation of the cave in the upward airflow mode. This case study from the Moravian Karst (MK) showed that the net weight of CO2 released annually from the Sloup-Šošůvka Caves (total volume of 131,580 m³ and a total area of 17,950 m²) into the external atmosphere was 348 kg. Extrapolating this value to all known MK caves (area about 352,080 m²) yielded a total of CO2 flux of 6820 kg yr⁻¹. This flux is representing only 0.024‰ of the annual soil respiration from entire MK area (about 2.81 × 10⁸ kg CO2 yr⁻¹).
... Differences between the threshold values obtained for the electricity supply's CO 2 -eq emission factor in this study and in literature are attributed to the methods and functional units utilized. Available literature also identified that electricity supply has a dominant impact on the GWP of SNG, and found that electrolysis with renewable energy sources reduces the GWP of PtSNG compared to that of the conventional production of natural gas [19][20][21]23,70]. Overall, this environmental assessment showed that the proposed PtSNG plant concept is environmentally beneficial to conventional natural gas production with regards to the global warming potential when renewable energy is used or when the electricity supply has an emission factor lower than 121 g CO 2 -eq/kWh el . ...
Synthetic Natural Gas (SNG) is the most researched option for a Power-to-Fuel pathway in Germany after hydrogen, having the advantage of being compatible with the existing infrastructure. However, it is not clear under which conditions SNG is economically and environmentally advantageous compared to natural gas usage, since this is determined by a complex interplay of many factors. This study analyzes the technical, economic and environmental aspects of a pilot SNG plant to determine the key parameters for profitable and sustainable operation. The SNG plant was simulated in Aspen Plus® with CO2 from biogas production as a feedstock and with hydrogen provided by a 1 MWel electrolyzer unit. A life cycle analysis (LCA) was undertaken considering several impact categories with a special focus on global warming potential (GWP). An SNG cost of 0.33–4.22 €/kWhth was calculated, depending on factors such as operational hours, electricity price and type of electrolyzer. It was found that the CO2 price has a negligible effect on the SNG cost, while the electricity is the main cost driver. This shows that significant cost reductions will be needed for SNG to be competitive with natural gas. For the investigated scenarios, a CO2 tax of at least 1442 €/t was determined, calling for more drastic measures. Considering the global warming potential, only an operation with an emission factor of electricity below 121 g CO2-eq/kWhel leads to a reduction in emissions. This demonstrates that unless renewable energies are implemented at a much higher rate than predicted, no sustainable SNG production before 2050 will be possible in Germany.
... Nowadays, there is exponential increase in the energy demand due to industrialization and fast human activities, which is expected to double by 2050 [1]. In addition, current utilization of non-renewable fossil fuels led to environmental and health problems as a result of greenhouse gas emissions, threatening the life on the earth [2,3]. It is essential to explore alternative technologies for sustainable and eco-friendly energy production in order to raise the living standards [4]. ...
This study aimed to optimize growth medium composition for enhanced lipid and fatty acid production by the green halophilic chlorophyte Tetraselmis elliptica. The impact of different ratios of natural seawater, nitrogen source/concentration, carbon source/concentration, and trace metals on the growth, biomolecules, lipid accumulation, and lipid productivity was studied. In addition, fatty acid profile of the optimized growth medium was compared with that of the typical medium as a control, and biodiesel production as well as essential polyunsaturated fatty acids (PUFAs) were evaluated. Among all studied factors, 0.1 g L⁻¹ KNO3, 0.01 g L⁻¹ glycerol, and 7.0 mg L⁻¹ FeSO4·7H2O significantly enhanced the lipid productivity of T. elliptica, and were used further to evaluate the impact of their combination. Cultivation of T. elliptica in the optimized medium showed enhancement of growth up to 16 days, which resulted in 30.9% and 17% increase in biomass and lipid productivities, respectively. Moreover, optimization of growth medium enhanced PUFAs proportion to 15.05% due to de novo synthesis of arachidonic acid and docosahexaenoic acids which represented 4.17% and 10.88%, respectively, of total fatty acids. Biodiesel characteristics of the optimized medium showed compliance of all studied parameters with the US standards. The present study provides new insights for commercial utilization of marine microalgae cultivated in optimized growth medium for dual purpose of ω-fatty acids and biodiesel production through biorefinery approach.
Graphical abstract
... Moreover, along with the steady growth of the palm oil industry, PKS will be a promising industrial fuel to replace coal and natural gas, at least partially, with recognizable advantages from its lower overall GHG emission, net zero carbon effect [52] and renewability due to the perpetual photosynthesis cycle in comparison to millions of years for fossil fuel formation [53]. By shifting the energy dependency of industries from fossil-based materials, the utilization of these materials can be directed towards more environmentally friendly usages, as suggested in the recent studies by Gagarin et al. [54] on coal for industrial materials and Hoppe et al. [23] on natural gas for chemical production. ...
The palm oil industry is a promising biomass source, as the production generates wastes more than four times that of the main product. In 2020, for 45 MT of crude palm oil production in Indonesia, it was estimated that around 12 MT of palm kernel shell were generated or equivalent to 5.4 MTOE in net calorific value. This high calorific value of solid waste can be used by industries as a source of renewable energy, once it is proven to be technically, environmentally and economically feasible. In this comparative study, the life cycle assessment method was deployed to determine the environmental feasibility of palm kernel shell usage as an alternative renewable energy source to coal and natural gas in ceramic tile production through the application of combustion technology. The novelty of this study lies in a cradle-to-gate approach by comparing the carbon footprint of biomass from agriculture industrial waste with common fossil fuels as sources of energy for a highly energy-intensive industry. This research demonstrates that by evaluating the total life cycle of a fuel, the perspective on environmental impacts can be quite different when compared to looking solely at the end-use process. This study shows how the deployment of life cycle assessment would create managerial implications toward the decision making of fuel selection with carbon footprint considerations.
... Conversion of methanol-to-olefins also has negative to near zero GHG emissions with values of 0.44 kg CO 2 eq./kg olefins using a municipal solid waste feedstock, − 4.15 kg CO 2 eq./kg olefins for corn, − 4.4 and − 8.7 kg CO 2 eq./kg olefins for wood chips [110,111]. These results do strongly depend on the source of the CO 2 and energy used during electrolysis [20,[112][113][114][115][116][117] with values rapidly rising to 4.6 kg CO 2 eq./kg methanol produced when coal-rather than wind-generated energy is used [106]. GHG emissions can be further reduced by introducing a CO 2 recovery unit [118] or incorporating the system within an existing production process, such as a pulp and paper mill with wood residue used as feedstock [106,119,120] or a biorefinery with e.g., methanol co-produced alongside ethanol [121][122][123]. ...
Immediate and widespread changes in energy generation and use are critical to safeguard our future on this planet. However, while the necessity of renewable electricity generation is clear, the aviation, transport and mobility, chemical and material sectors are challenging to fully electrify. The age-old Fischer-Tropsch process and natural gas industry could be the bridging solution needed to accelerate the energy revolution in these sectors – temporarily powering obsolete vehicles, acting as renewable energy’s battery, supporting expansion of hydrogen fuel cell technologies and the agricultural and waste sectors as they struggle to keep up with a full switch to biofuels. Natural gas can be converted into hydrogen, synthetic natural gas, or heat during periods of low electricity demand and converted back to electricity again when needed. Moving methane through existing networks and converting it to hydrogen on-site at tanking stations also overcomes hydrogen distribution, storage problems and infrastructure deficiencies. Useful co-products include carbon nanotubes, a valuable engineering material, that offset emissions in the carbon nanotube and black industries. Finally, excess carbon can be converted back into syngas if desired. This flexibility and the compatibility of natural gas with both existing and future technologies provides a unique opportunity to rapidly decarbonise sectors struggling with complex requirements.
... Lifecycle research suggests that the use of this renewable syngas-as feedstock for steam reforming to produce synthesis gas in the chemical industry could result in lower GWP than using natural gas, particularly if the SNG production occurs close to its end use. Yet, while there is no shortage of CO 2 for sequestration, limited availability of renewable power for electrolyzed hydrogen production may limit such feedstock production [87]. ...
Natural gas is an important and highly flexible fuel across the industry sector globally. It provides fuel and energy services for both heat and power, and is also as a key feedstock in many industrial processes. Natural gas-based industrial technologies typically have lower capital costs, operating costs, and electricity consumption than coal-based technologies. These features make natural gas preferable for industrial use as compared to other fossil fuels. However, the future of natural gas remains uncertain, especially for industry planning to be net-zero or carbon neutral by mid-century. This review addresses the role that natural gas might play in global industrial decarbonization, and how it can help decarbonize industrial processes. We undertake a comprehensive and critical review of more than 400 studies on the topic of industrial decarbonization via natural gas. The review also provides evidence of critical barriers that range from financial and infrastructural to geopolitical and governance issues along with promising avenues for future research.
... We did not harmonize production infrastructure and transport emissions and follow the choices in the respective LCAs because these emissions contribute negligibly to the total GHG intensity. [124][125][126] For the substituted products, emissions were also determined based on a cradleto-grave basis. ...
The Paris Agreement’s temperature goals require global CO2 emissions to halve by 2030 and reach net zero by 2050. CO2 capture and utilization (CCU) technologies are considered promising to achieve the temperature goals. This paper investigates which CCU technologies—using atmospheric, biogenic, or fossil CO2—are Paris compatible, based on life cycle emissions and technological maturity criteria. We systematically gathered and harmonized CCU technology information for both criteria and found that CCU with technology readiness levels (TRLs) of 6 or higher can be Paris compatible in 2030 for construction materials, enhanced oil recovery, horticulture industry, and some chemicals. For 2050, considering all TRLs, we showed that only products storing CO2 permanently or produced from only zero-emissions energy can be Paris compatible. Our findings imply that research and policy should focus on accelerating development of CCU technologies that may achieve (close to) zero net emissions, avoiding lock-in by CCU technologies with limited net emission reductions.
... Differences between the threshold values obtained for the electricity supply's CO2-eq emission factor in this study and in literature are attributed to the methods and functional units utilised. Available literature also identified that electricity supply has a dominant impact on the GWP of SNG, and found that electrolysis with renewable energy sources reduces the GWP of PtSNG compared to that of the conventional production of natural gas (Parra et al., 2017, Hoppe et al., 2016, Sternberg and Bardow, 2016, Reiter and Lindorfer, 2015b, von der Assen et al., 2013. Overall, this environmental assessment showed that the proposed PtSNG plant concept is environmentally beneficial to conventional natural gas production when renewable energy is used or when the electricity supply has an emission factor lower than 105 g CO2-eq/kWhel. ...
... The main result is that the energy mix for electricity production and the CO 2 source dominates the life cycle emissions and therefore the reduction potential of this new technology in comparison with natural gas. On the same topic, Hoppe, Bringezu, and Thonemann (2016) concluded that SNG production from an industrial CO 2 source (in this case from raw biogas separation) in the German scenario saves greenhouse gas emissions if compared to natural gas. On the other, Sternberg and Bardow (2016) argued that the power-togas pathways imply higher global warming impact (GWI) and fossil depletion than conventional natural gas even in a 2050 electricity mix while proving promising GWI reduction with the power-to-syngas routes. ...
Among all power-to-fuel pathways, power-to-methane is regarded as one of the most promising and efficient pathways for its numerous routes and applications besides being the most widely investigated. Power to methane is the simplest synthetic fuel production process that allows carbon utilisation. Its implementation on a large scale could allow a vast and immediate decarbonisation of several sectors of the society and provide storage services while keeping the current infrastructure and know-how of existing technologies. In this chapter, both chemical and biological methanation, including state of the art and literature studies, are presented in detail with their most important features and operational parameters. A comparison between different available technologies is carried out with an outlook on power-to-methane plant economy. Finally, an insight on substitute natural gas production from biomass gasification and electrolytic hydrogen is proposed.
Link to the book:
https://www.elsevier.com/books/power-to-fuel/spazzafumo/978-0-12-822813-5
... Many LCAs investigate the conversion of electricity from either wind or solar PV with an electrolysis unit and a subsequent methanation step (e.g. in Refs. [48,73,136,139,140,195]). Due to the fluctuating properties of wind and PV, the PtG units need to be operated in transient modes in such scenarios. ...
Natural gas is an energy carrier of predominant significance for today’s electricity and heating sectors. However, science heavily discusses the actual environmental burden of natural gas mainly due to the uncertainty in up- stream methane losses during its extraction and transportation. In this context, numerous technologies pave the way for the production of renewable methane to replace natural gas: biomethane from anaerobic digestion of biomass, substitute natural gas (bio-SNG) from gasification and Power-to-Gas via water electrolysis and subse- quent methanation. In recent years, numerous studies aimed at analysing the life cycle carbon intensity of those renewable gases. Given the high degree of freedom in the methodology of life cycle assessment (LCA) however, the studies are highly dependent on the respective boundary conditions and assumptions. To summarise and discuss the different findings, this review identifies and quantitatively analyses 30 life cycle assessment studies on the greenhouse gas emissions of renewable gases, comparing their results and deriving the main determinants on their environmental friendliness. A comparison between the results for renewable gases and existing literature reviews on the LCA of fossil natural gas shows the considerable emission reduction potential of renewable gases. This however requires the consideration and right implementation of the main influencing factors (inter alia the storage of digestate in closed tanks for biomethane, heat extraction of excess heat for bio-SNG, or the use of renewable electricity for Power-to-Gas) and is not a mere result of the technologies per se.
... Several studies assessed the environmental impact of Hydrogen-to-Methane plants [180][181][182][183][184][185][186][187]. In all of these studies, methane is considered to be produced by the Sabatier reaction route. ...
In light of advancing climate change, environmentally-friendly methods for generating renewable energy are being employed to an increasing extent. This use, however, leads to rising spatial and temporal disbalances between electricity generation and consumption. To address the associated challenges, Power-to-X technologies are considered to harness surplus electricity from renewable sources and convert it into an alternative energy source that can be utilized, transported and stored. The aim of this paper is to compare four different Power-to-X technologies, whereby surplus electricity “Power” is converted to chemical entities “X”. It is shown that the implementation of PtX technologies and a shift of energy distribution to other transport methods could significantly relieve the electricity grid. Moreover, by converting the electricity from renewable sources, like wind farms, into chemical energy sources, the PtX concept offers the opportunity of making larger quantities of energy storable over longer periods of time. By considering a model case where electricity generation and consumption are several hundred kilometres apart, the generation of fuels emerges as a technology with the highest potential to mitigate climate change. Also with regard to transport, fuels emerge as the most favourable option for transporting chemically bound energy. Common to all options is the yield of a significant stream of oxygen as by-product. Utilizing this oxygen may be one of the key factors towards improving the economic viability of Power-to-X technologies.
... In particular, Parra et al. summarized the SNG carbon footprint in the range of 0.02 to 1.08 ton CO 2 -eq per MWh, depending on the scenario considered. [128] Hoppe et al. [130] compared carbon footprint between conventionally produced and CO 2 -based natural gas, used in transport versus chemical production. They showed emissions savings by using SNG instead of natural gas for both transport and chemical production applications. ...
Carbon dioxide utilization is increasingly attracting interest. CO2 utilization involves a multitude of processes and chemical reactions. In this context, the goal of this review is to analyze the techno‐economic feasibility, sustainability, and social opportunities of CO2 utilization, as a possible contribution to CO2 mitigation in Europe. Industries and the most recent European projects related to carbon capture and utilization are also discussed, illustrating Europe's performance dynamics in science, research, and innovation in this field. The latest developments in CO2 utilization are thus reviewed, including chemicals, mineral carbonation, and biological uses. This study examines a few CO2‐based pathways at high level of maturity covering a wide range of applications, and discusses their current technical feasibility, economic viability, sustainability, and social aspects. They are then evaluated using several indicators to provide a figure of merit, where qualitative results are intended. The mapping and ranking of CO2 utilization pathways may provide a valuable means in prioritizing support and funding to facilitate the development of large‐scale CO2 utilization projects in Europe. Finally, key challenges and opportunities are discussed. The review shows that CO2 utilization may not be a complete solution for Europe, but will support climate change objectives, circular economy, and resource and energy security.
... If this energy consumption rate continues, it is predicted that the world will face an energy crisis due to exhaustion of the worldwide fossil oil reserves in shorter than 3 decades [2]. In addition, dependence on fossil oil as a main energy source contributes to excessive CO 2 emission [3], with about 20% of the worldwide CO 2 emissions from transportation sector only [4]. Taking this sector as an example, the total new-vehicle annual sales in 2013 were 84 million, which is expected to increase to 127 million by 2035, bringing the total global vehicle number to 2 billion [5]. ...
Due to the negative environmental impacts of fossil fuels and the increasing global energy demands, biofuels are receiving increasing attention as the best short-term substitute for petroleum. Recently, thermochemical conversion of seaweeds is in industrial focus to obtain high-value products with more potential applications than the conventional raw material. Beside biofuel production and due to their autotrophic growth, seaweeds are receiving a great attention in the field of bioremediation. Thus, pyrolysis of seaweeds is a promising approach for renewable bio-oil production with positive environmental impacts. However, a pretreatment drying step is required to improve the conversion process of the biomass. Application of electro-osmotic dewatering as well as on-site mechanical dewatering methods prior to the drying process were reported as useful techniques to reduce the energy requirements. On the other hand, the bio-oil produced from pyrolysis of seaweeds usually has high contents of oxygen-, nitrogen- and sulphur-containing compounds, which should be as minimum as possible to enhance the bio-oil stability and reduce NOx and SOx emissions. The present review introduces a suggested route combining a number of technologies that create an economically-feasible process for conversion of seaweeds to high-grade crude bio-oil through pyrolysis. In addition, the paper sheds light on the environmental impacts and economic feasibility of the crude bio-oil production from seaweeds. The current status and challenges related to pyrolysis, as well as future perspectives for enhanced conversion and upgraded bio-oil production, are discussed.
... Most CCU technologies are in stages of early development and aim to reduce environmental impacts. Therefore, most LCA studies on CCU aim at quantifying the potential environmental impact reductions of CCU processes or products in comparison to existing processes (Aresta and Galatola, 1999;Aresta et al., 2002;Kim et al., 2011;Anicic et al., 2014;Souza et al., 2014;van der Giesen et al., 2014;Luu et al., 2015;Al-Kalbani et al., 2016;Garcia-Herrero et al., 2016;Hoppe et al., 2016Hoppe et al., , 2017Matzen and Demirel, 2016;Schakel et al., 2016;Sternberg and Bardow, 2016;Parra et al., 2017;Sternberg et al., 2017;Uusitalo et al., 2017;Zhang et al., 2017). Most studies also include a contribution analysis of environmental impacts to identify opportunities for improvement (Aresta and Galatola, 1999;Aresta et al., 2002;Kim et al., 2011;van der Giesen et al., 2014;Luu et al., 2015;Garcia-Herrero et al., 2016;Matzen and Demirel, 2016;Schakel et al., 2016;Parra et al., 2017;Uusitalo et al., 2017). ...
Carbon Capture and Utilization (CCU) is an emerging field proposed for emissions mitigation and even negative emissions. These potential benefits need to be assessed by the holistic method of Life Cycle Assessment (LCA) that accounts for multiple environmental impact categories over the entire life cycle of products or services. However, even though LCA is a standardized method, current LCA practice differs widely in methodological choices. The resulting LCA studies show large variability which limits their value for decision support. Applying LCA to CCU technologies leads to further specific methodological issues, e.g., due to the double role of CO2 as emission and feedstock. In this work, we therefore present a comprehensive guideline for LCA of CCU technologies. The guideline has been development in a collaborative process involving over 40 experts and builds upon existing LCA standards and guidelines. The presented guidelines should improve comparability of LCA studies through clear methodological guidance and predefined assumptions on feedstock and utilities. Transparency is increased through interpretation and reporting guidance. Improved comparability should help to strengthen knowledge-based decision-making. Consequently, research funds and time can be allocated more efficiently for the development of technologies for climate change mitigation and negative emissions.
... Both CO 2 and CH 4 are the most abundant renewable carbon sources [7,8]. Thus the chemical fixation of these GHGS into value added fine chemicals could be a promising strategy in order to encounter the issues of global warming [9,10]. ...
Development of a highly efficient and coke-resistant, nickel based nano-catalyst in the carbon dioxide reformation of methane is reported. The alumina supported Ni-based catalyst with a metal loading of 5wt% was prepared via the solution combustion synthesis (SCS) method as well as the conventional wetness impregnation method. The synthesized catalysts were thoroughly characterized by a combination of analytical techniques including high-resolution electron microscopy (HRTEM-SAED), X-ray diffraction (XRD), nitrogen physisorption (BET surface area), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (H 2 -TPR) and temperature programmed oxidation (TPO). Compared to the conventional nickel-impregnated (Ni-I) catalyst, the Ni-SCS nano-catalyst was superior in activity and stability during dry reformation of methane. Ni-SCS catalyst exhibited higher percentage conversions of methane and carbon dioxide. The percentage yields of hydrogen and carbon monoxide over Ni-SCS catalyst were also significantly higher. During the investigated period on stream for 50 h, the Ni-I catalyst deactivated severely, by contrast the Ni-SCS stayed active. It was clear from the results of elemental carbon analysis and TPO that deactivation of the Ni-I catalyst was due to severe carbon deposition, whereas the Ni-SCS catalyst exhibited minor carbon deposition. These differences in the catalytic activities and stabilities between the Ni-I and Ni-SCS catalysts were attributed to the difference in their physicochemical properties and chemical structure, as obvious from the results of the above mentioned analysis techniques. The XRD and XPS analysis revealed that the Ni-SCS nanocatalyst resulted in the formation of uniformly distributed nickel aluminates (NiAl 2 O 4 ) nano-crystallite spinels together with nickel oxide. The results of H 2 -TPR analysis clearly distinguished between NiO and NiAl 2 O 4 . H 2 -TPR affirmed the formation of NiAl 2 O 4 and NiO species on the SCS nanocatalyst but only NiO within the impregnation catalyst. In this regards the exceptionally high catalytic activity and stability of Ni-SCS nanocatalyst during dry reformation was attributed to the presence of NiAl 2 O 4 nano-crystallites structures. On the other hand, the presence of weakly associated NiO species on the Ni-I catalyst was responsible for decaying its activity due to carbon formation during the dry reformation of methane.
... The assessment of GHG from different human activities is a research area covering fields as diverse as agricultural processes (Chareonpanich et al., 2017;García-Gusano et al., 2015), industrial applications (Nabavi-Pelesaraei et al., 2014;Raucci et al., 2015) as well as transport (Hoppe et al., 2016;Rob ert et al., 2017) and energy sectors (Marchi et al., 2018;Weldemichael and Assefa, 2016;Wesseh and Lin, 2015). ...
Most existing works using a displacement estimation method to estimate the CO2 emissions abated by wind energy are based on the current operating principles of the power system. They consider a fixed displacement emission factor since wind energy is assumed to replace high-carbon generation. This method may be unsuitable in the long run when the energy mix of most countries becomes more decarbonised. Consequently, wind energy would replace those technologies becoming increasingly predominant in the future, i.e. lower polluting fossil fuels such as natural gas and even other less competitive low-carbon technologies. In order to consider this effect, this paper proposes a new method that estimates a range of potential CO2 emissions abated by wind energy based on two dynamic displacement emission factors, which are periodically updated according to the evolution of the future energy mix. Such factors represent an upper and a lower limit of CO2 emissions avoided. The method is validated in the case study of the European Union over the period 2015–2050. The results show that the annual displacement emission factor by wind energy may vary from about 422 to 741 t CO2/GWh in 2015 to around 222–515 t CO2/GWh in 2050. The total CO2 abatement ranges from about 6600 to 13100 Mt CO2 in the period 2015–2050.
... However, most of the small gas reserves are stranded: in the case of associated production (i.e., gas produced with crude oil), the natural gas has to be re-injected. [1][2][3] This not only results in the loss of income but also pollutes the environment due to gas leakage to air. Because of this, there is a sustained demand for small-tomedium-sized gas-to-liquid (GTL) plants on floating production, storage, and offloading vessels (FPSOVs). ...
In this work, microwave (MW) was used to activate Co/Al2O3, Mo/Al2O3, and Co-Mo/Al2O3 catalysts for DRM reaction. Experimental results indicate that single metallic catalyst of either Co or Mo is inactive for dry reforming of methane (DRM) under all tested conditions due to its limited MW absorbing ability. In contrast, the Co-Mo bimetallic catalysts supported by Al2O3 performs high catalytic activity due to the formation of magnetodielectric Co0.82Mo0.18 alloy, which is playing the dual role to be a good MW acceptor and to provide active centers for DRM reaction. MW power level required to activate bimetallic catalysts for DRM is significantly dependent on the molar ratio between cobalt and molybdenum. CoMo2 catalyst (with a molar ratio of 2.0 Co: 1.0 Mo) supported on Al2O3 displays the best catalytic performance converting 80 % CH4 and 93 % CO2 to syngas with the ratio of H2/CO at 0.80 at the total volumetric hourly space velocity (VHSV) of 10 L.g-1.h-1 and 200 W. Compared to the reported carbon-based catalysts, Co-Mo/Al2O3 catalyst delivers a more favourable stability over 16 time-on-stream (TOS) by virtue of its intrinsic ability to absorb MW without the inclusion of auxiliary MW-acceptor.
... However, according to Hoppe et al., 23 as a generator of global warming, biogas contributes to approximately 20% of total atmospheric emissions and the rate is increasing by about 1-2% each year. Bitton 4 indicated that approximately 520 × 10 9 kg yr −1 of CH 4 is released into the atmosphere. ...
Organic solid wastes (OSWs) should be regarded as valuable resources rather than dead‐end landfill waste that causes public health and odor concerns. Anaerobic digestion (AD) is an ideal approach for managing organic solid waste issues and involves using a group of anaerobic microorganisms to transform OSWs into useful products. In this review, over 100 publications related to AD of OSWs have been compiled, discussed, and analyzed. A comprehensive analysis of the environmental and safety impacts of AD, its key environmental factors, co‐digestion, and pretreatment, as well as the AD of OSWs by various anaerobic microbes uncovered by high throughput sequencing‐based approaches, is presented. The purpose of this review is to provide an outline of the current knowledge of AD processes from a multi‐angle perspective. A comprehensive understanding of AD of OSWs and genome‐enabled biology development could be helpful for providing up‐to‐date knowledge of AD, developing it, overcoming its drawbacks and, ultimately, improving global waste control for more efficient environmental management. © 2018 Society of Chemical Industry
... If the development of the world energy consumption continues, the world will be threatened with an energy crisis, as the worldwide fossil oil reserves will be exhausted in shorter than 30 years (1). In addition to the fact of limited oil resources, extensive use of fossil fuel contributes to increase the atmospheric CO 2 (2). Currently, one-fifth of the global CO 2 emission is due to transportation and trucking (3). ...
Nowadays, biofuel production is a fast expanding industry and is facing a growing dilemma about a feedstock source capable of keeping up with demand. Recently, macroalgae have been attracting a wide attention as a source for biofuel. In the present study, ten macroalgae were collected and screened as biodiesel feedstocks. As a result of their high biomass production and relatively high lipid content, Ulva lactuca, Padina boryana and Ulva intestinalis showed the highest significant lipids and fatty acid methyl esters (FAMEs) areal productivities among the studied species. Saturated fatty acids (SAFs) showed insignificant differences in the selected species, with noticeably significant higher polyunsaturated fatty acids (PUFAs) content in U. lactuca by 4.2 and 3 times, with respect to P. boryana and U. intestinalis, respectively. The recorded increase in PUFAs was attributed to higher content of C16:4n-3, C18:3n-3 and C18:4n-3. By lipid fractionation, P. boryana showed significant higher concentration of neutral lipids (37.7 mg g(-1) CDW, representing 46.7% of total fatty acids) in comparison to U. lactuca and U. intestinalis, which showed 16% and 17% lower neutral lipid fractions, respectively. In addition, biodiesel characteristics of the studied macroalgae complied with that of international standards. Furthermore, oil-free residual biomass can be readily converted into fermentable sugars or biogas due to its high carbohydrates content, which adds to the economics of macroalgae as biofuel feedstock. In conclusion, the present study confirmed that macroalgae represent an attractive alternative renewable feedstock for biodiesel and other biofuels.
... Unfortunately, conventional combustion process results in low fuel-utilization efficiency and high level carbon dioxide (CO 2 ) emissions. CO 2 , however, is recognized as a major component of greenhouse gas that contributes to irreversible global warming (Diego et al., 2016;Hoppe et al., 2016). In terms of conventional SMR, CO 2 from combustion flue gas is generally captured via chemical or physical absorbents for limiting anthropogenic climate change (Damartzis et al., 2016;Zhang et al., 2013). ...
Photovoltaic solar energy is one of the immaculate non-pollutant origins of inexhaustible sources of energy. As a result of the increase in energy demand and the bad effects of carbon-containing fuels on the world environment, several nations reflect on photovoltaic solar energy as the appropriate and possible choice for electrification in rural agriculture applications and household practices. To satisfy the increasing electrical energy need and reduce the production of gas. The use of photovoltaic energy cannot be overemphasized in agricultural applications in rural areas. Photovoltaic and electrification in agriculture is the formation of photovoltaic production of electricity, heat, and some other forms of energy. In agriculture, it means making available green energy and being able to maintain electricity for farming activities. The review will focus on energy access/usage for boosting farming activities in rural communities of Sub-Saharan African nations. It will also offer a critical review of the methodical investigation by different researchers on photovoltaic solar energy and electrification in agricultural applications for quality improvement in energy generation in rural areas for agricultural purposes, which in turn generates employment opportunities for people living in rural communities in Sub-Saharan African countries. The investigation covers several forms of photovoltaic systems, such as solar energy for cooling storages, pumping water for irrigation activities, heating/cooling greenhouses and drying crops for rural communities in Sub-African. It describes different principal application forms of photovoltaic solar energy in agriculture, photovoltaic solar energy issues, the principle of operation of photovoltaic, its uses, problems, and opportunities. Furthermore, this study discusses the economic analysis and market related opportunities of photovoltaic systems. It has been shown beyond reasonable doubt that photovoltaic solar energy would be an appropriate option for electrification in agriculture, particularly in the distant typical remote environment. The review concludes that the prospects of the research will be economic development potential and employment creation opportunities in the Sub-Saharan African communities.
This research involved performing steam-assisted dry reformation (SDR) on methane over a CoMo 2 /Al 2 O 3 nanoflake catalyst irradiated at microwave frequencies. CoMo 2 nanoflakes showed great catalytic activity for reforming reactions due to their excellent exposed surface to the incident MW and better ability to absorb MW. Fischer-Tropsch (F-T) synthesis is used to manufacture liquid fuels, and the predicted syngas ratio (H 2 /CO) can be easily modified by adjusting the quantity of steam to carbon ratio (S/C) supplied into the reactor. With an intake S/C ratio of less than (0.1) and (200 W) of MW power, it is possible to get an H 2 /CO ratio greater than one. Compared to carbon-based catalysts, the catalytic stability of the CoMo 2 nanoflakes catalysts was much higher after 16 hours of time-on-stream (TOS) of the SDR process while being exposed to MW irradiation. Steam combination dry reforming, MW assistance, and a CoMo catalyst are some keywords that might be used here.
Part of the gaseous carbon dioxide (CO 2 ) produced in karst soils / epikarst is transported into underground cavities / caves during the growing season by advective flux, diffusive flux, and flux associated with the degassing of seeping water. Accumulated CO 2 is released into the outside atmosphere during the autumn-winter period through advective fluxes associated with ventilation of the cave in the upward airflow mode. The case study from the Moravian Karst (MK) showed that the net weight of CO 2 released annually from the Sloup-Šošůvka caves (total volume of 131,580 m ³ and a total area of 17,950 m ² ) into the external atmosphere was 348 kg. Extrapolating this value to the known MK caves (area about 352,080 m ² ) yielded the total CO 2 flux of 6820 kg yr − 1 . This flux is not very significant, representing only 0.024‰ of the annual soil respiration from entire MK area (about 2.81×10 ⁸ kgCO 2 yr − 1 ). Globally, reduced summer flux with intensified winter flux out of cave could contribute to seasonal fluctuations in CO 2 concentration in the external atmosphere.
Global energy demand and consumption have increased as the world's population has grown at a faster rate than industrial activity. The depletion of fossil fuels as well as rising prices for other energy sources are causing us to move toward “environmentally friendly” systems that seek out alternate cost-effective energy sources. Biodiesel made from oil crops has the potential to be a renewable energy source. Biodiesel made from oil crops is a viable renewable alternative to petroleum fuels, but it is insufficient to meet demand. Algae appears to be a viable source of renewable biodiesel that can meet such high worldwide demand. The goal of this chapter is to examine the existing potential and efficiency of algae as a bioenergy source. The advanced manufacturing procedures will also be discussed to determine the most cost-effective method for bigger scale production.
Developing efficient and inexpensive electrocatalysts for CO2 reduction reaction (CRR) has been a key scientific issue. Several factors limit the electrocatalyst efficiency of materials, including the relatively high overpotential, low stability and low selectivity for CRR. The use of bimetallic catalyst systems is an efficient approach to improve the catalytic performance. In this study, by using the density functional theory (DFT) calculations, we explore the CRR processes of three different bimetal doped graphenes (M¹M²/DG (M¹, M²= Cu, Fe, Ni)). Various reduction reaction pathways of CO2 lead to different products, including CH4, CH3OH, HCOOH and CO. The Eads of different intermediates on different M¹M²/DG, the free energy variation and the overpotential of the different M¹M²/DG were analyzed. The obtained results confirm the CO2 capture ability of all the studied M¹M²/DG systems. The low overpotential of 0.49 V for Cu_Ni/DG is even lower than that of the most outstanding metallic electrocatalyst (Cu (211)). This work provides useful information for the development of efficient CRR electrocatalysts.
Power-to-Gas technologies (PtG) are regarded as promising options to defossilize the energy system by converting and storing renewable electricity to gases. When combined with carbon capture and utilization from large point sources, such as energy intensive and hard-to-abate sectors, where a major part of CO2 emissions cannot be avoided, PtG technologies can also play a role to mitigate CO2 emissions. However, these technologies have several environmental impacts throughout their lifetimes that must be assessed, due to the use of resources, materials, and energy, as well as the formation of chemical by-products. Using a Life Cycle Assessment (LCA) methodology, this paper aims to assess the most significant environmental impacts of an integrated PtG system including the conversion of renewable energy to hydrogen through water wind-based electrolysis, that is further converted to synthetic natural gas (SNG) by reacting with captured CO2 from a cement plant flue gas. More precisely, the present work innovates on both the technical and methodological perspectives. An advanced CO2 capture process is implemented, using mixed amines solvent and innovative configuration to reduce the energy consumption to 2.3 GJ per tCO2, and include an optimized heat integration with the CO2 conversion step. A hybrid approach combining physical and economic input data is also considered for the life cycle inventory. Additionally, both subdivision and system expansion via substitution approaches are applied to consider the multi-functionality of the systems. Simulation results show that the PtG process with CO2 captured from cement plants flue gas reduces the overall GHG emissions by 76%. Similarly, the fossil resource scarcity is drastically reduced by over 80% thanks to the heat integration between the CO2 capture and the CO2 conversion processes, but also thanks to the substitution of natural gas by the CO2-based SNG. Nevertheless, environmental impacts of PtG are higher than conventional natural gas production for other impact categories, including freshwater eutrophication, terrestrial acidification, and mineral resource scarcity. Both data uncertainties, assessing the knowledge base underlying the input data parameters, and sensitivity analysis, assessing the value range of the parameters respectively to the environmental indicators, are conducted to test the results and highlight the uncertainty hotspots.
Climate change is one of the greatest challenges of our time. Under the auspices of the UN Framework Convention on Climate Change and through the Paris Agreement, there is a commitment to keep global temperature rise this century to well below two degrees Celsius compared with pre-industrial levels. This will require a variety of strategies, including increased renewable power generation, broad-scale electrification, greater energy efficiency, and carbon-negative technologies. With increasing support worldwide, innovations in carbon capture and utilization (CCU) technologies are now widely acknowledged to contribute to achieving climate mitigation targets while creating economic opportunities. To assess the environmental impacts and commercial competitiveness of these innovations, Life Cycle Assessment (LCA) and Techno-Economic Assessment (TEA) are needed. Against this background, guidelines (Version 1.0) on LCA and TEA were published in 2018 as a valuable toolkit for evaluating CCU technology development. Ever since, an open community of practitioners, commissioners, and users of such assessments has been involved in gathering feedback on the initial document. That feedback has informed the improvements incorporated in this updated Version 1.1 of the Guidelines. The revisions take into account recent publications in this evolving field of research; correct minor inconsistencies and errors; and provide better alignment of TEA with LCA. Compared to Version 1.0, some sections have been restructured to be more reader-friendly, and the specific guideline recommendations are renamed ‘provisions.’ Based on the feedback, these provisions have been revised and expanded to be more instructive.
Carbon capture and utilization technologies promise to reduce greenhouse gas emissions and abiotic resource depletion while contributing to a circular economy. However, the environmental benefits of carbon capture and utilization technologies need to be proven. Life cycle assessment is the most applied method when it comes to the evaluation of environmental impacts. Previous life cycle assessments are limited in three aspects. First, previous studies lack in consistently considering the environmental impacts of carbon capture and utilization technologies. Second, the research to date has not been able to provide decision support on whether to introduce carbon capture and utilization technologies in the chemical industry. Third, recent studies failed to prospectively apply a methodological approach for emerging carbon capture and utilization technologies. This dissertation aims to fill these research gaps by the following: first, by applying a systematic literature review accompanied by a meta-life cycle assessment; second, by using a change-oriented life cycle assessment in order to provide decision support on how to treat CO2 in the chemical industry; and third, by developing a consistent methodological framework for prospective life cycle assessment and testing this framework with a case study on an emerging carbon capture and utilization technology.
One major finding of this dissertation is that the introduction of carbon capture and utilization technologies in the chemical industry can reduce environmental impacts compared to current production practices. Nevertheless, according to the results of the life cycle assessments, priority should be given to promising chemicals. The most promising products investigated in this dissertation are formic acid and dimethyl ether. The CO2-based formic acid production via hydrogenation and dimethyl ether reduces greenhouse gas emissions and abiotic resource depletion regardless of the applied assessment approach, scenario, and electricity supplier. Additionally, the developed framework for prospective life cycle assessment provides guidance to evaluate emerging technologies. The framework is tested by the application to the case study of the electrochemical CO2 reduction to produce formic acid under supercritical conditions. The results of the case study support process engineers on how to further develop the investigated emerging technology.
Fuel production from hydrogen and carbon dioxide is considered an attractive solution as long-term storage of electric energy and as temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology and, ultimately, on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aimed at modeling a Power-to-Gas (PtG) plant and assessing the most suitable carbon sources from a Life Cycle Assessment (LCA) perspective. The PtG plant was supplied by electricity from a 2030 scenario for Italian electricity generation. The plant impacts were assessed using data from the ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron, and steel plants). A detailed discussion on how to handle multi-functionality was also carried out. The results showed that capturing CO2 from hydrogen production plants and integrated pulp and paper mills led to the lowest impacts concerning all investigated indicators. The choice of how to handle multi-functional activities had a crucial impact on the assessment.
Capturing and utilizing CO2 as carbon feedstock for chemicals, fuels, or polymers is frequently discussed to replace fossil carbon and thereby help mitigate climate change. Emission reductions by Carbon Capture and Utilization (CCU) depend strongly on the choice of the CO2 source because CO2 sources differ in CO2 concentration and the resulting energy demand for capture. From a climate-change perspective, CO2 should be captured at the CO2 source with the lowest CO2 emissions from capture. However, reported carbon footprints differ widely for CO2 captured: from strongly negative to strongly positive for the same source. The differences are due to methodological ambiguity in the treatment of multifunctionality in current assessment practice. This paper reviews methodological approaches for determining the carbon footprint of captured CO2 as carbon feedstock, shows why approaches lead to suboptimal choices of CO2 sources and that increased consistency in life cycle assessment (LCA) studies on CCU is needed. Based on strict application of Life Cycle Assessment (LCA) standards and guidelines, it is shown that substitution should be applied to avoid suboptimal choices of CO2 sources. The resulting methodological recommendations are applied to estimate the carbon footprint of feedstock CO2 for current CO2 sources in Europe and for future CO2 sources in a scenario for a low carbon economy. For all CO2 sources, the cradle-to-gate footprint of captured CO2 is negative ranging from - 0.95 to - 0.59 kg CO2-eq per kg of feedstock CO2 today and from - 0.99 to - 0.98 kg CO2-eq in a low carbon economy. The carbon footprints of different CO2 sources differ mainly due to their energy demands. The presented assessment method and the carbon footprints of the CO2 feedstocks CO2 provide the basis for future assessments of carbon capture and utilization processes.
Carbon capture and utilization (CCU) is perceived as a technology to mitigate climate change and conserve non-renewable resources, especially in the chemical industry. Numerous life cycle assessments (LCA) of individual CCU systems have been carried out. The goal of this review is to understand the environmental effects of CO2-based chemical production comprehensively. In order to achieve this goal, a systematic literature review and a meta-analysis were conducted. 52 peer-reviewed articles were found that deal with LCA and CO2-based chemical production. Amongst the case studies found, the methodological choices and technological parameters differ. The meta-analysis reveals that there is no CO2-based chemical production technology that performs better in all analyzed impact categories (IC) compared to conventional production. Nevertheless, looking at the results from the meta-analysis, it has been found that the CO2-based production of formic acid (FA) via H2 is a promising CCU pathway. FA produced via hydrogenation performs better in 11 out of 15 ICs using the German grid mix as the electricity supplier and better in 14 out of 15 ICs using wind power as the electricity supplier compared to the conventional production. The global warming impact of FA production can be reduced by 95.01% when produced via CO2 hydrogenation. The meta-analysis also unveils CCU technologies that are not favorable from an environmental perspective because CO2-based kerosene and dimethyl carbonate (DMC) production lead to higher impacts in all ICs compared to conventional production. This study can inform decision-makers about the differences in published LCA studies on CCU and the harmonized environmental impacts of CO2 based chemical production.
Fuel production from hydrogen and carbon dioxide looks an attractive solution as a long-term storage of electric energy and as a temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology, and, ultimately on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aims at modeling a Power-to-Gas (PtG) plant and assessing the most suitable carbon sources from a life cycle assessment perspective. The PtG plant is supplied by electricity from a 2030 scenario for Italian electricity generation. The plant
impacts are assessed using data from the Ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron and steel plants).
The storage of excess or low-carbon electricity in the form of synthetic gas using power-to-gas technologies is a promising approach to enable high shares of renewables in power generation and reduce the fuel carbon content. However, the efficiency of standalone, low-temperature electrolysis-based power-to-methane (PtM) processes is presently limited. As a way of enhancing the potential of this technology to support the decarbonization of energy systems, this study investigates a high-temperature electrolysis-based PtM process and its integration with oxyfuel combustion to co-generate synthetic methane, heat and power. The system incorporates in-situ heat, oxygen, carbon dioxide (CO2) and water recycling. The energy and exergy-based performance of the compound system and its main structures are investigated using an overpotential-based electrochemical model. Depending on electrolysis operating temperature (800–1000 °C) and pressure (1–10 bar), overall energy and exergy efficiencies range from 75.8% to 79.3% and 64.5% to 67.4%, respectively. In quasi-continuous operation, a 6.4 MWe (AC input) hybrid PtM system would avoid approximately 1.9 GWhe of electricity consumption for oxygen-air separation, and sink 6.6 kt of CO2 from the oxyfuel co-generation plant annually. In parallel, 3.1 MWth of heat could be recovered from the pre-methanation compressor and oxyfuel conversion products for use in external applications. Based on a carbon balance evaluation from initial resource extraction to SNG conversion, the PtM-oxyfuel hybridization investigated could effectively contribute to raise the electricity greenhouse gas (GHG) emission threshold below which SNG could environmentally compete with natural gas, relative to low-temperature electrolysis-based PtM and conventional post-combustion CO2 capture.
Climate change has become a major concern in the world. These changes are due to the use of fossil fuels and consequently increased emissions of greenhouse gasses, especially carbon dioxide (CO2). Agriculture, plays an important role in generating these changes through greenhouse gas emissions, as the main source of energy in this sector is fossil fuels. Regarding the reduction of fossil fuels resources and the need to reduce greenhouse gas emissions, the agriculture sector has to find and use an appropriate alternative to survive. This appropriate alternative is definitely renewable energy. Therefore, this article was conducted using a library research method to study the process of carbon dioxide production and renewable energy in the world, and the necessity of application of this type of energy in the agricultural sector.
Key words: Carbon dioxide, greenhouse gases, renewable energy, fossil fuels;
To download the document, please visit: http://umlib.us/CO2Guidelines. ___
Climate change is one of the largest challenges of our time. One of the major causes of anthropogenic climate change, carbon dioxide, also leads to ocean acidification. Left unaddressed, these two challenges will alter ecosystems and fundamentally change life, as we know it. Under the auspices of the UN Framework Convention on Climate Change and through the Paris Agreement, there is a commitment to keep global temperature increase to well below two degrees Celsius. This will require a variety of strategies including increased renewable power generation and broad scale electrification, increased energy efficiency, and carbon-negative technologies. We believe that Life Cycle Assessment (LCA) is necessary to prove that a technology could contribute to the mitigation of environmental impacts and that Techno-Economic Assessment (TEA) will show how the technology could be competitively delivered in the market. Together the guidelines for LCA and TEA that are presented in this document are a valuable toolkit for promoting carbon capture and utilization (CCU) technology development.
Catalytic conversion of CO2 into chemicals and fuels is a “two birds one stone” approach towards solving climate change problem and energy demand-supply deficit in the modern world. The recent advances in the mechanistic insights and design of suitable catalysts for direct thermocatalytic hydrogenation of CO2 to C1 products have been thoroughly discussed in this perspective. The role of catalyst composition and process conditions in determining the selective pathways to various products like carbon monoxide, methanol, methane and dimethyl ether, has been overviewed in the light of thermodynamic and kinetic considerations. After extensive elaboration of the main motivation of reaction pathways, catalytic roles, and reaction thermodynamics, we summarized the most important macroscopic aspects of CO2 hydrogenation technology development which includes reactor innovations, industrial status of the technology and life cycle assessment and techno-economic analysis. Finally, a critical perspective of the future challenges and opportunities in both the fronts of core and overall technology development has been provided.
Distributed energy systems are key in building a sustainable energy economy. Biofuels are an example of an industry that needs to be based on a system of rather small-scale local production units due to the limited transportation radius of biomass. Moreover, the benefits of biofuels are greater if their production is based on the integration of local production activities and consumption among traditionally separate industries, as implied by the notion of industrial symbiosis. Such an arrangement, however, requires the establishment of industrial ecosystems that are customised to local conditions, which increases costs and uncertainty for the involved stakeholders and the integrating company. In this paper, we discuss replication strategy as a means of transferring not only technical knowledge, but also the business format to new locations, thereby achieving ‘economies of repetition’. The case of a biogas-for traffic solution serves as an illustrative example. We analyse the establishment of a ‘vanguard’ ecosystem and assess the potential of replicating the solution in six other locations. Based on this, we propose a replication framework that builds on functional modularisation, collaboration mechanisms required for cooperating with the relevant stakeholders, and organisational learning. The replication approach is expected to be useful for the companies attempting to build sustainable distributed energy systems based on industrial symbiosis.
Um die ambitionierten Ziele zur Reduktion des Kohlendioxid-Ausstosses zu erreichen, ist der Ausbau von Stromerzeugung aus regenerativen Energiequellen wie Windkraft und Photovoltaik ein wesentlicher Hebel. Da diese Energieträger sehr volatil sind, werden auch Systeme benötigt, die Stabilität innnerhalb der Stromnetze sichern und darüber hinaus Erzeugungsüberschüsse und Versorgungsengpässe vermeiden helfen. Groß-Elektrolyseure wandeln mittels regenerativem Strom Wasser in Wasserstoff um und sorgen dafür, dass große Energiemengen im Terawatt-Bereich für lange Zeiträume speicherbar werden. Solche Elektrolyse-Systeme haben eine Leistung von 50 Megawatt und mehr und sind technisch in der Lage, in diesem hochdynamischen Umfeld hocheffizient zu arbeiten. Siemens treibt die Hochskalierung und den Bau solcher Systeme voran.
The extension of power generation out of regenerative sources, such as wind power and photovoltaic is a major lever to achieve the ambitious targets to reduce the emission of carbon dioxide. Those sources are extremely volatile. Therefore, systems are needed to stabilize the grids and furthermore help to avoid excess generation and supply bottlenecks. Large-scale electrolysis systems convert water into hydrogen using for instance regenerative energy. Thereby huge amounts of energy will be storable for long periods. Such PEM electrolysis systems must have a power of at least 50 MW and must technically also be able to operate highly efficiently in such an extreme dynamic environment. Siemens is pushing the upscaling and the production of such large-scale PEM electrolysis systems.
As the transport sector transitions away from fossil fuels and renewable fuels shift into focus, it is important that the terminology around renewable fuels is clarified. A number of terms such as synthetic fuel and electrofuel are used to describe both renewable and alternative fuels. The aim of this article is to identify and review these terms to avoid any potential misuse. An integrative review of terminology has been made. This review did not differentiate the articles in terms of the methodologies applied, but had the main objective to identify the terminology used and its definition. The results confirm that the term synthetic fuel is used generically in the majority of articles, without providing information about the production process of the fuel or differentiating between fossil-based and renewable-based synthetic fuels. The majority of the articles use the term synthetic fuel to describe fuels produced with coal-, gas- and biomass-to-liquid (xTL) technologies. However, a number of articles use the term beyond this definition. Results for the term electrofuel gave a similar outcome, as it was not clear which processes were used for the fuel production. In some cases, both synthetic and electrofuel referred to fuels produced through the same process, even though in reality the two processes are distinctly different. This could lead to a misinterpretation, especially if the terminology is utilized by policymakers. To prevent this, the article ends with a preliminary proposal for how to differentiate synthetic fuels from electrofuels based on the production process.
In this paper we present the optimal year round production of synthetic methane from water electrolysis and CO2 comparing the use of solar PV systems and wind turbines on a monthly basis. The process starts obtaining electricity in a wind farm or a solar field, which is then used to produce oxygen and hydrogen in a system of electrolyzers. The oxygen is purified and stored, and the hydrogen, after being purified using a deoxygenating reactor, reacts with CO2 to synthesize methane. We study the operation of the plant for a year considering the wind or solar availability. The use of wind or solar energy depends on the region and the area available for the installation of solar panels or wind turbines. Europe and the US have been screened for the use of both sources of energy, being solar preferable in most regions. We present a detailed case of study in the South of Europe, Gulf of Cádiz. Solar is cheaper than wind in terms of inversion (240 M€ vs. 363 M€) and production costs (0.33 €/m3 vs. 0.49 €/m3), while the monthly operation differs due to the availability of renewable energy.
The reclamation of greenhouse gas CO2 which brings the new opportunity in the area of C1 chemistry will become a new hot topic in the research frontier of green catalysis. The topics on the reclamation of CO2 discussed in the review are as follows: (i) hydrogenation to methanol, dimethyl ether, methane, alkene, formic acid, etc. (ii) reaction with hydrocarbons, including CO2 reforming of methane to syngas; hydrocarbons oxidation to alkene, aldehyde, and carboxylic acid; C1-C3 hydrocarbons and aromatics carboxylation. (iii) reaction with oxy-organics, such as methanol, propylene glycol and epoxide, to obtain valuable chemicals and materials. (iv) Reaction of CO2 with others. In this review, the performance of the catalysts involved was evaluated, and the underlying reaction mechanisms of CO2 activation by catalysis were analyzed. In addition, opportunities and prospects in the other utilization of carbon dioxide were introduced, such as conversion of carbon dioxide to biodiesel and biogas by biological microalgae technologies, progress of CO2 utilization as new hydrogen storage materials. Carbon dioxide has good chemical stability, and the activation of CO2 is believed to be the key of the whole utilization process. It is necessary to develop suitable catalysts with high activity and selectivity in the further work. The exploitation of homogeneous catalyst may greatly enhance the conversion and selectivity of the reaction. Multi-functional catalysts with desirable adsorption-catalysis activity also need to be developed in order to directly use carbon dioxide emitted from different practical sources. Moreover, the investigation of metal ligand coordination catalysis, photocatalysis and biological biomimetic catalysis is beneficial to both the utilization of new energy and the mitigation of greenhouse gas.
There are several hydrogen production technologies. They range from the most widely used fossil fuel based systems such as natural gas steam methane reforming to the least used renewable energy based systems such as wind electrolysis. Currently almost all the industrial hydrogen need worldwide is produced using fossil fuels. Electrolytic hydrogen production based on electricity generated from renewable resources and hydrogen's energetic use could contribute to the global need for a sustainable energy supply. However, these technologies are also not free from environmental burdens. A life cycle assessment (LCA) helps to identify such impacts considering the entire life cycle of the process chains. This paper reviews twenty-one studies that address the LCA of hydrogen production technologies, a majority of them employing electrolytic technologies. It has been observed that global warming potential (GWP) is the impact category analyzed by almost all the authors. Acidification potential (AP) ranks second. Other categories such as toxicity potential are often not analyzed. The main environmental concern associated with electrolytic hydrogen production is electricity supply. The GWP contribution of the electrolyzer unit is relatively small (e.g. only about 4% in wind based electrolysis including hydrogen production and storage systems). From an LCA perspective, it can be concluded that electrolysis using wind or hydropower generated electricity is one of the best hydrogen production technologies, compared to those using conventional grid electricity mix or fossil fuel feedstocks.
Methane has proven to be an outstanding energy carrier and is the main component of natural gas and substitute natural gas (SNG). SNG may be synthesized from the CO2 and hydrogen available from various sources and may be introduced into the existing infrastructure used by the natural gas sector for transport and distribution to power plants, industry, and households. Renewable SNG may be generated when H2 is produced from renewable energy sources, such as solar, wind, and hydro. In parallel, the use of CO2-containing feed streams from fossil origin or preferably, from biomass, permits the avoidance of CO2 emissions. In particular, the biomass-to-SNG conversion, combined with the use of renewable H2 obtained by electrolysis, appears a promising way to reduce CO2 emissions considerably, while avoiding energy intensive CO2 separation from the bio feed streams. The existing technologies for the production of SNG are described in this short review, along with the need for renewed research and development efforts to improve the energy efficiency of the renewables-to-SNG conversion chain. Innovative technologies aiming at a more efficient management of the heat delivered in the exothermic methanation process are therefore highly desirable. The production of renewable SNG through the Sabatier process is a key process to the transition towards a global sustainable energy system, and is complementary to other renewable energy carriers such as methanol, dimethyl ether, formic acid, and Fischer-Tropsch fuels.
Die Umstellung fossil dominierter Energiesysteme auf eine Versorgung mit hohem Anteil erneuerbarer Energien macht einen massiven Ausbau der Speichersysteme erforderlich. Gängige Technologien wie Pumpspeicherkraftwerke oder Druckluftspeicher sind in ihrer Kapazität beschränkt oder haben den Nachteil eines geringen Prozesswirkungsgrads. Eine vielversprechende Route ist die chemische Energiespeicherung über Wasserstoff in energietragenden Stoffe (ETS). Dieser Weg stellt eine verlustfreie Speicherung regenerativer Energie in frei wählbaren Zeiträumen in Aussicht. Es werden Effizienzwerte für die Prozessketten Methanisierung und ETS berechnet und gegenübergestellt.
Reconstructing current energy infrastructures dominated by fossil fuels towards a high share of renewable energy requires a drastic extension of energy storage capacities. Common storage technologies like compressed air or pumped hydro are either limited in capacity or have to face low efficiencies. A promising alternative is proposed with the use of energy carrying compounds for hydrogen storage. This route is shown to offer the possibility to combine high process chain efficiency with lossless energy storage for stationary and mobile applications. In this article, efficiencies for energy storage by methane and energy transport substances are calculated and compared to each other.
Power-to-Gas Toward a Global Low Carbon Energy System
- G Waldstein
- For Power
- Bio-Energy
- Mobility
- Hannover
- S Walspurger
- W G Haije
- B Louis
Waldstein, G., 2015. Power-to-Gas: New Solutions for Power, Bio-Energy and Mobility, Hannover.
Walspurger, S., Haije, W.G., Louis, B., 2014. CO 2 Reduction to Substitute Natural Gas. Toward a Global
Low Carbon Energy System. Isr J Chem 54, 1432–1442.
Energy storage via methane and renewable energy carriers -a thermodynamic comparison
- B Müller
- K Müller
- D Teichmann
- W Arlt
Müller, B., Müller, K., Teichmann, D., Arlt, W., 2011. Energy storage via methane and renewable
energy carriers -a thermodynamic comparison (in German). Chem Ing Tech 83, 2002-2013.
Use of the BCM-process for the production of synthesis gas and its further processing to gas-to-liquids and biomass-to-liquids (in German), From: INNOGAS Symposium: Production of biomethane from biogas and its further processing
- L Günther
Günther, L., 2007. Use of the BCM-process for the production of synthesis gas and its further
processing to gas-to-liquids and biomass-to-liquids (in German), From: INNOGAS Symposium:
Production of biomethane from biogas and its further processing, 29 and 30 November 2007,
Dessau, Germany.
Biogas treatment plants. Data sheet of MT-amine-scrubbing
- Mt-Biomethan
- Gmbh
MT-Biomethan GmbH, 2012. Biogas treatment plants. Data sheet of MT-amine-scrubbing (in
German), Zeven, Germany. http://www.mtbiomethan.com/de/medien/broschueren.html?tx_mmdamfilelist_pi1[showUid]=2272&cHash=e7
9804c78c84d8fdaa72861bd3333347. Accessed July 7, 2015.
Occurrence and export of natural gas Crossborder price development as from
- Bundesamt Für Wirtschaft Und Ausfuhrkontrolle
Bundesamt für Wirtschaft und Ausfuhrkontrolle, 2015. Occurrence and export of natural gas. Crossborder price development as from 1991 (in German), Eschborn, Germany.
http://www.bafa.de/bafa/de/energie/erdgas/ausgewaehlte_statistiken/egasmon.pdf. Accessed
February 27, 2015.
Shell passenger car scenarios for Germany to 2040. Facts, trends and prospects for car mobility
- A G Prognos
Prognos AG, 2014. Shell passenger car scenarios for Germany to 2040.
Facts, trends and prospects for car mobility (in German), Hamburg.
http://www.prognos.com/uploads/tx_atwpubdb/140900_Prognos_Shell_Studie_Pkw-Szenarien2040.pdf. Accessed November 14, 2015.
Occurrence and export of natural gas. Crossborder price development as from 1991
- A Ciroth
- M Srocka
- J Hildenbrand
Bundesamt für Wirtschaft und Ausfuhrkontrolle, 2015. Occurrence and export of natural gas. Crossborder price development as from 1991 (in German), Eschborn, Germany.
http://www.bafa.de/bafa/de/energie/erdgas/ausgewaehlte_statistiken/egasmon.pdf. Accessed
February 27, 2015.
Ciroth, A., Srocka, M., Hildenbrand, J., 2015. OpenLCA. Greendelta GmbH, Berlin.
Use of the BCM-process for the production of synthesis gas and its further processing to gas-to-liquids and biomass-to-liquids
- L Günther
Günther, L., 2007. Use of the BCM-process for the production of synthesis gas and its further
processing to gas-to-liquids and biomass-to-liquids (in German), From: INNOGAS Symposium:
Production of biomethane from biogas and its further processing, 29 and 30 November 2007,
Dessau, Germany.
Facts and trends. Monthly statistical report
- Wirtschaftsverband V Erdöl-Und Erdgasgewinnung E
Wirtschaftsverband Erdöl-und Erdgasgewinnung e.V., 2015. Facts and trends. Monthly statistical
report, December 2014 (in German), Hannover, Germany. http://www.erdoelerdgas.de/content/download/6602/72274/file/Bericht%20Dezember%202014%20Seite%201-3.pdf. Accessed March 26, 2015.