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Carbon dioxide resource utilization in methanol products: Carbon emission projections, visual analysis, life cycle assessment
... Carbon emission accounting is the basis for formulating effective carbon-reduction strategies, and carbon emission peak prediction is an important tool for evaluating and planning emission reduction paths [18]. Currently, to predict peak carbon emissions, researchers have used various methods, including scenario analyses, statistical models, and complex models, such as machine learning. ...
Urban carbon emissions account for 75% of the total social emissions and are a key area for achieving the country’s “dual carbon” goals. This study takes the Sino-Singapore Tianjin Eco-City as a case, constructs a multi-dimensional carbon emission accounting model, integrates six systems, including buildings, transportation, water systems, solid waste, renewable energy, and carbon sinks, and proposes a comprehensive research method that takes into account both long-term prediction and a short-term dynamic analysis. The long-term emission trends under different scenarios are simulated through the KAYA model. It is found that under the enhanced low-carbon scenario, the Eco-City will reach its peak in 2043 (2.253 million tons of CO2) and drop to 2.182 million tons of CO2 in 2050. At the same time, after comparing models, such as random forest and support vector machine, the XGBoost algorithm is adopted for short-term prediction (R² = 0.984, MAE = 0.195). The results show that it is significantly superior to traditional methods and can effectively capture the dynamic changes in fields, such as buildings and transportation. Based on the prediction results, the study proposes six types of collaborative emission-reduction paths: improving building energy efficiency (annual emission reduction of 93800 tons), promoting green travel (58,900 tons), increasing the utilization rate of non-conventional water resources (3700 tons), reducing per capita solid waste generation (14,400 tons), expanding the application of renewable energy (288,200 tons), and increasing green space carbon sinks (135,000 tons). The total annual emission-reduction potential amounts to 594,000 tons. This study provides a valuable reference for developing carbon reduction strategies in urban areas.
As the urgency to achieve net-zero emissions by 2050 intensifies, industries face an imperative to reimagine their role in the fight against climate change. One promising avenue arises from the realization that industrial emissions, often deemed pollutants, can be the building blocks of a circular economy strategy. By directly utilizing these carbon emissions as raw materials, we can produce net-zero or low-carbon fuels, carbonates, polymers, and chemicals. At the heart of this paradigm shift lies the production of carbon-neutral methanol from industrial flue gas-a technically viable approach that has gained significant momentum in recent years. The conditions under which such a circular economy model for producing renewable methanol becomes commercially sustainable based on realistic constraints, however, are not sufficiently explored in the existing literature. This paper fills this gap by investigating if and when net-zero methanol production from industrial flue gas will be a sustainable long-term strategy. Using detailed technoeconomic modeling of integrated hydrogen and methanol production ecosystems for two production capacities, I will evaluate 32 practical production scenarios using realistic regulatory, economic, and market conditions. Even though renewable methanol from industrial emissions can be a viable technical solution to address climate change and global warming, I will show why this strategy will be commercially feasible only under favorable economic, regulatory, and market conditions. Furthermore, I will demonstrate how the market price of methanol and the cost of carbon-free electricity critically influence the commercial feasibility of this approach. When these two parameters are unfavorable, I will show why other factors, namely, carbon credits and byproduct (oxygen) sales, will not be sufficient to create an economically sustainable circular economy of renewable methanol from industrial emissions. Finally, I will provide arguments on why one has to think through stakeholder cooperation and public-private partnerships to mitigate various project risks. Despite the importance of this topic, it is not sufficiently covered in the available scientific literature. To advance policy and regulatory frameworks in this area, I strongly believe that further research and development is needed. I will also share perspectives on regulatory derisking mechanisms, which can help align regulations with private investors' preferences. With the analyses and arguments showcased in this paper, I will firmly assert that without favorable conditions, strong partnerships, and stakeholder cooperation, the production of renewable net-zero methanol from industrial emissions risks becoming a dead-end strategy.
Carbon intensity is one of the key indexes in the process of decarbonizing development. Therefore, our paper investigates possible pathways of China’s carbon intensity to 2050 depending on China’s development stage and trends. We first investigate the major influence factors of carbon intensity based on the Kaya identity, and then forecast China’s future carbon intensity with a generalized regression neural network model coupled with a scenario analysis with official data from 1978 to 2020. Our results show that: (1) China’s carbon intensity will decrease under the benchmark growth, high growth, and low growth scenarios but vary by amounts and rates of decrease due to the settings of the influences factors; (2) China is able to achieve the reduction targets of 2025 under the benchmark growth and low growth scenario, but cannot achieve the target under the high grow scenario. However, China can meet its reduction target by 2030 in all scenarios. (3) The Chinese government should aim to reduce carbon intensity by 23–25%, 40–44% and 64–70% by 2035, 2040 and 2050 as compared to the level in 2030. Therefore, China should keep promoting the deep low-carbon transformation of economic development model, and realize high-quality economic development in order to achieve these objectives.
Road vehicles make important contributions to a wide range of pollutant emissions from the street level to global scales. The quantification of emissions from road vehicles is, however, highly challenging given the number of individual sources involved and the myriad factors that influence emissions such as fuel type, emission standard, and driving behavior. In this work, we use highly detailed and comprehensive vehicle emission remote sensing measurements made under real driving conditions to develop new bottom-up inventories that can be compared to official national inventory totals. We find that the total UK passenger car and light-duty van emissions of nitrogen oxides (NO
x
) are underestimated by 24-32%, and up to 47% in urban areas, compared with the UK national inventory, despite agreement within 1.5% for total fuel used. Emissions of NO
x
at a country level are also shown to vary considerably depending on the mix of vehicle manufacturers in the fleet. Adopting the on-road mix of vehicle manufacturers for six European countries results in up to a 13.4% range in total emissions of NO
x
. Accounting for the manufacturer-specific fleets at a country level could have a significant impact on emission estimates of NO
x
and other pollutants across the European countries, which are not currently reflected in emission inventories.
Global emissions pathways that would limit warming to 1.5 or well below 2°C, consistent with the temperature goal of the Paris Agreement, rely on substantial reductions of agricultural greenhouse gases (methane and nitrous oxide) along with reaching net zero carbon dioxide emissions from fossil fuels. Failure to reduce agricultural emissions would require even more rapid cuts of carbon dioxide emissions and could jeopardize the ability to limit warming to 1.5°C. Modeled pathways that achieve the necessary agricultural emission reductions do so by pricing agricultural emissions. However, there is a large gap between such model scenarios and reality when it comes to the agricultural sector. To date, no single country currently exposes agricultural emissions to any mandatory carbon price and current evidence suggests considerable reluctance to the application of other climate policies with comparable stringency to agriculture. A more realistic view is needed if we are to avoid modeled emission scenarios providing an overly optimistic picture of mitigation potentials from the agricultural sector. There are entry points for mitigation of agricultural greenhouse gases outside government price policies, but many questions remain around their scalability and efficacy. A comprehensive and accelerated effort will be needed to bridge the gap from modeled emissions to realistic policy pathways.
Despite China’s emissions having plateaued in 2013, it is still the world’s leading energy consumer and CO2 emitter, accounting for approximately 30% of global emissions. Detailed CO2 emission inventories by energy and sector have great significance to China’s carbon policies as well as to achieving global climate change mitigation targets. This study constructs the most up-to-date CO2 emission inventories for China and its 30 provinces, as well as their energy inventories for the years 2016 and 2017. The newly compiled inventories provide key updates and supplements to our previous emission dataset for 1997–2015. Emissions are calculated based on IPCC (Intergovernmental Panel on Climate Change) administrative territorial scope that covers all anthropogenic emissions generated within an administrative boundary due to energy consumption (i.e. energy-related emissions from 17 fossil fuel types) and industrial production (i.e. process-related emissions from cement production). The inventories are constructed for 47 economic sectors consistent with the national economic accounting system. The data can be used as inputs to climate and integrated assessment models and for analysis of emission patterns of China and its regions.
CO 2 hydrogenation to methanol with renewable H 2 is an ideal process for coupling reduction of greenhouse gas and development of sustainable methanol economy, and Cu-ZnO-ZrO 2 is regarded as a promising catalyst for this process. Identification of the key descriptors that control the catalytic activity and selectivity is one of the most important issues for this reaction. Here, we identify the role of water in the hydrogenation of CO 2 to methanol, which strongly affects the selectivity and yield of methanol. Our results reveal that methanol is generated via the hydrolysis of methoxy formed by the hydrogenation of formate, and the desorbed water vapor facilitates the hydrolysis of methoxy. A suitable amount of water in the feed can promote the formation of methanol. The enhancement on the water vapor diffusion in catalysts by structural and/or surface modification offers a new strategy for tuning the selectivity and yield of methanol.
In order to make further steps in dealing with climate change, China proposed to peak carbon dioxide emissions by about 2030 and to make best efforts for the peaking early. The carbon emission peak target (CEPT) must result in a forcing mechanism on China’s economic transition. This paper, by following the logical order from “research on carbon emission history” to “carbon emission trend prediction,” from “research on paths of realizing peak” to “peak restraint research,” provides a general review of current status and development trend of researches on China’s carbon emission and its peak value. Furthermore, this paper also reviews the basic theories and specific cases of the forcing mechanism. Based on the existing achievements and development trends in this field, the following research directions that can be further expanded are put forward. First, from the perspective of long-term strategy of sustainable development, we should analyze and construct the forcing mechanism of CEPT in a reverse thinking way. Second, economic transition paths under the forcing mechanism should be systematically studied. Third, by constructing a large-scale policy evaluation model, the emission reduction performance and economic impact of a series of policy measures adopted during the transition process should be quantitatively evaluated.
China is the world’s top energy consumer and CO2 emitter, accounting for 30% of global emissions. Compiling an accurate accounting of China’s CO2 emissions is the first step in implementing reduction policies. However, no annual, officially published emissions data exist for China. The current emissions estimated by academic institutes and scholars exhibit great discrepancies. The gap between the different emissions estimates is approximately equal to the total emissions of the Russian Federation (the 4th highest emitter globally) in 2011. In this study, we constructed the time-series of CO2 emission inventories for China and its 30 provinces. We followed the Intergovernmental Panel on Climate Change (IPCC) emissions accounting method with a territorial administrative scope. The inventories include energy-related emissions (17 fossil fuels in 47 sectors) and process-related emissions (cement production). The first version of our dataset presents emission inventories from 1997 to 2015. We will update the dataset annually. The uniformly formatted emission inventories provide data support for further emission-related research as well as emissions reduction policy-making in China.
For the accurate calculation of CO2 emission in utility boilers, the calculation model of CO2 emission suitable for most coal-fired boilers is built. In this model, BP neural networks were adopted to predict the carbon content of burning coal. This model took the proximate analysis data and fuel consumption flow / coal consumption as inputs, and output the CO2 emission. Under the BP network prediction model, the average difference of carbon content of burning coal was about 1.80%, while that of CO2 emission were 3.92% and 0.96%. Compared with emission factor method and capacity standard method, the method in this paper is more suitable to count the CO2 emission of utility boilers.
To investigate the impact of carbon emission reduction paths on energy demand and CO2 emissions in China, in this study, quantitative carbon emission reduction paths in the period 2014–2020 are established by decomposing the target for emissions reduction. An optimization model of energy demand, into which reduction paths are incorporated, is then constructed from a goal-oriented perspective. The results suggest that energy consumption varies under different emission reduction paths. Coal demand is found to be much more sensitive to the choice of emission reduction path than other forms of energy; in particular, it responds strongly to the decreasing reduction path. We conclude that the decreasing reduction path is a better means than the increasing reduction path of achieving China’s emission reduction target for 2020 with the least amount of energy and the least amount of CO2 emissions.
This paper studied greenhouse gas inventory data acquisition and analytics for municipalities in Thailand. A complete and transparent GHG inventory of eight municipalities was developed to document the current situation, and to help decision-makers to clarify their priorities for reducing greenhouse gas emissions. The Global Protocol for Community-Scale Greenhouse Gas Emissions Inventories guidelines was used to investigate and calculate the greenhouse gas emissions and assess data accuracy. The results indicated that the data source, data format, and data collection of each municipality are relatively similar. Moreover, the activity data needed to be obtained from several authorities. The results showed that Nonthaburi Municipality had the highest greenhouse gas emissions at 2,286,838 tCO2e/yr and Buriram Municipality, the lowest at 239,795 tCO2e/yr. On a per-capita basis, Lamphun Municipality was the highest with 10.1 tCO2e/capita and Buriram Municipality the lowest with 3.8 tCO2e/capita. The results suggest that the municipalities should continually develop a GHG database by creating a routine procedure. An information management system should be produced in the shape of big data which can lead to state policies, plans, and actions for city development to ensure the reduction of greenhouse gas emissions. This in turn will lead to a low carbon city.
Nearly-zero energy buildings (NZEB) would effectively improve building energy efficiency and promote building electrification. By using a carbon emission model integrated into a bottom-up mid-to-long term energy consumption model, this study analyzes the contribution of NZEB standards to carbon emission targets in the urban area of China by 2060. Three scenarios are set, namely BAU, steady development (S1), and high-speed development (S2). For BAU, the total carbon emissions will reach a peak of 1.94 Gt CO2 by 2040. In S1 scenario, total building carbon emissions will reach the peak of 1.72 Gt CO2 by 2030. In S2 scenario, the carbon emissions will reach a peak by 2025 with 1.60 Gt CO2. Carbon emission target, and Under S1 scenario, which features consistency with NZEB market development and periodic improvement of building energy-efficiency standards, the carbon emission peak in 2030 will be accomplished. To achieve carbon neutrality by 2060, the upgrading of building energy standards to NZEB will contribute 50.1%, while zero-carbon electricity contribution is 49.9%. It is concluded that 2025, 2030, and 2035 could be set as mandatory enforcement years for ultra-low energy buildings, NZEB and zero energy building (ZEB), respectively.
A coal-to-methanol (CTM) process is one of the great important industrial methanol production processes, which has attracted a lot of attention in light of dwindling petroleum sources and rising prices of natural gas and oil. However, the CTM process will typically result in a certain amount of CO2 emission and thereafter lead to severe environmental problems. Facing historic global warming, a carbon emissions trading system drives the CTM process to adopt CO2 reduction technologies. In this paper, a CO2 hydrogenation-to-methanol unit, regarded as one of the most promising technology for CO2 reduction, is integrated with the CTM process to achieve CO2 reduction under the carbon emissions trading system. A detailed simulation of the CTM process integrated with the CO2 hydrogenation-to-methanol unit is built based on a typical industrial process. Mass and energy balance results indicate that the CTM process without a CO2 reduction unit emits 3.1 kg of CO2·kg CH3OH-1. The CO2 hydrogenation-to-methanol unit, consuming 0.12 kg of H2 and 7.4 MJ of energy, could achieve a net CO2 reduction with H2-associated CO2 emission below 1.8 kg of CO2·kg H2-1. The energy efficiency of the CTM process only slightly decreases from 52.9 to 51.6% when the carbon cap drops from 3.1 to 2 kg of CO2·kg CH3OH-1. Furthermore, an overall profit could be obtained with the CO2 hydrogenation unit when the H2 price is under the critical point at 1.4 US$·kg H2-1.
The carbon dioxide generated by building sector accounts for approximately 30% of the total CO2 emissions in China. The building sector plays a significant role in Chinese low-carbon development. This study develops the CAS bottom-up model system to predict the future trend of carbon emissions in China's building sector. Firstly, we sets three scenarios: business as usual (BAU), policy scenario, and synergistic emission reduction (SER) scenario, which consider the influence of low-carbon building policies and emission factors (i.e. power and heat emission factor (PEF and HEF)). Then we develop an emission reduction potential model to assess the CO2 abatement potential of the building sector in 2016–2050. The results reveal that low-carbon policies of building sector in policy scenario can only slow down but not curb the CO2 emission completely. The CO2 emissions will reach its peak before 2030 in the SER scenario, taking into account the impact of PEF and HEF. The analysis demonstrates that the synergistic reduction effect of inter-department will be better than that of one sector. Furthermore, green buildings, renewable energy building and energy conservation policies for district heating have a great influence on emission abatement in the building sector.
The utilization of fossil fuels has enabled an unprecedented era of prosperity and advancement of well-being for human society. However, the associated increase in anthropogenic carbon dioxide (CO2) emissions can negatively affect global temperatures and ocean acidity. Moreover, fossil fuels are a limited resource and their depletion will ultimately force one to seek alternative carbon sources to maintain a sustainable economy. Converting CO2 into value-added chemicals and fuels, using renewable energy, is one of the promising approaches in this regard. Major advances in energy-efficient CO2 conversion can potentially alleviate CO2 emissions, reduce the dependence on nonrenewable resources, and minimize the environmental impacts from the portions of fossil fuels displaced. Methanol (CH3OH) is an important chemical feedstock and can be used as a fuel for internal combustion engines and fuel cells, as well as a platform molecule for the production of chemicals and fuels. As one of the promising approaches, thermocatalytic CO2 hydrogenation to CH3OH via heterogeneous catalysis has attracted great attention in the past decades. Major progress has been made in the development of various catalysts including metals, metal oxides, and intermetallic compounds. In addition, efforts are also put forth to define catalyst structures in nanoscale by taking advantage of nanostructured materials, which enables the tuning of the catalyst composition and modulation of surface structures and potentially endows more promising catalytic performance in comparison to the bulk materials prepared by traditional methods. Despite these achievements, significant challenges still exist in developing robust catalysts with good catalytic performance and long-term stability. In this review, we will provide a comprehensive overview of the recent advances in this area, especially focusing on structure-activity relationship, as well as the importance of combining catalytic measurements, in situ characterization, and theoretical studies in understanding reaction mechanisms and identifying key descriptors for designing improved catalysts.
Carbon emission peak has become a focus of political and academic concern in global community since the launch of Kyoto Protocol. China, as the largest carbon emitter, has committed to reaching the carbon peak by 2030 in Paris Agreement. This ambitious national goal requires the endeavors of individual sectors, particularly those carbon-intensive ones. Predicting the sectoral peaks under current endeavors and understanding driving forces for the carbon emission changes in the past years are substantial for guiding the allocation of the country's future efforts. In the past studies contextualized in China, the prediction of its carbon peaks seldom appeared at the sectoral level, which is considered as a research gap. Therefore, this study predicts the peaks at four carbon pillar sectors (i.e. industrial, building, transport and agricultural sectors) and identifies the driving forces for the carbon emission changes of them. This study hypothesized Carbon Kuznets curve (CKC) as the theoretical model for predicting the peaks and used Logarithmic mean Divisia index (LMDI) as the method to identify the driving forces. The results show that the carbon emission in the country will peak in 2036, six years later than the agreed year. The lateness of the national peak can be attributed to the significant lateness of three pillar sectors' peaks, occurring in 2031 for the industrial sector, 2035 for the building sector, 2043 for the transport sector, peak for the agricultural sector occurs four years earlier in 2026 though. Furthermore, the results show that carbon emission is significantly driven by the booming economic output and inhibited by decreasing energy intensity, but the slight fluctuation of energy structure plays a minor role in the four sectors. Policy adjustments are proposed for effectively and efficiently urging the on-time occurrence of the national peak.
During the last years, hydrogen based transportation presented a significant growth consisting of the commercialisation of fuel cell electric vehicles and the development on new infrastructure schemes.
This study demonstrates the state-of-the art and the future potential of the emerging hydrogen-based market in road transportation. To this end, a detailed analysis of the current technologies associated with hydrogen refuelling stations including stations’ components and categories is presented. Subsequently, future forecasts concerning the development of hydrogen infrastructure along with its corresponding financial evaluation is documented through a thorough literature review. All the referred sources were discussed and compared, concluding to a general outcome showing the prospects of hydrogen in the transportation sector.
Acknowledging the above, this review identified a growing trend in the expansion of hydrogen infrastructure, albeit at this time is still at an initial stage of development, mostly due to the low H2 fuel demand for transportation. However, based on the acquired information and the analysis of the presented data, an increase of the H2 fuel demand in the future will require high investments in the infrastructure sector, which may exceed several billion EUR through the construction of an adequate number of hydrogen refuelling stations. In this regard, the presented studies indicated a number of hydrogen refuelling stations for the next decades based on different scenarios of the future alternative vehicles mix, ranging from several thousands to hundreds of thousands.
Hence, it is concluded that there is a two-way relationship between hydrogen infrastructure and H2 based vehicles. Investments in hydrogen refuelling stations are profitable if the fuel cell vehicles number will grow, and on the other hand, fuel cell vehicles market will be hindered if there is no adequate hydrogen infrastructure development.
The conversion of CO2 to methanol is seen as a potential environmental benign alternative source of fuel and chemicals. Manganese-cobalt catalyst shows promise for CO2 hydrogenation to methanol, but its selectivity towards hydrocarbons and other oxygenates needs to be suppressed. In this work, we report the activity of mesoporous manganese-cobalt spinel oxides with different Co/Mn ratios for CO2 hydrogenation to methanol. The catalysts were thoroughly characterized by N2 adsorption-desorption, XRD, XPS, TEM, ICP-OES, H2-TPR, and CO2-TPD. A significant improvement in methanol selectivity was observed over the manganese doped catalysts compared to the monometallic catalysts. The highest methanol selectivity of 29.8% (reaction conditions: 250 °C, 10 bar, 44, 400 h⁻¹) was obtained with 20 wt.% manganese with a CO2 conversion of 49.1%, resulting in a methanol formation rate of 2280 mg/(gcat h). The enhanced methanol selectivity was attributed to a synergistic effect between cobalt and manganese as well as an increase in surface basicity.
The present study was carried out to assess the possibility of using the HCNG in the commercially available CNG vehicles, as the available literature indicated the benefits of adding hydrogen to CNG in small percentages by volume, leading to improved combustion characteristics of CNG and yielding sizeable benefits, regarding improved engine performance and reduced engine emissions in automotive applications. In the present study, a commercially available CNG manifold carburation kit, commonly known as “sequential injection” in the market, is evaluated for its operation characteristics, on a Spark Ignited (SI), MPFI automotive engine, of a mass-produced passenger vehicle, converted for gas operation, using, gasoline, CNG, HCNG 10% and HCNG 18% as fuels. In the study, the following performance parameters, torque, power, thermal efficiency, brake specific energy consumption (BSEC), lambda, engine oil temperature, exhaust gas species were measured. After exhaustive engine testing, a comparison of engine performance emission characteristics for gasoline, CNG and HCNG 10% and HCNG 18% is presented. The engine performance using the optimized MAP tables demonstrated torque and power improvements for HCNG 10% and HCNG 18% in comparison to CNG. The torque benefits up-to 6% and power benefits up-to 4% were observed. The fuel energy consumption was measured to be reduced, and improvement in fuel conversion efficiency was also observed. Hydrogen substitution in CNG helped in reducing CO, HC, CO 2 emissions for HCNG in comparison to CNG. Increase in NO x emission was observed for HCNG in comparison with CNG. Superior engine emission characteristics in comparison to gasoline and CNG is also demonstrated. The commercially available sequential gas manifold carburation was found to be suitable for HCNG 10% and HCNG 18%.
In this work, we demonstrate the process and economic viability of a new production route for methanol utilizing captured CO2 and H2 produced from renewable, photocatalytic water splitting. Initial assessments of H2 production from this approach revealed a low-cost potential through inexpensive feedstock, but with one major drawback. Simultaneous production of H2 and O2 increases the risk of forming an explosive mixture. In our previous work, we identified membrane-based processes to safely recover the H2 product. To reduce the H2 capture costs, we developed a conceptual process comprised of integrated facilities to produce methanol while solving the flammability constraints. The first unit supplies captured CO2, which is used as a raw material and a diluent to recover H2 from the photocatalytic reactors. The tertiary mixture (H2/O2/CO2) is safely processed in an optimized membrane-based separation plant to produce a 3:1 H2 and CO2 mixture. This binary mixture is then used as feedstock for methanol production via direct CO2 hydrogenation. Based on a detailed economic analysis, the break-even value of the methanol produced is higher than the current market price. The main drivers for the high cost are the separation plant and the feedstock costs of CO2. The best-case scenario (for the selected parameters), where the plant lifetime is 30 years with 0.060 /kg CO2 cost, has a break-even value for methanol at 0.96 $/kg. Based on a target solar-to-hydrogen efficiency of 10% in the photocatalytic reactor, the gross energy efficiency of the process was 6.25%. As a final element, we compared our process with alternative renewable methanol synthesis route from the literature to highlight the differences in electrochemical and thermochemical approaches.
The global increase in electricity production by wind and photovoltaic plants poses challenges for local electricity grids as well as for electricity markets. These renewable energy sources rely heavily on current weather conditions, by that producing electricity in a fluctuating manner. This results in temporary electricity surpluses causing temporarily low or even negative electricity prices. Additionally, a stable operation of the electricity grid must be maintained even locally.
To solve these problems, the intelligent coupling of the electricity, gas and heat sectors could be a promising approach. So called “Power-To-X” concepts such as Power-to-Heat (P2H) or Power-to-Fuel (P2F) cover technologies that aim to convert electrical energy into material energy storages, synthetic fuels and energy-intensive chemical raw products. For conventional power plants, the production of methanol is currently the most discussed option in Germany.
In this paper a techno-economic analysis of the implementation of a Power-to-Methanol plant (P2MeOH) into a conventional power plant is presented. This study is based on real power generation data of the real hard coal-fired power plant “Westphalia E” in Germany in 2017. It takes into account parameters such as P2MeOH invest costs, costs for carbon dioxide emission as well as electricity, methanol and oxygen market prices. The required mass and energy flows for the techno-economic analysis are calculated by a custom implemented thermodynamic model.
This study shows that an additional revenue could be generated under current market situations and that this possible revenue sums up to 5.2 million € per year. In ecological regards, around 150,000 tons CO2 could be saved per year. The calculated P2MeOH invest costs amount to 137.5 million €. Additionally, it could be obtained that by far most costs are caused by the electrolyser. As further technical progress in that field is expected, this could lead to higher economic benefits in the future.
Towards zero emission and zero energy buildings, literature reviews highlight the importance of embodied energy and embodied carbon emissions. The current review analyses 95 case studies of residential buildings, as an effort to identify the range of embodied carbon emissions and the correlation between the share of embodied energy and carbon for different levels of building's energy efficiency. The assessment identifies a range of embodied carbon emissions between 179.3 kgCO2e/m2-1050 kgCO2e/m2 (50-year building lifespan) that reflects a share between 9% and 80% to the total life cycle impact. That same share follows similar trends with the respective for embodied energy and ranges between 9% and 22% for conventional, between 32% and 38% for passive and between 21% and 57% for low energy buildings, while the normalised results indicate a sensitivity for the share of operating emissions that relates to the electricity mix. Considering the deviation of the results, even though a two-step normalisation procedure increases the homogeneity and comparability of the sample, the differences in the electricity mix, in LCI databases or even in the overall building design could not be neutralised and confirm the need for further standardisation in LCA.
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In this paper, we report photoelectrochemical (PEC) conversion of carbon dioxide (CO2) using photocathodes based on Cu2O nanowires (NWs) overcoated with Cu⁺-incorporated crystalline TiO2 (TiO2 Cu⁺) shell. Cu2O NW photocathodes show remanent photocurrent of 5.3% after 30min of PEC reduction of CO2. After coating Cu2O with TiO2 Cu⁺ overlayer, the remanent photocurrent is 27.6%, which is an increase by 5.2 fold. The charge transfer resistance of Cu2O/TiO2 Cu⁺ is 0.423kΩ/cm², whereas Cu2O photocathode shows resistivity of 0.781kΩ/cm² under irradiation. Mott-Schottky analysis reveals that Cu⁺ species embedded in TiO2 layer is responsible for enhanced adsorption of CO2 on TiO2 surface, as evidenced by the decrease of capacitance in the Helmholtz layer. On account of these electrochemical and electronic effects by the Cu⁺ species, the Faradaic efficiency (FE) of photocathodes reaches as high as 56.5% when TiO2 Cu⁺ is added to Cu2O, showing drastic increase from 23.6% by bare Cu2O photocathodes.
This study provides an in-depth investigation of Turkish trainee teachers perceptions of the greenhouse effect. The sample of the research is composed of total 218 elementary level trainee teachers at Uludag University in Turkey, in 2014. Within the targeted group of respondents, 35.3% were at Science Education, 32.6% at Primary Education and 32.1% at Social Studies Education Department. Besides, this study aimed to investigate the influence of gender and being at different departments on trainee teachers perceptions regarding of the greenhouse effect. It was used the Environmental Issues Questionnaire during data collection process. There is a statistically significant difference between girls and boys and the average of boys is higher than the average of girls. One-Way Anova test results show that there is not a statistically significant difference between groups. Based on the findings, it can be concluded that many trainee teachers have several misconceptions concerning the greenhouse effect. Many aspects of the greenhouse effect are still confusing for them. It is thought that the complexity of environmental problems leads to elementary trainee teachers many misconceptions.
Hydrogen produced from low-emission primary energy sources, particularly renewable energy, is a potential alternative transport fuel to gasoline and diesel that can contribute to reducing greenhouse gas emissions and improving global energy security. Hydrogen fuelling stations are one of the most important parts of the distribution infrastructure required to support the operation of hydrogen fuel cell electric vehicles and hydrogen internal combustion engine vehicles. If there is to be substantial market penetration of hydrogen vehicles in the transport sector, the introduction of commercial hydrogen vehicles and the network of fuelling stations to supply them with hydrogen must take place simultaneously. The present paper thus reviews the current state of the art and deployment of hydrogen fuelling stations. It is found that by 2013, there were 224 working hydrogen stations distributed over 28 countries. Some 43% of these stations were located in North and South America, 34% in Europe, 23% in Asia, and none in Australia. The state of the art in the range of hydrogen production processes is briefly reviewed. The importance of producing hydrogen using renewable energy sources is emphasised for a transition to hydrogen fuel cell vehicles to contribute to greenhouse gas emission reduction targets. 2.3–5.8/H2kg for SMR A classification of hydrogen refuelling stations is introduced, based on the primary energy source used to produce the hydrogen, the production process, and whether the hydrogen is made on site or delivered to the site. The current state of deployment of hydrogen fuelling stations in each major region of the world is then reviewed in detail. The costs of producing hydrogen vary from 6–7.4/H2 kg for wind power and $6.3–25.4/H2 kg depending on the cost of the PV system. The lowest cost of hydrogen is nearing competitiveness with petroleum fuels. Finally conclusions are drawn about the progress to date in establishing this crucial component of the infrastructure to enable hydrogen-powered vehicles to become a commercial reality.
Small Au, Cu, and Ni particles in contact with TiC(001) display a very high activity for the catalytic hydrogenation of CO2. The major product over these catalysts is CO which is produced by the reverse water gas shift reaction (RWGS, CO2 + H-2 -> CO + H2O). In the cases of Au/TiC(001) and Cu/TiC(001), a substantial amount of methanol is also produced, but no methane is detected. Ni/TiC(001) produces a mixture of CO, methanol, and methane. The highest catalytic activity is found for small two-dimensional particles or clusters of the admetals in close contact with TiC(001). The catalytic activity of the supported metals can be orders of magnitude higher than those-of Au(100), Cu(100), or Ni(100). Density functional calculations point to HOCO as a key intermediate for the generation of CO through the RWGS, with the production of methanol probably involving the hydrogenation of a HCOO intermediate or the CO generated by the RWGS.
The amount of bottom ash formed in a pulverized coal-fired power plant was predicted by artificial neural network modeling using one-year operating data of the plant and the properties of the coals processed. The model output was defined as the ratio of amount of bottom ash produced to amount of coal burned (Bottom ash/Coal burned). The input parameters were the moisture contents, ash contents and lower heating values of the coals. The total 653 data were divided into two groups for the training (90% of the data) and the testing (10% of the data) of the network. A three-layer, feed-forward type network architecture with back-propagation learning was used in the modeling study. The activation function was sigmoid function. The best prediction performance was obtained for a one hidden layer network with 29 neurons. The learning rate and the tolerance value were 0.2 and 0.05, respectively. R2 (coefficient of determination) values between the actual (Bottom ash/Coal burned) ratios and the model predictions were 0.988 for the training set and 0.984 for the testing set. In addition, the sensitivity analysis indicated that the ash content of coals was the most effective parameter for the prediction of the ratio of bottom ash to coal burned.
The low temperature (403–453 K) conversions of CO/hydrogen and CO2/hydrogen mixtures (6 bar total pressure) to methanol over copper catalysts are both assisted by the presence of small amounts of water (mole fraction ∼0.04–0.5%). For CO2/hydrogen reaction mixtures, the water product from both methanol synthesis and reverse water–gas shift serves to initiate both reactions in an autocatalytic manner. In the case of CO/D2 mixtures, very little methanol is produced until small amounts of water are added. The effect of water on methanol production is more immediate than in CO2/D2, yet the steady-state rates are similar. Tracer experiments in 13CO/12CO2/hydrogen (with or without added water) show that the dominant source of C in the methanol product gradually shifts from CO2 to CO as the temperature is lowered. Cu-bound formate, the major IR visible surface species under CO2/hydrogen, is not visible in CO/moist hydrogen. Though formate is visible in the tracer experiments, the symmetric stretch is absent. These results, in conjunction with recent DFT calculations on Cu(1 1 1), point to carboxyl as a common intermediate for both methanol synthesis and reverse water–gas shift, with formate playing a spectator co-adsorbate role.
The only comprehensive study comparing structural decomposition analysis (SDA) and index decomposition analysis (IDA) was conducted around 2000. There have since been new developments in both techniques in energy and emission studies. These developments have been studied systematically for IDA but similar studies for SDA are lacking. In this paper, we fill the gap by examining the new methodological developments in SDA. A new development is a shift towards using decomposition methods that are ideal. We compare four such SDA methods analytically and empirically through decomposing changes in China's CO2 emissions. We then provide guidelines on method selection. Finally, we discuss the similarities and differences between SDA and IDA based on the latest available information.
A global assessment of the potential impact of climate change on world food supply suggests that doubling of the atmospheric carbon dioxide concentration will lead to only a small decrease in global crop production. But developing countries are likely to bear the brunt of the problem, and simulations of the effect of adaptive measures by farmers imply that these will do little to reduce the disparity between developed and developing countries.
There is increased recognition by the world’s scientific, industrial, and political communities that the concentrations of greenhouse gases in the earth’s atmosphere, particularly CO_2, are increasing. For example, recent studies of Antarctic ice cores to depths of over 3600 m, spanning over 420 000 years, indicate an 80 ppm increase in atmospheric CO_2 in the past 200 years (with most of this increase occurring in the past 50 years) compared to the previous 80 ppm increase that required 10 000 years.2 The 160 nation Framework Convention for Climate Change (FCCC) in Kyoto focused world attention on possible links between CO2 and future climate change and active discussion of these issues continues.3 In the United States, the PCAST report4 “Federal Energy Research and Development for the Challenges of the Twenty First Century” focused attention on the growing worldwide demand for energy and the need to move away from current fossil fuel utilization. According to the U.S. DOE Energy Information Administration,5 carbon emission from the transportation (air, ground, sea), industrial (heavy manufacturing, agriculture, construction, mining, chemicals, petroleum), buildings (internal heating, cooling, lighting), and electrical (power generation) sectors of the World economy amounted to ca. 1823 million metric tons (MMT) in 1990, with an estimated increase to 2466 MMT in 2008-2012 (Table 1).
To analyze and understand historical changes in economic, environmental, employment or other socio-economic indicators, it is useful to assess the driving forces or determinants that underlie these changes. Two techniques for decomposing indicator changes at the sector level are structural decomposition analysis (SDA) and index decomposition analysis (IDA). For example, SDA and IDA have been used to analyze changes in indicators such as energy use, CO2-emissions, labor demand and value added. The changes in these variables are decomposed into determinants such as technological, demand, and structural effects. SDA uses information from input–output tables while IDA uses aggregate data at the sector-level. The two methods have developed quite independently, which has resulted in each method being characterized by specific, unique techniques and approaches. This paper has three aims. First, the similarities and differences between the two approaches are summarized. Second, the possibility of transferring specific techniques and indices is explored. Finally, a numerical example is used to illustrate differences between the two approaches.
Utilization of carbon dioxide (CO2) has become an important global issue due to the significant and continuous rise in atmospheric CO2 concentrations, accelerated growth in the consumption of carbon-based energy worldwide, depletion of carbon-based energy resources, and low efficiency in current energy systems. The barriers for CO2 utilization include: (1) costs of CO2 capture, separation, purification, and transportation to user site; (2) energy requirements of CO2 chemical conversion (plus source and cost of co-reactants); (3) market size limitations, little investment-incentives and lack of industrial commitments for enhancing CO2-based chemicals; and (4) the lack of socio-economical driving forces. The strategic objectives may include: (1) use CO2 for environmentally-benign physical and chemical processing that adds value to the process; (2) use CO2 to produce industrially useful chemicals and materials that adds value to the products; (3) use CO2 as a beneficial fluid for processing or as a medium for energy recovery and emission reduction; and (4) use CO2 recycling involving renewable sources of energy to conserve carbon resources for sustainable development. The approaches for enhancing CO2 utilization may include one or more of the following: (1) for applications that do not require pure CO2, develop effective processes for using the CO2-concentrated flue gas from industrial plants or CO2-rich resources without CO2 separation; (2) for applications that need pure CO2, develop more efficient and less-energy intensive processes for separation of CO2 selectively without the negative impacts of co-existing gases such as H2O, O2, and N2; (3) replace a hazardous or less-effective substance in existing processes with CO2 as an alternate medium or solvent or co-reactant or a combination of them; (4) make use of CO2 based on the unique physical properties as supercritical fluid or as either solvent or anti-solvent; (5) use CO2 based on the unique chemical properties for CO2 to be incorporated with high ‘atom efficiency’ such as carboxylation and carbonate synthesis; (6) produce useful chemicals and materials using CO2 as a reactant or feedstock; (7) use CO2 for energy recovery while reducing its emissions to the atmosphere by sequestration; (8) recycle CO2 as C-source for chemicals and fuels using renewable sources of energy; and (9) convert CO2 under either bio-chemical or geologic-formation conditions into “new fossil” energies. Several cases are discussed in more detail. The first example is tri-reforming of methane versus the well-known CO2 reforming over transition metal catalysts such as supported Ni catalysts. Using CO2 along with H2O and O2 in flue gases of power plants without separation, tri-reforming is a synergetic combination of CO2 reforming, steam reforming and partial oxidation and it can eliminate carbon deposition problem and produces syngas with desired H2/CO ratios for industrial applications. The second example is a CO2 “molecular basket” as CO2-selective high-capacity adsorbent which was developed using mesoporous molecular sieve MCM-41 and polyethylenimine (PEI). The MCM41-PEI adsorbent has higher adsorption capacity than either PEI or MCM-41 alone and can be used as highly CO2-selective adsorbent for gas mixtures without the pre-removal of moisture because it even enhances CO2 adsorption capacity. The third example is synthesis of dimethyl carbonate using CO2 and methanol, which demonstrates the environmental benefit of avoiding toxic phosgene and a processing advantage. The fourth example is the application of supercritical CO2 for extraction and for chemical processing where CO2 is either a solvent or a co-reactant, or both. The CO2 utilization contributes to enhancing sustainability, since various chemicals, materials, and fuels can be synthesized using CO2, which should be a sustainable way in the long term when renewable sources of energy are used as energy input.
Energy and the environment are two of the most important issues this century. More than 80 % of our energy comes from the combustion of fossil fuels, which will still remain the dominant energy source for years to come. It is agreed that carbon dioxide produced from the combustion process to be the most important anthropogenic greenhouse gas leading to global warming. Atmospheric CO(2) concentrations have indeed increased by almost 100 ppm since their pre-industrial level, reaching 384 ppm in 2007 with a total annual emission of over 35 Gt. Prompt global action to resolve the CO(2) crisis is therefore needed. To pursue such an action, we are urged to save energy without the unnecessary production of carbon emissions and to use energy in more efficient ways, but alternative methods to mitigate the greenhouse gas have to be considered. This Minireview highlights some recent promising research activities and their prospects in the areas of carbon capture and storage and chemical fixation of CO(2) in constructing a future low-carbon global economy with reference to energy source, thermodynamic considerations, net carbon emissions and availability of reagents.
Few industrial processes utilize carbon dioxide as a raw material because it is the most oxidized state of carbon with a low energy level. However, using CO2 as a raw material do not necessarily help mitigate the greenhouse effect, although it is a green chemical reagent in many cases. The significance of the transformation of CO2 into useful chemicals should be attributed to the importance of utilizing a renewable feedstock. There are four methodologies to transform CO2 into useful chemicals: (i) using high-energy starting materials such as hydrogen, unsaturated compounds, small-membered ring compounds, and organometallics; (ii) choosing oxidized low-energy synthetic targets; (iii) shifting the equilibrium to the product side by removing a particular compound; and (iv) supplying physical energy such as light or energy. It is important to execute research on CO2 to increase the number of industrial applications by improving reactions for commercialization, to improve reactions with low catalytic performance, to establish foundations for science to research for new reactions and new catalysts, and to elucidate reaction mechanisms at the molecular level.
The need to reduce the accumulation of CO(2) into the atmosphere requires new technologies able to reduce the CO(2) emission. The utilization of CO(2) as a building block may represent an interesting approach to synthetic methodologies less intensive in carbon and energy. In this paper the general properties of carbon dioxide and its interaction with metal centres is first considered. The potential of carbon dioxide as a raw material in the synthesis of chemicals such as carboxylates, carbonates, carbamates is then discussed. The utilization of CO(2) as source of carbon for the synthesis of fuels or other C(1) molecules such as formic acid and methanol is also described and the conditions for its implementation are outlined. A comparison of chemical and biotechnological conversion routes of CO(2) is made and the barriers to their exploitation are highlighted.
Carbon emission deduction model and application base on production function theory
- Wu
Together development of ‘methanol economy’and ‘hydrogen economy’driven by CO2 utilization
- Wang