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A sustainability assessment of utilising energy crops for heat and electricity generation in Turkey
... There are sustainability assessment studies such as [3][4][5][6][7][8][9][10][11], along with those related to the environmental impacts associated with biomass use in general terms [12][13][14][15]. Each of them provides a unique assessment perspective. ...
Multi-criteria methods are highly attractive tools to address the inherent complexity of evaluating problems in various scientific areas. The combination of methods such as Delphi/AHP is emerging as a robust alternative to evaluate the sustainability of renewable energy sources. In this theoretical-descriptive research, the use of the Delphi method is proposed to select criteria and sub-criteria to obtain a high level of reliability, while the AHP method is used to establish an order of preference among the alternatives analyzed. This process requires the support of a committee of experts, whose role is to identify the various biomass alternatives that can be used in the sugar industry, considering aspects related to sustainability. The selected experts have identified energy, exergy, and emergetic indicators, in which economic, environmental, and social aspects are integrated. The multi-criteria analysis shows that the V1 variant was the most satisfactory in terms of biomass sustainability, representing 45% and 53% of the overall priorities in the evaluated case studies. In addition, the sensitivity analysis under an equal-weighted scenario for both study cases evidenced that variant V1 acquired the highest score (38.17%) among all alternatives. Variant V4 achieved the second highest score (31.79%), while alternative V2 achieved only 29.04%, respectively. The integration of Delphi/AHP methods emerges as a novel tool to assess sustainability in different industries of the energy sector.
... Due to the increase in this type of company, electrical energy consumption has also increased, becoming a large expense for entrepreneurs [12]. Furthermore, by providing a greater amount of electrical energy to businesses, rural places are left unattended [13]. It has been estimated that, by 2050, the increase in energy consumption will be 15-18% more than today [14]. ...
Agroindustry waste has exponentially increased in recent years, generating economic losses and environmental problems. In addition, new ways to generate sustainable alternative electrical energy are currently being sought to satisfy energy demand. This investigation proposes using avocado waste as fuel for electricity generation in single-chamber MFCs. The avocado waste initially operated with an ambient temperature (22.4 ± 0.01 °C), DO of 2.54 ± 0.01 mg/L, TDS of 1358 ± 1 mg/L and COD of 1487.25 ± 0.01 mg/L. This research managed to generate its maximum voltage (0.861 ± 0.241 V) and current (3.781 ± 0.667 mA) on the fourteenth day, operating at an optimal pH of 7.386 ± 0.147, all with 126.032 ± 8.888 mS/cm of electrical conductivity in the substrate. An internal resistance of 67.683 ± 2.456 Ω was found on day 14 with a PD of 365.16 ± 9.88 mW/cm² for a CD of 5.744 A/cm². Micrographs show the formation of porous biofilms on both the anodic and cathodic electrodes. This study gives preliminary results of using avocado waste as fuel, which can provide outstanding solutions to agro-industrial companies dedicated to selling this fruit.
... Para potencias menores a 5 MWe, la gasificación presenta menores costos de inversión, operación y mantenimiento; mientras que para potencias mayores a 5 MWe la combustión representa la mejor opción. Hidrovo, et al.,2021;Balcioglu et al., 2023;Sadaghiani, et al., 2023). Otros estudios enfocados en aspectos sociales o del territorio, sin duda deben complementar los primeros. ...
Resumen: en este capítulo se revisa el concepto de biocombustibles sólidos, las características a nivel físico y químico que deben analizarse para su aprovechamiento energético, los métodos de análisis de laboratorio, las técnicas de acondicionamiento o pretratamiento y los principales proce-sos y tecnologías de conversión energética para las aplicaciones más comunes: biocalor y bioelec-tricidad. Se revisan, asimismo, las clasificaciones actuales acordadas en normativas internaciona-les para facilitar su comercialización. Se explora el contexto mundial en relación con la participación de estos biocombustibles, su rol en la matriz energética y su comercio, como así, se replica este análisis a menor escala considerando la realidad de Argentina. Se discuten, por último, las oportu-nidades y los desafíos para el uso de biocombustibles sólidos a futuro. CITA: Manrique SM, Mosconi L, Subelza C y Honorato M (2023). Biocombustibles sólidos, 57-89. En: Usos y Aplicaciones Energéticas de la Biomasa: Hacia una bioeconomía circular. Guía científico-técnica. Una publicación de la Red Iberoamericana de Tecnologías de Biomasa y Bioenergía Rural (ReBiBiR-T). CYTED Ediciones. ISBN: 978-84-15413-58-5. Madrid, España. 252 páginas.
... Para potencias menores a 5 MWe, la gasificación presenta menores costos de inversión, operación y mantenimiento; mientras que para potencias mayores a 5 MWe la combustión representa la mejor opción. Hidrovo, et al.,2021;Balcioglu et al., 2023;Sadaghiani, et al., 2023). Otros estudios enfocados en aspectos sociales o del territorio, sin duda deben complementar los primeros. ...
This paper examines how best to use forest wood for energy application, considering that it is a limited natural resource. Eight systems are considered, including wood stoves, steam systems (boiler, power plant, and combined heat and power (CHP)), and gasification combined systems (gas turbine and combined cycle power plant, CHP, and Fischer–Tropsch). The methodology uses energy analysis and modelling and environmental/sustainability considerations to compare the energy systems. In terms of energy conversion efficiency, steam boilers and high-efficiency wood stoves for heating applications provide the highest efficiencies (~80 to 90%) and should be considered. Steam CHP systems provide lower overall energy conversion efficiencies (~75 to 80%) but do provide some electrical energy, and thus should be considered. The use of wood for the production of electricity on its own should not be considered due to low efficiencies (~20 to 30%). Particulate emissions hinder the application of high-efficiency stoves, especially in urban areas, whereas for industrial-scale steam boilers and CHP systems, particle separators can negate this problem. Gasification/Fischer–Tropsch systems have a lower energy efficiency (~30 to 50%); however, a sustainability argument could be made for liquid fuels that have few sustainable alternatives.
Bioenergy aims to reduce greenhouse gas (GHG) emissions and contribute to meeting global climate change mitigation targets. Nevertheless, several sustainability concerns are associated with bioenergy, especially related to the impacts of using land for dedicated energy crop production. Cultivating energy crops can result in synergies or trade-offs between GHG emission reductions and other sustainability effects depending on context-specific conditions. Using the United Nations Sustainable Development Goals (SDGs) framework, the main synergies and trade-offs associated with land use for dedicated energy crop production were identified. Furthermore, the context-specific conditions (i.e., biomass feedstock, previous land use, climate, soil type and agricultural management) which affect those synergies and trade-offs were also identified. The most recent literature was reviewed and a pairwise comparison between GHG emission reduction (SDG 13) and other SDGs was carried out. A total of 427 observations were classified as either synergy (170), trade-off (176), or no effect (81). Most synergies with environmentally-related SDGs, such as water quality and biodiversity conservation, were observed when perennial crops were produced on arable land, pasture or marginal land in the ‘cool temperate moist’ climate zone and ‘high activity clay’ soils. Most trade-offs were related to food security and water availability. Previous land use and feedstock type are more impactful in determining synergies and trade-offs than climatic zone and soil type. This study highlights the importance of considering context-specific conditions in evaluating synergies and trade-offs and their relevance for developing appropriate policies and practices to meet worldwide demand for bioenergy in a sustainable manner.
Heat from biomass is being promoted in an effort to reduce GHG emission. However, the full life cycle environmental and economic implications of biomass heat are currently unknown and are therefore explored in this paper. The results indicate that heat from solid biomass can reduce global warming potential as well as depletion of fossil resources and the ozone layer by >90% compared to fossil fuels. However, acidification, eutrophication and human and eco‐toxicities are much higher than for heat from natural gas. Biomass heat is also 23% more expensive than heat from gas boilers. However, with the subsidies available in the UK, it is 52% cheaper. Using the waste wood and energy crops available in the UK could meet 5% of the national heat demand and save 7.3 Mt CO2 eq./yr, or 1.5% of UK emissions. Increasing cultivation of energy crops could provide 20% of heat demand by 2030 and save 25 Mt CO2 eq./yr, or 5.1% of national emissions. Therefore, government should continue to incentivise biomass heat while tightening regulations to prevent an increase in other impacts. However, increasing biomass heat provision will be challenging owing to a large number of installations needed (27,000–85,000) and lack of district heating networks in the UK. This article is protected by copyright. All rights reserved.
This work aims to assess the environmental and economic sustainability of poultry litter gasification for heat and electricity generation. The results are compared with gasification of two other biomass feedstocks (Miscanthus and waste wood) and energy from fossil fuels. The findings suggest that poultry litter gasification can lead to significant reductions in 14 out of 16 impacts considered in the study in comparison with fossil-fuel alternatives. Compared to combined heat and power (CHP) from natural gas, most impacts from gasification of the litter are lower by more than 90%, including global warming potential. However, human toxicity and depletion of minerals are 25% and three times higher, respectively. Energy from poultry litter also has lower impacts than from waste woodchips and Miscanthus across all the categories, except for acidification. Owing to high capital costs, the unsubsidised cost of generating heat and electricity from poultry litter is similar to that of natural gas CHP but significantly cheaper than from other fossil-fuel alternatives. However, with the current subsidies in the UK, the payback time for poultry litter gasification is 13.5 years. It is estimated that 4.55 Mt of poultry litter is currently available in the UK, 2.73 Mt of which is suitable for conversion to energy. If this waste is utilised in gasification plants, it could potentially provide 0.6% of electricity and heat in the UK and save 1.7 Mt of GHG per year, equivalent to around 0.4% of UK’s GHG emissions. However, the successful uptake of this technology will depend on a future reduction in capital costs.
Industrial heat is important in Europe’s energy consumption and dominated by fossil fuels. Therefore, promoting renewables in this sector is vital to move Europe towards a low-carbon economy. Since solid biomass is the only renewable with significant industrial use, it is crucial to know the status of its present use and to analyze the prospects of its future utilization by the industry. The current European industrial energy consumption is reviewed, with a focus on bioheat. The available solid biomass feedstock and energy conversion alternatives are examined, along with future perspectives for further biomass consumption in several industrial sectors. Defining global strategies for industrial heat is not easy because of the diversity of industrial processes. Combustion dominates industrial heat production from biomass, but gasification systems are already commercially available. Combined heat and power production is mainly based on steam cycles. The full temperature range required by industry can be attained with biomass efficiently. The use of biomass-fired systems is generalized in the industries that generate solid biomass by-products, but the implementation of additional, more efficient and alternative biomass uses should be sought. Biomass penetration into sectors with no own biomass resources is more difficult. Major barriers are the high investment costs of biomass systems, strong competition with fossil fuels, and feedstock availability and security of supply. Although Europe’s solid biomass production and consumption are almost balanced, the pressure on resources is increasing. Therefore, it is important that resources are monitored and that sustainability is taken into consideration.
In order to limit global warming to around 1.5–2.0 °C by the end of the 21st century, there is the need to drastically limit the emissions of CO2. This goal can be pursued by promoting the diffusion of advanced technologies for power generation from renewable energy sources. In this field, biomass can play a very important role since, differently from solar and wind, it can be considered a programmable source. This paper reports a techno-economic analysis on the possible commercial application of gasification technologies for small-scale (2 MWe) power generation from biomass. The analysis is based on the preliminary experimental performance of a 500 kWth pilot-scale air-blown bubbling fluidized-bed (BFB) gasification plant, recently installed at the Sotacarbo Research Centre (Italy) and commissioned in December 2017. The analysis confirms that air-blown BFB biomass gasification can be profitable for the applications with low-cost biomass, such as agricultural waste, with a net present value up to about 6 M€ as long as the biomass is provided for free; on the contrary, the technology is not competitive for high-quality biomass (wood chips, as those used for the preliminary experimental tests). In parallel, an analysis of the financial risk was carried out, in order to estimate the probability of a profitable investment if a variation of the key financial parameters occurs. In particular, the analysis shows a probability of 90% of a NPV at 15 years between 1.4 and 5.1 M€ and an IRR between 11.6% and 23.7%.
Akdeniz iklimine sahip ve ülkemizde seracılığın yoğun olarak yapıldığı Antalya ili ve karasal iklim özelliği gösteren ve seracılığın gelişmekte olduğu Kırşehir illerinde farklı donanım özelliğine sahip seralarda iç sıcaklığın 18 °C’de sabit tutulması durumunda gereksinim duyulan ısı enerjisi, yakıt miktarı, karbondioksit emisyon değerleri ve rekabet edebilirlik açısından jeotermal enerjinin fiyat belirlemesinin yapıldığı çalışmada, Kırşehir ve Antalya illerinde kurulacak tek katlı polietilen plastik ile örtülü seralarda içi sıcaklığın 18 °C’de sabit tutulması durumunda ihtiyaç duyulan maksimum ısı gücü gereksinimi Kırşehir ili için (253 W m-2), Antalya ili için (141 W m-2) olarak belirlenmiştir. Bunun yanında ülkemizde yaygın olarak kullanılan tek katlı PE plastiğin ısı korunum önlemleri alınmadan kullanılması halinde üretim periyodu süresince ihtiyaç duyulan ısı enerjisi gereksinimi Kırşehir ili için 589.02 kWh m-2 yıl-1 ve Antalya ilinde 219.06 kWh m-2 yıl-1 olarak hesaplanmıştır. Seralarda çift katlı PE plastiğin ve yalıtımı iyi yapılmış ısı perdelerinin kullanılması durumunda ise bu değerler Kırşehir ili için 304.09 kWh m-2 yıl-1 ve Antalya ili için 103.35 kWh m-2 yıl-1 olarak belirlenmiştir. Elde edilen sonuçlara göre Kırşehir ilinde seralar için gerekli olan ısı enerjisinin fosil yakıtlar ile sağlanması durumunda Kırşehir ilinin Antalya ili ile rekabet edebilme şansı bulunmamaktadır. Ancak sahip olduğu jeotermal enerjinin seracılıkta kullanılması ve kWh maliyetinin en fazla 0.115 TL olması durumunda Kırşehir ilinin Antalya gibi seracılığın geliştiği iller ile rekabet edebilmesinin yanında, fosil yakıtların (ithal kömür, kalorifer yakıtı ve doğalgaz) atmosfere verdiği karbondioksit salınımının azaltması açısından da önemli üstünlükleri olacaktır.
Electricity generation from coal is one of the leading contributors to greenhouse gas emissions in the U.S. and has adverse effects on the environment. Biomass from forest residue can be co-fired with coal to reduce the impact of fossil-fuel power plants on the environment. W. A. Parish power plant (WAP, Richmond, TX, USA) located in the greater Houston area is the largest coal and natural gas-based power generation facility in Texas and is the subject of the current study. A life cycle assessment (LCA) study was performed with SimaPro® and IMPACT 2002+ method, for the replacement of 5%, 10%, and 15% coal (energy-basis) with forest residue at the WAP power plant in Texas. Results from the LCA study indicate that life cycle air emissions of CO2, CO, SO2, PM2.5, NOX, and VOC could reduce by 13.5%, 6.4%, 9.5%, 9.2%, 11.6%, and 7.7% respectively when 15% of coal is replaced with forest residue. Potential life cycle impact decreased across 9 mid-point impact categories of, human/aquatic toxicity, respiratory organics/inorganics, global warming, non-renewable energy, mineral extraction, aquatic acidification, and terrestrial acidification/nitrification. The potential impact across damage/end-point categories of human health, ecosystem quality, climate change, and resources reduced by 8.7%, 3.8%, 13.2%, and 14.8% respectively for 15% co-firing ratio.
In recent years, considerable progress has been made in miscanthus research: improvement of management practices, breeding of new genotypes, especially for marginal conditions, and development of novel utilization options. The purpose of the current study was a holistic analysis of the environmental performance of such novel miscanthus-based value chains. In addition, the relevance of the analyzed environmental impact categories was assessed. A Life Cycle Assessment was conducted to analyse the environmental performance of the miscanthus-based value chains in 18 impact categories. In order to include the substitution of a reference product, a system expansion approach was used. In addition, a normalization step was applied. This allowed the relevance of these impact categories to be evaluated for each utilization pathway. The miscanthus was cultivated on six sites in Europe (Aberystwyth, Adana, Moscow, Potash, Stuttgart and Wageningen) and the biomass was utilized in the following six pathways: (1) small-scale combustion (heat)—chips; (2) small-scale combustion (heat)—pellets; (3) large-scale combustion (CHP)—biomass baled for transport and storage; (4) large-scale combustion (CHP)—pellets; (5) medium-scale biogas plant—ensiled miscanthus biomass; and (6) large-scale production of insulation material. Thus, in total, the environmental performance of 36 site × pathway combinations was assessed. The comparatively high normalized results of human toxicity, marine, and freshwater ecotoxicity, and freshwater eutrophication indicate the relevance of these impact categories in the assessment of miscanthus-based value chains. Differences between the six sites can almost entirely be attributed to variations in biomass yield. However, the environmental performance of the utilization pathways analyzed varied widely. The largest differences were shown for freshwater and marine ecotoxicity, and freshwater eutrophication. The production of insulation material had the lowest impact on the environment, with net benefits in all impact categories expect three (marine eutrophication, human toxicity, agricultural land occupation). This performance can be explained by the multiple use of the biomass, first as material and subsequently as an energy carrier, and by the substitution of an emission-intensive reference product. The results of this study emphasize the importance of assessing all environmental impacts when selecting appropriate utilization pathways.
Bioenergy systems will play a key role in many countries achieving their climate change, emission reduction and renewable energy contribution targets. It is important that implemented bioenergy pathways maximise GHG reductions, particularly since demand and competition for biomass resource is likely to increase in future. This research analyses the actual GHG performance of utilising different biomass resources to generate heat. Life cycle assessment (LCA) is undertaken to evaluate 2092 variants of bioheat options focused on utilising: UK agricultural and food wastes through anaerobic digestion pathways; UK straw agricultural residues and UK grown energy crops through combustion pathways. The results show a very broad range of GHG performances. Many pathways demonstrate GHG savings compared to conventional generation, although some have potential to actually increase GHG emissions, rather than reduce them. Variations in GHG performance do not correlate with feedstocks or technologies, but are most sensitive to the inclusion of specific processing steps and the displacement of certain counterfactuals. This suggests that policies should be developed that target resources with high GHG intensity counterfactuals, and where possible avoid energy intensive processing steps such as pelletisation.
For avoiding competition with food production, marginal land is economically and environmentally highly attractive for biomass production with short-rotation coppices (SRC) of fast-growing tree species such as poplars. Herein, we evaluated the environmental impacts of technological, agronomic and environmental aspects of bioenergy production from hybrid poplar SRC cultivation on marginal land in southern Germany. For this purpose different management regimes were considered within a 21-year lifetime (combining measurements and modeling approaches) by means of a holistic Life Cycle Assessment (LCA). We analyzed two coppicing rotation lengths (7x3 and 3x7 years) and seven nitrogen fertilization rates and included all processes starting from site preparation, planting and coppicing, wood chipping and heat production up to final stump removal.
The 7-year rotation cycles clearly resulted in higher biomass yields and reduced environmental impacts such as nitrate (NO3) leaching and soil nitrous oxide (N2O) emissions. Fertilization rates were positively related to enhanced biomass accumulation, but these benefits did not counterbalance the negative impacts on the environment due to increased nitrate leaching and N2O emissions. Greenhouse gas (GHG) emissions associated with the heat production from poplar SRC on marginal land ranged between 8-46 kg CO2-eq. GJ-1 (or 11-57 Mg CO2-eq. ha-1). However, if the produced wood chips substitute oil heating, up to 123 Mg CO2-eq.ha-1 can be saved, if produced in a 7-year rotation without fertilization.
Dissecting the entire bioenergy production chain, our study shows that environmental impacts occurred mainly during combustion and storage of wood chips, while technological aspects of establishment, harvesting and transportation played a negligible role
This paper evaluates life cycle greenhouse gas (GHG) emissions from the use of different biomass feedstock categories (agriculture residues, dedicated energy crops, forestry, industry, parks and gardens, wastes) independently on biomass-only (biomass as a standalone fuel) and cofiring (biomass used in combination with coal) electricity generation systems. The statistical evaluation of the life cycle GHG emissions (expressed in grams of carbon dioxide equivalent per kilowatt hour, gCO2e/kWh) for biomass electricity generation systems was based on the review of 19 life cycle assessment studies (representing 66 biomass cases). The mean life cycle GHG emissions resulting from the use of agriculture residues (N = 4), dedicated energy crops (N = 19), forestry (N = 6), industry (N = 4), and wastes (N = 2) in biomass-only electricity generation systems are 291.25 gCO2e/kWh, 208.41 gCO2e/kWh, 43 gCO2e/kWh, 45.93 gCO2e/kWh, and 1731.36 gCO2e/kWh, respectively. The mean life cycle GHG emissions for cofiring electricity generation systems using agriculture residues (N = 10), dedicated energy crops (N = 9), forestry (N = 9), industry (N = 2), and parks and gardens (N = 1) are 1039.92 gCO2e/kWh, 1001.38 gCO2e/kWh, 961.45 gCO2e/kWh, 926.1 gCO2e/kWh, and 1065.92 gCO2e/kWh, respectively. Forestry and industry (avoiding the impacts of biomass production and emissions from waste management) contribute the least amount of GHGs, irrespective of the biomass electricity generation system.
The decarbonization of the economy will require large quantities of biomass for energy and biomaterials. This biomass should be produced in sufficient quantities and in a sustainable way. Perennial crops in particular are often cited in this context as having low environmental impacts. One example of such crops is miscanthus, a tall perennial rhizomatous C4 grass with high yield potential. There are many studies which have assessed the global warming potential (GWP) of miscanthus cultivation. This is an important impact category which can be used to quantify the environmental benefit of perennial crops. However, the GWP only describes one impact of many. Therefore, the hypothesis of this study was that a holistic assessment also needs to include other impact categories. A life cycle assessment (LCA) with a normalization step was conducted for perennial crops to identify relevant impact categories. This assessed the environmental impact of both miscanthus and willow cultivation and the subsequent combustion for heat production in eighteen categories using a system expansion approach. This approach enables the inclusion of fossil reference system hot spots and thus the evaluation of the net benefits and impacts of perennial crops. The normalized results clearly show the benefits of the substitution of fossil fuels by miscanthus or willow biomass in several impact categories (e.g. for miscanthus: climate change -303.47 kg CO2 eq./MWhth; terrestrial acidification: -0.22 kg SO2 eq./MWhth). Negative impacts however occur, for example, in the impact categories marine ecotoxicity and human toxicity (e.g. for miscanthus: +1.20 kg 1.4-DB eq./MWhth and +68.00 kg 1.4-DB eq./MWhth, respectively). The results of this study clearly demonstrate the necessity of including more impact categories than the GWP in order to be able to assess the net benefits and impacts of the cultivation and utilization of perennial plants holistically.
This paper presents for the first time an integrated life cycle sustainability assessment of the electricity sector in Turkey, considering environmental, economic and social aspects. Twenty life cycle sustainability indicators (11 environmental, three economic and six social) are used to evaluate the current electricity options. Geothermal power is the best option for six environmental impacts but it has the highest capital costs. Small reservoir and run-of-river power has the lowest global warming potential while large reservoir is best for the depletion of elements and fossil resources, and acidification. It also has the lowest levelised costs, worker injuries and fatalities but provides the lowest life cycle employment opportunities. Gas power has the lowest capital costs but it provides the lowest direct employment and has the highest levelised costs and ozone layer depletion. Given these trade-offs, a multi-criteria decision analysis has been carried out to identify the most sustainable options assuming different stakeholder preferences. For all the preferences considered, hydropower is the most sustainable option for Turkey, followed by geothermal and wind electricity. This work demonstrates the importance for energy policy of an integrated life cycle sustainability assessment and how tensions between different aspects can be reconciled to identify win-win solutions.
This paper reviews and assesses conditions for increased and efficient use of biomass in Central America (CA), providing an overview of conditions for biomass supply in each country. Then, a Fuzzy Multi-Actor Multi-Criteria Decision-Making (MCDM) method is applied to identify a portfolio of biomass conversion technologies appropriate for CA, considering technical, economic, environmental and socio-political aspects. The work is motivated by the relatively large availability of biomass in CA at the same time as current conversion of biomass is carried out in inefficient processes. The assessment of technologies includes thermochemical processes (pyrolysis, combustion and gasification) for production of different energy carriers, including improved cooking stoves (ICSs).
Bioenergy (i.e., bioheat and bioelectricity) could simultaneously address energy insecurity and climate change. However, bioenergy’s impact on climate change remains incomplete when land use changes
(LUC), soil organic carbon (SOC) changes, and the auxiliary energy consumption are not accounted for in the life cycle. Using data collected from Belgian farmers, combined heat and power (CHP) operators, and a life cycle approach, we compared 40 bioenergy pathways to a fossil-fuel CHP system. Bioenergy required between 0.024 and 0.204 MJ (0.86 MJth + 0.14 MJel)1, and the estimated energy ratio (energy output-to-input ratio) ranged from 5 to 42. SOC loss increased the greenhouse gas (GHG) emissions of residue based bioenergy. On average, the iLUC represented 67% of the total GHG emissions of bioenergy from perennial energy crops. However, the net LUC (i.e., dLUC + iLUC) effects substantially reduced the GHG emissions incurred during all phases of bioenergy production from perennial crops, turning most pathways based on energy crops to GHG sinks. Relative to fossil-fuel based CHP all bioenergy pathways
reduced GHG emissions by 8–114%. Fluidized bed technologies maximize the energy and the GHG benefits of all pathways. The size and the power-to-heat ratio for a given CHP influenced the energy and GHG
performance of these bioenergy pathways. Even with the inclusion of LUC, perennial crops had better GHG performance than agricultural and forest residues. Perennial crops have a high potential in the multidimensional approach to increase energy security and to mitigate climate change. The full impacts of bioenergy from these perennial energy crops must, however, be assessed before they can be deployed on a large scale.
Turkey has great potential with respect to renewable energy sources (RES) and, among such sources, “biomass energy” is of particular importance. The purpose of this study is to determine the primary electrical energy potential obtainable from the biomass potential, according to different biomass source types. In this study, the biomass sources of municipal solid wastes, energy crops, animal manure and urban wastewater treatment sludge are evaluated. For each source, individual biogas and biomass energy potential calculations are made. Methods for energy conversion from wastes applicable to the conditions of Turkey, and technical and economic parameters are used. As a result of the calculations made, the total primary energy value of biogas obtainable from the examined sources is 188.21 TWh/year. The total primary energy value related to the potential of the evaluated biomass sources is 278.40 TWh/year.
This paper presents for the first time the life cycle environmental impacts of electricity generation from fossil fuel power plants in Turkey which supply three quarters of national demand. There are 16 lignite, eight hard coal and 187 gas power plants in Turkey, all of which are considered in the study. The results suggest that electricity generation from gas has the lowest impacts for 10 out of 11 impacts considered. However, its ozone layer depletion is 48 times higher than for lignite and 12 times greater than for hard coal electricity. Lignite is the worst option overall, with eight impacts higher than for hard coal, ranging from 11% higher fossil fuel depletion to six times greater freshwater ecotoxicity. Conversely, its depletion of elements and ozone layer are four times lower than for hard coal; global warming is 6% lower. Most impacts are mainly caused by the operation of power plants and transportation of imported fuels. Annually, electricity generation from fossil fuels emits 109 Mt CO2-eq. and depletes 1660 PJ of primary fossil energy. These and the majority of other impacts are from lignite and hard coal power, despite the gas plants generating almost three and five times more electricity, respectively. Therefore, reducing the share of lignite and hard coal power and expanding the contribution of natural gas would lead to significant reductions of environmental impacts from the electricity sector in Turkey, including greenhouse gas emissions; however, ozone layer depletion would increase substantially.
Financial incentives in many European countries have led to a surge in anaerobic digestion (AD) installations to produce heat and/or electricity from biogas. This paper presents the life cycle environmental impacts of a system producing biogas from agricultural wastes by AD and co-generating heat and electricity in a combined heat and power (CHP) plant. The results suggest that this can lead to significant reductions in most impacts compared to fossil-fuel alternatives, including the global warming potential (GWP) which can be reduced by up to 50%. However, the acidification and eutrophication potentials are respectively 25 and 12 times higher than for natural gas CHP. The impacts are influenced by the type and source of feedstock, digestate storage and its application on land. Using energy crops such as maize instead of waste reduces the GWP owing to higher biogas yields, but eight out of 11 impacts increase compared to using waste feedstocks. If digestate is not used to displace artificial fertilisers, the majority of impacts are higher than from natural gas CHP. Some other bioenergy options have lower GWP than energy from biogas, including woodchip CHP plants. Implications for policy are discussed based on the results of the study.
1 IntroductionSociety of Environmental Toxicology and Chemistry(SETAC) has published a code of practice for environmentallife-cycle costing (LCC), which provides a framework forevaluating decisions with consistent, but flexible systemsboundaries as a component of product sustainabilityassessments (Swarr et al. 2011). The code of practicebuilds on an earlier monograph that summarized 3 years ofeffort by the SETAC-Europe Working Group on Life-Cycle Costing (Hunkeler et al.2008).Thecodeofpracticeis grounded in a conceptual framework for life-cyclesustainability assessment (LCSA) of products that usesdistinct analyses for each of the three pillars of sustainability,environment, economy, and social equity.LCSA ¼ LCAþ LCCþ SLCA ð1ÞLife-cycle assessment (LCA) is the only pillar that has beenstandardized to date (ISO 2006a, b). UNEP (2009)haspublished guidelines for social LCAs and is currentlydeveloping methodological sheets for impact subcategories.The code of practice reviews historical development of life-cycle methods, outlines the technical requirements and guide-lines for LCC, and illustrates various methodological choiceswith a detailed case study. The objective of the code of practiceis to provide readers with a solid understanding of how to applyLCC in parallel with LCA to stimulate additional case studiesand peer-reviewed research to further refine the methodology.The ultimate goal is to build consensus for an internationalstandard that parallels the ISO 14040 standard for LCA.2 DiscussionLCC predates LCA, and distinct and different conceptualfoundations and methodological approaches can betraced to its developmental roots in systems engineering(Blanchard 1978). There has been limited integration ofthese methods, although the value of LCC for sustainabilityassessmentshasbeenrecognized(Norris2001;Hunkelerand
Perennial grasses have received particular attention as bioenergy crops in recent years due to their high biomass productivity and environmental benefits. The objective of the present study was to compare four perennial grasses: miscanthus (Miscanthus x giganteus Keng), switchgrass (Panicum virgatum L.), giant reed (Arundo donax L.), and bulbous canary grass (Phalaris aquatica L.) in terms of biomass yield, energy balance, and biomass quality under four nitrogen fertilization rates (0, 100, 150, 200 kg ha-1 y-1) and 2 harvest times (autumn, winter) over three growing seasons in the Mediterranean environment of Turkey. The crop biomass and net energy yields were optimized with none or 100 kg ha-1 y-1 N input in the study. Although the winter harvest resulted in significant yield reductions in all of the grass species, it improved the biomass quality of miscanthus, switchgrass, and giant reed due to reduced moisture and ash contents. On the contrary, the autumn harvest resulted in a considerably lower moisture and ash contents in bulbous canary grass, mainly because of leaf defoliation the during summer dormancy period. Giant reed produced the highest average biomass yield (between 12.86 and 36.78 t ha-1) over the three years, followed by miscanthus (between 12.75 and 23.54 t ha-1), switchgrass (be-tween 11.88 and 18.91 t ha-1), and bulbous canary grass (between 5.21 and 10.83 t ha-1). On the other hand, bulbous canary grass provided the highest average energy ratio (19.7-64.5) over the three years, due mainly to a lack of energy input for irrigation. These results suggest that satisfactory biomass production can be achievable from miscanthus, switchgrass, and giant reed in the semi-arid Mediterranean environment under adequate moist conditions, but the irrigation requirement increases the energy cost, thus decreasing the energy ratio. In this respect, bulbous canary grass may be evaluated as an alternative bioenergy crop in the dry marginal lands of Mediterranean for sustainable biomass production.
The concerns related to the environmental impact related to energy production from fossil fuel are increasing. In this context, the substitution of fossil fuel based energy by bio-energy can be an effective solution. In this study, the production of electricity and heat in Italy in a combined heat and power plant (CHP) based on an Organic Rankine Cycle (ORC) turbine from wood based biomass both from forest and agricultural activities has been analysed considering four potential alternative scenarios to the current energy status: biomass from very short rotation forestry (VSRF) poplar and willow stands as well as residues from natural forests and from traditional poplar plantations. The evaluation has been performed by applying Life Cycle Assessment (LCA) method and an attributional cradle-to-gate approach has been followed. The expected savings of greenhouse gases emission and fossil fuels demand have been quantified, as well as derived emissions of toxic pollutants and substances responsible for acidification, eutrophication and photochemical oxidant formation.The results have been also compared with the conventional Italian scenario considering the current Italian electricity profile and heat production from natural gas. Among the different scenarios, due to the lower transport distance, the use of biomass from traditional poplar plantation residues shows the lowest impact. The biomass combustion emissions are the main hotspot for several evaluated impact categories (e.g., particulate matter formation, human toxicity). In fact, when the produced bio-energy is compared to the reference system (i.e., electricity produced under the Italian electric profile) the results do not favor bio-energy systems. The results reported in this study support the idea that forest residues would be an interesting and potential feedstock for bio-energy purposes although further research is required specifically with the aim of optimizing biomass supply distances.
A modeling process was developed to examine the economic and environmental benefits of utilizing energy crops for bioenergy products in the northeastern United States. Three energy crops (hybrid willow, switchgrass, and Miscanthus) that can potentially grow on marginal agricultural land or abandoned mine land in the region were considered in the analytical process for the production of biofuels, biopower, and pellet fuel. The supply chain components for the economic analysis and life cycle modeling processes included feedstock establishment, harvest, transportation, storage, preprocessing, conversion, distribution, and final usage of the bioenergy products. Sensitivity analysis was conducted to assess the effects of energy crop yield, transportation distance, conversion rate, facility capacity, and internal rate of return (IRR) on the production of bioenergy products. The required selling price (RSP) ranged from 47.9/GJ for different bioenergy products. The production of biopower had the highest RSP and pellet fuel had the lowest RSP. The results also indicated that bioenergy production using hybrid willow demonstrated lower RSP than the other two perennial grasses. Pellet production had presented the lowest greenhouse gas (GHG) emissions (less than 10 kg CO2 eq per 1000 MJ) and fossil energy consumption (less than 150 MJ per 1000 MJ). The production of biofuel resulted in the highest GHG emissions. Sensitivity analysis indicated that IRR was the most sensitive factor to RSP, followed by conversion rate for biofuel and biopower production. Fuel conversion efficiency and feedstock transport distance had a significant effect on the life cycle environmental impact of the bioenergy products studied.
Combined bioheat and biopower (CBHBP) is named to emphasize that a biomass source is used as the feedstock for the production of combined heat and power (CHP). Turkey is a country with rich biomass potential; however, traditional utilization is predominant. The purpose of this paper is to describe the entire value chain of biomass-to-biopower by focusing on the current commercial technologies in the world and to provide an alternative solution for modern utilization of solid biomass sources in Turkey, while being a reference for other countries interested in biopower. The first aim is to explore the major conversion technologies for CBHBP production considering the entire value chain of biomass-to-biopower, with a focus on the most established path applied to solid biomass sources worldwide. The next aim is to examine the status of biomass energy in Turkey, concentrating on current biopower applications.
On a global scale, bioenergy is highly relevant to renewable energy options. Unlike fossil fuels, bioenergy can be carbon neutral and plays an important role in the reduction of greenhouse gas emissions. Biomass electricity and heat contribute 90% of total final biomass energy consumption, and many reviews of biofuel Life Cycle Assessments (LCAs) have been published. However, only a small number of these reviews are concerned with electricity and heat generation from biomass, and these reviews focus on only a few impact categories. No review of biomass electricity and heat LCAs included a detailed quantitative assessment. The failure to consider heat generation, the insufficient consideration of impact categories, and the missing quantitative overview in bioenergy LCA reviews constitute research gaps. The primary goal of the present review was to give an overview of the environmental impact of biomass electricity and heat. A systematic review was chosen as the research method to achieve a comprehensive and minimally biased overview of biomass electricity and heat LCAs. We conducted a quantitative analysis of the environmental impact of biomass electricity and heat. There is a significant variability in results of biomass electricity and heat LCAs. Assumptions regarding the bioenergy system and methodological choices are likely reasons for extreme values. The secondary goal of this review is to discuss influencing methodological choices. No general consensus has been reached regarding the optimal functional unit, the ideal allocation of environmental impact between co-products, the definition of the system boundary, or how to model the carbon cycle of biomass. We concluded that a higher level of transparency and a harmonisation of the preparation of biomass electricity and heat LCAs are needed to improve the comparability of such evaluations.
The technical, environmental and economic analysis of two small scale biomass fuelled CHP applications is the subject of this study. For this analysis, the process simulation software ECLIPSE is used. Modelling and simulation have been conducted over two configurations: Organic Rankine Cycle (ORC) based and biomass gasification based systems for generating heat and electricity. The nominal power outputs of both systems are given at around 150 kWe. Based on the results achieved, the key technical and environmental issues have been examined. The study also investigates the impact of different biomass feedstock on the performance of CHP systems. Finally, an economic evaluation of the system is performed. According to the ECLIPSE simulation, the overall efficiencies of the ORC based CHP system are around 76% when willow chip was used and around 81% with miscanthus. The difference was found to be due to the moisture content. For the biomass gasification based CHP system, the overall efficiencies of CHP were found to be around 58% with willow chip and 64% with miscanthus. These values are better than for any other biomass-fired electricity generation technologies of similar scale. On the other hand, the results of the economic analysis demonstrated that the breakeven electricity selling price (BESP) for the ORC-CHP systems varies from 40 to 50 pound/MW h and for the biomass gasification based CHP systems was between 87 and 97 pound/MW h. These values could be further improved if agricultural or forestry wastes could be used at lower costs.
In this paper, the life cycle environmental performance of miscanthus gasification for electricity production in Denmark is evaluated and compared with that of direct combustion and anaerobic digestion. Furthermore, the results obtained are compared to those of natural gas to assess the potential of miscanthus as an energy source. Our results indicate that production of 1 kWh electricity from miscanthus via gasification leads to a global warming potential (100-year GWP) of 26 g and 296 g CO2e, without and with consideration of CO2 emissions from indirect land use change respectively. For other impact categories, the production results in non-renewable energy use of 0.6 MJ primary, acidification of 1.6 g SO2e, eutrophication of 7.8 g NO3e and respiratory inorganics of 0.1 g PM2.5e. Of the three alternatives, gasification is found to have the best performance in all impact categories considered, with the exception of non-renewable energy use where anaerobic digestion performs best. Our results also show that replacing natural gas with miscanthus reduces global warming and non-renewable energy use. The results of the study are region-specific, i.e., valid for Denmark, but we believe that the general conclusions are applicable to those regions/areas with similar conditions.
Sweden has the potential to increase fuel pellet production from alternative raw materials, such as willow and poplar, and also to use former agricultural land for energy crop production. This study used a life cycle perspective to investigate district heat production from pellets produced from willow or poplar cultivated on fallow land in Sweden. The energy efficiency and global warming potential of the systems was evaluated, additionally was the climate impact, expressed in global mean surface temperature change, evaluated from annual greenhouse gas data, including the most relevant fossil and biogenic sources and sinks. The systems were also compared with a fossil fuel alternative in which coal was assumed to be used for heat production. The results showed that the systems investigated had a cooling effect on both global mean surface temperature and global warming potential within the 100-year study period owing mainly to an increase in live biomass and a more long-term increase in soil organic carbon (C), which shows the importance of land use. At the same time, the systems produced renewable energy. The poplar system contributed to a larger cooling effect than the willow system due to more C being sequestered in live biomass and soil in the longer growth periods between harvests and to higher yield. The energy efficiency of the willow and poplar systems used for pellet fuel production was about 11 times the energy input.
Forest biomass is a renewable source that has the potential to substitute fossil fuels in many applications, from the generation of bioenergy (heat, electricity or transportation fuels) to the production of bioproducts (chemicals and other materials). The increased use of forest biomass could support the reduction of anthropogenic carbon emissions to the environment and could help forest-dependent communities achieve energy independence while generating jobs. The viability and feasibility of generating valuable products from forest biomass depend on ensuring the long-term availability of biomass supply with the required quality at a competitive cost. This calls for a cost-efficient design of the forest biomass supply chain. Social and environmental aspects have to be considered in the design as well to guarantee sustainable use of this renewable resource. In this paper, we present a review of studies that assessed or optimized economic, social and environmental aspects of forest biomass supply chains for the production of bioenergy and bioproducts. The majority of studies so far considered either economic (techno-economic and optimization studies) or environmental (life cycle assessment studies) aspects of bioenergy projects. Nevertheless, there is a recent trend to integrate economic, environmental and social aspects in the assessment and optimization of forest biomass supply chains. Combined approaches integrating multi-objective optimization and life cycle assessment have started to flourish. In these studies, GHG emissions are the most frequently used environmental indicator, production and capital costs are the preferred economic measures and the number of created jobs is the most considered social criterion. Further research has to be done to study and assess the potential social impacts of using forest biomass. There is a need for further development of decision support tools that consider economic, environmental and social criteria to aid the design and planning of forest biomass supply chains.
Gasification of Miscanthus x giganteus (MxG) was conducted in an air-blown bubbling fluidized bed (BFB) gasifier using magnesite as bed material and a moderate rate of biomass throughput (246.82–155.77 kg/m2h). The effect of equivalence ratio (ER) (0.234–0.372) and bed temperature (645–726 °C) on the performance of gasification was investigated. The results reveal that MxG is a promising candidate for energy production via BFB gasification; of the conditions tested, the optimal ER and temperature are approximately 0.262 and 645 °C, where no sign of agglomeration was found. The product gas from this condition has a higher heating value of 6.27 MJ/m3, a gas yield of 1.65 N m3/kgbiomass (39.5% of CO and 18.25% of H2 on N2 free basis), a carbon conversion efficiency of 94.81% and a hot gasification efficiency of 78.76%. Agglomeration was observed at some higher temperature conditions and believed to be initiated by the formation of fuel-ash derived low melting temperature K-rich (potassium) silicates (amorphous material that cannot be detected by XRD). It is suggested that relatively low temperature (650 °C) needs to be used for the gasification of MxG to avoid potential agglomeration.
Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source of biomass to contribute to renewable energy goals. The aim of this study is to evaluate the energy requirements and environmental impacts associated with willow (Salix sp.) cultivation, harvest, and transport using life cycle assessment (LCA). In this study, only emissions from the production of the willow chip are included, end-use emissions from combustion are not considered. In this LCA study, three impact categories are considered; acidification potential, eutrophication potential and global warming potential. In addition, the cumulative energy demand and energy ratio of the system are evaluated. The results identify three key processes in the production chain which contribute most to all impact categories considered; maintenance, harvest and transportation of the crop. Sensitivity analysis on the type of fertilizers used, harvesting technologies and transport distances highlights the effects of these management techniques on overall system performance. Replacement of synthetic fertilizer with biosolids results in a reduction in overall energy demand, but raises acidification potential, eutrophication potential and global warming potential. Rod harvesting compares unfavourably in comparison with direct chip harvesting in each of the impact categories considered due to the additional chipping step required. The results show that dedicated truck transport is preferable to tractor-trailer transport in terms of energy demand and environmental impacts. Finally, willow chip production compares favourably with coal provision in terms of energy ratio and global warming potential, while achieving a higher energy ratio than peat provision but also a higher global warming potential.
Life cycle energy and environmental performances of nine different biomass/coal co-firing pathways to power generation were compared. Agricultural residue (AR), forest residue (FR), and whole trees (WT) as feedstock were analyzed for direct (DC) and parallel co-firing (PC) in various forms (e.g., chip, bale and pellet). Biomass co-firing rate lies in the range of 7.53–20.45% (energy basis; rest of the energy comes from coal) for the co-firing pathways, depending on type of feedstock and densification. Net energy ratios (NER) for FR-, WT-, and AR-based co-firing pathways were 0.39–0.42, 0.39–0.41, and 0.37–0.38, greenhouse gas (GHG) emissions were 957–1004, 967–1014, and 1065–1083 kg CO2eq/MWh, acid rain precursor (ARP) emissions were 5.16–5.39, 5.18–5.41, and 5.77–5.93 kg SO2eq/MWh, and ground level ozone precursor (GOP) emissions were 1.79–1.89, 1.82–1.93, and 1.88–1.91 kg (NOx + VOC)/MWh, respectively. Biomass/coal co-firing life cycle results evaluated in this study are relevant for any jurisdiction around the world.
Since economic profitability is the most important factor for the adoption of short rotation coppice (SRC)
for energy from biomass, our objective was to analyze and summarize published knowledge about the
economic evaluation of SRC. Of 37 studies, 43% reported economic viability of SRC in comparison to a
reference system; whereas 19% stated economic disadvantages of SRC, and 38% reported mixed results,
depending on the underlying assumptions. We found a wide variety of underlying assumptions,
underlying costs, process chains and methods used to evaluate SRC systems. Of the 37 studies, 8% used
static approaches of capital budgeting ,84% used dynamic approaches and 8% applied approaches in
which uncertainties were taken into account. Due to the long-term nature of investment in SRC, and
therewith, the uncertain development of sensitive assumptions, approaches which consider uncertain-
ties were best suited for economic evaluation. The profitability of SRC was found to be most sensitive to
the price for biomass and biomass yield, but site-specific biomass data was lacking. Despite the wide
variation within each cost unit,costs for land rent, harvesting, chipping, and establishment consistently
made up the largest proportion of overall costs, and should therefore, be chosen carefully. We close with
suggestions for improving the economic evaluation of SRC and enhancing trace ability and comparability
of calculations.
Bioenergy and energy crops are an important part of the UK’s renewable energy strategy to reach its greenhouse gas reduction target of 80% by 2050. Ensuring the sustainability of biomass feedstocks requires a greater understanding of all aspects of energy crop production, their ecological impacts and yields. This work compares the life-cycle environmental impact of natural gas and biomass from two energy crop systems grown under typical UK agronomic practice. As reported in previous studies the energy crops provide significant reductions in global warming potential (GWP) compared to natural gas. Compared to no fertiliser application, applying inorganic fertiliser increases the GWP by 2% and applying sewage sludge increases the GWP by a lesser extent. In terms of an equivalent GWP savings per unit area of land, the emissions associated with fertiliser production and application can be offset by a yield increase of
Energy crops are expected to greatly develop in a very short-term bringing to significant social and environmental benefits. Nevertheless, a significant number of studies report from very positive to negative environmental implications from growing and processing energy crops, thus great uncertainty still remains on this argument. The present study focused on the cradle-to-grave impact assessments of alternative scenarios including annual and perennial energy crops for electricity/heat or first and second generation transport fuels, giving special emphasis to agricultural practices which are frequently surprisingly neglected in Life Cycle Assessment studies despite a not secondary relevance on final outcomes. The results show that cradle-to-farm gate impacts, i.e. including the upstream processes, may account for up to 95% of total impacts, with dominant effects on marine water ecotoxicity. Therefore, by increasing the sustainability of crop management through minimizing agronomic inputs, or with a complementary use of crop resides, can be expected to significantly improve the overall sustainability of bioenergy chains, as well as the competitiveness against fossil counterparts. Once again, perennial crops resulted in substantially higher environmental benefits than annual crops. It is shown that significant amount of emitted CO2 can be avoided through converting arable lands into perennial grasslands. Besides, due to lack of certain data, soil carbon storage was not included in the calculations, while N2O emission was considered as omitted variable bias (1% of N-fertilization). Therefore, especially for perennial grasses, CO2 savings were reasonably higher that those estimated in the present study. For first generation biodiesel, sunflower showed a lower energy-based impacts than rapeseed, while wheat should be preferred over maize for first generation bioethanol given its lower land-based impacts. For second generation biofuels and thermo-chemical energy, switchgrass provided the highest environmental benefits. With regard to bioenergy systems, first generation biodiesel was less impacting than first generation bioethanol; bioelectricity was less impacting than first generation biofuels and second generation bioethanol by thermo-chemical hydrolysis, but highly impacting than Biomass-to-Liquid biodiesel and second generation bioethanol through enzymatic hydrolysis.
Through the Renewable Energies Plan 2000–2010, Spain has fixed the objective of covering 12% of the primary energy demand from renewable sources. The achievement of this objective implies an annual increase of 22.4% of the energy produced from renewable sources. In this context, the objective of this study is to determine if the electricity from biomass produced in Spain would be environmentally competitive with electricity from natural gas or from the Spanish electricity mix. For that, the environmental impacts associated to the whole life cycle of two energetic crops in Spain, Poplar and Ethiopian mustard, used for power generation were evaluated. The overall assessment includes the cultivation and collection of biomass, its transport and the processes of its energetic transformation. We calculated different scenarios of electricity production from biomass in different capacity power plants (10, 25 or 50 MW), different transport scenarios and different productivities for biomass production. Our results show that, given the assumptions of this study, Ethiopian mustard is more impacting than Poplar when used for electricity production. Also, the transportation of biomass from the field to the power plant is an important stage that has to be carefully planned in order to get the maximum amount of electricity with a minimum environmental impact. Compared to electricity from natural gas or the Spanish electricity mix, the electricity obtained from biomass is more impacting in three from six impact categories we present here.
The economic feasibility of biomass based combustion projects of various capacities to generate electricity from rice straw is evaluated for Thailand. For an assumed lifespan of 20 years, rice straw-fueled combustion facilities would generate Net Present Values (NPV) of −3.15, 0.94, 2.96, 9.33, and 18.79 million USD for projected 5, 8, 10, 15, and 20 MWe plants, respectively. Examining the effects of scale on the cost of generated electricity (COE) over the considered range of capacities indicates that COE varies from 0.0676 USD/kWh at 20 MWe to 0.0899 USD/kWh at 5 MWe. By scaling up the power plants, the variations of the financial parameters, namely NPV values, become less sensitive to the critical variables. As an example, if the fuel price, selling price of electricity, and the plant factor change by +36% (31.0 USD/t), −16% (0.0758 USD/kWh), and −14% (5650 h/yr), respectively, the largest scale project is still appealing for investment. Nevertheless, to ensure a secure fuel supply, smaller scale power plants, i.e., 8 and 10 MWe may be more practicable. A further sensitivity analysis is discussed in terms of the financial feasibility of the projects (i.e., NPV ⩾ 0), and the investment appraisal condition (here, Internal Rate of Return or IRR ⩾ 11%).Highlights► A cost correlation model is developed to investigate the capital cost of straw-based power plants. ► Economic criteria for plant capacities of 5, 8, 10, 15, and 20 MWe are evaluated. ► COE for such systems is 0.0676 USD/kWh at 20 MWe rising to 0.0899 USD/kWh at 5 MWe. ► NPV is greatly influenced by the economies of scale. ► Changes in plant factors, electricity prices, fuel prices, and capital costs are examined.
The aim of this work was to assess the environmental consequences of anaerobic mono- and co-digestion of pig manure to produce bio-energy, from a life cycle perspective. This included assessing environmental impacts and land use change emissions (LUC) required to replace used co-substrates for anaerobic digestion. Environmental impact categories considered were climate change, terrestrial acidification, marine and freshwater eutrophication, particulate matter formation, land use, and fossil fuel depletion. Six scenarios were evaluated: mono-digestion of manure, co-digestion with: maize silage, maize silage and glycerin, beet tails, wheat yeast concentrate (WYC), and roadside grass. Mono-digestion reduced most impacts, but represented a limited source for bio-energy. Co-digestion with maize silage, beet tails, and WYC (competing with animal feed), and glycerin increased bio-energy production (up to 568%), but at expense of increasing climate change (through LUC), marine eutrophication, and land use. Co-digestion with wastes or residues like roadside grass gave the best environmental performance.
A parametric study of the gasification of four feedstocks (corn stover, switchgrass, wheat straw, and wood) has been performed on an experimental, pilot-scale (0.5 ton/day) gasification facility. A comparison was made of the performance of the gasifier as a function of feedstock, in terms of the syngas production and composition. In these experiments, pelletized feedstock was used, so that the shapes and sizes of the materials did not influence the results. A total of 22 statistically designed experimental conditions were examined for each feedstock, including the effects of varying the temperature of the fluidized bed, the temperature of the secondary thermal cracker, and the steam-to-biomass ratio. For each experimental condition, the permanent-gas composition was measured continuously by gas chromatography (GC). Tars were measured continuously using a molecular-beam mass spectrometer (MBMS). Sulfur analysis by GC was also conducted for three of the feedstocks studied. The results from this study show that there were significant differences between the feedstocks studied in terms of light gases formed, but less apparent variation in tar formation. In general, the variations in products were smaller at higher temperatures. A preliminary analysis of gasifier efficiency was performed using an Aspen Plus process model for selected gasification conditions. Finally, a comparison was made between the results of this work and other similar biomass gasification studies.
Short-rotation woody crops (SRWC) such as poplar and willow are an important source of renewable energy. They can be converted into electricity and/or heat using conventional or modern biomass technologies. In recent years many studies have examined the energy and greenhouse gas (GHG) balance of bioenergy production from poplar and willow using various approaches. The outcomes of these studies have, however, generated controversy among scientists, policy makers, and the society. This paper reviews 26 studies on energy and GHG balance of bioenergy production from poplar and willow published between 1990 and 2009. The data published in the reviewed literature gave energy ratios (ER) between 13 and 79 for the cradle-to-farm gate and between 3 and 16 for cradle-to-plant assessments, whereas the intensity of GHG emissions ranged from 0.6 to 10.6 g CO2 Eq MJbiomass−1 and 39 to 132 g CO2 Eq kWh−1. These values vary substantially among the reviewed studies depending on the system boundaries and methodological assumptions. The lack of transparency hampers meaningful comparisons among studies. Although specific numerical results differ, our review revealed a general consensus on two points: SRWC yielded 14.1–85.9 times more energy than coal (ERcoal∼0.9) per unit of fossil energy input, and GHG emissions were 9–161 times lower than those of coal (GHGcoal∼96.8). To help to reduce the substantial variability in results, this review suggests a standardization of the assumptions about methodological issues. Likewise, the development of a widely accepted framework toward a reliable analysis of energy in bioenergy production systems is most needed.
Life cycle assessment (LCA) methodology is increasingly used to determine the potential environmental impacts of biofuels and bioenergy. This paper presents the outcomes of screening LCAs of 13 future energy crops for Europe summarizing the results of the EC-funded project 4F CROPS – Future Crops for Food, Feed, Fiber and Fuel. For analysis, these dedicated energy crops – representing seven environmental zones in Europe – are combined with a multitude of processing and utilization options, resulting in 120 different biofuel and bioenergy chains. Compared to fossil fuels and energy carriers, all biofuel and bioenergy chains show environmental advantages in terms of life-cycle energy use and greenhouse gas (GHG) emissions but mostly disadvantages regarding other environmental impact categories. Quantitative results vary widely across environmental zones, depending on crop species, agricultural inputs, and yield. Moreover, coproduct accounting and coproduct utilization, as well as the agricultural and fossil reference system play an important role. In view of environmental advantages and disadvantages, subjective trade-offs are required between the environmental impact categories. If saving GHG emissions is given the highest environmental priority, combined heat and power generation from herbaceous lignocellulosic crops is the most efficient option in terms of land use, provided that the biomass is cultivated on surplus agricultural land, thus avoiding indirect land-use change. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd
Two commercial and representative plantations of poplar located in the Po Valley (Italy) under very short rotation (VSRC) and short rotation (SRC) regimes dedicated to biomass production for energy purposes have been analysed to identify their environmental effects and to define the best option for a biomass production system. The standard framework of Life Cycle Assessment (LCA) was followed in this study and detailed inventories for both regimes were provided. The environmental profile was analysed in terms of abiotic depletion, acidification, eutrophication, global warming, ozone layer depletion, photochemical oxidants formation, human toxicity and ecotoxicity. In addition, an energy analysis was performed using the cumulative energy demand method. Differences were identified in terms of biomass yield, fertilizers requirement as well as intensive agricultural activities and, according to the results, SRC presents the best environmental profile in seven of the eleven environmental impacts assessed. The key processes in both regimes were: nutrient application and agricultural activities such as mechanical weed control, harvesting and biomass collection due to the energy consumption and derived emissions. Improvement alternatives were proposed based on these results and two sensitivity analyses were carried out based on the use of only cattle manure as nutrient input under a VSRC regime and on the increment of biomass yield in the future (2020 and 2030 seasons) due to better clones but under an SRC regime. As a general conclusion, in a short period of time, poplar plantations dedicated to energy purposes should be driven towards SRC regimes instead of VSRC.
The sustainability of electricity generation from biomass has been assessed in this work according to the key indicators of price, efficiency, greenhouse gas emissions, availability, limitations, land use, water use and social impacts. Biomass produced electricity generally provides favourable price, efficiency, emissions, availability and limitations but often has unfavorably high land and water usage as well as social impacts. The type and growing location of the biomass source are paramount to its sustainability. Hardy crops grown on unused or marginal land and waste products are more sustainable than dedicated energy crops grown on food producing land using high rates of fertilisers.
Purpose
Ambitious targets for the use of renewable energy have recently been set in the European Union. To reach these targets, a large share of future energy generation will be based on the use of woody biomass. Therefore, there is an increasing interest in the cultivation of fast-growing tree species on agricultural land outside forests. Intensive crop production is always considered to harm the environment. The study explores the environmental burdens of the cultivation of fast-growing tree species on agricultural land and their subsequent energetic conversion in comparison to the fossil reference energy system.
Methods
Life cycle assessment (LCA) methodology according to the ISO 14040 and 14044 is used. Input data were partly collected within the German joint research project AGROWOOD. Two utilization paths of short rotation poplar chips are analyzed: heat and power generation in a cogeneration plant and the production of Fischer–Tropsch (FT) diesel. Subsequently, the bioenergy systems are compared with their fossil references.
Results and discussion
The production and distribution of 1 oven dry tonne (odt) of short-rotation poplar chips require 432 MJ non-renewable energy. This equals an output–input ratio of 43:1, which includes all process steps from field preparation to road transport. Emissions of this energy use amount to a global warming potential of 38.4 kg CO2 eq odt-1, an acidification potential of 0.24 kg SO2 eq odt-1, and a eutrophication potential of 0.04 kg PO4 eq odt-1. The greatest reductions of environmental impacts can be achieved by substituting power from lignite with cogenerated power from short-rotation coppice (SRC). Compared with the average German power generation mix GWP and AP of power generation from short rotation poplar chips are lower by 97% and 44%, respectively, while eutrophication potential is about 26% higher. FT diesel made from short-rotation poplar chips has an 88% lower global warming potential and a 93% lower acidification potential than fossil diesel. But, the eutrophication potential of FT diesel is twice as high as of fossil diesel.
Conclusions
It was found that even intensively produced wood from SRC can reduce environmental burdens if it is used for biofuel instead of fossil fuel. The utilization of the same amount of short-rotation poplar chips for heat and power production causes fewer environmental impacts than its use for FT diesel.
Co-firing biomass with coal is being increasingly seen in the EU region as an option that could contribute not only towards
reaching the Kyoto targets on greenhouse gas emissions but also towards compliance with the EU directives on renewable energy
and large combustion plants. Perennial grasses, short rotation coppice, seasonal agricultural residues and waste forestry
wood are all considered as viable alternatives. However, although the use of biomass for electricity generation could help
reduce direct emissions of pollutants generated during combustion of coal, including carbon dioxide, sulphur dioxide and nitrogen
oxides, the whole life cycle implications of using biomass are less clear. This paper uses a life cycle approach to evaluate
the environmental impacts and economic costs of co-firing with coal three types of biomass: miscanthus, willow and waste forest
wood. Both direct combustion and gasification of biomass are considered. The results of life cycle assessment indicate that
all biomass options lead to a substantial reduction in the environmental impacts compared to the coal-only power generation.
Overall, use of waste wood appears to be environmentally the most sustainable option. In comparison to direct combustion,
biomass gasification has higher global warming potential due to the higher consumption of biomass and energy for gasification.
The results of the life cycle economic costing show that electricity from biomass is economically less attractive than from
coal. Direct firing is two times more expensive than coal and gasification up to three times. Therefore, while attractive
from the environmental point of view, biomass appears currently to be less sustainable economically.
KeywordsBiomass–Climate change–Electricity generation–Economic assessment–Life cycle assessment
Our strong dependence on fossil fuels results from the intensive use and consumption of petroleum derivatives which, combined with diminishing oil resources, causes environmental and political concerns. The utilization of agricultural residues as raw materials in a biorefinery is a promising alternative to fossil resources for production of energy carriers and chemicals, thus mitigating climate change and enhancing energy security. This paper focuses on a biorefinery concept which produces bioethanol, bioenergy and biochemicals from two types of agricultural residues, corn stover and wheat straw. These biorefinery systems are investigated using a Life Cycle Assessment (LCA) approach, which takes into account all the input and output flows occurring along the production chain. This approach can be applied to almost all the other patterns that convert lignocellulosic residues into bioenergy and biochemicals. The analysis elaborates on land use change aspects, i.e. the effects of crop residue removal (like decrease in grain yields, change in soil N2O emissions and decrease of soil organic carbon). The biorefinery systems are compared with the respective fossil reference systems producing the same amount of products/services from fossils instead of biomass. Since climate change mitigation and energy security are the two most important driving forces for biorefinery development, the assessment focuses on greenhouse gas (GHG) emissions and cumulative primary energy demand, but other environmental categories are evaluated as well.
The objective of this study is to perform a techno-economic analysis on a typical wood pellet and wood residue boiler for generation of heat to an average-sized greenhouse in British Columbia. The variables analyzed included greenhouse size and structure, boiler efficiency, fuel types, and source of carbon dioxide (CO2) for crop fertilization. The net present value (NPV) show that installing a wood pellet or a wood residue boiler to provide 40% of the annual heat demand is more economical than using a natural gas boiler to provide all the heat at a discount rate of 10%. For an assumed lifespan of 25 years, a wood pellet boiler system could generate NPV of C74,695 with ESP, respectively. While, installing a wood residue boiler with or without an ESP could provide NPV of C1,104,538, respectively. Using a wood biomass boiler could also eliminate over 3000 tonne CO2 equivalents of greenhouse gases annually. Wood biomass combustion generates more particulate matters than natural gas combustion. However, an advanced emission control system could significantly reduce particulate matters emission from wood biomass combustion which would bring the particulate emission to a relatively similar level as for natural gas.