Net GHG Emissions Research Articles

Greenhouse gas emissions and energy balances of jatropha biodiesel as an alternative fuel in Tanzania

This paper evaluates GHG emissions and energy balances (i.e. net energy value (NEV), net renewable energy value (NREV) and net energy ratio (NER)) of jatropha biodiesel as an alternative fuel in Tanzania by using life cycle assessment (LCA) approach. The functional unit (FU) was defined as 1 tonne (t) of combusted jatropha biodiesel. The findings of the study prove wrong the notion that biofuels are carbon neutral, thus can mitigate climate change. A net GHG equivalent emission of about 848 kg t−1 was observed. The processes which account significantly to GHG emissions are the end use of biodiesel (about 82%) followed by farming of jatropha for about 13%. Sensitivity analysis indicates that replacing diesel with biodiesel in irrigation of jatropha farms decreases the net GHG emissions by 7.7% while avoiding irrigation may reduce net GHG emissions by 12%. About 22.0 GJ of energy is consumed to produce 1 t of biodiesel. Biodiesel conversion found to be a major energy consuming process (about 64.7%) followed by jatropha farming for about 30.4% of total energy. The NEV is 19.2 GJ t−1, indicating significant energy gain of jatropha biodiesel. The NREV is 23.1 GJ t−1 while NER is 2.3; the two values indicate that large amount of fossil energy is used to produce biodiesel. The results of the study are meant to inform stakeholders and policy makers in the bioenergy sector.

Ethanol or Bioelectricity? Life Cycle Assessment of Lignocellulosic Bioenergy Use in Light-Duty Vehicles

Our study evaluates life cycle energy use and GHG emissions of lignocellulosic ethanol and bioelectricity use in U.S. light-duty vehicles. The well-to-pump, pump-to-wheel, and vehicle cycle stages are modeled. All ethanol (E85) and bioelectricity pathways have similar life cycle fossil energy use (~ 100 MJ/100 vehicle kilometers traveled (VKT)) and net GHG emissions (~5 kg CO2eq./100 VKT), considerably lower (65-85%) than those of reference gasoline and U.S. grid-electricity pathways. E85 use in a hybrid vehicle and bioelectricity use in a fully electric vehicle also have similar life cycle biomass and total energy use (~ 350 and ~450 MJ/100 VKT, respectively); differences in well-to-pump and pump-to-wheel efficiencies can largely offset each other. Our energy use and net GHG emissions results contrast with findings in literature, which report better performance on these metrics for bioelectricity compared to ethanol. The primary source of differences in the studies is related to our development of pathways with comparable vehicle characteristics. Ethanol or vehicle electrification can reduce petroleum use, while bioelectricity may displace nonpetroleum energy sources. Regional characteristics may create conditions under which either ethanol or bioelectricity may be the superior option; however, neither has a clear advantage in terms of GHG emissions or energy use.

Embodied greenhouse gas emission by Macao

Comprehensive inventory of cities' greenhouse gas emissions (GHG) is the basis for cities to make appropriate mitigation plans. However, previous studies on cities' GHG emissions consider emissions occurring within the city boundary (Scope 1) and out of boundary electricity emissions (Scope 2), but neglect indirect emissions associated with commodities consumed by cities (Scope 3), resulting in emission leakage. To cope with this problem, a systematic accounting covering all 3 scopes is presented in a case study of Macao for the years 2005–2009, based on the latest embodied emission intensity databases for China and for the world. The results show that total emissions are dominated by indirect emissions mainly embodied in imports, which is 3–4 times direct emissions during the period concerned. It is verified that accounting under Scopes 1 and 2 cannot capture the full picture of cities' emissions, especially cities like Macao which are dominated by service industry and inevitably sustained by massive materials and services from other regions. Our study suggests that Macao should adjust its current GHG mitigation policies which consider only its emissions occurring within its border, as Macao is a net GHG emissions importer. This work is the first assessment of Macao's embodied GHG emissions.

Life cycle assessment of greenhouse gas emissions of feedlot manure management practices: Land application versus gasification

Animal waste is an important source of anthropogenic GHG emissions, and in most cases, manure is managed by land application. Nevertheless, due to the huge amounts of manure produced annually, alternative manure management practices have been proposed, one of which is gasification, aimed to convert manure into clean energy-syngas. Syngas can be utilized to provide energy or power. At the same time, the byproduct of gasification, biochar, can be transported back to fields as a soil amendment. Environmental impacts are crucial in selecting the appropriate manure strategy. Therefore, GHG emissions during manure management systems (land application and gasification) were evaluated and compared by life cycle assessment (LCA) in our study. LCA is a universally accepted tool to determine GHG emissions associated with every stage of a system. Results showed that the net GHG emissions in land application scenario and gasification scenario were 119 and -643 kg CO2-eq for one tonne of dry feedlot manure, respectively. Moreover, sensitive factors in the gasification scenario were efficiency of the biomass integrated gasification combined cycle (BIGCC) system and energy source of avoided electricity generation. Overall, due to the environmental effects of syngas and biochar, gasification of feedlot manure is a much more promising technique as a way to reduce GHG emissions than is land application.

The economic and environmental performance of the production of bioethanol from municipal solid waste in the UK

Background: Waste management, energy resource development and sustainability are all subject matters of global interest that have led to the development of low-carbon alternative fuels, such as bioethanol from biological wastes. The purpose of this study was to determine the economic and environmental performance of using municipal solid waste (MSW) for bioethanol production within the UK. Results: Life cycle analysis and economic evaluation techniques were used to determine the GHG emissions and economic performance of a prospective MSW plant operating to recover recyclables and produce ethanol from the remaining biological component. It was determined that an MSW plant producing 26 million l of ethanol per year and recovering a total of 49,000 tonnes per year of glass metals and plastics would have an internal rate of return of 27% and net GHG emissions savings of 137%. Conclusion: The process was shown to be a favorable option for treating MSW in the UK, provided appropriate tipping fees and government subsidies are in place.

A model‐based quantitative assessment of the carbon benefits of introducing iLUC factors in the European Renewable Energy Directive

AbstractThe European Commission has a mandate from the EU's Renewable Energy and Fuel Quality Directives to propose a methodology, consistent with the best available science, to address indirect land use change (iLUC). One proposed solution to the iLUC problem is the application of iLUC factors in European fuels policy – it is widely expected that should the EU adopt such iLUC factors, they would be based on iLUC modelling using the International Food Policy Research Institute's (IFPRI) MIRAGE model. Taking the iLUC factors from IFPRI MIRAGE as our central estimate, we use Monte Carlo analysis on a simple model of potential biofuel pathways for Europe to assess the likely average carbon saving from three possible European biofuel policy scenarios: no action on iLUC; raised GHG thresholds for direct emissions savings; and the introduction of iLUC factors. We find that without iLUC factors (or some other effective iLUC minimization approach) European biofuel mandates are unlikely to deliver significant GHG emissions benefits in 2020, and have a substantial probability of increasing net GHG emissions. In contrast, the implementation of iLUC factors is likely to significantly increase the carbon savings from EU biofuel policy. With iLUC factors, it is likely that most permitted pathways would conform to the Renewable Energy Directive requirement for a minimum 50% GHG reduction compared to fossil fuels.

Whole Farm Net Greenhouse Gas Abatement from Establishing Kikuyu-Based Perennial Pastures in South-Western Australia.

Simple SummaryGreenhouse gas (GHG) emissions from ruminant livestock production (sheep, cattle and goats) have contributed to a common perception that a shift in the human diet from animal to plant-based products is environmentally responsible. In this study we found that the level of net emissions from livestock production systems is strongly influenced by the type of farming system that is used, and in fact GHG emission levels from some livestock production systems may be comparable with cropping systems. By introducing into farming systems ‘perennial’ pasture plants that are able to capture more atmospheric carbon, which is then stored in the soil, emission levels from livestock production can be substantially reduced.On-farm activities that reduce GHG emissions or sequester carbon from the atmosphere to compensate for anthropogenic emissions are currently being evaluated by the Australian Government as carbon offset opportunities. The aim of this study was to examine the implications of establishing and grazing Kikuyu pastures, integrated as part of a mixed Merino sheep and cropping system, as a carbon offset mechanism. For the assessment of changes in net greenhouse gas emissions, results from a combination of whole farm economic and livestock models were used (MIDAS and GrassGro). Net GHG emissions were determined by deducting increased emissions from introducing this practice change (increased methane and nitrous oxide emissions due to higher stocking rates) from the soil carbon sequestered from growing the Kikuyu pasture. Our results indicate that livestock systems using perennial pastures may have substantially lower net GHG emissions, and reduced GHG intensity of production, compared with annual plant-based production systems. Soil carbon accumulation by converting 45% of arable land within a farm enterprise to Kikuyu-based pasture was determined to be 0.80 t CO2-e farm ha−1 yr−1 and increased GHG emissions (leakage) was 0.19 t CO2-e farm ha−1 yr−1. The net benefit of this practice change was 0.61 t CO2-e farm ha−1 yr−1 while the rate of soil carbon accumulation remains constant. The use of perennial pastures improved the efficiency of animal production almost eight fold when expressed as carbon dioxide equivalent emissions per unit of animal product. The strategy of using perennial pasture to improve production levels and store additional carbon in the soil demonstrates how livestock should be considered in farming systems as both sources and sinks for GHG abatement.

Greenhouse gas emission intensities and economic efficiency in crop production: A systems analysis of 95 farms

To increase food production while mitigating climate change, cropping systems in the future will need to reduce greenhouse gas emission per unit of production. We conducted an analysis of 95 arable farms in Norway to calculate farm scale emissions of greenhouse gases, expressed both as CO2 eq per unit area, and CO2 eq per kg DM produced and to describe relationships between the farms’ GHG intensities and their economic efficiencies (gross margin). The study included: (1) design of a farm scale model for net GHG emission from crop production systems; (2) establishing a consistent farm scale data set for the farms with required soil, weather, and farm operation data; (3) a stochastic simulation of the variation in the sources of GHG emission intensities, and sensitivity analysis of selected parameters and equations on GHG emission intensities; and (4) describing relationships between GHG emission intensities and gross margins on farms. Among small seed and grain crops the variation in GHG emissions per kg DM was highest in oilseed (emission intensity at the 75th percentile level was 1.9 times higher than at the 25th percentile). For barley, oats, spring wheat, and winter wheat, emissions per kg DM at the 75th percentile levels were between 1.4 and 1.6 times higher than those at the 25th percentiles. Similar trends were observed for emissions per unit land area. Invariably soil N2O emission was the largest source of GHG emissions, accounting for almost half of the emissions. The second largest source was the off farm manufacturing of inputs (∼25%). Except for the oilseed crop, in which soil carbon (C) change contributed least, the on farm emissions due to fuel use contributed least to the total GHG intensities (∼10%). The soil C change contributed most to the variability in GHG emission intensities among farms in all crops, and among the sensitivity elasticities the highest one was related to environmental impacts on soil C change. The high variation in GHG intensities evident in our study implies the potential for significant mitigation of GHG emissions. The GHG emissions per kg DM (intensity) decreased with increasing gross margin in grain and oilseed crops, suggesting that crop producers have economic incentives to reduce GHG emissions.

The potential of waste-to-energy in reducing GHG emissions

Background: The combustion of municipal solid waste (MSW) to generate heat or electricity (waste-to-energy [WTE]) could reduce net GHG emissions in the USA compared with combusting methane from landfills. Moreover, negative CO2 emissions could be achieved with CCS because 66% of the carbon in MSW is typically biogenic. Results and conclusion: For the five largest landfill sites in each state, we estimate that at least 58 and 11 sites have enough MSW to fuel WTE plants of >50 MWe and >100 MWe, respectively. Furthermore, half of these sites lie within 20 km of potential underground saline and other CO2 storage reservoirs. We estimate that the levelized electricity cost for WTE without CO2 capture is US$94/MWh and is $285/MWh with amine-based post-combustion capture technology. The cost of CO2 capture is $58/Mg CO2, resulting in a cost for carbon negative emissions of $93/Mg CO2; substantially lower than for some geoengineering methods, including capturing CO2 from air.

The impact of information and communication technology on GHG emissions: how green are virtual worlds?

Information and communication technology (ICT) has the potential to either increase or decrease global anthropogenic GHG emissions. Through its various life cycle phases, ICT now represents a rapidly growing source of GHG emissions from the energy and manufacturing sectors, but through its use to avoid emissions in other sectors, in particular those of the transport sector, ICT also has the potential to significantly reduce emissions. Here we explore the potential of so-called ‘virtual world’ technologies to provide a substitute for physical meetings, highlighting the resulting GHG emission savings that can be achieved. These virtual world technologies exemplify the double-edged nature of ICT in climate change mitigation, as their use may generate significant direct emissions through energy use, while, at the same time, reduce emissions from other sources, such as business travel. Actual and potential use, of virtual world technology (VWT) in a nonrandom sample of four large organizations was assessed. For two of these organizations a quantitative assessment of the impact of VWT on net GHG emissions from a specific event was carried out. Subsequent to this, a qualitative assessment of the barriers to increased VWT was made for the other two organizations. We found that, in the two quantitative case studies, VWT was successfully used to substitute physical meetings with virtual ones and that the extent of avoided transport-related GHG emissions was several times greater than the direct emissions generated by the VWT in its use phase. However, our qualitative assessments of current and potential VWT use in the two additional organizations indicated the existence of significant technical and cultural barriers to more widespread use. We conclude that increased use of VWT can potentially lead to significant net GHG emissions savings – primarily via reduced business travel. However, there remain a number of barriers, such as low levels of user engagement, which must be overcome if uptake of VWT at the scale required for globally-significant emissions reductions is to be achieved.

Corn ethanol and associated greenhouse gas emissions in the USA: importance of the nitrous oxide emission factor

Increasing concern over anthropogenic global warming, finite oil reserves and a desire for energy security have all to helped bring about an increased interest in biofuels worldwide. The US is currently the world’s leading ethanol biofuel producer, with most being derived from a corn (Zea mays L.) feedstock. The net climate forcing benefits of some biofuels have been questioned in recent years, in particular the potential enhancement of nitrous oxide (N2O) emissions during cultivation of their feedstocks. This study aims to determine whether US corn ethanol can reduce net GHG emissions from surface transport relative to gasoline under two N2O emission scenarios: one using the an emission factor for managed soils of 1.3% (scenario A) derived from Intergovernmental Panel on Climate Change default values, and the other using an upper N2O emission factor of 5% (scenario B). It also aimed to determine the GHG reductions that could be achieved relative to future US ethanol production targets under these two scenarios. This study shows that a net reduction in GHG emissions can be achieved under both scenarios, although the emissions reduction benefits of ethanol production are considerably reduced where an emission factor of 5% is applied. Under the latter scenario, new-facility corn ethanol production in the US would fail to meet the US Environmental Protection Agency mandate for a 20% net reduction in GHG emissions relative to gasoline.

Prospects for producing low carbon transportation fuels from captured CO2 in a climate constrained world

Abstract The climate implications of technologies that capture CO 2 to produce transportation fuels (CCTF) are investigated by studying two examples: Biodiesel from microalgae and Sandia National Laboratory’s S2P process. Simple performance and economic models for each technology are examined in the context of a bifurcated–“pre-CCS” vs. “post-CCS”–climate regime in which CCTF uses CO 2 that is, respectively, captured from power plant flue gases or taken from CCS pipelines. CCTF promises to improve domestic energy security by converting sunlight and waste CO 2 into transportation fuels; in addition, these fuels are roughly climate neutral when CO 2 is captured from either flue gases or directly from the atmosphere. However, after the power sector becomes largely decarbonized under a stringent climate policy, large point sources of concentrated CO 2 are likely to be relatively rare, and unfortunately, fuels made from pipeline CO 2 destined for storage do not have markedly reduced net GHG emissions. Thus, absent the development of economical CO 2 capture from air, it’s difficult to see how CCTF can play a significant long term role in decarbonizing the US transportation sector (and thus reaching US climate goals).

Security of feedstocks supply for future bio-ethanol production in Thailand

This study assesses the security of feedstock supply to satisfy the increased demand for bio-ethanol production based on the recent 15 years biofuels development plan and target (year 2008–2022) of the Thai government. Future bio-ethanol systems are modeled and the feedstock supply potentials analyzed based on three scenarios including low-, moderate- and high-yields improvement. The three scenarios are modeled and key dimensions including availability; diversity; and environmental acceptability of feedstocks supply in terms of GHG reduction are evaluated through indicators such as net feedstock balances, Shannon index and net life cycle GHG emissions. The results show that only the case of high yields improvement scenario can result in a reliable and sufficient supply of feedstocks to satisfy the long-term demands for bio-ethanol and other related industries. Cassava is identified as the critical feedstock and a reduction in cassava export is necessary. The study concludes that to enhance long-term security of feedstocks supply for sustainable bio-ethanol production in Thailand, increasing use of sugarcane juice as feedstock, improved yields of existing feedstocks and promoting production of bio-ethanol derived from agricultural residues are three key recommendations that need to be urgently implemented by the policy makers.

Incorporating macroeconomic feedback into an energy systems model using an IO approach: Evaluating the rebound effect in the Korean electricity system

This paper approximates the emissions rebound effects 1 1 As per Binswanger (2001), we take the “rebound effect” to be defined in broad terms. In this paper we refer generally to the “ emissions rebound”. It is taken to mean the increase in emissions due to the introduction of some measure which is lower in cost and emissions than business as usual practice. associated with substituting expensive and GHG emitting natural gas (LNG) power plants, with apparently cheaper and lower emitting nuclear plant. It then evaluates the effect this has on economy wide electricity use as well as net GHG emissions changes. The analysis is undertaken by combining aspects of an input–output model with an optimizing energy systems model. The scope of the case study is limited to the effects of the electricity sector (and its emissions) on the Korean economy from 2005 to 2030. Its primary basis (in terms of data and assumptions) is the recent national Basic Plan for Long-Term Electricity Supply and Demand ( KPX, 2006). 2 2 That work extends only to 2020, but for this effort is extrapolated using consistent assumptions to 2030. KPX (2006) describes a national power expansion plan developed by the Korea Power exchange and does not include any specific technology focus. The cases considered a limited increase of the share of Advanced Pressurised Reactor (APR) nuclear plant at the expense of combined cycle gas turbine (CCGT) plant running on imported liquefied natural gas (LNG). Three scenarios are studied, based on KPX (2006). These include (1) a Reference scenario, 3 3 The reference case is not the least cost case in a pure sense: as determined by the KPX (2006) planning process, it is the least cost case subject to a political (neither economic nor technical) constraint on upper limit of nuclear power. In related work, a soft technical limit—which is significantly higher—is estimated ( IAEA, 2006a, b ). It is also entirely possible that site considerations may force another technical limit which is not considered here. Current work indicates that sites have been identified for the next ten nuclear power plants, see: OPR 1000 (2008) and APR 1400 (2008), with investigation for further sites or site expansion currently taking place. (2) a Mitigation scenario (where an extra 5000 MW of nuclear is allowed to enter the system at the expense of LNG plant, but no emissions rebound is calculated) and (3) a Mitigation+rebound scenario (where some emissions savings of the extra nuclear plant are offset by an emissions rebound). 4 4 Using the IO-Optimization model developed, a feedback mechanism is introduced. This would invoke the use of offsetting GHG emitting technologies, if for some reason (directly and indirectly), the effect of the increased introduction of nuclear power was to increase the demand for electricity. To achieve this, there is a limit placed on the introduction of new nuclear. If that nuclear power is introduced (to its limit) and demand for electricity increases it must be met by other power plants. In the Korean system, the other power plants that are economic in our scenarios are CO 2 emitting fossil plant. Interestingly while our limit is arbitrary and conservative, there are technical limits associated with the characteristics of the power system which would limit nuclear, albeit at a higher level of about 60% of total generation ( IAEA, 2006b). The modelling approach developed is useful as it provides a method of including and indicating some economic interactions with the energy system in a relatively transparent manner. Stand alone economic models can lack energy system dynamics, while energy systems model are often decoupled from detailed economic interactions.

Urban Water and Energy Use From Current US Use to Cities of the Future

The article describes and estimates the carbon greenhouse gas and water footprint of the urban water sector to achieving the sustainability goals of future (eco) cities. Specifically, the article focuses on two goals of reducing water use by 50% and zero net carbon (GHG) emissions. Water conservation from the current use to an achievable sustainable use cannot be achieved by water conservation only. Further reduction of the water demand by desalination and high degree treatment (e.g., nanofiltration or reverse osmosis) requires a significant amount of energy and there is a limit on the maximum percent of water that can be reused in a closed water cycle. Cluster semi-distributed water delivery, reclamation and reuse with heat energy recovery is described, followed by presenting a proposal for a regional integrated resource recovery facility (IRRF) which reclaims water for ecologic flow, irrigation and other uses, produces biogas, hydrogen, electric energy, struvite and residual organic solids for soil conditioning. It was estimated that the contribution of the water sector towards the net zero GHG emissions goal could be about 10%.

A GIS-based methodology for highlighting fuelwood supply/demand imbalances at the local level: A case study for Central Mexico

When fuelwood is harvested at a rate exceeding natural growth and inefficient conversion technologies are used, negative environmental and socio-economic impacts, such as fuelwood shortages, natural forests degradation and net GHG emissions arise. In this study, we argue that analyzing fuelwood supply/demand spatial patterns require multi-scale approaches to effectively bridge the gap between national results with local situations. The proposed methodology is expected to help 1) focusing resources and actions on local critical situations, starting from national wide analyses and 2) estimating, within statistically robust confidence bounds, the proportion of non-renewable harvested fuelwood. Starting from a previous work, we selected a county-based fuelwood hot spot in the Central Highlands of Mexico, identified from a national wide assessment, and developed a grid-based model in order to identify single localities that face concomitant conditions of high fuelwood consumption and insufficient fuelwood resources. By means of a multi-criteria analysis (MCA), twenty localities, out of a total of 90, were identified as critical in terms of six indicators related to fuelwood use and availability of fuelwood resources. Fuelwood supply/demand balances varied among localities from −16.2 ± 2.5 Gg y−1 to 4.4 ± 2.6 Gg y−1, while fractions of non-renewable fuelwood varied from 0 to 96%. These results support the idea that balances and non-renewable fuelwood fractions (mandatory inputs for Clean Development Mechanism (CDM) cookstoves projects) must be calculated on a locality by locality basis if gross under or over-estimations want to be avoided in the final carbon accounting.

A CER discounting scheme could save climate change regime after 2012

We can generate a net global GHG emission reduction from developing countries (in an UNFCCC term, non-Annex 1 Parties) without imposing targets on them, if we discount CERs generated from CDM projects. The CER discounting scheme means that a part or all of CDM credits, i.e., CERs, made by developing countries through unilateral CDM projects will be retired rather than sold to developed countries to increase their emissions. It is not feasible to impose certain forms of target (whether sectoral or intensity targets) on non-Annex 1 whose emission trend is hard to predict and whose industrial structure is undergoing a rapid change. Instead of imposing targets (a command and control approach), we should apply market instruments in generating a net global emission reduction from non-Annex 1. Since April 2005 when the first unilateral CDM was approved by the CDM Executive Board, CDM has been functioning as a market mechanism to provide incentives for developing countries to initiate their own emission reduction projects. As CDM is the only market mechanism engaging developing countries in the Kyoto Protocol, we should try to re-design CDM so that it can generate net global emission reductions by introducing the idea of discounting CERs. But in order to produce meaningful GHG emission reductions by discounting CERs, the project scope of CDM has to be expanded by relaxing project additionality criteria while maintaining strict technical additionality criteria. Agreeing on the CERs Discounting Scheme will have a better political chance than agreeing on imposing emission reduction targets on developing countries.

Cost efficient rotation and tillage options to sequester carbon and mitigate GHG emissions from agriculture in Eastern Canada

The economic efficiency of cropping options to mitigate net GHG emissions from agriculture in Eastern Canada was analyzed. Data on yield response to tillage (moldboard plow and chisel plow) and six-corn (Zea mays L.)-based rotations were obtained from a 20-year field experiment in Ontario. Budgets were constructed for each cropping system while GHG emissions were accounted for by soil carbon measurements and estimates of nitrous oxide according to IPCC methodology. Complex crop rotations with legumes, such as corn–corn–soybeans (Glycine max. L.)–wheat (Triticum aestivum L.) with red clover (Trifolium pratense L.) underseeded, have higher net returns and substantially lower GHG emissions than continuous corn. Conservation tillage reduces GHG emissions due to lower input use but sequestration levels did not vary significantly between tillage systems. Rotation had a much bigger effect on the mitigation potential of GHG emissions than tillage. However, opportunity costs of more than $90 per Mg CO2 eq indicate the limits to increase the mitigation potential beyond the level of the most profitable cropping system.

Economics and GHG emission reduction of a PLA bio-refinery system—Combining bottom-up analysis with price elasticity effects

This paper analyses energy savings, GHG emission reductions and costs of bio-refinery systems for polylactic acid (PLA) production. The systems comprise ‘multi-functional’ uses of biomass resources, i.e. use of agricultural residues for energy consumption, use of by-products, and recycling and waste-to-energy recovery of materials. We evaluate the performance of these systems per kg of bio-based polymer produced and per ha of biomass production. The evaluation is done using data of Poland assuming that biomass and PLA production is embedded in a European energy and material market. First, the performance of different bio-refinery systems is investigated by means of a bottom-up chain analysis. Second, an analysis is applied that derives market prices of products and land depending on the own-price elasticity of demand. Thus, the costs of bio-refinery systems depending on the demand of land and material are determined. It is found that all PLA bio-refinery systems considered lead to net savings of non-renewable energy consumption of 70–220 GJ/(ha yr) and net GHG emission reductions of 3–17 Mg CO 2eq/(ha yr). Most of these PLA bio-refinery systems lead to net costs for the overall system of up to 4600 €/(ha yr). PLA production from short rotation wood leads to net benefits of about 1100 €/(ha yr) if a high amount of a high value product, i.e. fibres, is produced. Multi-functionality is necessary to ensure the viability of PLA bio-refinery systems from biomass with regard to energy savings and GHG emission reduction. However, the multi-functional use of biomass does not contribute much to overall incomes. Multifunctional biomass use – especially the use of biomass residues for energy consumption – contributes significantly to savings of non-renewable energy sources. Own-price elasticity of the demand for materials influences the overall costs of the bio-refinery system strongly. The own-price elasticity of land demand markets could become important if bio-refineries are introduced on a large scale.

Life cycle energy requirements and greenhouse gas emissions from large scale energy storage systems

Abstract Using life cycle assessment, metrics for calculation of the input energy requirements and greenhouse gas emissions from utility scale energy storage systems have been developed and applied to three storage technologies: pumped hydro storage (PHS), compressed air energy storage (CAES) and advanced battery energy storage (BES) using vanadium and sodium polysulphide electrolytes. In general, the use of energy storage with electricity generation increases the input energy required to produce electricity, as well as the total greenhouse gas emissions. Despite this increase, the life cycle GHG emission rate from storage systems when coupled with nuclear or renewable sources is substantially lower than from fossil fuel derived electricity sources. GHG emissions from PHS when coupled with nuclear and renewable energy systems are lower than those from BES or CAES. When coupled with fossil generation, CAES has significantly lower net GHG emissions than PHS or BES.