Emission scenario of non-CO2 gases from energy activities and other sources in China

This paper gives a quantitative analysis on the non-CO₂ emissions related to energy demand, energy activities and land use change of six scenarios with different development pattern in 2030 and 2050 based on IPAC emission model. The various mitigation technologies and policies are assessed to understand the corresponding non-CO₂ emission reduction effect. The research shows that the future non-CO₂ emissions of China will grow along with increasing energy demand, in which thermal power and transportation will be the major emission and mitigation sectors. During the cause of future social and economic development, the control and mitigation of non-CO₂ emissions is a problem as challenging and pressing as that of CO₂ emissions. This study indicates that the energy efficiency improvement, renewable energy, advanced nuclear power generation, fuel cell, coal-fired combined cycle, clean coal and motor vehicle emission control technologies will contribute to non-CO₂ emissions control and mitigation.

     

Emission scenario of non-CO2 gases from energy activities and other sources in China

This paper gives a quantitative analysis on the non-CO2 emissions related to energy demand, energy activities and land use change of six scenarios with different development pattern in 2030 and 2050 based on IPAC emission model. The various mitigation technologies and policies are assessed to understand the corresponding non-CO2 emission reduction effect. The research shows that the future non-CO2 emissions of China will grow along with increasing energy demand, in which thermal power and transportation will be the major emission and mitigation sectors. During the cause of future social and economic development, the control and mitigation of non-CO2 emissions is a problem as challenging and pressing as that of CO2 emissions. This study indicates that the energy efficiency improvement, renewable energy, advanced nuclear power generation, fuel cell, coal-fired combined cycle, clean coal and motor vehicle emission control technologies will contribute to non-CO2 emissions control and mitigation.     

Emission scenario of non-CO2 gases from energy activities and other sources in China

This paper gives a quantitative analysis on the non-CO2 emissions related to energy demand, energy activities and land use change of six scenarios with different development pattern in 2030 and 2050 based on IPAC emission model. The various mitigation technologies and policies are assessed to understand the corresponding non-CO2 emission reduction effect. The research shows that the future non-CO2 emissions of China will grow along with increasing energy demand, in which thermal power and transportation will be the major emission and mitigation sectors. During the cause of future social and economic development, the control and mitigation of non-CO2 emissions is a problem as challenging and pressing as that of CO2 emissions.This study indicates that the energy efficiency improvement, renewable energy, advanced nuclear power generation, fuel cell, coal-fired combined cycle, clean coal and motor vehicle emission control technologies will contribute to non-CO2 emissions control and mitigation.     

Energy crops: current status and future prospects

Energy crops currently contribute a relatively small proportion to the total energy produced from biomass each year, but the proportion is set to grow over the next few decades. This paper reviews the current status of energy crops and their conversion technologies, assesses their potential to contribute to global energy demand and climate mitigation over the next few decades, and examines the future prospects. Previous estimates have suggested a technical potential for energy crops of～400 EJ yr^?1 by 2050. In a new analysis based on energy crop areas for each of the IPCC SRES scenarios in 2025 (as projected by the IMAGE 2.2 integrated assessment model), more conservative dry matter and energy yield estimates and an assessment of the impact on non‐CO₂ greenhouse gases were used to estimate the realistically achievable potential for energy crops by 2025 to be between 2 and 22 EJ yr^?1, which will offset～100–2070 Mt CO₂‐eq. yr^?1. These results suggest that additional production of energy crops alone is not sufficient to reduce emissions to meet a 550 μmol mol^?1 atmospheric CO₂ stabilization trajectory, but is sufficient to form an important component in a portfolio of climate mitigation measures, as well as to provide a significant sustainable energy resource to displace fossil fuel resources. Realizing the potential of energy crops will necessitate optimizing the dry matter and energy yield of these crops per area of land through the latest biotechnological routes, with or without the need for genetic modification. In future, the co‐benefits of bioenergy production will need to be optimized and methods will need to be developed to extract and refine high‐value products from the feedstock before it is used for energy production.     

Spatiotemporal Characteristics,Determinants and Scenario Analysis of CO2 Emissions in China Using Provincial Panel Data

This paper empirically investigated the spatiotemporal variations, influencing factors and future emission trends of China’s CO₂ emissions based on a provincial panel data set. A series of panel econometric models were used taking the period 1995–2011 into consideration. The results indicated that CO₂ emissions in China increased over time, and were characterized by noticeable regional discrepancies; in addition, CO₂ emissions also exhibited properties of spatial dependence and convergence. Factors such as population scale, economic level and urbanization level exerted a positive influence on CO₂ emissions. Conversely, energy intensity was identified as having a negative influence on CO₂ emissions. In addition, the significance of the relationship between CO₂ emissions and the four variables varied across the provinces based on their scale of economic development. Scenario simulations further showed that the scenario of middle economic growth, middle population increase, low urbanization growth, and high technology improvement (here referred to as Scenario BTU), constitutes the best development model for China to realize the future sustainable development. Based on these empirical findings, we also provide a number of policy recommendations with respect to the future mitigation of CO₂ emissions.     

Climate change mitigation potential of local use of harvest residues for bioenergy in Canada

We estimate the mitigation potential of local use of bioenergy from harvest residues for the 2.3 × 10⁶ km² (232 Mha) of Canada's managed forests from 2017 to 2050 using three models: Carbon Budget Model of the Canadian Forest Sector (CBM‐CFS3), a harvested wood products (HWP) model that estimates bioenergy emissions, and a model of emission substitution benefits from the use of bioenergy. We compare the use of harvest residues for local heat and electricity production relative to a base case scenario and estimate the climate change mitigation potential at the forest management unit level. Results demonstrate large differences between and within provinces and territories across Canada. We identify regions with increasing benefits to the atmosphere for many decades into the future and regions where no net benefit would occur over the 33‐year study horizon. The cumulative mitigation potential for regions with positive mitigation was predicted to be 429 Tg CO₂e in 2050, with 7.1 TgC yr ^?1 of harvest residues producing bioenergy that met 3.1% of the heat demand and 2.9% of the electricity demand for 32.1 million people living within these regions. Our results show that regions with positive mitigation produced bioenergy, mainly from combined heat and power facilities, with emissions intensities that ranged from roughly 90 to 500 kg CO₂e MWh^?1. Roughly 40% of the total captured harvest residue was associated with regions that were predicted to have a negative cumulative mitigation potential in 2050 of ?152 Tg CO₂e. We conclude that the capture of harvest residues to produce local bioenergy can reduce GHG emissions in populated regions where bioenergy, mainly from combined heat and power facilities, offsets fossil fuel sources (fuel oil, coal and petcoke, and natural gas).     

共享社会经济路径下中国2020—2100年碳排放预测研究

碳排放和减碳经济代价研究日益受到学术界和决策者的关注,中国政府做出的关于争取在2060年前实现碳中和的表态引起了国际社会的热议。在此背景下,开展中国未来长时间序列碳排放的情景预测具有切实意义。基于可拓展的随机性环境影响评估模型（STIRPAT）评估了人口、经济和受教育程度对碳排放的影响,对比历史数据并验证了碳排放预测模型的准确性,结合共享社会经济路径（SSPs）情景的设定和模型参数,预测了5种情景下中国2020年至2100年的碳排放轨迹及经济代价。结果表明：（1）考虑碳排放达峰目标的实现,SSP3情景是中国未来发展的最佳情景,在此情景下,中国有望提前三年实现碳排放达峰目标;（2） SSP3情景可使中国年度总碳排放量和人均碳排放量处于相对其他四种情景的最低值,但需要付出累积GDP下降5.49%至8.80%的代价;（3）为完成在2060年前实现碳中和的承诺,中国政府在未来的40年需面对409.36-467.42 Gt的碳中和量;（4）2020年中国的碳排放强度将会较2005年水平下降40.52%至41.39%,2030年碳排放强度将会较2005年水平下降59.64%至60.75%。5种情境中,SSP5情景是降低碳排放强度的最佳情景,可最大程度地超额实现碳排放强度目标。未来,受经济发展、人口增长等重要因素影响,中国政府减碳压力将进一步加大。后疫情时代,考虑到能源供应的减少和高科技产业的发展,碳排放社会成本的上升将为中国创造一个使能源系统脱碳的机遇。中国应在"十四五"期间继续提升能源利用效率、升级产业结构、提倡低碳消费、实施隐含碳战略,以尽快实现碳减排目标。     

中国电力行业CO2减排潜力及其贡献因素

电力行业低碳转型是中国低碳经济转型进程中关键行业之一,如何科学分析电力行业的碳减排潜力,确定操作性强的低碳转型路线、提出有效的政策措施是中国政府亟待解决的焦点问题之一。考虑终端电力消费、低碳能源发电占比、火力发电结构、火力发电效率、线损率等因素,构建了自底向上的电力行业CO2排放核算模型,在此基础上,利用情景分析方法探索中国电力行业2015和2020年的CO2减排潜力,进一步利用对数平均权重分解法(LMDI,Logarithmic Mean weight Divisia Index method)对电力行业CO2减排影响因素的贡献度做了归因分析。结果显示,相比基准情景,在当前政策情景和低碳政策情景下,电力行业将分别带来27.0亿t和36.9亿t的CO2减排量。低碳能源发电和火力发电效率是未来对CO2减排最重要的两个贡献因素。终端电力消费量一直是促进电力行业CO2排放增长最重要的贡献因素,因此通过电力需求侧管理等手段控制电力消费量对电力行业的低碳发展至关重要。最后结合减排贡献因素分析的结果为中国电力行业低碳发展提出了相应的政策建议。     

能源活动CO2排放不同核算方法比较和减排策略选择

能源活动CO₂排放是温室气体排放的最重要部分,这部分CO₂排放量的核算是温室气体清单编制和减排方案制定的关键和基础。采用直接法、电热终端法和隐含终端法核算了2009年中国能源消费的CO₂排放量,对不同核算法的CO₂排放部门分布、部门排放强度进行了比较,明确不同核算方法的差异和适用范围。采用电热终端法的核算结果定量分析了各产业部门和工业行业的经济增长和排放强度变化对中国能源活动CO₂排放增长的影响。结果表明,中国2009年隐含终端CO₂排放量为65.6亿t,略高于直接和电热终端CO₂排放量62.2亿t。3种核算方法的CO₂排放部门分布和排放强度有明显的差异:电、热力生产与供应业的直接排放占比为45.2%,而电热终端CO₂排放仅占4.5%;制造业的直接法、电热终端法和隐含终端法核算的CO₂排放占比分别为35.3% 、61.1%和65.5%,是终端能源消费CO₂排放最主要的部门;制造业、电热力生产与供应业和交通运输业的电热终端CO₂排放强度分别为2.166、1.72和1.622 t CO₂/万元GDP,是排放强度较高的部门。在产业部门中,制造业的色金属冶炼及压延加工业、非金属矿物制品业等5个行业以9.8%的经济增长贡献,排放了52.4%的CO₂,是产业结构调整、技术和工程减排的重点;服务业以7.2%的CO₂排放,贡献了38.4%的经济增长,应作为中国低碳经济优先发展的产业。     

Challenges and opportunities for hydrogen production from microalgae

The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050. Together with rising economic growth, this is forecast to result in a 50% increase in fuel demand, which will have to be met while reducing carbon dioxide (CO₂) emissions by 50–80% to maintain social, political, energy and climate security. This tension between rising fuel demand and the requirement for rapid global decarbonization highlights the need to fast‐track the coordinated development and deployment of efficient cost‐effective renewable technologies for the production of CO₂ neutral energy. Currently, only 20% of global energy is provided as electricity, while 80% is provided as fuel. Hydrogen (H₂) is the most advanced CO₂‐free fuel and provides a ‘common’ energy currency as it can be produced via a range of renewable technologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae, to power the next generation of H₂ fuel cells. Microalgae production systems for carbon‐based fuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating the potential of microalgal technologies for the commercial production of solar‐driven H₂ from water. It summarizes key global technology drivers, the potential and theoretical limits of microalgal H₂ production systems, emerging strategies to engineer next‐generation systems and how these fit into an evolving H₂ economy.     

新疆风力发电减碳效益全生命周期评估

风力发电减碳效益评估有助于从减碳角度更好制定能源发展相关政策。以风力资源总体丰富且亟需发展风力发电以实现能源系统脱碳的新疆为研究区,将生命周期方法与风力发电模型结合,在省、市级尺度分别评估了风力发电全生命周期的排放水平及发电效益,核算了风力发电相对于火力发电和光伏发电的减碳效益,有效弥补了传统生命周期评估中空间差异考虑不充分的问题。结果表明,风机全生命周期平均发电量为13.1×10⁷ kWh,风力发电全生命周期共排放3944.24 tCO₂-eq,通过材料处置回收和循环再利用可减少1424.79 tCO₂-eq。新疆发展风力发电具有低排放强度和高减碳效益的特点,与火电相比可减少97.44%排放,减碳效益平均可达906.72 gCO₂-eq/kWh,并且应优先布局在哈密、巴音郭楞蒙古自治州和北屯市;与光伏相比,减碳效益可分别达到43.85 gCO₂-eq/kWh(衰减率DR=1%)和169.84 gCO₂-eq/kWh(DR=3%),此情景下风电应主要部署在克孜勒苏柯尔克孜自治州、喀什和和田。在风电减碳效益较差地区如石河子市、铁门关市和双河市应考虑利用本地充足太阳能资源发展光伏发电。需注意风电的排放强度和减碳效益在局地小尺度评估中存在不确定性,获取更精细的结果仍需进一步评估。未来应大力发展新疆本地的风电产业,打造绿色供应链和加快发展处置回收技术以增加减碳效益。     

Environmental assessment of German electricity generation from coal-fired power plants with amine-based carbon capture

Background, aim, and scope  

One of the most important sources of global carbon dioxide emissions is the combustion of fossil fuels for power generation. Power plants contribute more than 40% of the worldwide anthropogenic CO₂ emissions. Therefore, the increased requirements for climate protection are a great challenge for the power producers. In this context a significant increase in power plant efficiency will contribute to reduce specific CO₂ emissions. Additionally, CO₂ capture and storage (CCS) is receiving considerable attention as a greenhouse gas (GHG) mitigation option. CCS allows continued use of fossil fuels with no or little CO₂ emissions given to the atmosphere. This could approve a moderate transition to a low-carbon energy generation over the next decades. Currently, R&D activities in the field of CCS are mainly concentrated on the development of capture techniques, the geological assessment of CO₂ storage reservoirs, and on economic aspects. Although first studies on material and energy flows caused by CCS are available, a broader environmental analysis is necessary to show the overall environmental impacts of CCS. The objectives in this paper are coal-based power plants with and without CO₂ capture via mono-ethanolamine (MEA) and the comparison of their environmental effects based on life cycle assessment methodology (LCA).     

我国典型城市化石能源消费CO2排放及其影响因素比较研究

城市是化石能源消费和CO_2排放的主要区域。分析典型城市化石能源消费CO_2排放特征,明确不同城市CO_2排放动态及主要影响因素的差异,是开展城市减排行动的重要科学依据。采用IPCC推荐方法及中国的排放参数核算11个典型城市2006—2015年间化石能源消费产生的CO_2排放量。根据各城市经济发展和CO_2排放特征将之分为四类:经济高度发达城市(北京、上海、广州)、高碳排放城市(重庆、乌鲁木齐、唐山)、低排放低增长城市(哈尔滨、呼和浩特和大庆)和低排放高增长城市(贵阳、合肥),并运用对数平均迪氏指数法(Logarithmic Mean Divisia Index,即LMDI分解法)对比分析了四类城市CO_2排放量的影响因素。结果表明:(1)研究期内大部分城市CO_2排放总量有所增加,仅北京和广州呈下降趋势,工业部门CO_2排放在城市排放总量及其变化中占据主导地位;四类城市的人均CO_2排放量表现出与排放总量相似的变化趋势;CO_2排放强度整体上表现为经济高度发达城市(均值为0.88 t CO_2/万元)低排放低增长城市(均值为2.82 t CO_2/万元)低排放高增长城市(均值为3.05 t CO_2/万元)高碳排放城市(均值为6.62 t CO_2/万元)。(2)在城市CO_2排放的影响因素中,经济发展和人口规模均是4类城市CO_2排放增长的促进因素,但经济发展效应的累积贡献值大于人口规模效应;能源强度降低是4类城市CO_2排放最主要的抑制因素,且经济高度发达和高碳排放城市的抑制作用强于其他两类城市;对第三产业GDP年平均增速高于第二产业的6个城市来说,产业结构是CO_2排放的抑制因素;能源结构的变化仅对煤炭消费比重较低且降幅较大的北京和广州的CO_2排放是抑制作用,累积贡献值分别为-21.73Mt和-0.03Mt,而对其他城市,特别是高碳排放城市的CO_2排放具有明显的促进作用。     

Herd-level versus animal-level variation in methane emission prediction in grazing dairy cattle

In response to the increased concern over agriculture’s contribution to greenhouse gas (GHG) emissions, more detailed assessments of current methane emissions and their variation, within and across individual dairy farms and cattle, are of interest for research and policy development. This assessment will provide insights into possible changes needed to reduce GHG emissions, the nature and direction of these changes, ways to influence farmer behavior and areas to maximize the adoption of emerging mitigation technologies. The objectives of this study were to (1) quantify the variation in enteric fermentation methane emissions within and among seasonal calving dairy farms with the majority of nutritional requirements met through grazed pasture; (2) use this variation to assess the potential of new individual animal emission monitoring technologies and their impact on mitigation policy. We used a large database of cow performance records for milk production and survival from 2 398 herds in New Zealand, and simulation to account for unobserved variation in feed efficiency and methane emissions per unit of feed. Results showed an average of 120 ± 31.4 kg predicted methane (CH₄) per cow per year after accounting for replacement costs, ranging 8.9–323 kg CH₄/cow per year. Whereas milk production, survival and predicted live weight were reasonably effective at predicting both individual and herd average levels of per cow feed intake, substantial within animal variation in emissions per unit of feed reduced the ability of these variables to predict variation in per animal methane output. Animal-level measurement technologies predicting only feed intake but not emissions per unit of feed are unlikely to be effective for advancing national policy goals of reducing dairy farming enteric methane output. This is because farmers seek to profitably utilize all farm feed resources available, so improvements in feed efficiency will not result in the reduction in feed utilization required to reduce methane emissions. At a herd level, average per cow milk production and live weight could form the basis of assigning a farm-level point of obligation for methane emissions. In conclusion, a comprehensive national database infrastructure that was tightly linked to animal identification and movement systems, and captured live weight data from existing farm-level recording systems, would be required to make this effective. Additional policy and incentivization mechanisms would still be required to encourage farmer uptake of mitigation interventions, such as novel feed supplements or vaccines that reduce methane emissions per unit of feed.     

Alternatives for natural‐gas‐based heating systems: A quantitative GIS‐based analysis of climate impacts and financial feasibility

The heating of buildings currently produces 6% of global greenhouse gas emissions. Sustainable heating technologies can reduce heating‐related CO₂ emissions by up to 90%. We present a Python‐based GIS model to analyze the environmental and financial impact of strategies to reduce heating‐related CO₂ emissions of residential buildings. The city‐wide implementation of three alternatives to natural gas are evaluated: high‐temperature heating networks, low‐temperature heating networks, and heat pumps. We find that both lowering the demand for heat and providing more sustainable sources of heat will be necessary to achieve significant CO₂‐emission reductions. Of the studied alternatives, only low‐temperature heating networks and heat pumps have the potential to reduce CO₂ emissions by 90%. A CO₂ tax and an increase in tax on the use of natural gas are potent policy tools to accelerate the adoption of low‐carbon heating technologies.     

Policy options in addressing livestock's contribution to climate change

There is a great potential to reduce greenhouse gas (GHG) emissions related to livestock production. For achieving this potential will require new initiatives at national and international levels that include promoting research and development on new mitigation technologies; deploying, diffusing and transferring technologies to mitigate emissions; and enhancing capacities to monitor, report and verify emissions from livestock production. This study describes the sources of livestock-related GHG emissions and reviews available mitigation technologies and practices. We assess the main policy instruments available to curb emissions and promote carbon sinks, and discuss the relative merits of alternative approaches. We discuss recent experiences in countries that have enacted mitigation strategies for the livestock sector to illustrate some of the key issues and constraints in policy implementation. Finally, we explore the main issues and challenges surrounding international efforts to mitigate GHG emissions and discuss some possible ways to address these challenges in future climate agreements.     

Lithium-ion battery cell production in Europe: Scenarios for reducing energy consumption and greenhouse gas emissions until 2030

The market for electric vehicles is growing rapidly, and there is a large demand for lithium-ion batteries (LIB). Studies have predicted a growth of 600% in LIB demand by 2030. However, the production of LIBs is energy intensive, thus contradicting the goal set by Europe to reduce greenhouse gas (GHG) emissions and become GHG emission free by 2040. Therefore, in this study, it was analyzed how the energy consumption and corresponding GHG emissions from LIB cell production may develop until 2030. Economic, technological, and political measures were considered and applied to market forecasts and to a model of a state-of-the art LIB cell factory. Notably, different scenarios with trend assumptions and above/below-trend assumptions were considered. It could be deduced that, if no measures are taken and if the status quo is extrapolated to the future, by 2030, ∼5.86 Mt CO₂-eq will be emitted due to energy consumption from European LIB cell production. However, by applying a combination of economic, technological, and political measures, energy consumption and GHG emissions could be decreased by 46% and 56% by 2030, respectively. Furthermore, it was found that political measures, such as improving the electricity mix, are important but less dominant than improving the production technology and infrastructure. In this study, it could be deduced that, by 2030, through industrialization and application of novel production technologies, the energy consumption and GHG emissions from LIB cell production in Europe can be reduced by 24%.     

Can Industrial Restructuring Lead to a Sustainable Future? A Critical Environmental Risk Assessment of Industrial Policy in Shandong Province,China

Shandong Province is attempting to realize a sustainable development path by industrial restructuring. This article attempts to forecast the outcomes of this policy, looking ahead to 2010 and 2020 by quantifying its resource demand and environmental effects. Prediction and analysis indicate that the industrial restructuring policy of Shandong Province is likely to prove beneficial to the environment, reducing energy and water consumption from the 2004 baseline. However, the analysis also indicates that the high anticipated economic growth rates will override any resource saving and pollutants reduction achieved. Natural resource supplies are insufficient to meet demand, and environmental quality is likely to deteriorate, rendering economic growth targets unachievable. However, if Shandong puts in place policies designed to achieve average energy and water consumption efficiency, SO₂ emission efficiency and wastewater treatment efficiency of OECD countries in 2004, then energy consumption, SO₂ emissions, wastewater, and Chemical Oxygen Demand discharges in 2020 will reduce in real terms with only water demand showing a slight increase over the 2004 baseline. The assessment suggests that further measures such as developing new and alternative energy sources, raising the utilization efficiency of energy and water resources, and improving pollution treatment are required if Shandong Province is to realize a balanced and sustainable development for its society, economy, and environment.     

From photons to biomass and biofuels: evaluation of different strategies for the improvement of algal biotechnology based on comparative energy balances

Microalgal based biofuels are discussed as future sustainable energy source because of their higher photosynthetic and water use efficiency to produce biomass. In the context of climate CO₂ mitigation strategies, algal mass production is discussed as a potential CO₂ sequestration technology which uses CO₂ emissions to produce biomass with high-oil content independent on arable land. In this short review, it is presented how complete energy balances from photon to harvestable biomass can help to identify the limiting processes on the cellular level. The results show that high productivity is always correlated with high metabolic costs. The overall efficiency of biomass formation can be improved by a photobioreactor design which is kinetically adapted to the rate-limiting steps in cell physiology. However, taking into account the real photon demand per assimilated carbon and the energy input for biorefinement, it becomes obvious that alternative strategies must be developed to reach the goal of a real CO₂ sequestration.     

Dry Matter Losses and Methane Emissions During Wood Chip Storage: the Impact on Full Life Cycle Greenhouse Gas Savings of Short Rotation Coppice Willow for Heat

A life cycle assessment (LCA) approach was used to examine the greenhouse gas (GHG) emissions and energy balance of short rotation coppice (SRC) willow for heat production. The modelled supply chain includes cutting multiplication, site establishment, maintenance, harvesting, storage, transport and combustion. The relative impacts of dry matter losses and methane emissions from chip storage were examined from a LCA perspective, comparing the GHG emissions from the SRC supply chain with those of natural gas for heat generation. The results show that SRC generally provides very high GHG emission savings of over 90 %. The LCA model estimates that a 1, 10 and 20 % loss of dry matter during storage causes a 1, 6 and 11 % increase in GHG emissions per MWh. The GHG emission results are extremely sensitive to emissions of methane from the wood chip stack: If 1 % of the carbon within the stack undergoes anaerobic decomposition to methane, then the GHG emissions per MWh are tripled. There are some uncertainties in the LCA results, regarding the true formation of methane in wood chip stacks, non-CO₂ emissions from combustion, N₂O emissions from leaf fall and the extent of carbon sequestered under the crop, and these all contribute a large proportion of the life cycle GHG emissions from cultivation of the crop.