Integrating future scenario‐based crop expansion and crop conditions to map switchgrass biofuel potential in eastern Nebraska,USA

Switchgrass (Panicum virgatum) has been evaluated as one potential source for cellulosic biofuel feedstocks. Planting switchgrass in marginal croplands and waterway buffers can reduce soil erosion, improve water quality, and improve regional ecosystem services (i.e. it serves as a potential carbon sink). In previous studies, we mapped high risk marginal croplands and highly erodible cropland buffers that are potentially suitable for switchgrass development, which would improve ecosystem services and minimally impact food production. In this study, we advance our previous study results and integrate future crop expansion information to develop a switchgrass biofuel potential ensemble map for current and future croplands in eastern Nebraska. The switchgrass biomass productivity and carbon benefits (i.e. NEP: net ecosystem production) for the identified biofuel potential ensemble areas were quantified. The future scenario‐based (‘A1B’) land use and land cover map for 2050, the US Geological Survey crop type and Compound Topographic Index (CTI) maps, and long‐term (1981–2010) averaged annual precipitation data were used to identify future crop expansion regions that are suitable for switchgrass development. Results show that 2528 km² of future crop expansion regions (~3.6% of the study area) are potentially suitable for switchgrass development. The total estimated biofuel potential ensemble area (including cropland buffers, marginal croplands, and future crop expansion regions) is 4232 km² (~6% of the study area), potentially producing 3.52 million metric tons of switchgrass biomass per year. Converting biofuel ensemble regions to switchgrass leads to potential carbon sinks (the total NEP for biofuel potential areas is 0.45 million metric tons C) and is environmentally sustainable. Results from this study improve our understanding of environmental conditions and ecosystem services of current and future cropland systems in eastern Nebraska and provide useful information to land managers to make land use decisions regarding switchgrass development.     

环境足迹的核算与整合框架——基于生命周期评价的视角

环境足迹及其与生命周期评价(LCA)的关系是工业生态学关注的新热点。从探讨环境足迹与LCA的关系入手,以碳足迹、水足迹、土地足迹和材料足迹为例,分别对每一项足迹指标两个版本的核算方法进行了比较。根据清单加和过程的特点,将所有足迹指标划分为基于权重因子和基于特征因子两类,总结了两者的适用性和局限性。在此基础上提出了一个环境足迹核算与整合的统一框架。该框架基于LCA视角建立,但对系统边界和清单数据的要求相对灵活,因而也适用于生命周期不甚明确的情形。研究在一定程度上揭示了足迹指标的方法学实质,同时也为环境影响综合评估提供了一条规范化的途径。     

Can intensification reduce emission intensity of biofuel through optimized fertilizer use? Theory and the case of oil palm in Indonesia

Closing yield gaps through higher fertilizer use increases direct greenhouse gas emissions but shares the burden over a larger production volume. Net greenhouse gas (GHG) footprints per unit product under agricultural intensification vary depending on the context, scale and accounting method. Life cycle analysis of footprints includes attributable emissions due to (i) land conversion (‘fixed cost’); (ii) external inputs used (‘variable cost’); (iii) crop production (‘agronomic efficiency’); and (iv) postharvest transport and processing (‘proportional’ cost). The interplay between fixed and variable costs results in a nuanced opportunity for intermediate levels of intensification to minimize footprints. The fertilizer level that minimizes the footprint may differ from the economic optimum. The optimization problem can be solved algebraically for quadratic crop fertilizer response equations. We applied this theory to data of palm oil production and fertilizer use from 23 plantations across the Indonesian production range. The current EU threshold requiring at least 35% emission saving for biofuel use can never be achieved by palm oil if produced: (i) on peat soils, or (ii) on mineral soils where the C debt due to conversion is larger than 20 Mg C ha^?1, if the footprint is calculated using an emission ratio of N₂O–N/N fertilizer of 4%. At current fertilizer price levels in Indonesia, the economically optimized N fertilizer rate is 344–394 kg N ha^?1, while the reported mean N fertilizer rate is 141 kg N ha^?1 yr^?1 and rates of 74–277 kg N ha^?1 would minimize footprints, for a N₂O–N/N fertilizer ratio of 4–1%, respectively. At a C debt of 30 Mg C ha^?1, these values are 200–310 kg N ha^?1. Sustainable weighting of ecology and economics would require a higher fertilizer/yield price ratio, depending on C debt. Increasing production by higher fertilizer use from current 67% to 80% of attainable yields would not decrease footprints in current production conditions.     

Environmental Assessment of Wood‐Based Biofuel Production and Consumption Scenarios in Norway

In Norway, the boreal forest offers a considerable resource base, and emerging technologies may soon make it commercially viable to convert these resources into low‐carbon biofuels. Decision makers are required to make informed decisions about the environmental implications of wood biofuels today that will affect the medium‐ and long‐term development of a wood‐based biofuels industry in Norway. We first assess the national forest‐derived resource base for use in biofuel production. A set of biomass conversion technologies is then chosen and evaluated for scenarios addressing biofuel production and consumption by select industry sectors. We then apply an environmentally extended, mixed‐unit, two‐region input?output model to quantify the global warming mitigation and fossil fuel displacement potentials of two biofuel production and consumption scenarios in Norway up to 2050. We find that a growing resource base, when used to produce advanced biofuels, results in cumulative global warming mitigation potentials of between 58 and 83 megatonnes of carbon dioxide equivalents avoided (Mt‐CO₂‐eq.‐avoided) in Norway, depending on the biofuel scenario. In recent years, however, the domestic pulp and paper industry—due to increasing exposure to international competition, capacity reductions, and increasing production costs—has been in decline. In the face of a declining domestic pulp and paper industry, imported pulp and paper products are required to maintain the demand for these goods and thus the greenhouse gas (GHG) emissions of the exporting region embodied in Norway's pulp and paper imports reduce the systemwide benefit in terms of avoided greenhouse gas emissions by 27%.     

Life cycle carbon footprint of the packaging and transport of New Zealand kiwifruit

Purpose

The aim of this study is to assess the life cycle carbon footprint of the New Zealand kiwifruit packaging and transport supply chain to retailers in two major markets (Japan and Germany). Results of this study have been used to identify areas of the New Zealand kiwifruit packaging and transport supply chain that contribute significantly to the carbon footprint and to identify options for reduction.

Methods

This study is based on the ISO standards for life cycle assessment (namely, ISO 14040:2006 and ISO 14044:2006). The PAS 2050 also provided further methodological guidance. Primary packaging data were sourced from Zespri’s suppliers. End-of-life data were sourced from the market and waste statistics of the relevant countries. Gabi 4.4 was used for upstream material information and modelling.

Results and discussion

The carbon footprint of the packaging and transport of kiwifruit ranged from 0.33 to 0.67 kg CO₂e per kilogram of fruit delivered to a store depending on pack type and market. Shipping accounted for the majority of these emissions (58–82 %), and Zespri is actively working with shipping companies to reduce this. There are also opportunities to reduce the carbon footprint through reducing the amount of fruit repacked in the market, using trains for long-distance transport and increasing packaging recycling rates.

Conclusions

There is a range of options for reducing the carbon footprint of the New Zealand kiwifruit packaging and transport supply chain. These will tend to be incremental (i.e. a number of small gains) and would involve working closely with partners in the supply chain. Options include increased efficiency in shipping, use of trains for land transport, reductions in the addition of structural packaging in the market, managing the product mix to minimize those supply chains with a higher carbon footprint, identifying alternative material for components of the packaging, replacing the use of polystyrene clamshells with alternative materials or plastic bags and maximizing recycling rates along all stages of the supply chain.     

Cellulosic feedstock production on Conservation Reserve Program land: potential yields and environmental effects

Producing biofuel feedstocks on current agricultural land raises questions of a ‘food‐vs.‐fuel’ trade‐off. The use of current or former Conservation Reserve Program (CRP) land offers an alternative; yet the volumes of ethanol that could be produced and the potential environmental impacts of such a policy are unclear. Here, we applied the Environmental Policy Integrated Climate model to a US Department of Agriculture database of over 200 000 CRP polygons in Iowa, USA, as a case study. We simulated yields and environmental impacts of growing three cellulosic biofuel feedstocks on CRP land: (i) an Alamo‐variety switchgrass (Panicum virgatum L.); (ii) a generalized mixture of C4 and C3 grasses; (iii) and no‐till corn (Zea mays L.) with residue removal. We simulated yields, soil erosion, and soil carbon (C) and nitrogen (N) stocks and fluxes. We found that although no‐till corn with residue removal produced approximately 2.6–4.4 times more ethanol per area compared to switchgrass and the grass mixture, it also led to 3.9–4.5 times more erosion, 4.4–5.2 times more cumulative N loss, and a 10% reduction in total soil carbon as opposed to a 6–11% increase. Switchgrass resulted in the best environmental outcomes even when expressed on a per liter ethanol basis. Our results suggest planting no‐till corn with residue removal should only be done on low slope soils to minimize environmental concerns. Overall, this analysis provides additional information to policy makers on the potential outcome and effects of producing biofuel feedstocks on current or former conservation lands.     

Transport biofuels in global energy–economy modelling – a review of comprehensive energy systems assessment approaches

The high oil dependence and the growth of energy use in the transport sector have increased the interest in alternative nonfossil fuels as a measure to mitigate climate change and improve energy security. More ambitious energy and environmental targets and larger use of nonfossil energy in the transport sector increase energy–transport interactions and system effects over sector boundaries. While the stationary energy sector (e.g., electricity and heat generation) and the transport sector earlier to large degree could be considered as separate systems with limited interaction, integrated analysis approaches and assessments of energy–transport interactions now grow in importance. In recent years, the scientific literature has presented an increasing number of global energy–economy future studies based on systems modelling treating the transport sector as an integral part of the overall energy system and/or economy. Many of these studies provide important insights regarding transport biofuels. To clarify similarities and differences in approaches and results, the present work reviews studies on transport biofuels in global energy–economy modelling and investigates what future role comprehensive global energy–economy modelling studies portray for transport biofuels in terms of their potential and competitiveness. The results vary widely between the studies, but the resulting transport biofuel market shares are mainly below 40% during the entire time periods analysed. Some of the reviewed studies show higher transport biofuel market shares in the medium (15–30 years) than in the long term (above 30 years), and, in the long‐term models, at the end of the modelling horizon, transport biofuels are often substituted by electric and hydrogen cars.     

Water,land and carbon footprints of sheep and chicken meat produced in Tunisia under different farming systems

Meat production puts larger demands on water and land and results in larger greenhouse gas emissions than alternative forms of food. This study uses footprint indicators, the water, land and carbon footprint, to assess natural resources use and greenhouse gas emissions for sheep and chicken meat produced in Tunisia in different farming systems in the period 1996–2005. Tunisia is a water-scarce country with large areas of pasture for sheep production. Poultry production is relatively large and based on imported feed. The farming systems considered are: the industrial system for chicken, and the agro-pastoral system using cereal crop-residues, the agro-pastoral system using barley and the pastoral system using barley for sheep. Chicken meat has a smaller water footprint (6030 litre/kg), land footprint (9 m²/kg) and carbon footprint (3 CO₂-eq/kg) than sheep meat (with an average water footprint of 18900 litre/kg, land footprint of 57 m²/kg, and carbon footprint of 28 CO₂-eq/kg). For sheep meat, the agro-pastoral system using cereal crop-residues is the production system with smallest water and land footprints, but the highest carbon footprint. The pastoral system using barley has larger water and land footprints than the agro-pastoral system using barley, but comparable carbon footprint.     

足迹家族:概念、类型、理论框架与整合模式

足迹研究是当前生态经济学和可持续发展领域的热点与前沿课题。探讨了足迹类指标的内涵,将其定义为一类评估人类资源消费和废弃物排放等活动环境影响的指标;介绍了生态足迹、碳足迹、水足迹、能源足迹、化学足迹、氮足迹和生物多样性足迹7类典型足迹指标的概念与研究进展;在此基础上提出了普适性的足迹家族概念,总结了足迹家族的选择性、开放性、系统性和不确定性特征,并根据足迹类指标的一般运算流程构建了足迹家族的理论框架;基于大量文献成果系统比较了生态足迹、碳足迹和水足迹3类关键足迹的特征差异,提出了在足迹家族层面增强指标兼容性的措施;通过逐一测试各关键足迹与27项环境问题的相关程度,从决策相关性的角度初步探索了该足迹家族的整合模式;展望了未来足迹(家族)研究的重点方向。     

Strategies to enhance production of microalgal biomass and lipids for biofuel feedstock

ABSTRACT

Microalgae have enormous potential as feedstock for biofuel production compared with other sources, due to their high areal productivity, relatively low environmental impact, and low impact on food security. However, high production costs are the major limitation for commercialization of algal biofuels. Strategies to maximize biomass and lipid production are crucial for improving the economics of using microalgae for biofuels. Selection of suitable algal strains, preferably from indigenous habitats, and further improvement of those ‘platform strains’ using mutagenesis and genetic engineering approaches are desirable. Conventional approaches to improve biomass and lipid productivity of microalgae mainly involve manipulation of nutritional (e.g. nitrogen and phosphorus) and environmental (e.g. temperature, light and salinity) factors. Approaches such as the addition of phytohormones, genetic and metabolic engineering, and co-cultivation of microalgae with yeasts and bacteria are more recent strategies to enhance biomass and lipid productivity of microalgae. Improvement in culture systems and the use of a hybrid system (i.e. a combination of open ponds and photobioreactors) is another strategy to optimize algal biomass and lipid production. In addition, the use of low-cost substrates such as agri-industrial wastewater for the cultivation of microalgae will be a smart strategy to reduce production costs. Such systems not only generate high algal biomass and lipid productivity, but are also useful for bioremediation of wastewater and bioremoval of waste CO₂. The aim of this review is to highlight the advances in the use of various strategies to enhance production of algal biomass and lipids for biofuel feedstock.     

How sustainable are biofuels? Answers and further questions arising from an ecological footprint perspective

By using biofuels bioproductive land is devoted to supply energy. As the bioproductive land area on our planet is confined and actually decreasing, biofuels compete against other demands like the production of food, industrial resources, nature conservation etc. This not only results in higher prices for agricultural and forestry products, but also increases environmental pressures. The aim of this paper is to clarify if and to which extent biofuels might be sustainable by applying modified calculation methods of the ecological footprint. It can be concluded that biofuels can offer huge environmental benefits compared to fossil fuels. Yet, if and to which extent biofuel production is sustainable depends on the amount of land available and, therefore, can only be decided in a regional context. Ecological footprinting can significantly support these regional decision making processes.     

Sources of variability in greenhouse gas and energy balances for biofuel production: a systematic review

Across the energy sector, alternatives to fossil fuels are being developed, in response to the dual drivers of climate change and energy security. For transport, biofuels have the greatest potential to replace fossil fuels in the short‐to medium term. However, the ecological benefits of biofuels and the role that their deployment can play in mitigating climate change are being called into question. Life Cycle Assessment (LCA) is a widely used approach that enables the energy and greenhouse gas (GHG) balance of biofuel production to be calculated. Concerns have nevertheless been raised that published data show widely varying and sometimes contradictory results. This review describes a systematic review of GHG emissions and energy balance data from 44 LCA studies of first‐ and second‐generation biofuels. The information collated was used to identify the dominant sources of GHG emissions and energy requirements in biofuel production and the key sources of variability in published LCA data. Our analysis revealed three distinct sources of variation: (1) ‘real’ variability in parameters e.g. cultivation; (2) ‘methodological’ variability due to the implementation of the LCA method; and (3) ‘uncertainty’ due to parameters rarely included and poorly quantified. There is global interest in developing a sustainability assessment protocol for biofuels. Confidence in the results of such an assessment can only be assured if these areas of uncertainty and variability are addressed. A more defined methodology is necessary in order to allow effective and accurate comparison of results. It is also essential that areas of uncertainty such as impacts on soil carbon stocks and fluxes are included in LCA assessments, and that further research is conducted to enable a robust calculation of impacts under different land‐use change scenarios. Without the inclusion of these parameters, we cannot be certain that biofuels are really delivering GHG savings compared with fossil fuels.     

Ecosystem model parameterization and adaptation for sustainable cellulosic biofuel landscape design

Renewable fuel standards in the US and elsewhere mandate the production of large quantities of cellulosic biofuels with low greenhouse gas (GHG) footprints, a requirement which will likely entail extensive cultivation of dedicated bioenergy feedstock crops on marginal agricultural lands. Performance data for such systems is sparse, and non‐linear interactions between the feedstock species, agronomic management intensity, and underlying soil and land characteristics complicate the development of sustainable landscape design strategies for low‐impact commercial‐scale feedstock production. Process‐based ecosystem models are valuable for extrapolating field trial results and making predictions of productivity and associated environmental impacts that integrate the effects of spatially variable environmental factors across diverse production landscapes. However, there are few examples of ecosystem model parameterization against field trials on both prime and marginal lands or of conducting landscape‐scale analyses at sufficient resolution to capture interactions between soil type, land use, and management intensity. In this work we used a data‐diverse, multi‐criteria approach to parameterize and validate the DayCent biogeochemistry model for upland and lowland switchgrass using data on yields, soil carbon changes, and soil nitrous oxide emissions from US field trials spanning a range of climates, soil types, and management conditions. We then conducted a high‐resolution case study analysis of a real‐world cellulosic biofuel landscape in Kansas in order to estimate feedstock production potential and associated direct biogenic GHG emissions footprint. Our results suggest that switchgrass yields and emissions balance can vary greatly across a landscape large enough to supply a biorefinery in response to variations in soil type and land‐use history, but that within a given land base both of these performance factors can be widely modulated by changing management intensity. This in turn implies a large sustainable cellulosic biofuel landscape design space within which a system can be optimized to meet economic or environmental objectives.     

The Greenhouse Gas Footprint of China's Food System: An Analysis of Recent Trends and Future Scenarios

Food chain systems (FCSs), which begin in agricultural production and end in consumption and waste disposal, play a significant role in China's rising greenhouse gas (GHG) emissions. This article uses scenario analysis to show China's potential trajectories to a low‐carbon FCS. Between 1996 and 2010, the GHG footprint of China's FCSs increased from 1,308 to 1,618 megatonnes of carbon dioxide equivalent (Mt CO₂‐eq), although the emissions intensity of all food categories, except for aquatic food, recorded steep declines. We project three scenarios to 2050 based on historical trends and plausible shifts in policies and environmental conditions: reference scenario; technology improvement scenario; and low GHG emissions scenario. The reference scenario is based on existing trends and exhibits a large growth in GHG emissions, increasing from 1,585 Mt CO₂‐eq in 2010 to 2,505 Mt CO₂‐eq in 2050. In the technology improvement scenario, emissions growth is driven by rising food demand, but that growth will be counterbalanced by gains in agricultural technology, causing GHG emissions to fall to 1,413 Mt CO₂‐eq by 2050. Combining technology improvement with the shift to healthier dietary patterns, GHG emissions in the low GHG emissions scenario will decline to 946 Mt CO₂‐eq in 2050, a drop of 41.5% compared with the level in 2010. We argue that these are realistic projections and are indeed indicative of China's overall strategy for low‐carbon development. Improving agricultural technology and shifting to a more balanced diet could significantly reduce the GHG footprint of China's FCSs. Furthermore, the transition to a low‐carbon FCS has potential cobenefits for land sustainability and public health.     

International inequality of environmental pressures: Decomposition and comparative analysis

Natural resource scarcity is no longer merely a remote possibility and governments increasingly seek information about the global distribution of resource use and related environmental pressures. This paper presents an international distributional analysis of natural resource use indicators. These encompass both territorial (national production) and footprint (national consumption) indicators for land-related pressures (human appropriation of net primary production, HANPP, and embodied HANPP), for material use (domestic material extraction and consumption and material footprint), and for carbon emissions (territorial carbon emissions and carbon footprints). Our main question is “What, both from a territorial and a footprint perspective, are the main driving factors of international environmental inequality?”. We show that, for the environmental indicators we studied, inequality tends to be higher for footprint indicators than for territorial ones. The exception is land use intensity (as measured by HANPP), for which geographical drivers mainly determine the distribution pattern. The international distribution of material consumption is mainly a result of economic drivers whereas, for domestic extraction, demographic drivers can explain almost half of the distribution pattern. Finally, carbon emissions are the environmental pressure that shows the highest international inequality because of the larger contribution of economic drivers.     

Bioethanol and biodiesel: Alternative liquid fuels for future generations

The global population is expected to increase by approximately 3 billion people by 2050. With this increase in population, industry, transportation the cost of fossil fuels will grow dramatically. New technologies are needed for fuel extraction using feedstocks that do not threaten food security, cause minimal or no loss of natural habitat and soil carbon. At the same time, waste management has to be improved and environmental pollution should be minimized or eliminated. Liquid biofuels such as lignocellulosic‐based ethanol from plant biomass and algal‐based biodiesel are sustainable, alternative biofuels that could stabilize national security and provide clean energy for future generations. Ideally, the technology should also foster recycling of agricultural feedstocks and improve soil fertility and human health. This article provides updated information on the energy potential and breadth of liquid biofuel biotechnology.     

LIFE BEEF CARBON: a common framework for quantifying grass and corn based beef farms’ carbon footprints

Europe’s roadmap to a low-carbon economy aims to cut greenhouse gas (GHG) emissions 80% below 1990 levels by 2050. Beef production is an important source of GHG emissions and is expected to increase as the world population grows. LIFE BEEF CARBON is a voluntary European initiative that aims to reduce GHG emissions per unit of beef (carbon footprint) by 15% over a 10-year period on 2172 farms in four large beef-producing countries. Changes in farms beef carbon footprint are normally estimated via simulation modelling, but the methods current models apply differ. Thus, our initial goal was to develop a common modelling framework to estimate beef farms carbon footprint. The framework was developed for a diverse set of Western Europe farms located in Ireland, Spain, Italy and France. Whole farm and life cycle assessment (LCA) models were selected to quantify emissions for the different production contexts and harmonized. Carbon Audit was chosen for Ireland, Bovid-CO₂ for Spain and CAP’2ER for France and Italy. All models were tested using 20 case study farms, that is, 5 per country and quantified GHG emissions associated with on-farm live weight gain. The comparison showed the ranking of beef systems gross carbon footprint was consistent across the three models. Suckler to weaning or store systems generally had the highest carbon footprint followed by suckler to beef systems and fattening beef systems. When applied to the same farm, Carbon Audit’s footprint estimates were slightly lower than CAP’2ER, but marginally higher than Bovid-CO₂. These differences occurred because the models were adapted to a specific region’s production circumstances, which meant their emission factors for key sources; that is, methane from enteric fermentation and GHG emissions from concentrates were less accurate when used outside their target region. Thus, for the common modelling framework, region-specific LCA models were chosen to estimate beef carbon footprints instead of a single generic model. Additionally, the Carbon Audit and Bovid-CO₂ models were updated to include carbon removal by soil and other environmental metrics included in CAP’2ER, for example, acidification. This allows all models to assess the effect carbon mitigation strategies have on other potential pollutants. Several options were identified to reduce beef farms carbon footprint, for example, improving genetic merit. These options were assessed for beef systems, and a mitigation plan was created by each nation. The cumulative mitigation effect of the LIFE BEEF CARBON plan was estimated to exceed the projects reduction target (−15%).     

Projecting future grassland productivity to assess the sustainability of potential biofuel feedstock areas in the Greater Platte River Basin

This study projects future (e.g., 2050 and 2099) grassland productivities in the Greater Platte River Basin (GPRB) using ecosystem performance (EP, a surrogate for measuring ecosystem productivity) models and future climate projections. The EP models developed from a previous study were based on the satellite vegetation index, site geophysical and biophysical features, and weather and climate drivers. The future climate data used in this study were derived from the National Center for Atmospheric Research Community Climate System Model 3.0 ‘SRES A1B’ (a ‘middle’ emissions path). The main objective of this study is to assess the future sustainability of the potential biofuel feedstock areas identified in a previous study. Results show that the potential biofuel feedstock areas (the more mesic eastern part of the GPRB) will remain productive (i.e., aboveground grassland biomass productivity >2750 kg ha^?1 year^?1) with a slight increasing trend in the future. The spatially averaged EPs for these areas are 3519, 3432, 3557, 3605, 3752, and 3583 kg ha^?1 year^?1 for current site potential (2000–2008 average), 2020, 2030, 2040, 2050, and 2099, respectively. Therefore, the identified potential biofuel feedstock areas will likely continue to be sustainable for future biofuel development. On the other hand, grasslands identified as having no biofuel potential in the drier western part of the GPRB would be expected to stay unproductive in the future (spatially averaged EPs are 1822, 1691, 1896, 2306, 1994, and 2169 kg ha^?1 year^?1 for site potential, 2020, 2030, 2040, 2050, and 2099). These areas should continue to be unsuitable for biofuel feedstock development in the future. These future grassland productivity estimation maps can help land managers to understand and adapt to the expected changes in future EP in the GPRB and to assess the future sustainability and feasibility of potential biofuel feedstock areas.     

Impacts of land use change due to biofuel crops on carbon balance,bioenergy production,and agricultural yield,in the conterminous United States

Growing concerns about energy and the environment have led to worldwide use of bioenergy. Switching from food crops to biofuel crops is an option to meet the fast‐growing need for biofuel feedstocks. This land use change consequently affects the ecosystem carbon balance. In this study, we used a biogeochemistry model, the Terrestrial Ecosystem Model, to evaluate the impacts of this change on the carbon balance, bioenergy production, and agricultural yield, assuming that several land use change scenarios from corn, soybean, and wheat to biofuel crops of switchgrass and Miscanthus will occur. We found that biofuel crops have much higher net primary production (NPP) than soybean and wheat crops. When food crops from current agricultural lands were changed to different biofuel crops, the national total NPP increased in all cases by a range of 0.14–0.88 Pg C yr^?1, except while switching from corn to switchgrass when a decrease of 14% was observed. Miscanthus is more productive than switchgrass, producing about 2.5 times the NPP of switchgrass. The net carbon loss ranges from 1.0 to 6.3 Tg C yr^?1 if food crops are changed to switchgrass, and from 0.4 to 6.7 Tg C yr^?1 if changed to Miscanthus. The largest loss was observed when soybean crops were replaced with biofuel crops. Soil organic carbon increased significantly when land use changed, reaching 100 Mg C ha^?1 in biofuel crop ecosystems. When switching from food crops to Miscanthus, the per unit area croplands produced a larger amount of ethanol than that of original food crops. In comparison, the land use change from wheat to Miscanthus produced more biomass and sequestrated more carbon. Our study suggests that Miscanthus could better serve as an energy crop than food crops or switchgrass, considering both economic and environmental benefits.     

A method for calculating a land‐use change carbon footprint (LUC‐CFP) for agricultural commodities – applications to Brazilian beef and soy,Indonesian palm oil

The world's agricultural system has come under increasing scrutiny recently as an important driver of global climate change, creating a demand for indicators that estimate the climatic impacts of agricultural commodities. Such carbon footprints, however, have in most cases excluded emissions from land‐use change and the proposed methodologies for including this significant emissions source suffer from different shortcomings. Here, we propose a new methodology for calculating land‐use change carbon footprints for agricultural commodities and illustrate this methodology by applying it to three of the most prominent agricultural commodities driving tropical deforestation: Brazilian beef and soybeans, and Indonesian palm oil. We estimate land‐use change carbon footprints in 2010 to be 66 tCO₂/t meat (carcass weight) for Brazilian beef, 0.89 tCO₂/t for Brazilian soybeans, and 7.5 tCO₂/t for Indonesian palm oil, using a 10 year amortization period. The main advantage of the proposed methodology is its flexibility: it can be applied in a tiered approach, using detailed data where it is available while still allowing for estimation of footprints for a broad set of countries and agricultural commodities; it can be applied at different scales, estimating both national and subnational footprints; it can be adopted to account both for direct (proximate) and indirect drivers of land‐use change. It is argued that with an increasing commercialization and globalization of the drivers of land‐use change, the proposed carbon footprint methodology could help leverage the power needed to alter environmentally destructive land‐use practices within the global agricultural system by providing a tool for assessing the environmental impacts of production, thereby informing consumers about the impacts of consumption and incentivizing producers to become more environmentally responsible.