Accounting greenhouse gas emissions in the lifecycle of Brazilian sugarcane bioethanol: Methodological references in European and American regulations

Greenhouse gas release from land use change (the so-called "carbon debt") has been identified as a potentially significant contributor to the environmental profile of biofuels. The time required for biofuels to overcome this carbon debt due to land use change and begin providing cumulative greenhouse gas benefits is referred to as the "payback period" and has been estimated to be 100-1000 years depending on the specific ecosystem involved in the land use change event. Two mechanisms for land use change exist: "direct" land use change, in which the land use change occurs as part of a specific supply chain for a specific biofuel production facility, and "indirect" land use change, in which market forces act to produce land use change in land that is not part of a specific biofuel supply chain, including, for example, hypothetical land use change on another continent. Existing land use change studies did not consider many of the potentially important variables that might affect the greenhouse gas emissions of biofuels. We examine here several variables that have not yet been addressed in land use change studies. Our analysis shows that cropping management is a key factor in estimating greenhouse gas emissions associated with land use change. Sustainable cropping management practices (no-till and no-till plus cover crops) reduce the payback period to 3 years for the grassland conversion case and to 14 years for the forest conversion case. It is significant that no-till and cover crop practices also yield higher soil organic carbon (SOC) levels in corn fields derived from former grasslands or forests than the SOC levels that result if these grasslands or forests are allowed to continue undisturbed. The United States currently does not hold any of its domestic industries responsible for its greenhouse gas emissions. Thus the greenhouse gas standards established for renewable fuels such as corn ethanol in the Energy Independence and Security Act (EISA) of 2007 set a higher standard for that industry than for any other domestic industry. Holding domestic industries responsible for the environmental performance of their own supply chain, over which they may exert some control, is perhaps desirable (direct land use change in this case). However, holding domestic industries responsible for greenhouse gas emissions by their competitors worldwide through market forces (via indirect land use change in this case) is fraught with a host of ethical and pragmatic difficulties. Greenhouse gas emissions associated with indirect land use change depend strongly on assumptions regarding social and environmental responsibilities for actions taken, cropping management approaches, and time frames involved, among other issues.

Biofuels have gained increasing attention as an alternative to fossil fuels for several reasons, one of which is their potential to reduce the greenhouse gas (GHG) emissions from the transportation sector. Recent studies have questioned the validity of claims about the potential for biofuels to reduce GHG emissions relative to the liquid fossil fuels they are replacing when emissions due to direct and indirect land use changes (ILUCs) that accompany biofuels are included in the life-cycle GHG intensity of biofuels. Studies estimate that the GHG emissions released from ILUC could more than offset the direct GHG savings by producing biofuels and replacing liquid fossil fuels and create a “carbon debt” with a long payback period. The estimates of this payback period, however, vary widely across biofuels from different feedstocks and even for a single biofuel across different modeling assumptions. In the case of corn ethanol, this payback period is found to range from 15 to 200 years. We discuss the challenges in estimating the ILUC effect of a biofuel and differences across biofuels, and its sensitivity to the assumptions and policy scenarios considered by different economic models. We also discuss the implications of ILUC for designing policies that promote biofuels and seek to reduce GHG emissions. In a first best setting, a global carbon tax is needed to set both direct and indirect land use change emissions to their optimal levels. However, it is unclear whether unilateral GHG mitigation policies, even if they penalize the ILUC related emissions, would increase social welfare and lead to optimal emission levels. In the absence of a global carbon tax, incentivizing sustainable land use practices through certification standards, government regulations and market-based pressures may be a viable option for reducing ILUC.

Life cycle greenhouse gas emissions impacts of the adoption of the EU Directive on biofuels in Spain. Effect of the import of raw materials and land use changes

The Renewable Energy Directive of the European Union (EU-RED) established targets to be met by 2020, including a separate and uniform target for all Member States of 10% renewable energy in the transport sector. Biofuels used to achieve the EU targets must meet sustainability criteria, including restrictions on the types of land and minimum GHG reduction levels. The expansion in biofuels markets offers economic opportunities for developing countries to export to the EU while developing their own domestic markets. Imported biofuels can also have lower land use impact and GHG emissions than those produced in the EU. The current global biofuels market is dominated by the EU, Brazil and the US, with only the EU having a sustained level of imported biofuels or feedstocks. The EU market is dominated by domestic production of biodiesel, mainly from rapeseed, whereas imports are dominated especially by bioethanol from Brazil and soya biodiesel from Argentina. Least Developed Countries (LDCs) benefit from several different preferential tariffs, and are slowly beginning to export to the EU; in the case of bioethanol, Brazil dominates even with preferential tariffs, and thus the trade balance is more related to domestic demand in Brazil. For biofuels to be considered sustainable, they must be accredited by a voluntary or national scheme recognized by the European Commission or through a bilateral or multilateral agreement. The actual costs for compliance include not only direct costs of certification but also the cost of developing new information systems, administrative procedures and modifying equipment or management processes. Smaller farmers and producers will tend to have more difficulty absorbing additional costs; for reasons of equity institutional and technical support should be provided, especially in LDCs. Bilateral or multilateral agreements could provide such support and could also potentially provide direct incentives for using degraded lands and related measures to promote good governance in land use policies. The market for biofuels has thus experienced a rapid transformation, with many sustainability certification schemes vying for approval by the EU and the private sector. Technological advances, especially via second generation biofuels, have brought the biofuel industry closer to other biomass-based industries, such as pulp and paper or forestry; in the long-term, it is expected that biorefineries will produce multiple energy and non-energy products in a flexible and more efficient manner. The option of different final markets also implies increased competition for feedstock, just as agricultural biofuels created some competition with food or feed. This somehow blurs the borders between biofuels and biomass, opening options for broader and more comprehensive sustainability initiatives that can cover all biomass-based materials and products or services. Another concern arises from land use change; if biofuels demand leads directly or indirectly to deforestation or forest degradation, the goals of the EU-RED will not be met. The EU-RED provisions address direct land use change (dLUC) fairly well although some smaller forested areas are not covered and thus not protected by the definitions. High-yielding crops such as sugar cane and sugar beet tend to have lower indirect land use impacts, whereas lower-yielding first generation feedstocks such as wheat or soya can have significant land use impacts and GHG emissions. The use of a general factor for indirect Land Use Change (iLUC) rather than a crop-specific factor related to indirect land use change could thus penalise those feedstocks and regions that actually have lower impacts. The National Renewable Energy Action Plans suggest a significant level of imports of 25-37% but do not distinguish between intra-EU trade and external trade. Significant uncertainties remain in iLUC modelling, particularly in sub-national land use dynamics and the general difficulty in capturing socio-economic variables in large models, and methodological improvements are needed

This study updates the life cycle greenhouse gas (GHG) emissions for soybean biodiesel with revised system boundaries and the inclusion of indirect land use change using the most current set of agricultural data. The updated results showed that life cycle GHG emission from biodiesel use was reduced by 81.2% compared to 2005 baseline diesel. When the impacts of lime application and soil N2O emissions were excluded for more direct comparison with prior results published by the National Renewable Energy Laboratory (NREL), the reduction was 85.4%. This is a significant improvement over the 78.5% GHG reduction reported in the NREL study. Agricultural lime accounted for 50.6% of GHG from all agricultural inputs. Soil N2O accounted for 18.0% of total agricultural emissions. The improvement in overall GHG reduction was primarily due to lower agricultural energy usage and improved soybean crushing facilities. This study found that soybean meal and oil price data from the past ten years had a significant positive correlation (R2 = 0.73); hence, it is argued that soybean meal and oil are both responsible for indirect land use change from increased soybean demand. It is concluded that when there is a strong price correlation among co-products, system boundary expansion without a proper co-product allocation for indirect land use change produces erroneous results. When the emissions associated with predicted indirect land use change were allocated and incorporated using U.S. EPA model data, the GHG reduction for biodiesel was 76.4% lower than 2005 baseline diesel.

The iLUC dilemma: How to deal with indirect land use changes when governing energy crops?

Regional variations in the environmental impacts of plant biomass production are significant, and the environmental impacts associated with feedstock supply also contribute substantially to the environmental performance of biobased products. Thus, the regional variations in the environmental performance of biobased products are also significant. This study scrutinizes greenhouse gas (GHG) emissions associated with two biobased products (i.e., ethanol and soybean oil) whose feedstocks (i.e., corn and soybean) are produced in different farming locations. We chose 40 counties in Corn Belt States in the United States as biorefinery locations (i.e., corn dry milling, soybean crushing) and farming sites, and estimated cradle-to-gate GHG emissions of ethanol and of soybean oil, respectively. The estimates are based on 1 kg of each biobased product (i.e., ethanol or soybean oil). The system boundary includes biomass production, the biorefinery, and upstream processes. Effects of direct land use change are included in the greenhouse gas analysis and measured as changes in soil organic carbon level, while the effects of indirect land use change are not considered in the baseline calculations. Those indirect effects however are scrutinized in a sensitivity analysis. GHG emissions of corn-based ethanol range from 1.1 to 2.0 kg of CO2 equivalent per kilogram of ethanol, while GHG emissions of soybean oil are 0.4–2.5 kg of CO2 equivalent per kilogram of soybean oil. Thus, the regional variations due to farming locations are significant (by factors of 2–7). The largest GHG emission sources in ethanol production are N2O emissions from soil during corn cultivation and carbon dioxide from burning the natural gas used in corn dry milling. The second largest GHG emission source groups in the ethanol production system are nitrogen fertilizer (8–12%), carbon sequestration by soil (−15–2%), and electricity used in corn dry milling (7–16%). The largest GHG emission sources in soybean oil production are N2O emissions from soil during soybean cultivation (13–57%) and carbon dioxide from burning the natural gas used in soybean crushing (21–47%). The second largest GHG emission source groups in soybean oil production are carbon sequestration by soil (−29–24%), diesel used in soybean cultivation (4–24%), and electricity used in the soybean crushing process (10–21%). The indirect land use changes increase GHG emissions of ethanol by 7–38%, depending on the fraction of forest converted when newly converted croplands maintain crop cultivation for 100 years. Farming sites with higher biomass yields, lower nitrogen fertilizer application rates, and less tillage are favorable to future biorefinery locations in terms of global warming. For existing biorefineries, farmers are encouraged to apply a site-specific optimal nitrogen fertilizer application rate, to convert to no-tillage practices and also to adopt winter cover practices whenever possible to reduce the GHG emissions of their biobased products. Current practices for estimating the effects of indirect land use changes suffer from large uncertainties. More research and consensus about system boundaries and allocation issues are needed to reduce uncertainties related to the effects of indirect land use changes.

Chapter 7 - Implications of biofuel production on direct and indirect land use change: Evidence from Brazil

GHG sustainability compliance of rapeseed-based biofuels produced in a Danish multi-output biorefinery system

Direct and indirect land use changes issues in European sustainability initiatives: State-of-the-art, open issues and future developments

Indirect land use change for biofuels: Testing predictions and improving analytical methodologies

While debate on biofuels and bioenergy generally has sparked controversy over claimed greenhouse gas emissions benefits available with a switch to biomass, these claims have generally not taken into account indirect land use changes. Carbon emissions from land that is newly planted with biocrops, after land use changes such as deforestation, are certainly real – but efforts to measure them have been presented subject to severe qualifi cations. No such qualifications accompanied the paper by Searchinger et al. published in Science in February 2008, where the claim was made that a spike of ethanol consumption in the USA up to the year 2016 would divert corn grown in the USA and lead to new plantings of grain crops around the world to make up the shortfall, resulting in land use changes covering 10.8 million hectares and leading to the release of 3.8 billion tons of greenhouse gas emissions in terms of CO2 equivalent. These emissions, the paper argued, would more than offset any savings in emissions by growing biofuels in the first place; in fact they would create a ‘carbon debt’ that would take 160 years to repay. Such criticism would be devastating, if it were valid. The aim of this perspective is to probe the assumptions and models used in the Searchinger et al. paper, to evaluate their validity and plausibility, and contrast them with other approaches taken or available to be taken. It is argued that indirect land use change effects are too diffuse and subject to too many arbitrary assumptions to be useful for rule‐making, and that the use of direct and controllable measures, such as building statements of origin of biofuels into the contracts that regulate the sale of such commodities, would secure better results. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd

Use of ethanol as a transportation fuel in the United States has grown from 76 dam 3 in 1980 to over 40.1 hm 3 in 2009 — and virtually all of it has been produced from corn. It has been debated whether using corn ethanol results in any energy and greenhouse gas benefits. This issue has been especially critical in the past several years, when indirect effects, such as indirect land use changes, associated with U.S. corn ethanol production are considered in evaluation. In the past three years, modeling of direct and indirect land use changes related to the production of corn ethanol has advanced significantly. Meanwhile, technology improvements in key stages of the ethanol life cycle (such as corn farming and ethanol production) have been made. With updated simulation results of direct and indirect land use changes and observed technology improvements in the past several years, we conducted a life-cycle analysis of ethanol and show that at present and in the near future, using corn ethanol reduces greenhouse gas emission by more than 20%, relative to those of petroleum gasoline. On the other hand, second-generation ethanol could achieve much higher reductions in greenhouse gas emissions. In a broader sense, sound evaluation of U.S. biofuel policies should account for both unanticipated consequences and technology potentials. We maintain that the usefulness of such evaluations is to provide insight into how to prevent unanticipated consequences and how to promote efficient technologies with policy intervention.

Various regional and international standards have been developed to measure the environmental impacts of transportation fuels and minimize greenwashing and misinformation regarding their sustainability. These frameworks offer standardized methods and calculation guidelines for fuel producers to be able to verify compliance with predefined sustainability criteria and to achieve greenhouse gas emission reduction targets. However, significant inconsistencies exist among these standards in terms of methods, calculation rules, and default values assigned to specific fuels. This study reviews and analyses five fuel standards, namely the European Renewable Energy Directive, the United Nation’s Carbon Offsetting and Reduction Scheme for International Aviation, the California Low Carbon Fuel Standard, the United States Renewable Fuel Standard, and the UK Renewable Transport Fuel Obligation. A qualitative analysis of the different schemes’ methods identified several discrepancies. These were found to be primarily related to the modelling approach used, the burdens and credits arising from different feedstock types and co-products, and the modelling of electricity and land use changes. An example of this is that different standards provide credits for certain waste types, such as animal manure in the RED and RTFO, or municipal solid waste in CORSIA. In addition to the qualitative analysis, the carbon intensity was calculated – according to the rules set out by these frameworks – for case studies of eight fuel types, including biofuels and electrolysis-based fuels. These calculations further highlighted how the use of different fuel standards can lead to conflicting assessments of a fuel’s environmental impact. Overall, our findings demonstrate substantial variations in the methods and calculation rules prescribed by the five standards, often resulting in markedly different carbon intensity scores for the same fuel. Based on this analysis, we propose specific changes to the calculation rules to enhance harmonization and improve the accuracy in reflecting the environmental consequences of fuel production and use. These recommendations include that indirect land use changes are always included, and more transparency regarding the methods for calculating the fuel carbon footprint.

In the endeavor of optimizing the sustainability of bioenergy production in Denmark, this consequential life cycle assessment (LCA) evaluated the environmental impacts associated with the production of heat and electricity from one hectare of Danish arable land cultivated with three perennial crops: ryegrass (Lolium perenne), willow (Salix viminalis) and Miscanthus giganteus. For each, four conversion pathways were assessed against a fossil fuel reference: (I) anaerobic co-digestion with manure, (II) gasification, (III) combustion in small-to-medium scale biomass combined heat and power (CHP) plants and IV) co-firing in large scale coal-fired CHP plants. Soil carbon changes, direct and indirect land use changes as well as uncertainty analysis (sensitivity, MonteCarlo) were included in the LCA. Results showed that global warming was the bottleneck impact, where only two scenarios, namely willow and Miscanthus co-firing, allowed for an improvement as compared with the reference (-82 and -45 t CO₂-eq. ha⁻¹, respectively). The indirect land use changes impact was quantified as 310 ± 170 t CO₂-eq. ha⁻¹, representing a paramount average of 41% of the induced greenhouse gas emissions. The uncertainty analysis confirmed the results robustness and highlighted the indirect land use changes uncertainty as the only uncertainty that can significantly change the outcome of the LCA results.