Indirect Land Use Research Articles

Mitigating bioenergy-driven biodiversity decline: A modelling approach with the European brown hare

The cultivation of energy crops leads to direct and indirect land use changes that impair the biodiversity of the agricultural landscape. In our study, we analyse the effects of mitigation measures on the European brown hare (Lepus europaeus), which is directly affected by ongoing land use change and has experienced widespread decline throughout Europe since the 1960s. Therefore, we developed a spatially explicit and individual-based ecological model to study the effects of different landscape configurations and compositions on hare population development. As an input, we used two 4 × 4 km large model landscapes, which were generated by a landscape generator based on real field sizes and crop proportions and differed in average field size and crop composition. The crops grown annually are evaluated in terms of forage suitability, breeding suitability and crop richness for the hare. In six mitigation scenarios, we investigated the effects of a 10 % increase in the following measures: (1) mixed silphie, (2) miscanthus, (3) grass-clover ley, (4) alfalfa, (5) set-aside, and (6) general crop richness. All mitigation measures had significant effects on hare population development. Compared to the base scenario, the relative change in hare abundance ranged from a factor of 0.56 in the grass-clover ley scenario to -0.16 in the miscanthus scenario. The mitigation measures of mixed silphie, grass-clover ley and increased crop richness led to distinct increases in hare abundance in both landscapes (> 0.3). The results show that both landscape configuration and composition have a significant effect on hare population development, which responds particularly strongly to compositional changes. The increase in crop diversity, e.g., through the cultivation of alternative energy crops such as mixed silphie and grass-clover ley, proves to be beneficial for the brown hare.

The Land Use Impacts of the EU Biodiesel Policy: Assessing the Direct, Indirect and Induced Effects

AbstractThis paper deals with the controversial measure of indirect land use changes of the European biodiesel policy. Two studies sponsored by the European Commission find significant, but contrasted, land use impacts for the different vegetable oils used for biodiesel production. The first study uses an aggregate computable general equilibrium model capturing direct, indirect and induced effects. The second more recent study uses a biotechnical partial equilibrium model providing a detailed representation of the indirect effects occurring through the livestock sectors. We develop an original economic emulator to understand the diverging key results of these studies and test their sensitivity. We find that the direct and indirect effects on vegetable oil and land markets explain most of the differences. We also find that indirect effects on the feed markets and the induced effects have less influence on the biodiesel results. We finally argue that the development of emulators as done here can help to understand complex policy assessments.

Environmental and energy assessment of biomass residues to biochar as fuel: A brief review with recommendations for future bioenergy systems

Abstract This study explores the environmental and energy benefits of biomass residues, including crop residues and agricultural waste, for the production of renewable energy in the form of biochar as fuel, in order to offer recommendations for policy makers, by reviewing information regarding the key environmental issues associated with the implementation of the systems. The highest environmental benefits for biochar-to-fuel systems were most observed in reduction of global warming potentials (i.e., carbon abatement), particularly for those integrated with combined heat and power technology, or for those incorporating electricity offsets from biochar combustion and co-firing. But all of these practices come at the cost of hidden environmental burdens, such as elevations in eutrophication, acidification, carcinogens and ecotoxicity impacts, as a consequence from land use change, additional infrastructure requirement or additional fertilizer application connected to biochar production or post-treatment. Other notable challenges, including regional availability of biomass residues, improper management of the residues, limited economic incentives, low energy efficiency and synergies, as well as mistreating adverse impacts from indirect land use change, were discussed. This suggests the flexibility to adjust the biomass-biochar ratio to optimize desired energy yields, carbon abatement and environmental beneficial objectives. Comprehensive analysis of the trade-offs between energy yields, carbon abatement and other associated environmental impacts is therefore recommended for future studies. Future studies in this field are also advised to explore the solution and to develop methodologies capable of quantifying the impacts and other equally relevant trade-offs, to better reflect the changes in real-world trends for decision making.

Stochastic economic and environmental footprints of biodiesel production from Jatropha curcas Linnaeus in the different federal states of Nepal

This study presents a set of essential parameters specific to geography, climate, soil conditions, and irrigation, which can be used to classify commercially feasible Jatropha farming land, globally. The results are demonstrated considering Nepal as a representative case and including system-level economic feasibility and environmental sustainability analyses for each of the Federal States of Nepal. Probabilistic results describe a distribution of the minimum selling price and greenhouse gas (GHG) emissions of Jatropha-based biodiesel, respectively, with an average of $1.35/L and 46.51 gCO2e/MJ-biodiesel, and the 95% likelihood to be less than $4.57/L and 127.67 gCO2e/MJ-biodiesel. Considering direct, and then both direct and indirect land use changes increase the GHG emissions relative to the baseline by 3.5 and 8 times, respectively. Jatropha oil yield, biodiesel yield and recovery rates, and Jatropha seed production rates were found to be the most influential factors on the selling price of biodiesel and associated GHG emissions. The results imply that at the Jatropha oil yield of 50 wt%, a Jatropha seed yield of at least 3.9 t/ha and 5 t/ha are required to achieve a market-competitive biodiesel selling price of $1/L, and GHG emissions including direct land use change effects below the petroleum baseline of 87.2 gCO2e/MJ. Avoiding the disturbance of forest lands in favor of Jatropha afforestation is one of the identified strategies to minimize the impacts from land use changes. These methods demonstrate a pathway towards addressing current challenges and developing an environmentally and commercially viable Jatropha-based biodiesel industry in many countries including Nepal.

Consequences of agricultural total factor productivity growth for the sustainability of global farming: accounting for direct and indirect land use effects

Most of the growth in agricultural output in the last thirty years comes from increases in the efficiency with which both land and non-land inputs are used. Recent work calls for a better understanding of whether this efficiency, known as total factor productivity (TFP), contributes to a more sustainable food system. Key to this understanding is the documented phenomenon that, instead of saving lands, the introduction of technologies that improve agricultural productivity encourage cropland expansion. We extend the results of a recently published econometric model of cross-country cropland change and TFP growth to explore the extent to which improvements in technology were associated with lower greenhouse emissions from land conversion to agriculture as well as with lower land conversion pressures in biodiversity-rich biomes. We focus on the decade of 2001–2010, a period in which our sample of 70 countries (≈75% of global croplands) experienced net land contraction. Except in sub-Saharan Africa and South and East Asia, regional TFP growth was associated with regional land expansion, thus confirming the existence of Jevons paradox in most regions of the world. However, such expansion was more than offset by indirect land use effects stemming from increases in productivity somewhere else. These indirect effects are far from trivial. In the absence of TFP growth, our estimates suggest that ≈125 Mha would have been needed to satisfy demand, half of which are in the four most biodiverse biomes of the world; estimated land use emissions from the ensuing changes in land use range from a lower bound of 17 Gt CO2eq to an upper bound of 84 Gt CO2eq, depending on whether the expansion would have occurred on pasturelands or forest, in contrast to the ≈1 to 15 Gt CO2eq imputed to observed cropland expansion. Our projections of the land needed to satisfy projected growth in TFP per capita during 2018–2023 indicate that current rates of TFP growth are insufficient to prevent further land expansion, reversing in most cases the in-sample trends in land contraction observed during 2001–2010.

Consequential life cycle assessment of miscanthus livestock bedding, diverting straw to bioelectricity generation

AbstractStraw is an important livestock bedding material facing increasing demand for alternative uses in Europe and is often transported long distances from arable to livestock regions. Alternative bedding materials cultivated directly on livestock farms could potentially avoid this transport and competition for use. For the first time, we applied consequential life cycle assessment (LCA) to account for the direct and indirect implications of miscanthus bedding production on livestock farms, considering displacement of fodder or livestock, and substitution of fossil fuels with straw in electricity generation. We modelled the effect of substituting straw with ‘home‐grown’ miscanthus bedding across seven beef and sheep farms. The consequences of displacing grass forage (or animal) production with home‐grown miscanthus bedding cultivation were evaluated via three farmer decision scenarios: buy extra concentrate feed (D1), utilize remaining pasture areas more efficiently (D2) and buy grass silage (D3). Electricity generated from displaced straw (bedding) substituted either natural gas or coal electricity. Sensitivity analyses were undertaken using 34 scenario permutations to represent combinations of feed and electricity substitution, miscanthus fertilization rates and yields, and the quality of displaced pasture. Consequential LCA indicates that miscanthus bedding production could be environmentally beneficial, under scenarios involving D2 and D3. However, greenhouse gas emissions and wider environmental burdens may be increased under D1 scenarios, owing to the environmental cost of additional concentrate feed production, and possible indirect land use change, outweighing the benefits from: (a) fossil electricity substitution with straw bioelectricity; (b) reduced animal emissions via improved digestibility of concentrate feed; (c) avoided straw transport. The ratio of the yield of miscanthus to replaced grass was found to be a critical determinant of D1 environmental outcomes. We conclude that if grass forage production can be better managed, the use of miscanthus as a bedding material on livestock farms provides environmental benefits via diversion of straw to bioenergy use.

Project level assessment of indirect land use changes arising from biofuel production

AbstractThe use of land resources has a strong influence on the sustainability of biofuel production. An assessment of both direct and indirect changes in land use is necessary if an accurate assessment of sustainability is to be made. An increasing number of studies have developed approaches to estimate the Indirect Land Use Change (ILUC) impacts of biofuels at global, national or regional level, but assessing ILUC remains a challenging task and estimates vary widely. In this study, we suggest that a socially motivated, project level approach can provide robust insight into the conditions affecting land use change dynamics. We developed a causal‐descriptive approach named ILUC Project ASsessment Tool (ILUC PAST) for project level assessment of ILUC. It uses a tiered multitool analysis—from local to global—combined with extensive stakeholder engagement. A real‐world project for the production of cellulosic ethanol in Sardinia (Italy) was used to evaluate the tool and benchmark the results against two alternatives for project level assessment: the ‘Low Indirect Impact Biofuel’ methodology and the ‘iLUC Club’ method. The results of the case study of advanced biofuels suggest that the quantitative estimates of ILUC combined with the in‐depth understanding of the cause‐and‐effect dynamics provided by ILUC PAST are sufficiently credible, salient and legitimate to support project level and local decision‐making.

Inter-Crops-Allocation (ICA) of CO2 Emissions from Land Use Change

The quantification of CO2 emissions from indirect land use change (ILUC) is proposed by some stakeholders for the inclusion in carbon footprints (CF) of biofuels. The ILUC concept does not appropriately consider so far that each ILUC of a biofuel is direct land use change (DLUC) of another product. This leads to either double counting or free-rider incentives. The articles purpose is to introduce and test inter-crops-allocation (ICA); this new approach allocates CO2 emissions from natural ecosystem conversion between all agricultural activities responsible for the land use change - be it directly or indirectly.

Comparing soil respiration and carbon pools of a maize-wheat rotation and switchgrass for predicting land-use change-driven SOC variations

The deployment of dedicated energy crops and the related land-use change are topical issues, particularly in relation to carbon storage and climate change mitigation effects. In order to maximize their mitigation potential and to fully supply new biorefineries, perennial energy crops may be established, not only on former idle and grazing lands, but also on the least remunerative cropland, as indirect land use change effects are still very uncertain. Possibly becoming a future land-use change option, the carbon flows of the most common crop rotation in Europe (maize-wheat) and the perennial grass switchgrass were measured, and later included in a biogeochemical model to build possible scenarios. Yearly mean soil respiration did not statistically differ between switchgrass and the annual cereals (2.9 and 2.5 Mg CO2 ha−1 month−1, respectively), but in switchgrass the peak flux was reached during crop growth (6.1 Mg CO2 ha−1 month−1), while in the cereal system it occurred in bare soil (after harvest and soil tillage) (4.5 Mg CO2 ha−1 month−1). Harvest residues contributing to soil organic matter were highest in maize (12.4 Mg ha−1 y−1) and decreased in switchgrass (−79%) and wheat (−87%). Root biomass was much higher in switchgrass (10.0 Mg ha−1 y−1) than maize (−81%) or wheat (−94%). Model projections showed how continuous switchgrass cycles of 15 years following annual crops cultivation were capable to keep building up SOC inventories (0.24 or 0.32 Mg ha−1 y−1) up to the year 2100. On the opposite, maintaining the land under maize-wheat cultivation, depending on maize stover management, would either produce a SOC loss (−3.6 Mg ha−1) or could help the soil increasing SOC (+9.4 Mg ha−1) towards a new equilibrium after two decades.

Methods to Assess the Impacts and Indirect Land Use Change Caused by Telecoupled Agricultural Supply Chains: A Review

The increasing international trade of agricultural products has contributed to a larger diversity of food at low prices and represents an important economic value. However, such trade can also cause social, environmental and economic impacts beyond the limits of the countries directly involved in the exchange. Agricultural systems are telecoupled because the impacts caused by trade can generate important feedback loops, spillovers, rebound effects, time lags and non-linearities across multiple geographical and temporal scales that make these impacts more difficult to identify and mitigate. We make a comparative review of current impact assessment methods to analyze their suitability to assess the impacts of telecoupled agricultural supply chains. Given the large impacts caused by agricultural production on land systems, we focus on the capacity of methods to account for and spatially allocate direct and indirect land use change. Our analysis identifies trade-offs between methods with respect to the elements of the telecoupled system they address. Hybrid methods are a promising field to navigate these trade-offs. Knowledge gaps in assessing indirect land use change should be overcome in order to improve the accuracy of assessments.

How willing are different types of landowner to supply hardwood timber residues for bioenergy?

Among bioenergy feedstocks, timber and crop residues offer low marginal cost of production and low risk of indirect land use change that can boost greenhouse gas emissions. The potential economic supply depends on the willingness of producers to make residues available. Previous studies show that willingness to supply annual crop residues depends upon prices, attitudes toward bioenergy, biophysical setting, and demographic traits. For timber residues, a smaller literature on non-industrial private forest owners found similar results, but little is published about what drives the availability of timber residues from large public and commercial forests.Combining survey data on small-scale forest owners with interview data on managers of large-scale commercial, public and conservancy-owned forests, we find that willingness to provide timber residues varies by landowner type. At prices of $4-11 Mg−1, most commercial forest managers are willing to permit residue removal at timber harvest. At higher prices of $13-26 Mg−1, up to half of non-industrial private forest owners are also willing. However, among managers of large-scale public and conservancy forests, environmental conservation rules and/or insufficient motivation largely prevent the removal of timber residues at harvest. Future projections of timber residue supply should explicitly account for differences in the willingness of each type of forestland owner to supply residues as a bioenergy feedstock.

Multiple stressors and the role of hydrology on benthic invertebrates in mountainous streams

Hydrological alteration of rivers is recognised as a major threat to lotic biodiversity acting at broad spatial scales, however, the effect size and pathways of hydrology are rarely quantified in comparison with other stressors such as land use and physico-chemistry. Here we present a multiple stressor study that aims to disentangle the effect sizes and pathways of hydrological alteration on benthic invertebrate community structure and functional metrics. Therefore, we analyse the following four multiple stressor groups: land use, hydrology, physical habitat structure, and physico-chemistry at 51 sites including 72 surveys in the German mountain range. Stressor data were contrasted to benthic invertebrate data using partial canonical correspondence analysis to quantify the community-level response and path analysis to investigate the cause-effect pathway structure of single stressors affecting benthic invertebrate metrics either directly or indirectly (i.e. mediated by other stressors). Hydrological stressors showed a strong impact on community structure, with its unique effects being more dominant than those of any other stressor group. Path analysis confirmed strong direct effects of hydrological stressors on biological metrics but revealed land use to be the most influential stressor group in terms of the sum of direct and indirect effects on biology. Notably, indirect land use effects are mediated by hydrology. Our findings suggest a key role of hydrological stressors in lotic ecosystem assessment, which, however, are rarely addressed in operational river monitoring and management. In light of the wide-spread availability of hydrological data from gauging stations throughout Europe, we plea for a better involvement of hydrological data in river basin management.

Voluntary sustainability standards could significantly reduce detrimental impacts of global agriculture

Voluntary sustainability standards (VSS) are stakeholder-derived principles with measurable and enforceable criteria to promote sustainable production outcomes. While institutional commitments to use VSS to meet sustainable procurement policies have grown rapidly over the past decade, we still have relatively little understanding of the (i) direct environmental benefits of large-scale VSS adoption; (ii) potential perverse indirect impacts of adoption; and (iii) implementation pathways. Here, we illustrate and address these knowledge gaps using an ecosystem service modeling and scenario analysis of Bonsucro, the leading VSS for sugarcane. We find that global compliance with the Bonsucro environmental standards would reduce current sugarcane production area (-24%), net tonnage (-11%), irrigation water use (-65%), nutrient loading (-34%), and greenhouse gas emissions from cultivation (-51%). Under a scenario of doubled global sugarcane production, Bonsucro adoption would further limit water use and greenhouse gas emissions by preventing sugarcane expansion into water-stressed and high-carbon stock ecosystems. This outcome was achieved via expansion largely on existing agricultural lands. However, displacement of other crops could drive detrimental impacts from indirect land use. We find that over half of the potential direct environmental benefits of Bonsucro standards under the doubling scenario could be achieved by targeting adoption in just 10% of global sugarcane production areas. However, designing policy that generates the most environmentally beneficial Bonsucro adoption pathway requires a better understanding of the economic and social costs of VSS adoption. Finally, we suggest research directions to advance sustainable consumption and production.

Economic Impacts and Land Use Change from Increasing Demand for Forest Products in the European Bioeconomy: A General Equilibrium Based Sensitivity Analysis

The European forestry sector is a potential driver of transformation towards a sustainable bioeconomy. Forest products are increasingly used in high-tech and high-value-added industries, e.g., chemicals and the automotive industry. So far, however, research on the European bioeconomy has largely focused on agriculture as a provider of food, feed, fuel, and fiber to bio-based industries. Here we assess the potential impacts of a stronger reliance on forestry sector inputs to the European Union (EU28) bioeconomy on output, prices, final demand, and land use. Specifically, we run a sensitivity analysis of a 1% increase of input use of forest products in the EU28 economy in a Computable General Equilibrium (CGE) framework accounting for land use by Agro-Ecological Zones (AEZ) and greenhouse gas (GHG) emissions at high regional and sectoral resolution. We find that such a shift to a more forest-based bioeconomy would provoke small indirect land use effects globally due to existing international trade linkages and land market effects. Simulated increases in planted forest cover are associated with net GHG emission savings, but our scenario analysis also points to higher imports of forest products from countries with vulnerable tropical forest biomes, such as Brazil and Indonesia.

Land use mediated GHG emissions and spillovers from increased consumption of bioplastics

Bioplastic production is a small but fast growing sector in the global bioeconomy, which may benefit from public support measures in the future as governments seek to promote more sustainable consumption patterns. Here we assess the potential net economy-wide impacts of a 5% bioplastic target relative to current plastic consumption in the main producing regions. We compare two alternative policy strategies to achieve the target in a general equilibrium framework that allows for substitution between conventional and bio-based plastics: a subsidy on bioplastics versus a tax on fossil-based plastic consumption. Our study is the first to quantify global greenhouse gas (GHG) emissions from an increased demand for bioplastics on a global scale, produced from arable crops, considering both direct and indirect land use change (LUC). The tax provokes a contraction of all sectors that employ plastics, which leads to a drop of 0.07% in global real GDP, whereas the subsidy has no significant effect on the global economy. Both tax and subsidy reduce world demand for petroleum products, by 0.37% and 0.07%, respectively, boosting demand for sugar- and starch-based feedstock in the bioplastic industry. This leads to emissions from LUC globally, which correspond to a carbon payback time of 22 years on average, with the associated annual abatement costs of over US$2000 per tonne of CO2-eq. The tax has greater GHG reduction potential in bioplastic producing regions but generates greater economic and environmental spillover effects in countries that do not enforce the target. Results show that promoting bioplastic consumption is not a cost-effective strategy for climate change mitigation if based on conventional feedstock, due to market-mediated GHG emissions from LUC. Bioplastics are not necessarily more sustainable than conventional polymers just because they are bio-based, although further assessment of potential environmental gains associated with biodegradability and recyclability is desirable.

Using dynamic relative climate impact curves to quantify the climate impact of bioenergy production systems over time

AbstractThe climate impact of bioenergy is commonly quantified in terms of CO2 equivalents, using a fixed 100‐year global warming potential as an equivalency metric. This method has been criticized for the inability to appropriately address emissions timing and the focus on a single impact metric, which may lead to inaccurate or incomplete quantification of the climate impact of bioenergy production. In this study, we introduce Dynamic Relative Climate Impact (DRCI) curves, a novel approach to visualize and quantify the climate impact of bioenergy systems over time. The DRCI approach offers the flexibility to analyze system performance for different value judgments regarding the impact category (e.g., emissions, radiative forcing, and temperature change), equivalency metric, and analytical time horizon. The DRCI curves constructed for fourteen bioenergy systems illustrate how value judgments affect the merit order of bioenergy systems, because they alter the importance of one‐time (associated with land use change emissions) versus sustained (associated with carbon debt or foregone sequestration) emission fluxes and short‐ versus long‐lived climate forcers. Best practices for bioenergy production (irrespective of value judgments) include high feedstock yields, high conversion efficiencies, and the application of carbon capture and storage. Furthermore, this study provides examples of production contexts in which the risk of land use change emissions, carbon debt, or foregone sequestration can be mitigated. For example, the risk of indirect land use change emissions can be mitigated by accompanying bioenergy production with increasing agricultural yields. Moreover, production contexts in which the counterfactual scenario yields immediate or additional climate impacts can provide significant climate benefits. This paper is accompanied by an Excel‐based calculation tool to reproduce the calculation steps outlined in this paper and construct DRCI curves for bioenergy systems of choice.

Dynamic accounting of greenhouse gas emissions from cascading utilisation of wood waste

Cascading utilisation of post-consumer wood waste has recently gained increasing attention in the European Union, aiming for a society in which the resource's properties are optimized through sequential uses. To date, material utilisation of wood waste has been limited to particleboard production, with additional niche alternatives being restricted by quality requirements for wood waste. In this consequential life cycle assessment focusing on post-consumer wood collected at Danish recycling centres, Global Warming Potential (GWP) impacts from quality-driven choices for cascading management of wood waste were compared with those from handling mixed wood waste qualities. GWPs were modelled by considering the dynamic profile of greenhouse gas emissions (including biogenic carbon dioxide) for two time horizons (100 and 500 years). The robustness of the results was tested by varying modelling assumptions with respect to electricity system, wood sourcing and associated rotation period, and impacts from indirect land use changes. The results demonstrated that valuing quality over quantity in wood waste management can ensure larger GWP savings, especially if recycling applications have a long lifetime and/or substitute energy-intensive products; such results were confirmed under all scenario analyses. Inclusion of land use changes credited land-intensive products. More cascade steps of the wood waste resource ensured larger savings; however, assumptions on the electricity mix, on the source of the wood alongside the choice of the time horizon for GWP greatly influenced the results on cascading management.

Biogas and Ethanol from Wheat Grain or Straw: Is There a Trade-Off between Climate Impact, Avoidance of iLUC and Production Cost?

Current EU policy calls for decreased emissions of greenhouse gases (GHG) by i.e., replacing fossil fuel in the transportation sector with sustainable biofuels. To avoid indirect land use change (iLUC), the EU at the same time strives to limit the use of crops and to increase the use of residues. In this study we compare climate impact and production cost for biogas and ethanol based on wheat grain and straw, respectively, in a Swedish context. The economic competitiveness for ethanol from straw vs. grain is evaluated based on the mandatory emission reduction for fossil vehicle fuels implemented since July 2018 in Sweden. The result of this study clearly shows that biogas and ethanol from straw have the lowest GHG emissions regardless of the calculation method used, although biofuels from grain also fulfill EU GHG reduction criteria even when suggested iLUC factors are included. It was also shown that the cost of producing straw-based biofuels was higher, thus there is a trade-off between climate impact and costs. The GHG reduction mandate adopted in Sweden partly compensates for this, but is not enough to make ethanol from straw competitive from an economic perspective.

Moving from completing system boundaries to more realistic modeling of the economy in life cycle assessment

Existing process-based life cycle assessment (LCA) models can be supplemented by input-output (IO) models to correct for the so-called truncation error resulting from an “incomplete” system boundary. The resulting hybrid LCA is not necessarily but probably a closer approximation to an ideally complete process model with a global all-inclusive system boundary. Here, we discuss whether such a complete process model is a goal worth pursuing and whether system boundary is the main limitation of process-based LCA. We argue that the results of the ideally complete process model, with every single economic activity on earth embodied within, have little to limited implications and relevance for the decisions which LCA seeks to support and which involve changes aimed at reducing environmental impacts through altering product systems or promoting alternatives. The main limitations of process-based LCA, as a supply chain based linear model, lie not in the “incomplete” system boundary but in the narrow focus on supply chain and the unrealistic assumptions, such as omission of price effects and constraints. These assumptions reflect poorly how the economy works. Hybrid LCA, through adding IO models, which are also supply chain and linearity based, doubles down on both the narrow focus on supply chain and the unrealistic assumptions, and thus is a step forward but in the wrong direction. Reflecting on advances in corn ethanol research, we show that pursuing a more complete system boundary by, for instance, covering Chinese stuffed animal production does not make the LCA results more accurate or relevant for determining if corn ethanol in the US should be promoted. Not only is the theoretical argument for including Chinese stuffed animal industry tenuous, but there is no evidence it has been affected by US corn ethanol expansion. And by worrying about processes far away up the supply chain could distract us from focusing on the actual market mechanisms, such as indirect land use change, that are more likely to occur and are essential to predicting whether promoting corn ethanol would reduce total carbon emissions. We suggest future studies shifting focus from “completing” system boundary within the conventional supply chain and linear framework towards more realistic modeling of our complicated human-environment system. Instead of trying to always include everything, we argue for a flexible and market-based system boundary tailored to the decision in question, particularly considering the scale of potential changes it may cause and how it may affect the economy. A change at larger scales is likely to have a broader impact, thus justifying the definition of a broader system boundary. But to cover a broad system boundary for a small change will likely result in overestimates. More is not necessarily better.

Using steam explosion or AFEX™ to produce animal feeds and biofuel feedstocks in a biorefinery based on sugarcane residues

AbstractSustainable integration of biofuel (primarily bioethanol) and highly digestible livestock feed in production systems is a potential way to increase the economic returns to agriculture and simultaneously promote energy security, particularly in developing countries. In this work we evaluated the efficacy of steam explosion (StEx) and ammonia fiber expansion (AFEX™) as potential processes for improving the in vitro rumen digestibility, metabolizable energy, and ethanol yields from sugarcane crop residues (bagasse and cane leaf matter, CLM). Ammonia fiber expansion pretreatment enhanced the in vitro true digestibility and metabolizable energy content of sugarcane crop residues by 69% and 26%, respectively compared to untreated controls. On the other hand, StEx increased the true digestibility and metabolizable energy content of the sugarcane residues by 54% and 7%, respectively. Ammonia fiber expansion also increased the total nitrogen content of both sugarcane bagasse and CLM to more than 20.2 g kg−1 dry forage, a more than 230% improvement relative to untreated controls. High solid‐loading enzymatic hydrolysis and fermentation of StEx‐ and AFEX™‐pretreated sugarcane crop residues generated yields of up to 3368 and 4360 L of ethanol per hectare of sugarcane cultivated, respectively, at a biomass‐degrading enzyme dosage of 20 mg protein per gram glucan. This research strongly suggests that the use of suitably pretreated sugarcane crop residues in integrated sugarcane biofuel‐livestock production systems can increase the total per hectare agricultural output without increasing the area of sugarcane cultivated. In effect, this integrated approach promotes more sustainable biofuel production and increased food production while avoiding the potential for indirect land use change. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd