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Teaser, summary, work performed and final results

Periodic Reporting for period 2 - SIZE (Size matters: scaling principles for the prediction of the ecological footprint of biofuels)

Teaser

There is a major challenge in accurately quantifying the environmental footprints of a wide range of products and technologies in terms of ecologically relevant endpoints, such as the maintaining of biodiversity. This holds in particular for new products and technologies, like...

Summary

There is a major challenge in accurately quantifying the environmental footprints of a wide range of products and technologies in terms of ecologically relevant endpoints, such as the maintaining of biodiversity. This holds in particular for new products and technologies, like renewable energy production technologies, where information is typically restricted to data from laboratory experiments, pilots and small scale facilities. Using this limited information for comparing new with mature, industrial-scale products and technologies will severely skew results, most likely in favor of the mature products and technologies. Although environmental impacts are expected to increase with increased production or capacity, the increase is likely not linear, implying that a larger capacity can be beneficial in terms of the environmental impact per unit of output. These non-linear scaling effects are, however, typically ignored in environmental footprint analysis. Apart from the challenge to provide environmental footprints of products in an early stage of development, current footprint calculations suffer from a lack of information on impacts related to biodiversity. Species distribution models can be used to evaluate the global extinction sensitivity of species populations to environmental changes. These indicators have, however, never been used in environmental footprint analyses. As empirical information is not readily available for the vast majority of species to predict these extinction indicators, allometric relationships may be used instead. By using allometric relationships, an explicit relationship between body size and global extinction metrics can be established with limited data efforts. This provides a sound analytical framework that also explains the relationship between species sensitivity to global extinction and body size, which is currently lacking. Finally, ecosystem functioning is typically not analysed in environmental footprint analysis. Decreases in ecosystem functioning are, however, only expected, if specific species traits disappear, invoking a need to address functional attributes of biodiversity in environmental footprints as well. Predicting biodiversity footprints with limited data requirements, such as the size of technological production and species, will create a scientific breakthrough. The production of various first generation and second generation biofuels and biomaterials is a perfect case to apply the framework to. To address energy security and climate-change concerns, fossil-based fuels and materials are to be replaced. Biofuels and biomaterials are considered important candidates, but controversial at the same time due to large uncertainties concerning the claimed environmental benefits. The goal is to develop and apply a sound, analytical framework for assessing global biodiversity impacts of habitat destruction and greenhouse gas emissions caused by biofuel and biomaterial production, based on a limited set of commonly available product and species characteristics such as production capacity and the size of species. The focus of the research is on (1) liquid biofuel production (bioethanol and biodiesel) and bio-electricity with and without carbon capture and storage from various first and second generation feedstock as an important but controversial renewable energy source (2) vertebrate and vascular plant diversity as important species groups, and (3) habitat destruction and climate change, as important drivers of global change.

Work performed

In the ERC-project SIZE, a framework is developed to quantify biodiversity footprints of bio-energy and bio-material production with a number of biodiversity metrics on various geographical scales. The SIZE project is subdivided in three interrelated subprojects.

1: GHG EMISSIONS FROM BIO-ENERGY AND BIOMATERIALS

1.1 Co-firing of wood pellets: GHG parity times
Several EU countries import wood pellets from the south-eastern United States. The imported wood pellets are (co-) fired in power plants with the aim of reducing overall greenhouse gas (GHG) emissions from electricity and meeting EU renewable energy targets. To assess whether GHG emissions are reduced and on what timescale, we construct the GHG balance of wood-pellet electricity. This GHG balance consists of supply chain and combustion GHG emissions, carbon sequestration during biomass growth and avoided GHG emissions through replacing fossil electricity. We investigate wood pellets from four softwood feedstock types: small roundwood, commercial thinnings, harvest residues and mill residues. Per feedstock, the GHG balance of wood-pellet electricity is compared against those of alternative scenarios. Alternative scenarios are combinations of alternative fates of the feedstock materials, such as in-forest decomposition, or the production of paper or wood panels like oriented strand board (OSB). Alternative scenario composition depends on feedstock type and local demand for this feedstock. Results indicate that the GHG balance of wood-pellet electricity equals that of alternative scenarios within 0–21 years (the GHG parity time), after which wood-pellet electricity has sustained climate benefits. Parity times increase by a maximum of 12 years when varying key variables (emissions associated with paper and panels, soil carbon increase via feedstock decomposition, wood-pellet electricity supply chain emissions) within maximum plausible ranges. Using commercial thinnings, harvest residues or mill residues as feedstock leads to the shortest GHG parity times (0–6 years) and fastest GHG benefits from wood-pellet electricity. We find shorter GHG parity times than previous studies, for we use a novel approach that differentiates feedstocks and considers alternative scenarios based on (combinations of) alternative feedstock fates, rather than on alternative land uses. This novel approach is relevant for bioenergy derived from low-value feedstocks.

1.2 Global climate change mitigation potential of bioenergy with carbon capture and storage
Bio-energy with carbon capture and storage (BECCS) can result in so-called negative greenhouse gas (GHG) emissions and could thus strongly contribute to climate change mitigation. Climate change mitigation scenarios often rely heavily on BECCS to meet 1.5 to 2 C temperature targets, especially in the second half of the 21st century. Economic and bio-physical feasibility of BECCS have been questioned are well studied, but the exact (negative) GHG emission intensity of BECCS systems and how it relates to location is surprisingly little studied. We will provide a fully geo-spatially explicit global analysis of (negative) GHG emission factors for BECCS, based on a global vegetation model (LPJml) and a literature analysis of bioenergy supply chains. We look at both bioelectricity and biofuels, produced with and without carbon capture and storage (CCS) from ligno-cellulosic feedstocks. We present global and regional potential supply of bioenergy at increasing emission factors, henceforth called emission curves and explore their sensitivity to key parameters, including bioenergy crop yields, land occupation for food production and climate. We compare the GHG emission factors of electricity and fuels derived from BECCS against their fossil and renewable alternatives. Moreover, we compare global maps of GHG emission factors against biodiversity density and water scarcity maps to identify their trade-offs.

1.3 Variation in radiative forcing payback

Final results

1. We develop a novel, dynamic approach to quantify GHG emissions and radiative forcing payback times of bio-energy and biomaterial life cycles with and without carbon capture and storage in geospatially-explicit way. It is expected this has major implications for the footprints of bio-energy and biomaterials, especially in those cases where rotation periods are long. We also quantification the statisitical uncertainty in the calculations via Monte Carlo simulations. We will provide a coherent geospatially explicit method that can be used to assess climate change impacts of any bio-energy and biomaterial option at the global scale.

2. We develop a novel set of operational biodiversity indicators that can be applied in a footprint context at the global scale. Biodiversity indicators include (i) the extinction vulnerability of plant and vertebrate species, using functional traits such as size of the species, and (ii) functional diversity to provide insights in the resilience of ecosystems to disturbances by land use and climate change. We also provide insights on how species interactions may shape the global scale distributions of species and we will provide guidelines to decide when and how interactions between (plant) species should be accounted in constructing species distribution models at large spatial scales.

3. We combine the results from 1 and 2 as input to predict the current and future ecosystem impacts from habitat alternation and climate change caused by global bio-energy and biomaterial production. We will do this in a number of novel global applications with a mechanistic ecosystem model, a regression-based functional diversity model, and IUCN Red List predictions. We will provide a systematic global analysis on the pros and cons for biodiversity of various bio-energy and biomaterial options.