Spatial mapping of Great Britain's bioenergy to 2050

In this Special Issue, we present a series of papers arising from two related research projects funded by the UK Energy Research Centre (UKERC), ‘Spatial Mapping and Evaluation of Energy Crop Distribution in Great Britain (GB) to 2050’ and ‘The Disaggregated Scenarios for Demand Studies (DS4DS) project’, conducted by a team from the University of Aberdeen, University of East Anglia, Forest Research, University of Southampton, Centre for Ecology and Hydrology, Scotland's Rural College, University of Portsmouth and Loughborough University. Despite considerable interest in second generation, nonfood bioenergy crops, such as the giant grass Miscanthus, and short rotation coppice (SRC) species like willow or poplar, to date no attempt has been made to match potential supply with demand. In this project, we have attempted to do this. Currently, energy crops are cofired with fuels like coal in traditional power stations, but the most carbon- and cost-efficient way to use biomass energy is to generate heat and power at the same time through Combined Heat and Power (CHP) plants. To make the best use of bioenergy crops, a future infrastructure of small and medium-sized CHP plants using locally sourced biomass would be required. To see where heat and electricity are most needed, and where bioenergy crops are best grown to meet that demand, the papers collected in this special issue describe how the team have generated high resolution (1 km) maps of demand, potential bioenergy supply, and the size and location of the CHP plants that would be required to exploit the resource for energy. The final papers then examine the economics of using bioenergy to supply heat and electricity – i.e. whether it makes sense from an energy price and from a grower's perspective, and consider the cost of greenhouse gas abatement provided by bioenergy. The first paper (Lovett et al., 2014) examines the land available to grow bioenergy crops. Not all areas are suitable for energy crop production; for example protected areas and peatlands will be unsuitable, and these areas are mapped at high resolution. By applying different constraints, the available area for energy crops is found to be between 8.5 and 9 M ha (37–40% of GB), and the location of current energy crops is compared to these available areas. In Hastings et al. (2014), state-of-the-art, process-based models of Miscanthus, SRC and short rotation forestry are used to simulate potential yield under current conditions, and under future climate (to 2050). These models identify which crop produces the most biomass on land suitable for bioenergy crops. This paper defined the potential supply of biomass at high resolution (1 km) now and in the future, and shows significant technical biomass potential in GB. Having defined potential biomass supply, Taylor et al. (2014), used detailed energy and census statistics to map demand for heat and electricity at 1 km resolution for Great Britain, both now and, using UKERC scenarios, to project these demand surfaces out to 2050. These high resolution demand estimates are the first of their kind in GB, and provide the first opportunity to make a detailed comparison between supply and demand. With high resolution datasets of potential supply of biomass feedstock and electricity and heat demand, an economic optimization model is used in Wang et al. (2014) to determine how much demand could be met by the available supply at competitive energy prices, and where and what size the CHP plant would be needed to make use of the bioenergy efficiently. The optimization model was used by Wang et al. (2014) to map optimal supply and demand for GB now and to 2050 from an energy price perspective. In Alexander et al. (2014a), a farm-scale economic model is used to examine the farm level optimization problem, that is, at what price farmers might consider growing energy crops, taking account of the costs and returns associated with competing crops. In this paper, maps of bioenergy crops that match supply and demand are derived, avoiding unsuitable areas, and that make economic sense from an energy price and a grower's perspective. The areas for future growth of bioenergy crops are different to where they are currently grown because energy crops are currently grown to cofire in large conventional power plants, rather than in smaller CHP plants, which would be a more appropriate infrastructure for bioenergy use in the future. In the final paper in the special feature, Alexander et al. (2014b) use an agent-based model to investigate the behavior of the GB energy crop market and to examine the cost of emission abatement that the market might provide. The paper poses the question: do existing policies for perennial energy crops make this a more or less cost effective mitigation option if we consider how these policies are likely to affect market evolution? The paper considers the relative merits of providing incentives to farmers relative to energy producers. It also examines the trade-offs between increased or decreased subsidy levels and the rate and level of market uptake, and hence abatement cost. The analysis suggests that maintaining the energy crop scheme, which provides farmers' establishment grants, can increase both the emissions abatement potential and cost-effectiveness. A minimum carbon equivalent abatement cost is seen at intermediate subsidy levels for energy generation. The paper identifies an optimum level to cost-effectively stimulate the market to achieve emissions reduction. Alexander et al. (2014a) suggest (in table 2 of their paper) that, at a Miscanthus price of £60 odt−1 and an SRC price of £48 odt−1, energy crops could supply around 50 Pj yr−1 (=1.6 Gw yr−1) in GB, but the profitability of bioenergy crops is very sensitive to the price paid for the biomass. With relatively small increases in price, the area (and thereby the potential energy supplied by biomass) increases dramatically. The location of the nearest power plant is critical in decisions to grow bioenergy crops, so a bioenergy market may not thrive in Britain until a more distributed power generation infrastructure is developed. In addition, growers need a market and a good price to convert to growing bioenergy crops. To convert the potential for energy cropping outlined in the papers presented here into reality, biomass prices or productivity will need to increase, and a new power generation infrastructure (more, distributed CHP plants) would need to be developed in GB in the coming years.