Agriculture and the Environment X, Delivering Multiple Benefits from our Land: Sustainable Development in Practice (2014)

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1 RENEWABLE ENERGY FROM LAND: OPPORTUNITIES AND CONSTRAINTS W Towers 1, P Alexander 2, DR Miller 1, S Dunn 1, RL Hough 1, M Troldborg 1 and P Horne 1 1 The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK, willie.towers@hutton.ac.uk; 2 Scotland s Rural College (SRUC), King's Buildings, West Mains Road, Edinburgh, EH9 3JG, UK SUMMARY Scotland has an enormous potential for land based renewable energy generation from a range of different feedstock sources, but this has to be balanced by consideration of a number of environmental, social and economic factors. Multi-criteria analysis provides one method of identifying the most appropriate option although the output is highly dependent on the quality of data used in the analysis and the weightings applied to each factor. Part of the rationale that underpins renewable energy technologies is to reduce carbon emissions; the reduction from energy crops such as Miscanthus and short rotation coppice is highly dependent on both the subsidies for crop establishment and the energy producer. INTRODUCTION The Scottish Government has ambitious targets for the generation of renewable electricity and energy. Their 2020 Renewable Routemap for Scotland sets out the actions needed to achieve government targets, both by technology sectors, and addressing cross-cutting challenges such as public perceptions, planning and consents, and supply chains. In addition, a key aspiration of the Scottish Government s Land Use Strategy is to achieve multiple benefits from land and renewable energy provision is one sector that should be capable of achieving this. This short paper describes: an overview of options for renewable energy provision from land in Scotland; the use of multi-criteria analysis as a method to determine the appropriateness and sustainability of different options; and a case study which examines the cost and potential of carbon abatement from the UK perennial energy crop market. LAND BASED OPTIONS There is a suite of different options available within the agricultural and forestry sectors. The forestry sector is relatively mature with supply chains well established, and the agricultural sector has seen considerable investment in renewables over recent years. Indeed, agrirenewables has been identified as sufficiently important that the Scottish Government has recently developed an agri-renewables strategy to guide progress (Scottish Government, 2014). Woodfuel also provides an opportunity for the agricultural sector, although in smaller volumes. 92

2 The main alternative opportunities from land include dedicated energy crops such as Miscanthus and short rotation coppice, cereal and oilseed crops, straw, small scale hydro, anaerobic digestion, solar panels and onshore wind. All of these provide opportunities for land managers to diversify their activities and farm incomes. These can be within farmers individual holdings, for example single wind turbines, or as part of a collective effort such as large scale anaerobic digesters. All of these have their strengths and weaknesses in specific locations, and whilst not intending to be comprehensive, some of the key ones are listed below. These are based on biophysical considerations and do not take into account current financial incentives, which although clearly important can change quite quickly. Dedicated energy crops: the potential for alternative crops such as reed canary grass, switch grass, Miscanthus and short rotation coppice will be confined largely to land that is currently used for arable crops and improved grassland; there is also potential on derelict land. This is partly due to the growing conditions for these crops being broadly similar to cereals and grass reasonable climatic conditions, moderately fertile mineral soils and topography that allows machinery to operate safely and efficiently. In addition, this environment also has the necessary infrastructure of fields, roads and tracks that are required to allow the crop to harvested and transported to market without much further investment. Expansion would directly compete with food crops for the same area of land. The potential abatement potential of these crops is discussed later. The husbandry required for cereals and oilseed rape production is well known but their use as biofuels would seriously distort existing markets, particularly the drinks industry. Straw: Being the co-product of cereals, its production is restricted to where those crops are grown. Although energy could be produced from this supply, the economic constraints and more significantly, the alternative market as animal bedding and feed is so well embedded in Scottish agriculture, that the use of straw as a primary fuel source is restricted although there are opportunities on-farm for example with the drying of grain. It also has a valuable role as a soil conditioner. Small scale hydro: Scotland has enormous unconstrained potential for hydropower at a large number of scales and already contributes around 10% to Scotland s energy generation. The realistic potential for new hydroelectric power is strongly influenced by economic considerations and will be limited by environmental factors. One notable observation is that much of the potential for hydropower is in the wetter and more remote parts of Scotland. This is in contrast to the feedstocks that rely directly on the quality and use of the land for their production, such as existing and alternative crops, straw, and anaerobic digestion. Anaerobic digestion: Wet slurries and manures, processed by anaerobic digestion (AD), generates a biogas that can then be used to produce heat and/or power. Clearly this is only relevant for livestock that are housed for all or part of the year. The scale of operation can vary from small single farm units to collective or centralised systems such as those in Denmark where collection and generation are carried out on a co-operative basis. Other organic waste streams such as sewage sludge or those from the food, drink or fishing industries are utilised there as well. 93

3 Wind: This is the feedstock that is the currently the biggest single contributor to renewable energy targets in Scotland. A key issue currently is assessing the overall capacity of the landscape and of the electricity infrastructure to accommodate further increases in number. Land that is already highly managed has many settlements and the infrastructure that accompanies them has perhaps a greater capacity for accommodating a higher density than more sensitive upland areas. Their impact on landscape quality is the subject of much, often contentious debate; cultural services therefore are those most impacted in peoples minds. Solar: Will solar panels on agricultural land become a feature of Scotland s landscape? They do offer an alternative source of energy both on farm and for export off the farm and land can still be grazed, but it has the disadvantage of being seasonal in nature. On-land renewable energy production will produce both synergies and conflicts with other ecosystem services. Dedicated energy crops directly replace food crops, so one provisioning service (food production) is replaced by another (biomass production) but with the end target being a regulating service (climate mitigation). Permanent crops also have a positive impact on soil carbon balance. Similarly, energy from onshore wind produces renewable energy and reduces carbon emissions but dependent on location, can reduce the terrestrial carbon store and impacts on some cultural services, either negatively or positively, based on individuals perceptions. Anaerobic digestion should have positive impacts on water quality by reducing the volume of waste products being recycled directly to the land. WHAT OPTIONS ARE MOST APPROPRIATE? The 2020 Renewable Routemap seeks to optimise the location of different renewable options: By providing spatial guidance for developers and/or policies to steer and stimulate the correct types of development activity in the most suitable locations. Achieving a sufficiently diverse mix of renewables. But how can this be done? In many local contexts, some options can automatically be ruled in or out dependent on land use, but is there a method by which different technologies, and particularly their sustainability, can be compared objectively? Multi-criteria analyses (MCAs) have often been applied to assess and compare the sustainability of different renewable energy technologies or energy plans with the aim to provide decision support for choosing the most sustainable and suitable options either for a given location or more generically. MCAs are attractive given the multi-dimensional and complex nature of sustainability assessments which typically involves a range of conflicting criteria featuring different forms of data and information. However, the input information on which the MCA is based is often associated with uncertainties. The aim of a recent study was to develop and apply a MCA for a national-scale sustainability assessment and ranking of eleven renewable energy technologies in Scotland (include off-shore) and to investigate how the uncertainties in the applied input information influence the result. The basis of the MCA is an evaluation table, where a finite number of alternatives (here: renewable energy technologies) is assessed and compared against a set of, often conflicting, evaluation criteria. Usually there is not a single alternative that optimises all the criteria at the same time. The aim is therefore to identify the best compromise solution, i.e. the alternative 94

4 that is held most acceptable when all criteria are considered together. The developed MCA considered nine criteria comprising three technical (potential total power generation, technology maturity and security of energy supply), three environmental (greenhouse gas emissions, impacts on amenity and land requirements) and three socio-economic (levelised energy cost, contribution to economy and social acceptability) criteria. Some of these criteria are described in quantitative terms whereas others are qualitatively ranked. Extensive literature reviews for each of the selected criteria were carried out and the information gathered was used with MCA to provide a ranking of the renewable energy alternatives. Table 1: Ranking of the renewable energy technologies using fixed criteria values and assuming all criteria to be equally important Renewable technology Ranking Onshore wind 7 Offshore wind 3 Hydro power 6 Wave 8 Tidal 5 Geothermal 9 Photovoltaic 1 Solar thermal 4 Dedicated biomass 11 Waste treatment 10 Heat pumps 2 When all criteria are considered equally important (Table 1) PV, heat pumps and offshore wind come out as the best three options, while bioenergy and geothermal are the least favoured options based on the selected nine criteria. However this result must be treated with considerable caution as the ranking is highly sensitive to how the criteria are weighted in the assessment; for example, if greenhouse gas (GHG) emissions and cost of the energy-generating system were considered twice as important as the other criteria, then hydropower would be the most favoured technology, followed by onshore wind. Furthermore, the input information applied in the MCA was found to be very uncertain for most of the criteria. For example, values reported for the GHG emissions and land requirements in the literature are found to vary more than a factor of 10 for most of the technologies. To account for this uncertainty, each of the criteria values was defined by probability distributions and the MCA run using Monte Carlo simulation; hereby providing a probabilistic ranking of the technologies. Rankings have been produced from 10,000 Monte Carlo simulations and this clearly demonstrated the variation in the MCA output due to the uncertainty in the applied input information. Although there is some consistency across the simulations, the most striking result was perhaps that within the range of possible criteria values, almost any ranking of the eleven technologies was possible. Indeed, all of the technologies were found to be the most and the least favoured option in some of the simulations. The results from this study demonstrate a clear limitation in the use of MCA for assessing and comparing the sustainability of different energy technologies and/or schemes at the national scale. For actual site-specific energy projects, the degree of uncertainty may be smaller; whether MCA is the most appropriate method to identify the most sustainable option is open to question as local contexts and circumstances may push a project in a certain direction from the 95

5 start. However it does provide an objective method to compare options and provide evidence that the most intuitive option is indeed the most sustainable in a specific location. DO RENEWABLE TECHNOLOGIES ACTUALLY REDUCE CARBON EMISSIONS? A key part of the rationale that underpins the drive towards renewables is to reduce our reliance on carbon based fuels, given their impact on global warming. Another aspect that is as important but perhaps receives less recognition is the need to diversify our energy portfolio as fossil fuels run out. So do renewable technologies actually reduce our carbon footprint? Much debate has centred around the establishment of wind farms on carbon rich soils and the energy required in the transport and construction of the turbines from the outset. Given the predicted lifespan of turbines of around 25 years, what is the period before the carbon lost gets paid back through exploiting the wind resource as a substitute for fossil fuels? Similar questions arise with other renewable feedstocks. Biomass produced from perennial energy crops (e.g. Miscanthus, short-rotation coppice and others) is expected to contribute to UK renewable energy targets. The UK government has had incentive policies targeting both farmers and power plant investors to develop this market, but uptake has been slower than anticipated; indeed almost non-existent in Scotland. Market expansion clearly requires the interaction of farmers growing these crops, with the construction of biomass power plants or other facilities to consume them. Farmer behaviour and preferences are also believed important to selection decisions. A recent study used an agent-based model to investigate the UK energy crop market and examines the cost of CO 2 equivalent (CO 2 e) abatement that the market could provide. An existing GHG balance assessment was used as a framework to assess the emissions. The model is run for various policy scenarios, representing possible subsidy trajectories and divisions of support between farmers and energy producers, in an attempt to answer the following questions: Do existing policies for perennial energy crops provide a cost effective mechanism in stimulating the market to achieve emissions abatement? What are the relative benefits of providing incentives to farmers or energy producers? What are the trade-offs between increased or decreased subsidy levels and the rate and level of market uptake, and hence carbon abatement? The study calculated the emissions from generating electricity from energy crops and emissions avoided from displacement of this electricity from another source, to determine the net emissions abated, for each scenario. The total cost of subsidies was also calculated, allowing the cost of carbon abatement ( /t CO 2 e) to be estimated. Figure 1 shows this carbon price plotted against the emission abatement under a range of policy scenarios. Varying the electricity generator subsidy, for a fixed establishment grant rate, produces a U-shaped curve. This indicates that there is a subsidy level that offers a maximum cost-efficiency of carbon equivalent abatement. Initially, as the subsidy level increases this reduces the failure rates (for example crops planted with no market, or power stations built that prove unprofitable), and also supports larger and more efficient power plants. However, eventually the increase efficiency is not sufficient to overcome the progressively higher subsidy costs, and the carbon price rises with increasing subsidy rate. 96

6 Carbon price (2010 t CO 2 e -1 ) Agriculture and the Environment X, Delivering Multiple Benefits from our Land: Sustainable Development in Practice (2014) Figure 1: Cost of carbon dioxide equivalent (CO 2 e) abatement against annual emission reduction for various subsidy policies, assuming coal generation displacement. The values below each point show the minimum Renewable Obligation Certificate (ROC) rates (ROC MWh -1 ) used in that scenario The energy crop scheme, providing farmers with 50% establishment grants, appears to fulfil an important role in stimulating market development and increasing the cost-effectiveness of carbon abatement, see Figure 1. However the scheme closed to new applications in August 2013, and it is unclear whether there will be a replacement, although there have been calls for one. There could be implications for the size and efficiency of the energy crop market, i.e. lower uptake, emissions abatement and cost-effectiveness, if no replacement is put in place. Even if higher subsidy levels were available to the power generators, the overall system would achieve less adoption and more costly emissions reductions without direct farmer support. Increasing the farmer support for energy crops, from 50% to 100% of establishment cost, provides a substantial increase (six-fold) in abatement potential, at a relatively small increase in the carbon price ( 1 t CO 2 e -1 ) Emission reduction (Mt CO 2 e yr -1 ) % establishment grant 50% establishment grant No establishment grant CONCLUDING REMARKS Scotland s land resource has a huge theoretical potential to contribute to Scotland s renewable energy targets and at the same time providing an alternative source of revenue to rural Scotland. Renewable energy can add value to other services that land provides thereby contributing to multiple benefits - but robust methodologies are required to ensure that the most sustainable option is selected in specific and all environmental, social and economic factors are considered. The role of cost-effective subsidy levels is also a key aspect to ensure that emission reductions are achieved but represents good value to the public purse. Ultimately, renewables from the rural sector will only be achieved through the participation of those who are willing to take the risk to do so. 97

7 ACKNOWLEDGEMENTS This research was supported by the Scottish Government Strategic Research Programme on Environmental Change and the Natural Environment Research Council. REFERENCES Alexander P, Moran D, Rounsevell MDA, Hillier J and Smith P (2014). Cost and potential of carbon abatement from the UK perennial energy crop market. GCB Bioenergy 6, Scottish Government (2011) Routemap for Renewable Energy in Scotland. Scottish Government, Edinburgh. Scottish Government (2014). Agri-Renewables Strategy for Scotland. Scottish Government, Edinburgh. Towers W (2013). Renewable energy from land based sources. Renewable Energy Topic 6. The James Hutton Institute/Scottish Government. Troldborg M, Hough RL and Heslop S (submitted). Assessing the sustainability of renewable energy technologies using multi-criteria analysis: suitability of approach for national-scale assessments and associated uncertainties. Renewable and Sustainable Energy Reviews. 98