Maximising the Carbon Impact of Wind Power

The UK has invested heavily in wind power in recent years, and is widely expected to build much more capacity in future. One of the driving reasons is to reduce carbon emissions, but there has been no in-depth study of how effective wind power has been, or will be, at achieving this. The simple question of 'how much carbon dioxide does a wind farm save?' has a surprisingly complex answer as it depends not just on how much power the farm produces, but on how the rest of the electricity system responds to its production.

Past work by academics and government bodies has concentrated on calculating the average emissions (in grams of carbon dioxide per unit of electricity) from the entire UK power sector in various future scenarios. This project will be the first to understand the marginal emissions from wind power: the change in national emissions from adding one more or one less wind farm to the power system, the driving factors behind this, and how those factors can be used to maximise the savings. The more carbon dioxide that each turbine saves, the fewer turbines will have to be built, and the lower the cost to consumers and the UK economy.

This detailed study is necessary because not all power stations respond equally to the output from wind farms. We must identify which specific power stations reduce their output when wind generation increases: high-carbon coal or lower-carbon gas? Secondly, more power stations will have to run part-loaded to cope with the weather-driven variability in wind output. We must understand how large this effect is, how great an impact it has on station efficiency and thus on national emissions. Third, large-scale investment in wind power will change the mix of other power stations that the rest of the industry chooses to build, and those stations will have different emissions at times when the wind is not blowing. Finally, to provide a holistic view of emissions we must consider the carbon emitted when power stations are built or fossil fuels are extracted from the ground using Life Cycle Assessment methodology.

We will investigate these issues using a range of techniques intelligently integrated across several academic disciplines to give a complete whole-systems picture of the emissions displaced by wind, and:
1) Address fundamental problems in the emerging field of using reanalysis weather data to simulate historic wind farm outputs, allowing the output from the UK's future mix of wind farms to be quantified.
2) Produce the most detailed estimation of British power sector emissions, combining the output from every power station with their likely efficiency, derived from hourly emissions data from similar stations in the US (as these are not reported in Britain).
3) Develop statistical regression techniques to discover how these emissions vary with the level of wind output, with fuel and carbon prices, and the accuracy of the wind forecast.
4) Employ both engineering and economic models of the future electricity system to investigate how investment and operating decisions change with more wind power, and what this will mean for emissions.
5) Develop a reduced-order model of the global electricity system to replicate this analysis for other countries to ask whether the UK is well- or badly-placed to reduce emissions with wind power.

Our aim is to understand the factors that affect the emissions savings from investing in wind power, so that these savings can be maximised. Energy storage, international interconnections, accurate output forecasts and a high carbon price will all help to increase the emissions savings from wind power, and we will quantify the effects of each.

The immediate beneficiaries of this research are likely to be policy-makers in government, regulators such as Ofgem and advisers such as the Committee on Climate Change. The UK and other European countries will be investing billions of pounds in wind turbines over the next decade or so, and policy-makers need to know how this investment can be made most effective in decarbonising the UK and other economies.

We are therefore determined to bring the results of our work to policy-makers and to other interested parties. We expect to produce answers to the following policy-relevant questions:
1) How much carbon dioxide has been displaced by the UK's recent investment in wind power?
2) What factors, such as fuel and carbon prices or the accuracy of wind forecasts, have affected how the displaced emissions varied over time?
3) How much carbon dioxide will be displaced by different levels of further investment, compared to precisely specified counter-factuals?
4) How can complementary investments, such as energy storage or international interconnection, affect the level of emissions displaced?

These answers should help policy-makers develop a road-map for the development of the power sector that can assist it to reduce emissions at the lowest possible cost. Ensuring that policies are cost-effective can minimise the chances of an undeserved public backlash, as can providing accurate information about their impact on emissions. While the questions above are UK-focused, one of our work packages will have a global scope, giving similar information to policy-makers in other countries in Europe and around the world.

In setting and evaluating performance against emissions targets for the power sector, it is becoming critical for both DECC and CCC to understand the range of variation in actual emissions that may result from a generation mix designed to target a particular emissions intensity, and in this context, the project will provide new insights in relation wind generation.

Industry will benefit from learning which investments are likely to be cost-effective in reducing emissions, and from discovering which complementary investments should be encouraged. Specifically, National Grid will know how far any improvements in the accuracy of its wind forecasts can feed through into lower emissions from plant providing reserve. Current work by two of the applicants has estimated the economic benefits from dispersing wind farms around Great Britain and the surrounding seas; we will be able to generalise this work to include the impact on emissions and disseminate it to investors in wind farms.

The UK economy and electricity consumers will benefit if our insights lead to a reduced cost of decarbonisation; the sums involved are so high that even a small percentage change in costs will being worthwhile benefits in aggregate.

Training can bring a further economic benefit to the UK: we will train a PDRA (likely to have a background in economics or power system engineering) in the techniques of the other discipline, developing a multi-disciplinary researcher. The two Co-Is who are (relatively) early in their careers will gain experience, mentored by RG and GS. A PhD student at the Science and Solutions for a Changing Planet DTP at Imperial College will also be supervised by this research team for the project life (and beyond), further developing capacity.

The UK public will gain from better information about the role that wind power is playing and can play in future in the important task of decarbonising our country. Our work has the potential to reduce electricity bills for consumers and industry compared to those that would come from adopting a pathway with too large or too small a contribution from wind.