Integrating renewables: optimal mixes
Wind power seems likely to remain the main new renewable energy source for the UK given the large offshore and on land resource and its relatively good economics. However, some lobby groups, like the Renewable Energy Foundation (REF), argue that we have placed too much emphasis on wind and should also look more seriously to other renewable options. Actually, although the British Wind Energy Association (BWEA) sees wind supplying 30% of UK electricity in the decades ahead, it may agree. The BWEA no longer focuses just on wind – it has increasingly been looking to wave and tidal power, particularly tidal current turbines. It has just changed its name, to “RenewableUK” (RUK), to reflect this.
It’s not surprising that the BWEA/RUK has been keen to take wave and tidal power under its wing, as well as wind. They can all work together beneficially to help cope with the variability of each source. Wave energy is in effect stored/delayed wind energy and so is less sensitive to wind variations, while tides, though cyclic, are unrelated to wind.
A recent Redpoint scenario, produced for the BWEA, is the starting point for a study of the optimum balance between wind, wave and tidal. In particular it looks at the extent to which wave and tidal power could help reduce the grid balancing costs associated with the use of variable renewables, and also reduce the excess wind “spillage”, when there was too much wind to be used on the grid. The study, The Benefits of marine technologies with a diversified renewable mix, suggests that, to get the best from the different time correlations of these sources, the optimum might be around a 70% wind and 30% wave/tidal current mix, or, if tidal range projects were included, along with tidal current systems, a 60/40 wind to wave/tidal ratio. The former ratio could reduce the need for fossil fuel backup plants by 2.15 GW, the later by 2.3 GW, and the overall carbon savings could be increased by up to 6%, with wholesale costs reduced by up to 3.3%, since there would be less spillage of wind.
All of these options are about electricity production, and are mainly on the larger scale, whereas it can be argued that smaller scale electricity generation, and also renewable heat production, are equally important in developing an optimal mix. The BWEA has taken an interest in micro wind, but otherwise it has mainly been another trade lobby, the Renewable Energy Association (REA), which has covered the microgeneration area (e.g. PV solar), along with biomass-based heat and power generation (e.g. micro CHP). One of the REA’s main strengths has always been biomass/waste related energy systems, including sewage gas, landfill gas and other sources of biogas, with new community-scaled AD (Anaerobic Digestion) plants being one of the latest growth areas. Along with others, it’s pushed hard for a Feed-In Tariff for micro power systems, with some success – the government is introducing a clean Energy Cashback scheme for small project in April.
A year or so ago the BWEA and REA were discussing a merger, but that came to nothing. So now, while BWEA/RUK will focus on wind, wave and tidal, the REA will be left covering the rest – and possibly, increasingly, renewable heat options. That’s the focus of the proposed new Renewable Heat Initiative Feed-In Tariff that the government is planning, to start next year. It’s also something that the REF has focussed on in their belief that we need a more diversified approach.
The division of areas of technological interest by the trade lobbies is not absolute (e.g. REA still has a strong interest in wave and tidal power). And while some sort of rough division may make sense institutionally, it would be a shame if the potential for a more integrated approach was reduced – there is a lot of overlap. BWEA/RUK and REA have collaborated in the past. Hopefully that will continue. After all, what seems likely to emerge is a new energy system in which a range of electricity and heat producing renewable energy based technologies, large and small, are integrated together to balance heat and power needs via heating networks and smart power grids. For example, along the lines proposed by Neil Crumpton – as I reported in an earlier post.
The issue of integration, and of choosing the right mix of renewables, will no doubt be high on the agenda being addressed by Prof. Bernard Bulkin, ex-BP and ex-AEAT, who is now the “expert chair” of DECC’s new Office for Renewable Energy Deployment. DECC is currently looking at what we might expect by 2050. It will be interesting to see what emerges in its “2050 Roadmap”, which should be published in conjunction with the Budget in April.
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