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Energy storage

The UK Government is failing to provide sufficient support for electricity storage technologies, which are becoming increasingly important to secure electricity supplies, the Institution of Mechanical Engineers said in a new policy statement. It claims that UK electricity demand is set to double by 2050 due, in part, to the increase in use of electricity to provide heating and power cars and this increase in demand, combined with the UK’s ambitious climate change targets and the EU Renewables Directive, which means the UK is set to rely increasingly on renewable power. However, it says that renewable technologies like wind and solar power, although presenting many benefits, are inherently intermittent and as such cause problematic swings in supply on the UK grid. Hence the need for storage.

Dr Tim Fox, Head of Energy and Environment at the Institution of Mechanical Engineers, said: ‘For too long we’ve been reliant on using expensive “back-up” fossil-fuel plants to cope with the inherent intermittency of many renewables. Electricity storage is potentially cleaner and once fully developed is likely to be much cheaper.’ The IMechE also lists some other positive benefits: storage units are more modular and flexible, with faster start up rates than some backup plants, and can be used at various scales and locations

There are some problems with this analysis. Firstly it not at all clear that demand will double by 2050. That, it has been claimed, is just a projection adopted by DECC to justify nuclear expansion and has been challenged as unproven: see the ACE)/Unlock Democracy report ‘A Corruption of Governance’, and the new AECB study on energy efficiency: http://aecb.net/news/2012/02/less-is-more-energy-security-after-oil-lim-from-the-aecb/

Secondly, studies have indicated that we may not need extra backup plants (or storage) until after 2030, and then not that many (e.g. see Poyry’s 2011 study). Thirdly, since storage plants inevitably spend most of their time not doing anything, storage is expensive. Backup plants are cheaper and are likely to remain so - the cheapest form of storage is gas, which could be green gas, produced by AD from wastes and also by electrolysis using excess wind-derived power. That said, the wind-to-gas option is new and likely to be expensive, so at some point new electricity storage technologies (e.g. flow batteries, compressed air, cryogenic air storage) may prove to be economically viable. It depends on how the overall system is developed. It may be cheaper to get access to existing pumped hydro storage in Europe via supergrid links. That in turn depends on how the market is structured. If carbon prices as set high and renewables accelerate, then there could be a large new market for balancing services. The UK’s new Capacity market system, proposed as part of the Electricity Market Reforms, may help. But it’s not clear what are the best technologies for serving this market. For example, as I have argued in an earlier blog, heat storage is much cheaper than direct electricity storage, so we might consider a system in which heat - and gas - transmission and storage play major roles. http://environmentalresearchweb.org/blog/2012/04/wire-or-pipe.html

Given that there are uncertainties, it makes sense to push ahead with storage of various types as one balancing option, and IMechE is right to say that the Government incentives and policies to support development and deployment of electricity storage technologies are currently scant and ill-designed. But as well as ignoring heat storage, there is the risk that arguing that we have to have large amounts of expensive electrical storage backup for wind etc is actually a covert way of constraining them.

IMechE say that the UK currently has 2.8GW of electricity storage capacity in the form of pumped hydro-electric storage, and that, according to National Grid, we will need 8GW of electricity storage capacity by 2025 if the penetration of wind power in the network is 30%. But as indicated above, that’s not necessarily the only option. In addition to green gas production/storage for use in backup plants, and the potential for heat storage, the UK also has 2GW or so of HVDC grid connection links with continental Europe and that is planned to expand to maybe 10GW and could be as much as 20GW by 2050, which could be used for balancing. Building that would also be expensive. But then so would electricity storage. And as noted above, we might not need much of either.

So while it’s important to note that, as IMechE says, the worldwide market for electricity storage is estimated to be worth $20-$25 billion a year by 2020, we need to think through how much we might actually need in the UK. That thankfully is one of IMechE’s recommendations. They also suggest that the UK Government’s Electricity Market Reform (EMR), which is examining and revising the commercial and regulatory structure of the nation’s electricity market, should take into account the unique nature of electricity storage and remunerate investors and operators accordingly. And finally, that it should encourage and support UK development of storage technologies for exploitation in world markets, by advancing the commercial-scale demonstration of electricity storage technologies in the UK, and thereby creating technical value that UK companies can exploit in markets worldwide.

These are all sensible recommendation as far as they go, but they could perhaps be broadened- as I have indicated, electricity storage is only one option for grid balancing and electricity is only one option for energy transmission and use. As DECC now seems to be accepting, we might also make use of green gas and green heat as energy transmission and storage vectors, with balancing potential.

www.imeche.org/news

Posted by Dave Elliott on June 16, 2012 2:12 PM | Permalink