Select Committee on Innovation, Universities, Science and Skills Written Evidence

Memorandum 8

Submission from Supergen Energy Storage Consortium


  The Supergen Energy Storage Systems (ESS) consortium is an EPSRC sponsored grouping of academics and industrialists who are developing future energy storage solutions for electrical grid and automotive applications. Although our main activity is research (device production, modelling and applications) we monitor relevant technologies and offer independent, non-commercial and objective advice on all aspects of energy storage.


  This paper asserts that the weak link in the widespread deployment of energy from renewable sources is the development of economically viable and safe energy storage devices. Energy storage is needed to provide continuous power from intermittent sources and also to provide very stable power for the increasing demand from digital devices. There are a wide variety of possible technologies but only a few are suitable for widespread deployment. Large-scale energy storage is essential for the UK if we are to develop energy from renewable sources.

  We wish to draw to attention of the Science and Technology committee to the following regarding the status of energy storage technologies:

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  Over the next 20-30 years energy will increasingly come from a wider variety of sources, over a wide range of scale lengths varying form large nuclear facilities, wind farms to domestic electrical production. Additionally, the demands of the energy supply system will broaden to include an integration of the electrical and transport markets. For example, GM, Lucas/ZAP and Telsa are all developing "plug-in" Li-ion battery cars. Energy storage is necessary to integrate all of these power sources and applications. We note that an increasing fraction of the electrical market is for digital devices, which demand very good power quality. The problems of uninterrupted supply and power quality must be solved if the UK is to remain competitive over the next 20 years in all sectors including heavy and light industry and financial services. It is to be noted that poor power quality already causes productivity losses of $400 billion to the US economy. Similar estimates are not available for the UK economy.

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  We assert that the problem of how energy storage should be integrated into distribution and supply networks has not been resolved; indeed this is a key part of the ESS consortium work. It is certain that storage facilities covering a wide range of sizes will be needed. Although there different technologies are suited for different scale lengths, investment in technology development would be more efficient if the number of choices were as small as possible.

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  Energy from pumped hydroelectric sources is the only large-scale energy storage technology deployed in the UK. Most of the facilities are based in Scotland although the largest one is in Wales. The Dinorwig facility is an astounding piece of engineering although difficult to replicate elsewhere in the UK. Our conclusion is that pumped hydroelectric power is fully utilised within the UK and there is little scope for additional development. This is especially true for the large population base in the South East. Although there have been considerable developments in tunnelling and drilling technologies we feel that underground pumped hydroelectric will not be able to complete with other technologies on economic grounds: the initial capital costs and environmental impact are prohibitive.

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  Despite considerable effort and development, flow batteries have failed to live up to expectations. Flow batteries are systems that take up and release energy on a large scale and have the potential for grid stabilisation. The most advanced programme, Regenysis, has proved to be unacceptable industrially and potential orders in the USA have been cancelled. The opinion of the ESS consortium is that flow batteries deal with potentially toxic and environmentally damaging materials. We note that, although no chemicals are exported, these devices involve chemical transformations and the handling of extremely dangerous materials. Additionally, they use mechanical pumping and membranes, which will eventually breakdown. Accordingly, from a regulatory point of view they should be regarded as chemical plants with all of the safety considerations and thorough risk assessment that this involves. ESS is currently developing a guideline for the deployment of this technology in conjunction with leading chemical plant safety experts and will advise on these aspects.

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  We note that the UK trails many countries in the development and demonstration of Superconducting Magnetic Energy Storage. Although this will never be a cheap technology it may have applications for good quality power production for digital applications. This situation should be more closely monitored by DTI/OSI. The approximate time scale for any introduction of this technology is greater than ten years.

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  There is considerable effort in the development of new Li-ion battery technology, particularly in large DOE laboratories in the USA as well as industrial conglomerates in Japan and EU. This is because these devices have the potential to be the most efficient storage devices in the longer term and the technology is scalable from domestic situations to grid levelling applications. The UK is currently competitive in research terms and with some production capacity. If this situation is maintained then the UK could have a major role in the deployment of this technology. Li-ion batteries were one of two technologies selected for development under the ESS. It is to be noted that GM and others are already introducing Li-ion battery technology into the automotive market. This technology is mature enough to be introduced into the domestic market for energy storage from domestic wind and solar sources but introduction on a larger scale requires further materials development and the time scale is greater than 10 years.

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  Supercapacitors are devices that are capable of storing and releasing power very quickly and can be used for maintaining stable power quality (for digital power) and extending battery lifetimes. The storage and release is almost 100%. They are expected to have a major impact on future energy provision and are the other technology chosen by ESSS for development. We note that there is currently no production capacity in the UK. However, the essential material for the production of supercapacitors, nanoporous carbon for electrodes is undertaken by a number of progressive and innovative UK based companies. We therefore believe that there is scope for the industrial development of this technology within the UK and that this technology should be monitored and promoted by DTI.

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  Hydrogen is also considered as an energy storage technology and indeed here is considerable discussion of the "hydrogen economy". Despite hydrogen "road mapping" exercises appearing on a tri monthly basis it is important to view this technology critically. For stationary energy storage the process involves consists of hydrogen generation by electrolysis, pressurised hydrogen storage and subsequent electrical generation through a fuel cell. Although technically feasible and already introduced on a demonstration, this process is not without its limitations. The whole conversion process has unacceptable efficiency losses because it involves transforming electrical energy into chemical energy and back again. The theoretical maximum efficiency is less than 60% (operationally 35-40%, IEA figures) but this figure reduces even further when compression and inverter losses are included. Fuel cell power is notoriously expensive and fuel cell lifetimes are relatively short (2,000 hours mobile, 6,000 hours stationary, £9,000/kW, IEA figures). We do not foresee this technology being deployed on a wide scale within 10-20 years.

July 2007

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