Submission from Supergen Energy Storage
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:
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.
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.
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.
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.
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.
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.
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.
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.