|
 Summary of a report entitled RESCUING RENEWABLES: How energy storage can save green power, by Tony Lodge, Chairman, Bow Group Energy and Transport Committee
At present the demand for electricity fluctuates and may double at peak times, but the supply is always available so that blackouts are very rare. The electricity industry works hard to ensure that they meet this fluctuating demand, but the introduction of intermittent energy from wind and solar sources means that supply and demand are both fluctuating at different times. This causes inefficiencies and could damage the grid and lead to blackouts when supply is not sufficient to meet demand. To avoid this happening, fossil fuel plants are used as a back-up when the wind is not blowing and there are already instances when wind turbines have had to be closed down when demand was low. This means that the full benefit of a green unit of electricity, a kilowatt hour (kWh), entering the grid cannot be realized because 1kWh of green energy cannot displace 1kWh of fossil generated electricity.
HYDROGEN ‘WAREHOUSE’
Balance is the key to the electricity industry. The production and consumption of electricity are dynamically coupled; supply must match demand in a sub-second timescale. The addition of new unpredictable components, like weather dependent wind and solar energy, undermines the balance. Even small variations in system voltage and frequency can cause damage to modern electronics and other electrical equipment. When electricity is made it must be delivered, so a „warehouse‟, or electricity storage system, would be of great value to the electricity industry.
The present means of storing renewables include pumped storage, like the Dynorweg hydro-pumped storage power plant in Wales, which is 74% efficient. However, there are few suitable sites for pumped storage in the UK. The inertia in large rotating steam turbines powered by coal is also a form of energy storage when these plants are kept active as a „spinning reserve‟, but there are fewer of these stations as coal is now being phased out. Gas turbines do not provide spinning reserve, nuclear power can only be used to provide base load as it cannot be ramped up and down and oil fired plants are expensive, inefficient and carbon intensive. Batteries are only suitable for small scale, short term storage, but hydrogen storage is feasible at multi megawatt (MW) wind farm sites and, on the distributed level, for districts, streets, farms, villages and homes. This mass storage deployment would enable reductions in capital costs.
For comparison, the Scottish island of Eigg uses batteries for storage and the Norwegian island of Utsira uses hydrogen. Eigg found that its storage was not sufficient and is now considering an Utsira-style hydrogen storage system, which has provision for three days of stored power if a wind- be increased as required by expanding the hydrogen storage capability. Utsira could also boost its renewable energy portfolio with the installation of solar PV, wave and tidal capability. Denmark has a large number of wind farms which could in theory meet 70% of the country‟s peak demand, but this is rarely matched by supply when it is needed. Averaged over the last five years, wind power has only provided 9.7% of Denmark‟s annual electricity demand. Denmark therefore exports much of its surplus electricity via the grid to neighbouring countries at a discount to the cost of generation.
COST BENEFIT ANALYSIS
Over a 20 year period the net cost benefit of the UK Government‟s renewable energy policy is negative. This could be improved if local hydrogen storage is introduced with the following benefits:
- improved efficiency as supply matches demand
- the need for fossil fuel back-up is removed
- lower carbon emissions
- less investment in infrastructure costs
- reduced stress to the system as ramping up and down is minimized
- grid stability and continued freedom from blackouts
- community, business and individual self-sufficiency
RENEWABLE ENERGY STORAGE INCENTIVE (RESI)
However, further technical improvements and cost reductions are necessary to make wind power with hydrogen storage more viable and competitive against diesel generators. For this reason there is a strong argument for fostering a distributed renewable system which generates, stores and utilizes green energy at the point of use. As with other immature renewable technologies, initial financial incentives will be required to help cover the cost of systems of renewable energy plus storage. Alongside Feed in Tariffs for renewable energy, it is proposed that there should be a Renewable Energy Storage Incentive (RESI), which would offer huge potential benefits to the operational effectiveness of the grid. The value of storage from the commercial point of view is illustrated when at times of peak demand the electricity price can jump in half an hour from around £35 per megawatt hour (MWh) up to £140. There is little to be gained if homes export electricity to the grid at times when availability is high and demand is low. Energy storage would address this by mopping up intermittency in the form of a clean fuel consumed at household level. The Government should add a 10p tariff for storing green electricity to the present FIT rates, as renewable storage will reduce rather than increase fuel bills.
The Department of Energy and Climate Change (DECC) has published their Low Carbon Transition Plan, which recognizes the problem of back-up power for intermittent renewable energy but does not solve it. There is also likely to be an energy gap from 2017 as oil, coal and nuclear plants close down, even if wind power meets its targets. Biomass power plants are not the answer as they could cause significant pollution in urban areas and mis-spent Government subsidies on biofuels have encouraged the cultivation of non-sustainable crops, they have driven deforestation and caused rises in food prices. Local renewable energy storage is the only viable way both to slash UK carbon emissions in the short term and to meet strict renewable targets.
The mismatch between electricity supply and demand occurs with high peaks for a few hours per day and particularly at weekends. The peaks can be reduced by demand side management, but are best dealt with locally through the use of energy storage.
BRITISH POLICY LEAD
One British company is taking the lead with hydrogen for transport. Yorkshire-based ITM Power is developing a hydrogen infrastructure for transport operators and has a demonstration home powered by hydrogen at its factory. They are working with the global wind turbine manufacturer, Vestas, which is aiming to generate the most sustainable return on wind for their customers.
The electricity industry is extremely conservative and is reluctant to take on the risk of developing new technologies, so the Government should encourage the energy storage sector in the same way as it has done with the Renewable Obligation Certificates. The UK currently has less than a 5% share of the global market for green technology – less than Japan, France, Germany, Spain or the US. Analysis of R & D investment indicates that UK companies invest less in R & D regardless of their size as compared to their G8 competitors.
The proposed renewable electricity storage incentive (RESI) should now be made available for the micro-generation of green hydrogen by electrolysis. Various studies have shown that this route of absorbing excess renewable electricity at times of peak supply for use at times of high demand offers flexibility - for example, in emergency backup power and car refuelling. It is likely that a significant proportion of consumers will discover that they have a new role as micro-generators of green energy as well as users.
It would help those who wish to achieve more autonomous energy solutions and a low carbon footprint with the installation of suitable equipment such as a home hydrogen refueller. Green energy storage provides a „localist bottom-up‟ solution for the Coalition Government towards energy and environment policies, without Ministers having to cherry-pick technologies or pick winners.
Scotland has set a target to become 80% self sufficient in renewable energy by 2025, but this would not work without renewable energy storage. If the wind‟s power can be harnessed as stored energy to be used later, when it is required to meet demand, the potential for Scotland and the rest of the UK is huge. Countries that are early adopters of these energy storage technologies will benefit most in the development of hydrogen and fuel cell industries.
The flexibility of hydrogen energy storage is that it can do more than just clean up the power system, it can also clean up the transport system, improve air quality in towns and cities, dramatically reduce carbon emissions and provide the UK with a global manufacturing and engineering edge. Unlike batteries, hydrogen is a fuel which can be stored for long periods and therefore provides the security that society seeks, as well as independence from diminishing oil and gas reserves. |
