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Storing microgenerated electricity will shift power from energy companies to householders

Posted by James Page on 9 June 2011 at 10:03 am

In general self-sufficient communities are inherently sustainable. Not until the advent of companies whose very existence depended on an ever increasing trade in coal, oil or electricity did demand for energy, and carbon emissions, get out of hand. The question is how can we keep the benefits of being able to share energy with our neighbours but avoid the profligacy that accompanies efficient markets?

Renewable energy by itself isn't the answer. Cheap energy, whatever the colour, will help keep oil prices low and increase demand for energy overall. Other policies are needed to contain, and ultimately ration, carbon emissions.

But we are a long way off having too much renewable energy, and in agressively reviewing feed-in tariffs the government is in danger of preventing the conversion to green jobs that both the economy and our carbon budget badly needs.

Microgeneration policy is designed primarily to 'green' the grid in the long term. A tweak of the rules - both financial and technical - is timely. Further clarity is needed in places, and there is always room to improve the carbon savings from renewables. Some commentators in Germany made extravagant claims that solar energy hasn't reduced carbon emissions at all, since back up supplies are needed for when the sun stops shining. In reality there has to be back up available to cope with sudden rises in demand. The generation is being adjusted all the time to match demand. As clouds move across the country the variability in solar output nationally is not half as bad as it seems at one location.

Nevertheless the more that peaks and troughs can be smoothed the greater will be the carbon saved. This can either be done by shifting demand (fridges that automatically wait for the best time to come on are already being built) or storing the energy.

Electric cars - or eventually hydrogen - would be the ideal way to do this. Batteries have a storage efficiency of around 80% and electric motors are themselves inherently efficient over a wide range of speeds, unlike combustion engines. In cities housing developers should be made to provide charging points for cars. In fact most new housing should be reserved for the 1 in 4 without cars, or those with electric vehicles. Joined-up policies help with affordable housing, climate change and air quality in one go.

There is already a market incentive to store energy. Electricity companies are either paying peanuts (3.1p/kWh) or nothing at all for exported solar electricity. Storing energy would shift market power from the electricity company (the buyer) to the householder (the generator) leading to an increase in the market price paid to a figure closer to the true value. At the moment the energy is being sold on to your neighbours within nanoseconds at 400% profit. An increase in payment to the householder generating the energy will also improve the case for investing in solar in the first place.

Solar installations which are optimised for generating at times of peak demand ie winter evenings will in time attract a higher rate. Long-term thinkers are already installing their panels on west facing roofs!

Photo by Jon Callas

About the author: James Page is a chartered engineer and is head of engineering at Joju Solar. All views expressed are his own. He stores solar energy under the kitchen floor.

If you have a question about anything in the above blog, please ask it in the comments section below.

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