Supporters of fossil fuels often mention predictability of supply in their argument against renewable energy sources. Put simply solar power is only effective when the sun is shining and likewise wind power only generates electricity on a windy day. While this criticism is not valid for all forms of renewable power (hydro and geothermal are some of the most consistently reliable energy sources) it is true that solar and wind power are very susceptible to peaks and troughs in supply. The traditional response has been to vary the feed into the grid from more reliable power sources such as coal, gas or nuclear to balance energy production with demand.
However while it is the case that sometimes there is insufficient power generated othertimes too much power can be generated. Domestic energy requirements tend to be lower during the day, ironically when the sun is shining and solar power production is most effective. When the wind blows strongly massive wind turbines can generate more power than is required by the electricity grid. Recently there have been some interesting developments that promise to improve the reliability of supply from renewable sources by storing excess power so that it can be released later to better match demand.
In Germany domestic solar customers are able to benefit from a hybrid solar invertor and energy management system. At the heart of the systmem are advanced Li-ion batteries that enable electricity to be consumed in the evening when demand is highest.
A typical household is estimated to be able to produce 80% of it’s own power using this system. Similar improvements in battery life are also improving the reliability of electric cars giving greater range to emission free runabouts.
Apple have filed a patent application for a wind turbine that generates heat instead of electricity.
The heat is used to generate steam to turn turbines which produce electricity. The benefit of this design is that heat is easier to store for long periods than electricity.
But perhaps the most original solution has been put forward by the Belgium government who plan to build a doughnut shaped island 5km offshore to store excess energy from wind farms. When additional power is needed valves would be opened allowing the water to flow back into the island turning hydroelectric turbines in the process.
We think that these ideas are hugely exciting and variations that offer even more innovative solutions to store energy will further improve the reliability of renewable power sources in future years