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Tony Lodge: How energy storage can save green power

Tony Lodge Tony Lodge is Chairman of the Bow Group Energy and Transport Committee and a Research Fellow at the Centre for Policy Studies. His new paper, Rescuing Renewables – How Energy Storage Can Save Green Power (with a foreword by Deputy London Mayor, Kit Malthouse) is published today by the Bow Group.

The most common and advanced forms of renewable energy are characterised by their intermittent nature.  Put simply, the energy harvested from, for example a wind turbine or solar panel, is only available when the wind is blowing or the sun is shining.  The much pointed out drawback being power is not always generated when it is most needed.

In the quest to achieve lower carbon energy use, this fundamental characteristic of renewable power should be considered with respect to creating a low carbon future based on our ability to harness, store and use renewable energy at all times. 

Renewable power is the only genuinely green energy form, all other forms either release CO2 to the atmosphere and/or consume fossil fuel reserves. So if we are to maximise an energy system that is built mainly on renewable power present day policies must change quickly. Green electricity is arguably the most sustainable form of energy but it cannot always be matched to demands for heat, power and mobility without energy storage.

Britain’s present one-dimensional renewables policy that emphasises generation come what may needs replacing by a two-dimensional alternative that couples generation with storage.

The need for storage
As the penetration of renewables into the grid increases, intermittent wind power will need to be increasingly curtailed to maintain power system stability.  At any one time the grid has a block of base-load power in operation, reducing this to accommodate intermittent power risks destabilising power supply and increasing carbon emissions as fossil fuel plant is ramped up and down.  Alternatively, unpredictable wind energy’s admission to the grid could exceed consumer demand.  This will lead to this green energy being rejected and wasted by the grid.  In May, Scottish Power was paid £13,000 to de-couple turbines whose high input was unbalancing the grid. It should be stored, instead, as a clean fuel.

Denmark’s predicament is a lesson for the UK. The country has the highest concentration of installed wind energy in the EU but 50% of the wind generated electricity it produces has to be exported as it cannot be used, and is sold at a discount to the cost of generation to neighbouring Norway, Sweden and Germany. Wind generation has not displaced any of Denmark’s fossil fuel power stations because of intermittency and unpredictability.

There are occasions, usually in the coldest months of January and February, when Western Europe experiences vast anti-cyclonic weather systems resulting in long spells, occasionally weeks of very cold and windless days.  It is therefore all the more important that when the wind does blow it can be fully utilised through energy storage. 

There are a number of ways to store electricity ranging from small scale, such as batteries for short periods of time to large scale pump storage reservoirs for storing vast amounts for long periods of time.  But topography and demography dictate that the UK doesn’t have many available sites to flood in order to create pumped storage reservoirs.  There is however another option; energy can be stored as hydrogen, a clean fuel, that can be obtained from water and wind generated electricity, resources that the UK has in abundant.   The process is electrolysis, and the technology is British.

Not only does energy storage using hydrogen enable efficient capture of increasing amounts of variable renewable energy, it also has a beneficial impact on how power is generated from existing power stations. It allows those stations that have to be turned on and off, as we wake up or return from work, to be run at a steady load and hence high efficiency.

Instead, the hydrogen generated by electrolysis may be reconverted to power at a later time and can displace the “brown” hydrogen derived from fossil fuels that are used in the glass and fertilizer industries. More importantly it can be used as a clean transport fuel, as Deputy London Mayor and Chairman of the London Hydrogen Partnership, Kit Malthouse, highlights in his foreword to the Bow Group report.  This then burns with zero carbon emissions in a modified petrol engine and can be used to power fuel cell vehicles as well as the zero-carbon home of the future.

In other words the flexibility of hydrogen energy storage more than cleans up the power system, it can also decarbonise the transport system, thereby improving air quality in cities. Unlike batteries, hydrogen is a fuel that can be stored for long periods of time, providing security and independence from diminishing and unreliable oil and gas producers.

The UK will only be able to realise its ambitious renewable energy growth and carbon reduction targets if the public are incentivised to use renewables with storage through a new Renewable Energy Storage Incentive (RESI), to co-exist alongside the feed in tariff (FIT).  At the moment the FIT pays participants for generating renewable electricity, with a bit extra for every unit of surplus energy they export to the grid, but it provides no incentive for storage.

The UK has the opportunity to generate a clean fuel from its growing renewables portfolio to the benefit of energy security and clean air, so decarbonising its power, transport, cities and towns; with substantial benefits for the economy.    How many times has the UK threatened to become the world leader in an evolving sector and missed the boat?  This opportunity cannot be missed.


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