Intermittency – the next challenge for renewables by Andy Strowbridge

Renewables are increasingly winning the ‘cost war’ and becoming an accepted part of the global energy mix. That is a great first step as it reduces the industry’s dependence on regulatory support, which could change on a whim. Cost parity on its own does not, however, guarantee a rosy future for the industry. The next challenge is intermittency.

Intermittency limits the renewables capacity that can be accommodated on a network, as most of the drivers of renewable energy generation such as the wind and the sun are intermittent. Interconnectors between countries and demand management can provide some useful mitigation for the effects of intermittency. They will not be the whole answer –  storage solutions will also be needed.

Of course, ‘storage’ is not a single solution, it is a range of solutions. These will have different timescales and technologies to meet different needs and generation capabilities. While batteries can assist for short term support, as demonstrated by Tesla in South Australia, the bigger challenge is to store electrical energy for much longer periods.

While some forms of renewables, such as hydro electric power with reservoirs, combine storage and generation, other forms including wind energy have been developed independently of storage. We should not assume that the storage solution must be completely separate from the renewable technology, it is the end to end solution which is critical.

Wind turbines have been optimised to provide utility quality electric power, and are normally built with a grid connection sized to take the maximum installed capacity. What might an optimised end-to-end system of wind  storage look like? Here are  a couple of examples:

  • Sited in very remote off-grid and extremely high wind speed locations, such as Patagonia. Generating gas from wind which can easily be transported long distances to its point of use, as liquid natural gas or ammonia are often transported today, and the gas potentially used: to generate electricity, in the gas grid, or as a transport fuel. The turbines themselves could be adapted to meet these very different operating conditions.
  • Sited on an electricity transmission network and in a location with very good wind resource such as the Western Isles of Scotland. Using wind turbines similar to today, and either exporting electricity directly to the grid, or using massive hot rock storage which can generate electricity when required (as Siemens is currently demonstrating). If enough storage was included this could allow wind energy to provide a baseload of electricity and make more effective use of expensive transmission capacity.

The success in reducing onshore and offshore turbine costs over the last 25 years has shown that the wind industry can achieve results way beyond most expectations. Reducing end to end storage costs is the next great challenge of our time and will require input from academics, policy makers, turbine suppliers, storage specialists and project developers. I have no doubt that our industry  will rise to the challenge.

Andy Strowbridge