Managing the renewable energy intermittency challenge

Although there is no doubt that renewable energy sources have a vital role to play, it would be a mistake to view them as a panacea that will allow us to turn off the fossil fuel taps any day now, writes Steven Hardman, CEO, Conrad Energy. The reason that won’t be possible, even if there was sufficient renewable capacity to meet all of the UK’s energy needs, is intermittency.

Put simply, intermittency refers to the unreliability of renewable sources compared with their traditional counterparts such as coal or gas-fired power stations. This unreliability is not a technological problem that can be overcome through investment in research and development. Rather, it relates to the simple fact that whether the wind is blowing or the sun is shining is outside of our control.

This means that there is no guarantee wind and solar farms will always be able to generate electricity when it is needed. As a result, in a grid that is entirely powered by renewable sources, a gap could emerge between the volume of energy that is needed to meet demand and the volume of energy that is actually being produced, potentially causing blackouts.

A lack of power generation isn’t the only potential problem created by intermittency. On a very bright or windy day, the amount of energy generated by solar and wind farms could surpass demand. This threatens the stability of the grid and can cause damage to sensitive electronic equipment, requiring rapid adjustments to match supply with demand to avoid this outcome.

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Fortunately, there are solutions that can be deployed to meet the intermittency challenge, allowing efforts to decarbonise the grid to continue without the risk of being beholden to unpredictable levels of energy generation. Flexibility and adaptability will need to be at the centre of this, requiring the use of both established and emerging technologies.

Plugging the gaps and storing the excess

To help alleviate the intermittency challenge, it is necessary to have in place fail safes for when there is both too much and too little energy in the system. But because these problems are, in effect, opposites, there is no one-size-fits-all that can be used to solve them. That is to say, (at least until more and longer term battery storage is available) an excess of energy generation cannot be tackled using the same approach to deal with a shortfall. But that doesn’t mean an overarching strategy can’t be deployed.

For example, small-scale gas engines offer a highly efficient, lower-carbon stopgap to keep systems online during periods when the prevailing weather conditions prevent renewable sources from being able to meet demand. Similarly, grid-scale batteries can be deployed to store the excess energy generated above demand when weather conditions are ideal.

This stored energy can be released subsequently, offering another failsafe to ensure that the lights are kept on even when renewable sources aren’t able to meet demand. Batteries also enable a faster response, which helps to mitigate potential problems with the stability and frequency of the grid.

Other tools at our disposal to provide stability and consistency include hybrid renewable energy developments, which use both wind and solar resources, and demand and response programmes, such as the National Grid’s Demand Flexibility Scheme that has run over the last two winters. Demand and response programmes adjust consumption patterns against real-time energy availability, helping to balance the grid. Human choices can also make a meaningful difference. Moving factory production times, for instance, can have a significant impact on energy consumption.

Smart grids, meanwhile, use digital technologies, sensors and software to better match supply with demand. These can be used alongside advanced forecasting methods to better predict renewable energy outputs than was possible in the past. This enables grid operators to more effectively and efficiently manage resources to ensure they can meet the electricity demands of end users.

Where next?

Investment is helping to make currently expensive technologies more commercially viable across the energy industry. Consequently, although there are already a range of technologies that can be deployed to help tackle the intermittency challenge, the pace of change across the energy industry is such that the technologies deployed today may be rendered obsolete by future technological developments.

This investment is a reflection of the reality that despite some net zero targets being weakened or deadlines pushed back, the share of energy that is generated by renewable sources is set to continue growing. But in order for this transition to be managed without causing undue disruption to the energy grid, private investment into new technologies alone is unlikely to be sufficient.

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Rather, private investment will need to be supported by funding for grid modernisation and the development of a more supportive regulatory framework. Upgrading infrastructure will also benefit the wider resilience of the grid, in addition to making it easier to incorporate advanced technologies. Investment in the grid is already underway, for example through the National Grid ESO’s Pathfinder contracts.

The vital importance of renewables to the energy transition can’t be ignored, but this cannot be allowed to result in heads being buried in the sand when it comes to the challenges posed by renewables and a concerted effort will be needed in response. In the first instance, this should include educating both the public and policymakers about the problem, as well as potentially planning reform and taking steps to ensure new technologies are commercially scaleable.

Equally, however, it is not all doom and gloom. Far from it, in fact. There is scope for the technologies behind renewable energy to continue to develop and currently available technologies, including small gas engines and battery storage, alongside programmes such as the National Grid’s Demand Flexibility Scheme, provide the tools that are needed to manage the intermittency problem in the here-and-now, whilst more advanced technologies are developed.