Analysis: Long-duration energy storage technologies could help Ireland reach its goal of eliminating the use of fossil fuels by 2050
When we turn on a light, the electricity that powers that light bulb is produced from a mixture of fossil fuels and renewable energy. But with a goal of using renewable energy only by 2050, how will we be able to remove the use of fossil fuels completely from our electricity system?
Ireland has made great strides in the past 20 years to remove the use of fossil fuels by replacing them with renewable energy, such as solar and wind, but we are far from eliminating them completely. A key issue is what to do on those days when the sun isn't shining, or when the wind isn’t blowing. Do we need to turn to coal, oil or gas again? And what can be done when excess renewable energy is generated – more than can be used at that time?
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From RTÉ News, the ESB has officially opened a major battery energy storage plant at its Poolbeg site in Dublin
We already have batteries to store energy for short periods in the electricity system, similar to what we have in our mobile phones and in our electric cars. Batteries are relatively safe, easy to install, are easily integrated into the electricity system and can be made visually unobtrusive. However, they use precious and expensive materials and metals such as cobalt and lithium, which are likely to continue to be scarce and very expensive into the future.
At the International Energy Research Centre (IERC), we have calculated that five days of electricity for the Irish electricity system in winter 2030 would need over two million tons of batteries and cost over €200 billion, which represents almost 10% of current global lithium-ion battery production. This clearly isn’t feasible or possible, so we need alternative ways of storing huge amounts of energy for long periods of time.
From ESB (2015), the story of Turlough Hill, Ireland's only pumped storage generation station
Electrical energy can also be stored in pumped water storage systems, such as the one in Turlough Hill, Co. Wicklow, which has been managed by the ESB since the 1970s. This system pumps water up the hill to a lake higher in the mountain to store energy.
When that energy is needed, water is released down to a lake lower down the mountain via a turbine, which generates electricity. This allows ESB to storage almost 1600MWh of electricity which is equivalent to the energy stored in 40,000 electric vehicles. The system is very efficient but costly and there can be significant environmental impacts such as creating dams. Additionally, there are very few places this can be done as Ireland is relatively flat.
Hydrogen is a very promising technology for long-duration energy storage. In these systems, electricity is used to turn water into hydrogen and oxygen through the process of electrolysis. The hydrogen is stored in tanks and when needed, the energy is used in a gas turbine or in a fuel cell to generate electricity and water, rather than CO2.
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From RTÉ Radio 1's Today With Claire Byrne, could National Hydrogen Plan solve the energy crisis?
Energy can also be stored as heat, known as 'thermal storage'. When a substance, such as a salt, is heated to a high temperature, up to 1,200 degrees C, it can store electricity. To discharge this electricity, steam is generated from the high temperature salt, which can drive a turbine. Compressed Air Energy Storage, Liquid Air Energy Storage and new, cheaper, more environmentally friendly battery chemistries are also being consider for long-duration storage.
None of these technologies are perfect. Each have their own advantages and disadvantages but one or a combination of these technologies will be needed to take the carbon out of our electricity system forever. To accelerate the adoption of one, some or all of these technologies will require coordinated collaboration between research, industry and policy makers to ensure that the best and most cost-effective approach is realised to make a zero-carbon electricity system in Ireland a reality.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
