Electrochemical storage will have a vital role to play in the future low carbon economy in behind the meter and renewable energy integration applications, Nigel Holmes, CEO of the Scottish Hydrogen and Fuel Cell Association, told ESJ.
The technology’s fast response and cycling capabilities will secure its future in megawatt-scale applications, but Holmes warns it will fail to meet the terawatt-scale demands of a low-carbon power and heat network.
This is especially true as the UK positions its infrastructure to meet a Paris Agreement promise that requires 35% of its electricity to come from renewable generators by 2020.
Holmes believes fuel-sourced power such as hydrogen will be required if the UK is to reach its goal of an 80% reduction in CO2 emissions by 2050 (below 1990 levels), and a 26% reduction by 2020.
He told ESJ on the sidelines of the All-Energy event in Glasgow, Scotland on May 3, that: “Comparing all the technology available, the classic comparison I’m getting is between energy storage and hydrogen.
“And if asked which will be the winner, the answer is it depends, because looking at residential PV and battery storage in houses you can store all the output on a daily basis and use that, and the system will return energy 365 days a year.
“That for me is a good solution at that scale. The bit we are trying to understand is going bigger in terms of energy storage and big in terms of duration and demand. Scaling up with batteries in a linear way from kWh to MWh is not quite as simply as it is a 1,000 times bigger.
“With hydrogen there’s potentially very large economics of scale storing hydrogen in salt caverns. That’s happening in Texas.”
So would the UK be able to add enough electrochemical storage capacity to meet growing renewables integration to balance supply and demand over longer timeframes? His response was simple: “At present my answer is no.
“I struggle to envisage a situation where the UK battery storage capacity could economically satisfy the inter-seasonal demand for energy when you consider scenarios where we begin to significantly decarbonize heat.
“To meet the inter-seasonal energy demands for low carbon heat we will need many, many TWhs of energy storage.
“I can see a key role for battery storage in behind the meter (with PV for instance), and for local grid balancing at MW scale. But I struggle to see the case for TWh scale battery storage. The economics won’t stack up.”
The issue revolves around system operators balancing the weekly, monthly and seasonal heat demands as well as growing electrical and transportation demands, such as electric vehicle charging.
Grant Wilson, teaching and research fellow at Sheffield University, says electrochemical storage would, however, still play a crucial role in managing renewable integration at a sub-daily level, and day-to-day level.
He said: “Perhaps with time it may even help with balancing up to a week and beyond. However, when the sheer scale of balancing heat demands as well as electrical and transport demands over weeks to months to seasons is considered, electrochemical storage simply seems to be the wrong technology choice.
“Basically, if a system is looking to store TWhs (this is energy not power) of energy over longer periods of time — then it is very hard to see this being accomplished without the use of a fuel, and hydrogen has potential to fill this role.”
Last December the UK Renewable Energy Association and an interest group made up of members of the House of Lords and House of Commons, released a paper that suggested the UK would reach 8GW of battery storage by 2021 in a medium deployment scenario — up from 60MW today.
Putting this in perspective, if this had four hours of energy associated with this storage – it would be equivalent to 32GWh of stored energy. On March 1 this year the gas demand at the local area was nearly 3,500GWh; meaning 32GWh would be equivalent to less than 1% of local gas demand.
A best-case scenario, requiring major policy support and a rollout of all the policies contained in the UK government’s July 2017 smart systems and flexibility plan, Britain could have a 12GW battery market by 2021.
Transmission operator National Grid suggested that up to 40% of the UK’s electricity demand could be supplied by gas-fired generation in its Future Energy Scenarios report. The report noted that, in 2017, daily transmission fed gas-fired generation demand fluctuated between 990GW and 792GW.
Wilson said there is broadly about 3,800GWh of natural gas in the high pressure transmission gas lines, of which on a daily basis, the change in pressure allows the energy in the pipes to fluctuate by anywhere up to 450GWh over a day (but on average it fluctuates by just over 100GWh per day).
He said: “This fluctuation can be considered to be energy storage – as the amount of energy in the pipes can be changed to accommodate changes in demand further downstream in the gas network – this fluctuation itself is typically termed ‘linepack’.”