UK Government Sets 8-Hour Minimum For LDES Cap-And-Floor Sheme
The title of this post, is the sa,e as that of this article on Energy Storage News.
This is the sub-heading.
The UK government has published a Technical Decision Document confirming crucial aspects of its long duration electricity storage (LDES) cap-and-floor scheme, which includes increasing the minimum duration required from six hours to eight
These paragraphs give full details.
The document, released by regulator Ofgem on 11 March, details the final overarching rules and requirements for the scheme as well as how it will be implemented, though significant detail still remains to be worked out.
The scheme will provide a cap-and-floor revenue protection for 20-25 years that will allow all capital costs to be recoverable, and is effectively a subsidy for LDES projects that may not be commercially viable without it. Most energy storage projects being deployed in the UK today are lithium-ion battery energy storage systems (BESS) of somewhere between 1-hour and 3-hour in duration (very occasionally higher).
One of the most significant new details of the scheme is that, following industry feedback, the minimum duration for projects to qualify has been increased from six hours to eight hours of continuous rated power.
The ‘continuous rated power’ aspect prevents shorter duration projects from bidding in a smaller section of their MW capacity in order to act like an 8-hour system.
Another interesting detail pointed out by several commentators is that the cap is a ‘soft’ one, meaning it will allow extra revenue to be shared between developers and consumers. Exact details on the ratio are yet to be determined.
As a Graduate Control Engineer from Liverpool University in the 1960s, I hope that the move from a six to eight hours minimum duration is feasible.
I wasn’t dealing with power systems, but with multi-vessel chemical plants.
These are my thoughts.
The biggest project, I was dealing with a few years later in the 1970s, was the modeling of all the the reservoirs and pipelines by the Water Resoures Board.
As the supply side of the water industry hasn’t had too many issues with the volume of water supplied, I feel that the main modelers must have done a reasonable job.
Six To Eight Hours Of Continuous Operation
The article says this about uprating from six to eight hours of continuous operations.
All the systems that have been proposed for cap-and-floor operation, seem to have some form of physical storage.
- Energy Dome appears to have tents of carbon dioxide.
- Energy Vault uses stacks of heavy weights.
- Form Energy has tanks of rust.
- Gravitricity has huge weights in disued mine shafts.
- Highview Power has large tanks of liquid air.
- Pumped storage hydro has two lakes, that hold water.
- Rheenergise has two large tanks, of a water-based slurry.
So to go from six to eight hours will hopefully just need some more storage.
Highview Power appears to use similar gas tanks to those used to store natural gas or hydrogen.
This image clipped from Highview’s web site, shows large tanks for liquified gas storage.
With tanks like these, which can hold GW-equivalents of liquid air, Highview could be building batteries with storage to rival the smaller pumped storage hydroelectric power stations. They are already talking of 200 MW/2.5 GWh systems, which would have a 12.5 hour continuous rating and would probably need two to three tanks.
Coire Glas Pumped Storage
I’ll use Coire Glas pumped storage hydro electric power station as an example.
As currently planned SSE’s Cioire Glas pumped storage hydroelectric power station is 1.5 GW/30 GWh, so it has a a 20 hour continuous rating.
In The UK’s Pumped Storage Hydroelectricity, I gave a rough estimate of the pumped storage hydroelectricity systems in operation or planed as nearly 11 GW/224GWh.
The Soft Cap
The article says this about a soft cap.
Another interesting detail pointed out by several commentators is that the cap is a ‘soft’ one, meaning it will allow extra revenue to be shared between developers and consumers. Exact details on the ratio are yet to be determined.
I seem to remember that when I was modeling a larger multi-vessel chemical plant at ICI, I was using sharing between vessels, to get the system to operate on a PACE-231R analog computer.
So I suspect a soft cap is possible.
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