16 Storage matters


Storage will be crucial to the UK’s changing whole energy system solution. Sotiris Georgiopoulos and Robert Friel explain why.


Ensuring security of supply is central to energy policy. Given this, storing energy when it is not required, but ready for release when needed, is a key component of a reliable and secure energy system. Right now, Britain’s gas networks have enough storage capacity to provide one quarter of national gas demand within a few hours on a cold winter’s day. What’s more, transport networks also store large amounts of energy in vehicle fuel tanks. However, meeting the national electricity needs depends on a complex system of forecasting demand, and operating large centralised power stations which are available to meet that demand on a minute-by-minute basis. To successfully supply the required electricity, the system needs to have sufficient generation infrastructure to be able to satisfy demand reliably and also be flexible so that predicted and unpredicted variations in demand can be met.


The Climate Change Act has established a target for UK to reduce its emissions by at least 80% from 1990 levels by 2050. To achieve this, government policy has supported an increase in renewable energy sources in the electricity sector and electrification of heat and transport.


Storage success


UK Power Networks’ large scale electricity storage plant at Leighton Buzzard has been instrumental in proving Li-ion battery systems are an effective means of energy storage. For example, the project has shown the system is reliable and can be used to defer traditional reinforcement by providing peak shaving to maintain security of supply in the distribution network. What’s more, the system is a very fast responding technology, delivering full response within one second. It is also effective in providing power-intensive services, such as frequency response and energy-intensive services, such as reserve to the TSO, in a way that can offset the loss of synchronous generators. The technology can also be used to provide energy suppliers with tolling services that are used to hedge energy purchase and minimise the risk of energy portfolio unbalancing. It can provide reactive power compensation as an additional service to the local


In light of this, electricity generated from renewable sources has doubled since 2011, accounting for 25% of UK’s total generated electricity in 2015. But while we can store fuel for electricity generators, such as gas, coal and water, we clearly cannot do the same with wind or sunlight for renewable sources. Operating a power system with increased renewable integration poses new challenges. For example, the variability of these sources needs to be managed, as does the overall system stability following the decreasing mass inertia associated with fewer larger synchronously connected power plants. As highlighted in the UK government’s National Infrastructure Commission Smart Power Report, electricity storage will be key to managing future power systems with high renewable energy contributions. The technology provides a solution to address the variability of generation output and can also provide support services to the Transmission System Operator (TSO), such as frequency response and reserve capacity to maintain system stability.


Storage can also offer an alternative to reinforcing the distribution network by helping manage the existing capacity, being able to relieve both export and demand constraints.


Practical application


Through its Low Carbon Networks funded project “Smarter Network Storage” (SNS), UK Power Networks has been operating a


large scale, multi-million pound, electricity storage plant for the last 18 months, which will prove instrumental to the future of energy storage. Described as the largest electricity storage facility of its type in Great Britain, the plant is located at Leighton Buzzard in Bedfordshire and is based on Li-ion battery technology, currently the most mature technology for electricity storage. Housing a 6MW/10MWh battery system, the facility can provide power to around 1,100 typical UK homes for a whole day.


From the outset, the key project aim has been to prove that battery storage is technologically feasible and develop business models can make it economically favourable when used within a large electricity network. The SNS project has demonstrated that battery storage is a multi-purpose technology with many features that support the whole electricity system (see ‘Storage success’) and has also widely informed the industry discussion on regulatory and commercial barriers for wide scale adoption. Given the success of the pioneering SNS trials, it is clear electricity storage will be critical for a secure, affordable and clean future power system within the whole energy system.


Sotiris Georgiopoulos is Head of Smart Grid Development at UK Power Networks. Robert Friel is Regulatory Strategy Manager at UK Power Networks.


distribution and transmission networks and provides active and reactive power services, independently and simultaneously. The system also has the potential to address synergies across the whole electricity system between different applications and services:


n when storage systems export active power during winter evening periods, they are relieving congested local networks from peak loading while in parallel relieving regional peak loading and reducing the peak load at a national level (i.e. provide triad avoidance services).


n when storage systems utilise their reactive power capability for peak shaving, the power factor at the point of the storage connection with the distribution network is also improved. This leads to reduction in losses and improved efficiency of the distribution network, while reducing the reactive power demand at the transmission level.


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