What is Flexible Energy and Why Do We Need It?
The National Grid Electricity System Operator (ESO) is tasked with balancing the supply and demand of electricity on the grid every second of the year to keep it close to 230 volts and 50 Hz. Energy flexibility refers to the ability to adjust generation or demand to maintain this balance. To be compliant with Net Zero targets, the methods of achieving this balance are evolving.
Changes in Generation
If we look back to 2008, Britain’s electricity generation was dominated by power plants running on fossil fuels, which accounted for three quarters of the fuel mix. While these traditional generators are dispatchable and can turn up and down to match the demands on the grid, they are also carbon intensive. Fortunately, there’s been a shift towards renewables, and last year saw more than half of Britain’s fuel mix come from zero-carbon sources. However, there is still more that must be done, and flexibility is key to unlocking the full decarbonisation of the grid.
Last year saw a significant milestone of wind and solar generation accounting for over a third of Britain’s energy. This shift towards renewables is changing the energy landscape as they’re intermittent sources of energy. As more and more renewable projects come to fruition, there will be greater variability in generation driving the need for flexibility - and the way in which the grid is operated must adapt to make the most use of these resources.
Increasing Demand
With the electrification of heat and transport, electricity demand is expected to rise. This will require increased system capacity and upgrades to transmission and distribution networks. However, this rise in demand also opens new opportunities for flexibility.
Types of flexibility
Energy Storage
One key source of flexibility is the conversion of electricity to other forms of energy which can be stored. Examples of energy storage include compressed air as elastic potential energy, pumped hydro as gravitational potential energy, flywheels as kinetic energy and BESS (battery energy storage systems) as chemical potential energy. These methods of storing energy vary in terms of the capacity of energy that can be stored, their power, efficiency, ramp rates and duration.
With decreasing costs and increasing energy density, BESS assets are rapidly being deployed across Britain. They offer high efficiencies and are instantly available compared to more traditional power stations, making them ideal for load shifting (from high generation to low generation moments) and frequency response services. Storage assets are the most versatile form of flexibility as they can be utilised to both increase or decrease demand and supply.
Supply Side Flexibility
During periods of high demand, the traditional form of flexibility is the use of gas peaking power plants which increase the supply when called upon. However, the supply side of flexibility also includes renewables such as wind and solar. They may be entered into the Balancing Mechanism so that they can be turned down when generation is greater than the demand for power or if there are network constraints. Additionally, wind and solar sites may be co-located with a BESS asset which unlocks further flexibility.
Demand Side Flexibility
Electricity demand follows typical profiles which follow daily, weekly and seasonal patterns. Demand side response alters this profile to shift load from peak to off-peak periods. Certain industrial processes are well suited to this load shifting and in recent years a more distributed domestic approach is beginning to emerge. Time-of-use tariffs are one such example whereby EVs, domestic batteries and heat storage can have smart controls to allow flexibility in this space.
Interconnectors
Interconnectors are the sub-sea cables that link up Britain’s electricity system with neighbouring countries. The flow of electricity is dictated by the markets, meaning it will flow from systems with low prices where there is high supply/low demand to systems of high prices where there is a low supply/high demand. In a similar way to the Balancing Mechanism, the ESO is also able to utilise in the very short term the flexibility of interconnectors to ensure the system is balanced.
What We’re Doing
Here at Ecotricity Smart Grid, our team of energy, software and data experts have developed Ecolibrium. As the name suggests, this is our service which helps the ESO to keep the system in balance. We act as a route-to-market for energy storage and fossil-free generators. Ecolibrium connects to these assets and dispatches them according to the best-suited market or service at any given time.
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