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Introduction To Demand Response

Author: Christopher Hills, Sustainability Solutions Advisor

National Grid is responsible for managing the flows of electricity to homes and businesses in the UK on a real-time basis, to do this they must match, or balance, the consumption of electricity with supply every moment of the day. As part of their planning they forecast supply and demand over a variety of time periods – from months and hours in advance through to real time. This balancing act has historically been carried out through the use of modulating supply to match the changing demand.

The challenge we face today can be viewed as a two-fold one which is due to the decline in base-load attributed to the closure of fossil fuelled and nuclear power stations, with replacement stations being delayed. This creates the task of where to obtain the electricity that will make up the shortfall of closing these power stations.

Nuclear power is a great source of baseline generation but is not flexible enough that it can easily replace coal and gas fired power plants. Renewable energy is constantly attaining better efficiencies making it an ever more attractive addition to the energy mix, although the drawback of renewable generation is the reliance on the weather to provide the conditions to generate power.

Secondly, the rise in renewable energy sources which might address the issue around capacity but does not provide a steady base-load, instead they create an amount of unpredictability which is not good for security of supply relying on predictable electrical load.

This is where demand response can fit in, it can make electricity demand more flexible to reduce consumption during peak demand, and increase when there is more electricity available from renewables such as when the wind blows during the night. The short term operating reserve (STOR) has been used to provide extra generation onto the grid, and has now been joined by a host of different methods of balancing in both the demand and supply of electricity.

Demand response can use electricity-consuming assets to reduce electricity consumption, reducing the need to turn up a carbon dioxide producing power station. Typically, demand response can be used with a variety of assets such as back-up generators, UPSs, HVAC systems, fans, pumps and any asset which has stored mechanical energy. National Grid use demand response to modulate electricity consumption in line with demand, as we move towards a grid that uses flexible demand as opposed to generation.

Due to the reduction in use of fossil fuelled power stations demand response helps to lower the amount of carbon dioxide that is produced. This is due to greater flexibility in demand and the growing use of renewable energy, which can be enabled better by accounting for the uncertainty of when energy will be generated. Further benefits of demand response are to enable further growth of renewables, reduce reliance on fossil fuels and provide a smarter grid that makes more intelligent use of the energy that is produced.