Generating clean and reliable electricity is a key goal for the UK and advances in energy technology promise to bring a change in the way we generate and/or store electricity. There is a rising demand to deliver increased energy security, in turn, increasing the possibilities for renewable energy and creating a more flexible system and decarbonised grid.
Battery Storage systems can connect to any method of electrical generation and are charged up by any unused energy. They then store the energy in a similar way to a regular household rechargeable battery to be used at a later point in time to provide an instant source of electricity. The benefits are that energy is stored and not rejected or lost, it can be released at high use periods to reduce peak demands and the release of energy can be timed with high tariff periods to maximise returns. It is ‘clean’ energy and overall can increase the efficiencies of your energy scheme. This is a rapidly evolving technology with planned schemes having a wide range of storage capacities.
Hydrogen energy storage is the process in which electrical power is converted into hydrogen created by renewables during periods of low energy demand via electrolysis. Electrolysis is the process of using an electrical current to separate water into hydrogen and oxygen. The gas formed from electrolysis is a key interest for the hydrogen market because it aims to reduce fossil fuels in many combustion applications and has a much higher storage capacity than other energy storage systems. Moreover, hydrogen has the ability to be injected and blended into modern gas networks without the need to change the materials or the infrastructure of the pipework.
Pumped hydro energy systems use the raw natural power and energy of water to generate electricity to the grid. Pumped hydro power consist of facilities that store energy in the form of an elevated water mass. The water is withdrawn from an upper reservoir into a lower reservoir through pressure shafts and into water driven turbines. The water released from the reservoir produces kinetic energy and ultimately generates electricity via the turbines to provide power into the electricity network. The technology is proven effective but has limited potential as it is very dependent on suitable geography.
Thermal storage is a valuable technology which allows heat to be stored and then accessed at a later time. It is particularly useful in cogeneration and trigeneration schemes where heat is generated alongside electricity whereby the heat often needs to be rejected at times of low heat demand. Thermal storage can work alongside any heat generating technology to store heat until times of peak demand which assists in increased efficiency, flexibility and security to an energy scheme and whilst traditional methods have tended to use water there are some emerging phase change materials which bring the added benefits of smaller footprints, higher temperatures and the ability to be heated with electricity directly.
Sensible heat storage involves storing heat by raising the temperature of a material without changing its phase.
Latent heat storage uses the phase transition of a material, for example heat can be stored by melting a material, such as wax, and removed later, solidifying the material. During the phase change, energy is added or removed from the material at a constant temperature, therefore by using a phase change, we can store much larger amounts of energy over narrower temperature ranges compared to sensible storage.
Thermochemical storage technology is based on the use of reversible reactions and/or sorption/desorption processes which consume or generate heat depending on the direction of the process. A common example is hydrated salts, which can be dried with the addition of heat and which produce heat on the addition of water. These can have higher energy density than phase change materials and can store energy efficiently for longer periods as they have negligible thermal losses.
