Energy storage has the potential of substantially mitigating climate change since it allows for more efficient energy usage. However, to date, most energy being produced is not being stored. In fact, only 3% of power capacity is being placed in storage, which means that a lot of energy is being lost.[1] In fact, only 3-4% of electricity being generated by utilities is being stored.
At the same time, the Member States of the European Union have committed to the Paris Agreement, which means that the European energy system will have to head in the direction of carbon neutrality. What role does energy storage play in this? Carbon neutrality strongly depends on the use of renewables. These however are variable, which means that the output of solar and wind power is dependent on the time, the season and the weather. Storage is needed to bridge the gap between energy production and energy consumption. [2]
What kind of storage solutions exist? There are five main types of energy storage, which can be summarized as:
- Pumped Hydro Storage: this is one of the oldest and most widely used electricity storage technologies. This approach relies on pumping water uphill to a reservoir. Then, as soon as electricity is needed, the water is released from the reservoir to start a turbine and a generator.
- Thermal Energy Storage: This is energy storage in the form of heat. A simple way of achieving this is by running an electric hot water boiler when electricity is abundant and using the hot water at a later point in time. This can also be applied to heating, refrigeration and air conditioning systems.
- Batteries: These can include the batteries of electric vehicles, home storage devices, battery storage attached to renewable energy plants, and grid-scale batteries. The services batteries can provide include: frequency control, temporal shift of consumption, and flattening of demand peaks. In addition, they can serve as local buffers to store variable renewable energy close to the source of production for later local use or be injected into the grid during times of high demand and high prices.
- Compressed Air Energy Storage: This is a technical approach, which mechanically converts gaseous air. In times of excess electricity, a reversible motor/generator unit is utilized to inject air into a storage vessel and energy is stored in the form of high-pressure air. Later, when electricity is required, the stored compressed air is released and heated. Then, when the compressed air is released, its energy is captured by turbines.
- Gas and liquid storage: This is one of the simplest and most efficient technologies and allows for gas (mainly methane) or liquids to be compressed or absorbed in porous material under low pressure.
In addition to promoting carbon neutrality, storage also allows for high levels of energy security by facilitating the use of locally produced energy. For your average citizen, energy storage also means more control over the costs and the origin of the energy being consumed. At the same time, energy storage still battles with one substantial barrier: relatively high costs. For energy storage solutions to become more attractive, greater awareness about their benefits needs to be spread in society as well as greater investments in new technologies to lower upfront costs.[3]
[1] Beyond the Tipping Point: Future Energy Storage – Urban Insight (swecourbaninsight.com)
[2] https://www.europarl.europa.eu/thinktank/en/document/EPRS_BRI(2019)637962
[3] Beyond the Tipping Point: Future Energy Storage – Urban Insight (swecourbaninsight.com)