New white paper: ‘Energy storage systems for properties: Using renewable energy efficiently’
Integrating electricity and heat storage into a storage solution increases its reliability and cost efficiency. Storage systems can also make a key contribution towards decarbonisation of properties, as a new white paper shows.
Switzerland is aiming for a target of net zero by 2050. This means replacing fossil-based energies with renewables. However, the output from systems is dependent on weather conditions, the time of day, and the season. Getting supply and demand in sync calls for storage solutions. This also improves the property’s carbon footprint, because it requires less oil or gas to cover peak loads.
Electricity storage systems: battery-powered flexibility
Battery storage systems can temporarily store surplus solar power locally and supply household consumers, electric vehicles or the heat pump later on. This significantly increases the level of self-consumption and with it the cost-efficiency of solar power plants. Not only the operator benefits from a storage system – the electricity grid does as well. This means, for example, that when a solar power plant produces a surplus, it doesn’t have to be shut off for fear of overloading the grid. And in the reverse scenario – when demand outstrips supply – locally stored energy can help cover peak loads, which stabilises the grid and keeps costs low. Currently the standard means of electricity storage is the lithium-ion battery, while alternatives such as sodium-ion batteries and salt batteries have yet to become established. This also applies to bidirectional charging, in which the battery of an electric vehicle is used for local electricity storage.
Heat storage units: geothermal probes and containers
One alternative to storing surplus solar power is to transform it into thermal energy. Heat can be stored over weeks or months and used later for heating and hot water supply as required. This makes heat storage a great fit with renewable heating systems such as heat pumps and thermal networks. And some types of storage system can be used as heat sinks in summer to cool buildings with minimal use of energy. The most common storage types in Switzerland are geothermal heat storage units and container heat storage units. One interesting variant that requires less space is ice storage.
Hydrogen and methane: seasonal storage
Another way to store surplus solar power seasonally is to transform it into a carbon-neutral gas like hydrogen or methane (‘power-to-gas’). If required, the gas can be used either to produce heat and electricity or as a fuel for vehicles. Hydrogen is produced through the electrolysis of water, and the degree of efficiency in this transformation is up to 80 per cent. Transforming it further into methane has the advantage that it can be stored in the natural gas grid, so it doesn’t require separate infrastructure. The overall degree of efficiency depends on the method used, but with a current best-case result of 50 to 70 per cent, it is not yet cost-effective.
You can find much more information and real-life examples in the new ewz white paper ‘Energy storage systems for properties: Using renewable energy efficiently’.