What efficient ways are there to store energy on a relevant scale?
Renewable energy sources such as wind parks or solar panels do not provide continuous energy. Storage of energy is essential if we are to make optimal use of these sources. The problem is that existing storage methods are based entirely on buffered fossil resources and new, sustainable storage methods need to be realised on efficiently on a large scale.
Twenty IJssel lakes
In the Netherlands, about 2550 GWh (gigawatt hour) of energy is used every day, which compares to the amount of energy it would take to fuel a generator filling the IJssel lake in the Netherlands with water twenty times. To guarantee delivery of energy, an energy reserve of 91,25 days is legally prescribed. Energy storage becomes more important when non-continuous energy sources are implemented: it is not unlikely that wind and sun will drop simultaneously.
Store electricity as electricity and heat as heat
Much energy is need to heat and cool buildings. An efficient way to store heat is by extracting it from buildings in the summer (thereby cooling the buildings at the same time) and storing it in layers of water bearing rock underground. In winter the heat can be pumped up again.
Batteries are the most efficient way to store electricity. For a family a number of Lithium-ion batteries the size of a cardboard box is sufficient to store all the electricity needed. When used in conjunction with a smart grid, even a fleet of electric cars can provide a means of storing energy. For example, at times when there is a surfeit of wind energy, this can be temporarily stored in the batteries of electric cars, which are connected to the grid. Conversely, when energy is in short supply, use can be made of the reserves stored in the batteries of stationary cars. To store 100 GWh, however, about 7,6 million electrical vehicles are needed.
Hydrogen is an ideal energy carrier for storage on a large scale. Its production requires only water and energy. The use of hydrogen releases only water and no CO2. Hydrogen can be used effectively as a medium for storing energy that has been generated from renewable sources. It can be stored in large quantities under pressure in salt caves or depleted gas fields. If hydrogen is used in for example cars, it must be stored locally in for example materials or storage tanks.
How is TU Delft contributing?
Battery technology
At Delft we are working on lithium-ion batteries. The emphasis here is on capacity, safety, charging speed, cost and the weight. In the future cheaper and safer materials are needed. A larger storage capacity and faster charging and decharging speeds are also essential. Materials for energy storage is increasingly nanostructured. See also the information on the website of the department of NanoStructured Materials.
- Listen to a podcast (September 2009) in which battery researcher Marnix Wagemaker explains what his and his colleagues' publication in Advanced Materials is all about.
- Read the press release about the EuroLiion battery project, a European project with partners from the battery and automotive industry aimed at improving the Li-ion battery
Storage in hydrogen
A key research question is: what materials can most efficiently be used for storing hydrogen? Nanostructuring and catalysts are currently playing a central role in the development of new storage materials. Research is also needed into optimal storage capacities, conditions of use and the reusability of the materials. This research is taking place in the RID (Reactor Institute Delft) experimental nuclear reactor.
Links and contact
- Read more about stopping the wastage of heat
- Read more about the research into Smart Grids
- For more information about the research, please contact the Delft Energy Initiative.
