Supercharged salt

A civil-rights catalyst for Gandhi and a flavour maker for our taste buds, lowly salt might be ushering in a new means of energy storage.

A team of researchers from the Technical University of Denmark (DTU) are hard at work perfecting a system in which salt can store solar energy, an extremely sustainable source of energy readily available during the sunny seasons. The problem lies in the abundance of solar power when it is least needed and its scarcity when energy use peaks – the cold, dark winter.

The ability to collect and store this solar energy and release it when needed could dramatically cut energy consumption during the winter period. Cue the salt. The Solar Heating Group, headed by Simon Furbo at DTU Civil Engineering, has found a way for those grains to work some energetic magic.

Dubbed COMTES (Compact Thermal Energy Storage), the process works as follows: Sodium acetate is heated by solar energy and melts at 58°C. But unlike water, which cools when the heating subsides, the sodium acetate has a special property that stops the liquid from automatically turning back into a solid after it cools below its melting point.

This is because it can only cool into a crystalline structure if there is something to crystallise around. This means you can keep sodium acetate in a liquid form at a temperature below its freezing point. When you need some heat, all you need to do is add a crystal to activate the crystallising process, which releases an enormous amount of heat that can be used for any number of household purposes. The crystalline sodium acetate can then be melted with solar energy and the process repeated.

With partial funding by the EU, COMTES has partner researchers in China (the world’s largest solar energy market) and Austria. The project has yet to produce a commercially available storage system, as the group is working out the fine details and determining how much energy can actually be stored using the system. The Solar Heating Group, which anticipates the release of a commercial system soon, is currently building an average single family home to test whether the salty system has the capacity to power it year-round.

Let’s hope the cheap power will encourage some of the city’s residents to move into their summerhouses year round and ease the pressure on the housing market. M

News, Tech

By Nereya Otieno

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