Perhaps the only good thing to come out of climate change, other than moving to net-zero carbon in our economy, is the motivation it has given engineers to be creative in finding alternatives to oil and gas…

For all the technological and industrial progress we have seen in the last 200 years, the great disadvantage is that it has been powered by fossil fuels, with all the attendant problems they bring.

When is the Sun coming out?

The move away from fossil fuels to renewables has one disadvantage - renewables are inconsistent.  The sun does not always shine, the wind does not always blow, in contrast to fossil fuels, which are ‘always there.’  Even so, moving to net-zero carbon is essential to any attempts to mitigate and stabilise the problems thrown up by climate change.

As with anything, there are challenges and compromises. There is also creativity in finding solutions to the intermittency issue.  Batteries are one method of storing energy, but they struggle with holding a charge over a long period of time, besides, lithium-ion batteries (the most common) are a fire hazard.

Instead, there is a great deal of research going into alternatives to conventional batteries as a means of storing energy. One such alternative could be thermal batteries.

These store heat energy using materials such as salt, bricks and ‘phase changing materials’ – substances that use the cycle of freezing and melting to release energy.

Salt of the Earth

A number of companies in the US, and Europe have developed systems using molten salt,  placed in tanks installed on site. Salt is good at storing heat at temperatures of up to 500°C. These tanks can be charged with electricity during times of excess capacity or when the cost is low. This heat can be released at, for example, sunset to create steam to power a turbine, providing electricity overnight.

Salt tanks can go through thousands of charging cycles over a period of up to 40 years, some three times longer than is currently achievable.

Indeed, salt – strontium chloride rather than regular table salt - could be used to store heat generated by solar panels during summer, for use in the winter.

Winter warmers

Scottish company, Sunamp, has created a phase change material it calls ‘Plentigrade’, which uses a gel, similar to the material found in hand warmers. They claim Plentigrade stores heat four times more efficiently than water.

Elsewhere, Norwegian company EnergyNest has patented a thermal battery using a formulated concrete product it calls ‘Heatcrete.’ The material is placed in a 20 feet long unit, through runs steel tubing.  A high temperature transfer fluid (HTF) passes through the tubes, to heat the concrete. There is minimal heat loss, says EnergyNest,  while the energy is stored in the battery.

When it the battery is discharged, cold HTF leaves the bottom of the battery while the heat rises out of the top. The batteries are made with a material which uses non-toxic ingredients, prefabricated steel tubing tested before installation. Energy Nest claims the system is relatively cheap, and scalable, moving from MWh to GWh.

The Finnish line

In Finland, the interest is in sand batteries. At the small town of Pornainen, in the south of the country, a company called Polar Night Energy is installing what will be the world’s largest battery of its type.

It will remove heating oil consumption from the heating network and reduce emissions by 70%. This battery can store up to 100MWh of heat energy from renewable solar and wind.

The after casting around for a suitable storage material, the company chose sand, because it is an excellent storer of heat. In this case, the sand is made from crushed soapstone.

Low-grade sand is poured into a tower, which is then charged up using excess electricity from solar and wind turbines.  The heat is generated when electricity passes through the sand.  Because the sand is not a superconductor, the electrical current causes friction, which generates the heat, a process called Resistive Heating. This produces hot air which is circulated within the container via a heat exchanger.

This works by a process called resistive heating, whereby heat is generated through the friction created when an electrical current passes through any material that is not a superconductor. The hot air is then circulated in the container through a heat exchanger.

500°C heat can be stored for up to several months.  In the winter, hot air can be released to heat water for pumping through the local heating network. Even the local swimming pool can be warmed by the system.

As we can see, there is more than one way of generating and storing energy without resorting to fossil fuels. While the ideas may seem simple, they are complex and still require research, but these ideas can be used without too much trouble after being installed with the user. More, they are not reliant on fuels that will pollute the atmosphere or be affected by the headwinds from geopolitics.

It could be said Climate Change has been a good thing…for giving us the motivation to find better alternatives to fossil fuels.  What do you think? What can we do to encourage more of these ideas and mainstream them in the mix of energy provision? Leave your thoughts in the comments below.