The sun’s rays drive a reaction between water and natural gas which stores solar energy in the form of chemical bonds.
Solar Gas (SolarGas) is a combustible fuel, just like the original natural gas – but here’s the important thing: if you burn it, you get around 25% more energy than there was in the original natural gas. This extra energy is the ‘solar upgrade’. For example, if you were to use SolarGas in your gas stove to boil five eggs for breakfast, it’d be as if you were cooking one of those eggs with pure solar power. This may be a great way of storing solar energy by piggybacking it onto natural gas or other methane gas sources.
Solar Gas technology was developed by Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation(CSIRO).
How it’s made
It concentrates the sun’s rays to drive a reaction between water and natural gas which stores solar energy in the form of chemical bonds. The Solar Gas can then be used to produce high-efficiency electricity in a gas engine or turbine. Mirrors focus solar energy onto a series of metal pipes, which creates temperatures of around 800°C inside them. Through these pipes a flow of natural gas is mixed with something else. This ‘something else’ can be steam or carbon dioxide – both pretty common ingredients, suited to different situations.
These metal pipes form a SolarGas Reactor, that have been carefully designed so that inside the conditions are right for a chemical reaction to occur. This reaction converts the natural gas and steam (or carbon dioxide) to a new mix of gases, and in the process ‘sucks up’ a whole lot of solar energy into the new gas molecules in what is called an endothermic reaction. If you could touch the pipes where the reaction is going on, you’d feel that they’re actually cooled as energy transfers from solar heat to chemical bonds – thus changing it into a form that, unlike the energy in sunlight, can be stored in bottles or pumped from place to place.
It’s interesting to note that steam and carbon dioxide are the products of normal combustion. So here, they are used as the reactants. In essence turning the usual reaction around using energy from the sun. The net result is that a new gas is produced that has more energy than the gas started with – and this extra energy came from the sun. The video below gives an overview of the process. In this example, the more common steam version of the reaction is shown.
1. SolarGas can be burned to get heat or electricity
SolarGas is a combustible fuel, just like the original natural gas
2. SolarGas can be used to build transport fuels
The SolarGas molecules are useful chemical building blocks. They are ideal for connecting together in a process called Fischer-Tropsch to make fuels like methanol or diesel.
3. SolarGas can be used to make hydrogen
SolarGas is already 3/4 hydrogen gas by volume, but we can increase the amount of hydrogen by putting it through what’s called a Shift Reactor.
4. The stored solar energy can be recovered in the form of heat.
It is possible to extract the solar energy from the SolarGas by reversing the original reaction. This recreates the original natural gas – which can be re-used – and releases the solar energy in the form of heat at about 300°C. In essence, then, the natural gas is in a ‘closed-loop’ system – it goes round and round, picking up solar energy, storing it until it’s needed, releasing it, and then starting the cycle again.
5. Waste heat from making SolarGas can be put to other uses
No matter what is done with the SolarGas, in the process of making it there’ll be some ‘waste’ heat. As with the last scenario, this heat will be at temperatures lower than the original 800°C (otherwise we’d use it to produce more SolarGas). Even so, it’s a whole lot of energy that can be used to provide further efficiency by combining it with other processes.
India sees this as one of many solutions to their future energy needs. Quoting from The Times of India:
“More importantly for India it can also be used to produce hydrogen for industrial use, petrochemical applications and fertilizer manufacture, and to provide cleaner transport fuels,” according to a press release from the Australian High Commission, India.”The study has found that the Solar Gas technology has the potential to provide a sustainable and cost effective alternative for the production of hydrogen in some of India’s most important industries,” CSIRO Senior Research Scientist Dr Jim Hinkley said.
“There is a particularly strong potential to roll out the technology in Gujarat and Rajasthanbecause both states have excellent solar resources and natural gas infrastructure, as well as being major industrial users of hydrogen,” he said.
The study has found there are several potential benefits of the technology in India, such as, improved energy and food security by reducing natural gas consumption, new jobs created through local manufacturing and operation of the technology and the potential to produce solar liquid fuels for transport.”Energy and energy security are critical issues for Australia and India, and we have much to offer each other by sharing our renewable technology expertise and technology,” Australia’s High Commissioner to India Patrick Suckling said.”Solar Gas could provide both our countries with an exciting new commercial opportunity, and I hope this technology can play a part in India’s drive towards energy security,” he said.