The product resulting from this solar-charged gas technology, SolarGas™, contains more power than natural gas and embodies approximately 25 per cent of solar energy in the form of chemical bonds.
SolarGas can be stored and then transported, or used in its fuel form as an alternative to burning fossil resources for electricity provision, transport fuel and chemical production.
In development since 1998 at the CSIRO’s National Energy Centre in Newcastle, New South Wales, SolarGas is now produced via a tower and heliostat field at the Centre that combines water, gas and sunshine in high-temperature concentrated solar thermal (CST).
What is SolarGas?Article continues below…
The sun’s energy can be captured in an endothermic process, where a chemical reaction caused by absorbing heat transforms natural gas and water feedstock into a higher-energy product. When gas and water react at over 750° Celsius, SolarGas can be created.
“SolarGas uses CST energy to operate a methane reforming process,” says Mr Hart within the Solar Thermal Group at the CSIRO.
“Steam reforming of methane to produce syngas is an established industrial process, which traditionally is carried out in catalyst-filled tubes heated by the combustion of more gas. Our process instead generates the required temperatures of around 850° Celsius by heating the reactor using concentrated sunlight.”
Mr Hart co-ordinates the activities of the various engineering groups that work on the SolarGas production plant in NSW – such as for the heliostat design, reactor design and development of the gas facility – and he liaises with various government departments associated with the funding of the project.
It operates as a CSIRO Energy Transformed Flagship project, with a proportion of its funding coming from the Asia-Pacific Partnership on Clean Development and Climate.
A unique project
The SolarGas facility comprises 200 small, focusing, sun-tracking heliostats containing mirrors that deliver concentrated solar energy to reactors operating up to approximately 1,000° Celsius.
“At the time as we were developing this facility, most other solar tower systems around the world were using much bigger heliostats over larger areas to generate steam at 400–500° Celsius,” says Mr Hart. “This meant that our facility had to be unique in several ways.”
One such unique element was a compact field of closely-packed heliostats to maximise the use of available land on the Newcastle site, which meant that the field had to be carefully designed to avoid heliostat collisions and to minimise shading and blocking of sunlight.
“To meet the high-temperature requirements of the SolarGas project, we also decided to design and manufacture our own heliostats. This enabled us to develop a cost-efficient design that was optically precise enough for our needs,” Mr Hart notes.
To optimise heliostat targeting without the need to use expensive hardware, the CSIRO also developed a software system with a heliostat auto-calibration function.
“The decision to carry out our own design work was only made after our experiences with an initial heliostat field installed for our early experiments,” says Mr Hart.
“We decided to complete the new heliostats and control system without outsourcing tasks, which involved identifying capability gaps within our CSIRO team, reassigning staff to the research team and employing additional staff to meet any outstanding requirements.
“A small, multi-skilled team undertook everything from modelling and design to fabrication and installation, and the final result is that the CSIRO has a licensable concentrating solar thermal facility that meets our requirements.”
Another major challenge that faced the engineers and scientists involved in establishing SolarGas technology at the site was the design and operation of a steam-reforming reactor.
The SolarGas reactors are of a circular tube-in-tube design, and directly heated by concentrated sunlight. This design allows the gases produced to preheat water, and create steam for the reactor.
A pair of these coiled reactors is mounted inside an insulated receiver with an 800 mm aperture, through which the concentrated solar energy is focused.
“The fact that this receiver is mounted 17 metres up a tower also presented many additional engineering challenges,” Mr Hart says.
The CSIRO believes that the SolarGas end product could be used in a number of industries, including in the manufacture of fine chemicals, the production of hydrogen for fertiliser or fuel or for steel-making.
The organisation has developed the tech-nology beyond the research stage, and it is now ready for commercial application.
“I expect that SolarGas will be employed at small scale initially, and then, due to its modular nature, it will be scaled up in time,” Mr Hart says.
“It should find acceptance in a market where the value of gas needs to be maximised using renewable energy, such as in India and Australia.
“The CSIRO has developed this technology to a demonstration-scale, and although the current project is still continuing, one of its objectives is to produce a bankable report that will assist companies in making a commercial decision on the viability of this technology.”
The SolarGas facility in Newcastle concentrates approximately 500 kilowatts of solar energy, and with new and more efficient catalysts it has now achieved a 70 per cent reduction in water use.