Yesterday, he also showed a group of students from Richmond River High School in Lismore how that heat could create a flame within seconds.
"If you add a heating coil instead of a coffee pot you can make steam, which can be captured to generate electricity," he said.
"A five-metre dish and a tonne of hot rocks will store enough heat to power an average house for a week."
Mr Moxham was also demonstrating a method of producing 'biochar', which uses cellulose-based waste products to enrich agricultural land.
The demonstration was part of the launch of the Sustainable Living Expo, which will be a feature of this year's North Coast National agricultural show at Lismore in October.
Other stalls promoting sustainable technologies, such as Nimbin's Rainbow Power Company and water tank manufacturers, will be also part of the expo. Show organisers hope it will attract a wider audience and put the North Coast on the map as a leader in the field of sustainable living.
John Gibson is president of the Lismore A&I Society, which has been organising the Lismore show since 1885. "Back in those days people used to display horse-drawn ploughs. As far as I can see, this is a natural evolution for the show," he said.
Lismore Mayor Merv King said the traditional agricultural stalls at the show were still important because many kids didn't know where basic products such as eggs and milk came from, but welcomed the sustainable living initiative.
"We need to find better ways to manage our finite resources and this is a tremendous opportunity to put the message out to many people," Cr King said.