Can you run a paper mill on solar and “hot bricks”? Visy says it can – on paper, at least

Industrial businesses that need heat as well as power to make their products are still not quite ready to switch their gas boilers over to electric, but some are beginning to ask the right questions.

Recycling giant Visy is using price data from one of four ‘hot brick’ companies in Australia, Graphite Energy, to plan out how it might combine the electric thermal energy storage (eTES) with behind-the-metre solar to power its operations. 

ETES systems heat up carbon or ceramic blocks using electricity; that energy is then spooled out either as electricity, steam or heat.

It’s a technology that is particularly useful for enterprises that need energy in the form of more than just electrons.

The Australian Renewable Energy Agency (Arena) has been funding feasibility and design work to encourage companies to get off gas, with the Visy project being a beneficiary of the agency’s grant awards to push very low-cost solar.

While the plan to cut 40 per cent of gas use from one package boiler at its Coolaroo paper mill in Melbourne is still only on paper, technology manager Mark Langley says they’re taking the next step of figuring out how much it might cost to do in real life. 

“We proceeded with a configuration of two thermal storage units along with 12.5 megawatts (MW) of solar generation, along with a relatively small 600 kilowatt (kW) boiler,” Langley said at the Renewable Heat conference this week.

“From a benefits perspective… no grid connection so therefore no connection obligations to deal with. It’s fairly simple in terms of its architecture.”

The Melbourne site is currently run by a 20 MW cogeneration plant that burns waste from the paper recycling process for electricity and a backup gas boiler. 

While a network connection could be in the plans, just connecting to the grid can make up to 40 per cent of a project’s capital expenditure, while network charges are between 30-50 per of ongoing electricity costs.

Joe Coventry, a professor at Australian National University (ANU), says not having a grid connection helped cut costs in different ways too, from simplifying and reducing the number of components and removing the need entirely for transformers and substations.  

The ANU role was to develop the power converters that couple the solar PV with the thermal storage system. 

“We’re moving into testing the larger scale prototype at the moment,” Coventry said during the same presentation. 

And while the current coming from the converter is not as smooth as if the electricity was being taken from the grid, “the resistor doesn’t care as long as you’re putting you know electrons through it”, Coventry says.

Coventry has also been looking at where else their PV-plus-converter-plus-eTES might work, and came up with 100 sites with enough land nearby to host a solar farm and enough need for heat to make an eTES viable. 

“We’ve been coupling [PV mapping] together with estimates of heat demand from these sites around Australia, matching the two together to see what opportunity is there to actually generate energy on site and offset gas use in the process heat,” he says.

“Unfortunately, the demand data… is not public data. So we’ve sort of had to work backwards a bit from public data around pollutants and CO2 emissions and things to estimate the heat demand from sites. 

‘We’ve got fairly high error bounds, but nonetheless, the overall message is there’s really good potential.”

Companies selling eTES systems are finally signing contracts for feasibility studies and doing a bit more than just technology validation. 

Hot carbon brick eTES company MGA Thermal signed up Tronox in Western Australia for a feasibility study recently, and it and other companies in the same field say they have more deals to go public with this year.

If you would like to join more than 29,000 others and get the latest clean energy news delivered straight to your inbox, for free, please click here to subscribe to our free daily newsletter.