'Clean' steam engine developed to help cacao farmers

Mackwell & Co director Sam Mackwell has developed a 'clean' steam engine to help cacao farmers...
Mackwell & Co director Sam Mackwell has developed a 'clean' steam engine to help cacao farmers dry their beans. Photo: RNZ / Nate McKinnon
A Christchurch startup wants to bring "the cutting edge of low tech" to the Pacific to help cacao farmers dry their beans.

Mackwell & Co believes steam power has a role in moving the world away from fossil fuels.

"We are developing tools to empower energy sovereignty and we are doing that by reinventing, rediscovering, the steam engine," chief engineer and director of the company Sam Mackwell said.

Unlike traditional steam engines that have a reputation for being dirty, Mackwell said the burning process is clean.

"What we have developed is a combustion system that eliminates the smoke.

"When you eliminate that, you eliminate all of that dirt that would cover everything in the vicinity of the of a steam locomotive depot."

The engine uses organic biomass - such as wood chips - as fuel, allowing farms to become energy independent.

Mackwell said trees are nature's "solar panels and batteries all in one".

"A farm only needs to set aside about two per cent of its land area to grow enough fuel to run this technology indefinitely - so continuously forever, basically."

He said photosynthesis is a more inefficient process than solar but the difference is that trees build themselves.

The steam engine uses organic biomass, such as wood chips, as fuel. Photo: RNZ / Nate McKinnon
The steam engine uses organic biomass, such as wood chips, as fuel. Photo: RNZ / Nate McKinnon
"We don't need to build a factory to build the tree, right? It builds itself using the solar energy that it is capturing.

"This technology offers one of the fastest and lowest cost means to transition away from fossil fuel. It's different, it requires a change in behaviour and approach but transitioning beyond fossil fuels requires that anyway."

Mackwell & Co has its eyes set on helping cacao growers in the Pacific dry their beans which risk turning mouldy if not done in time.

Growers revert to drying cocoa through fires if they cannot rely on sunny weather, but smoke can bring down the price.

Keith Budd with Grow Asia Pacific said it is well known Pacific beans are smoky.

Budd said this year Samoa cacao farmers lost about 30 per cent of their product through the drying process.

"There are occasions, of course, when the rain comes in and if that happens for a number of days, the beans will get spoiled and, of course, it's a loss of production and loss of income for the farmers."

Budd said the engine also allows Pacific communities to dispose of organic waste.

"A lot of these countries don't have the ability to get rid of rubbish.

"They don't have a rubbish refuse collection or anything like that and this provides another opportunity to get rid of some of that."

Business development lead William Bowden said the only viable solution for farmers to dry their product other than fire is using LPG gas, but that was expensive, hard to get in remote areas, and contributes to climate change.

Bowden said the resource that is already going to waste - coconut husks and the by-products of cacao beans - is what his company would use for fuel.

The steam engine also creates electricity and clean water.

That, coupled with the low-tech nature, makes it a good fit for remote communities, he said.

"We have eliminated as best as we can, electrical components and other common fail areas.

"The idea being that any regional workshop and small towns in New Zealand or in the Pacific could fix and repair this technology."

The company hopes to get the engine into the Pacific by late next year.

By Caleb Fotheringham