Heating up world food production

Case study

A Callaghan Innovation-developed process that recovers carbon dioxide from the burning of forestry waste and feeds it to plants is set to boost global fruit and vegetable supply.

Hotlime strawbs

At a glance


We’ve all known it since primary school: plants do this cool thing called photosynthesis where they turn light, water and carbon dioxide (CO2) into food and oxygen.

What may be less well understood is that plants grow faster when there’s more CO2. In fact, commercial growers pump CO2 into their greenhouses to increase yields, and most operations would not be viable without this gas injection.

Now a process developed by a Callaghan Innovation scientist is set to provide the world’s greenhouse operators with a readily available, cost-effective and environmentally friendly way to give their crops both more CO2 and renewable heat.

Hot Lime Labs is a spinout from Callaghan Innovation’s Research and Development Solutions division.

Researcher Dr Vlatko Materic had been working on ways to extract CO2 from burning emissions using heated limestone. Initially his research focused on reducing pollution from power plants, until he realised that he needed to flip the economics around; while power plants don’t necessarily want to pay money to emit less CO2, greenhouse operators will pay to receive more CO2.

“I started talking to growers, and the response was ‘oh, can you do this? Can you do this now?’ There’s a big demand,” he says.

Capturing clean CO2

Currently many growers rely on natural gas as their only source of clean CO2, even though it is expensive and not renewable. Some have no access to natural gas lines, and those that do are limited by the amount of available supply.

Materic’s venture, Hot Lime Labs, has developed a process that can recover clean CO2 from the burning of wood chips and then release it into the greenhouse.

The Hot Lime Labs’ process uses pellets made of limestone and other components. The heated pellets act like a sponge, soaking up CO2 from the burn-off gas from the wood chips. The process is then reversed, and clean CO2 can be discharged simply by blowing air through the pellets.

The technology has the potential to improve crop yields by 15-25%. In a sector where growers typically operate on extremely small margins– and any small yield increases are hard to find – this could result in an annual revenue boost for growers of $40,000 to $80,000 per hectare, he says.

Hot Lime Labs has produced a pilot-scale system, capable of feeding up to 500kg of CO2 into a commercial greenhouse per day. This small-scale system underwent its first successful trial at NZ Gourmet Mokai, feeding CO2 into a tomato greenhouse at the end of 2019.

The pilot system will return for a long-term trial at NZ Gourmet in 2020, with the commercial scale system due to be installed in 2021.

Feeding the world from Wellington

Hot Lime Lab’s technology has huge implications for the global production of fruit and vegetables, Materic says. It can be applied to most greenhouse crops, and the global market opportunity is estimated at $800m a year.

To put it in perspective, NZ has 600 hectares of greenhouses, while the Netherlands has 12,000 hectares – 0.3% of its total land area.

This system will not only decrease overall greenhouse gas emissions by moving growers away from a reliance on fossil fuels but will also help maintain future food supply and production from these essential businesses.

Hot Lime Labs will remain based in Wellington and use the local market as a launch pad, Materic says. “The idea is we’ll start in NZ and Australia, but we’ll quickly look to expand in Europe, which is the main market.”

The venture was born out of technology Callaghan Innovation and its predecessor, Industrial Research Ltd, had been working on for some years, says Group Manager Advanced Materials Conrad Lendrum.

When Materic gained funding from the KiwiNet Emerging Innovator Programme, allowing him to take the plunge and set up the company, he and Callaghan Innovation came to an agreement over intellectual property rights. “Callaghan Innovation wasn’t seeking to generate a whole lot of revenue; it was about giving Hot Lime Labs the best chance of succeeding and for the benefit of NZ,” he says.

Callaghan Innovation has continued to provide R&D support to Hot Lime Labs through the Project Grant scheme, which allowed the scale-up of the technology from lab to pilot system.

The R&D team supported Materic with time, and access to expertise and equipment. “Vlatko has given up his job at Callaghan Innovation to pursue this and has personally invested in the venture. He’s very much leading it, but we’ve played a key role to this point,” Lendrum says.

“Vlatko taking the risk meant our technology found a home,” he says.

Visit www.hotlimelabs.co.nz for more information.

Find out more

Our Advanced Materials Group can help select or develop the materials you need to give your products a competitive edge when it comes to performance and/or functionality.

For a full list of our services, see Advanced materials.

Contact Us