Article by: Hari Yellina
The production of tomatoes at one of the major fruit and vegetable growers in the nation, New Zealand Gourmet, was reduced by roughly 20% at its 12-hectare facility near Taupo due to a state-wide scarcity of commercial carbon dioxide supplies, but the company believes it has now found a solution. And it’s a solution that could assist a young technological company in achieving success abroad. NZ Gourmet is the most recent major food company to identify effects from the carbon dioxide shortage, which also poses a threat to artisan beer and supermarket-packaged chicken production. Its facility in Mkai, north of Taupo, is unique in that it sustainably grows tomatoes and peppers during the winter by heating its greenhouses with geothermal energy rather than coal or gas boilers.
The drawback of employing carbon-neutral geothermal energy for heating, according to production director Roelf Schreuder, is that the company needs to purchase roughly 30 tonnes of carbon dioxide (CO2) each week to optimise growing conditions at the facility. Since the Marsden Point oil refinery shut down at the end of March, NZ Gourmet has not been able to purchase any CO2, according to Schreuder. Also, since fewer tomatoes are being grown due to high energy prices, fewer tomatoes will be available on the market over the winter. Due to production issues at Todd Energy’s Kapuni gas field in Taranaki, which is now closed, the Marsden refinery’s closure has had a greater negative impact on the environment than it already had.
In order to restore the vines’ full productivity, NZ Gourmet is relying on innovative technologies created by Callaghan Innovation spin-off Hot Lime Labs. Hot Lime Labs has created gasifiers that burn wood waste at night, when greenhouses need heat the most, but are designed to produce CO2 from combustion rather than heat. The CO2 is then kept in “patented limestone pellets” for subsequent release during the day, when it aids in photosynthesis and encourages plant development. The technology from Hot Lime Labs was tested by NZ Gourmet at its Mokai’s location last year, and its first commercial units are anticipated later this year.
The rising cost of natural gas, according to Tijs Robinson, chief growth officer of Hot Lime Labs, has given other growers who rely on gas for both heat and CO2 an incentive to move to a sustainable heat source and a separate supply of CO2. Robinson anticipated that its partnership with NZ Gourmet would also be a step towards expanding a market for its gasifiers outside of the United States in the sizable Netherlands market, where it has been looking for distribution and service partners. “The Netherlands has 10,000 to 15,000 ha of high-tech greenhouses; New Zealand has 500 to 700 ha.” Following Russia’s invasion, growers across Europe were forced to lessen their dependency on natural gas to generate heat and CO2, Robinson said.
“While in Europe, our chief executive spoke with individuals who are anticipating or have already experienced a treble increase in petrol prices.” As this improved plant growth by about 25%, Robinson noted that horticulture companies there typically tried to maintain levels of carbon dioxide in their glasshouse at between 800 and 900 parts per million, which is roughly double the level of 420ppm currently found in the atmosphere. But switching from fossil fuels to other heat sources would leave them short if there wasn’t a supplementary source of CO2. The process used by Hot Lime Labs, according to Robinson, is sustainable since carbon dioxide was “liberated” from waste wood, where it is typically thought to be in one stage of the natural atmospheric carbon cycle. When authorities were considering closing the Marsden Point refinery last year, Energy Minister Megan Woods stated “possible repercussions” on the CO2 supply chain were discussed in a Cabinet paper. However, she claimed that maintaining the supply of CO2 produced as a by-product of refining had not been a good enough justification to interfere with the closure.