Innovative combustion technology helps tomatoes grow faster by producing carbon dioxide directly into the greenhouse. Carbon dioxide fertilization can increase crop growth by as much as 50 per cent. When firing LPG, the nitrous oxide (NOx) emissions of Oilon’s LN30 burners are exceptionally low, no more than 10–30 ppm.
Taivalmaan puutarha, a tomato farm in Western Finland, recently adopted a new two-hectare greenhouse. What makes the greenhouse special is the new kind of burner that fires liquefied petroleum gas (LPG) to produce carbon dioxide for the plants.
“Previously, we’ve used CO2 cylinders, but they’re expensive. Now, we’re testing out combustion technology, because it’s a more economical option,” says the farm’s owner Robert Åman.
The tomatoes need extra CO2 to grow fast enough. Oilon’s LN30 burner increases the CO2 concentration in the greenhouse to around 800–1000 parts per million, while the concentration in normal atmosphere is slightly greater than 400 ppm.
Roughly 10 per cent of the burner’s flue gas is carbon dioxide. The burner is installed in a boiler, which means that it generates heating energy as a side product.
“Depending on the capacity used, the NOx emissions in the flue gas are between 10–30 ppm, which is a world record. Other burner manufacturers cannot achieve this level when firing LPG,” says Sales Manager Kari Puro from Oilon.
A too high NOx concentration will damage the leaves of tomato plants, disrupt photosynthesis, and alter conditions in the substrate. This slows down growth, resulting in lower yields. Additionally, high NOx levels are a health hazard.
The world’s lowest emission levels
The exceptionally low NOx emissions of LN30 burners are a sum of several combustion technology solutions. One specialty is the supply of fuel and combustion air: part of the fuel and air is fed into the combustion head separately, and the rest is pre-mixed. Another unique feature is the long combustion head that extends far into the combustion chamber. This allows the burner to feed fuel along the sides, resulting in a wide flame. The solution utilizes internal gas flows in the combustion chamber effectively, resulting in cleaner combustion. Another key factor is that the flame is cooled down with additional air supply. The lower the temperature, the lower the NOx emissions.
“I selected the Oilon burner especially due to its low NOx emissions. Another reason was that it is a Finnish product,” Åman says.
Globally, the most common way of producing CO2 is by firing natural gas. The flue gas generated by natural gas combustion has a lower NOx concentration than LPG. In Finland, however, the natural gas distribution network extends only to the Southern and South-Eastern part of Finland. Further north, other fuels, such as LPG, are required.
The green transition boosts sales
CO2 fertilization is a common practice in commercial greenhouses. It can increase crop growth by up to 50 percent. However, CO2 cylinders are expensive, which is why it is more economical to generate CO2 through combustion. Another factor that increases profitability is that a burner generates heating energy, which is especially useful in the winter season.
Now that the new extension is complete, the Taivalmaa tomato farm has a total of 5 hectares of greenhouse space. The farm has 35 employees, and in 2024, its turnover was EUR 3.6 million.
Oilon burners are used around the world in energy production and property heating as well as in industrial and marine applications. The burners are made in Oilon’s production facilities in Finland, China, and the United States. In 2024, the turnover of the company’s burner business was EUR 36.4 million.
“We have been developing clean combustion for decades. Now, we are at the point where our burners achieve the strictest emission norms in the world. The green transition boosts the demand for burners,” Puro says.
Photos: Robert Åman at Taivalmaa, Osuuskunta Närpiön Vihannes, LN30 burner, Oilon Kari Puro