Several Dutch growers sent an urgent letter about major shortages of external CO2 to Carola Schouten, Dutch Minister of LNV (Agriculture, Nature and Food Quality) and relevant national, provincial and local authorities, politics, Greenport Holland, regional Greenports, the industry, interest groups, horticultural businesses and research organizations stating Greenhouse horticulture urgently needs CO2 from elsewhere to allow plants to grow well.
"By moving more and more to sustainable energy sources such as geothermal energy, growers themselves produce less and less CO2. Without solutions for the shortage of external CO2, this could be the bottleneck for becoming more sustainable," says Jacco Besuijen, the energy manager at Prominent, leading the sent letter. The Prominent growers call on everyone who is involved in this matter in whatever way, to quickly come up with solutions in a collective.
Jacco Besuijen
The climate agreement, presented at the beginning of this month, shows that greenhouse horticulture is now making larger steps than expected. The sector expects to save 2.2 million tons of greenhouse gas until 2030 and even expects to be climate neutral by 2040. Entrepreneurs in greenhouse horticulture received a nice compliment from the 'table chairman' Pieter van Geel at the handing over of the Climate Agreement to Minister Wiebes at the beginning of this month. 'Extremely ambitious' he called the proposals of the greenhouse horticulture for CO2 reduction.
At the same time growers need a lot of CO2 to have the crops grow well, especially during the hot summer days. They produce this CO2 themselves with the gas fired cogeneration plants (CHP) - but in order to realize the ambitions, the CHPs will be phased out over time.
"The solution is found in reusing the gas from the industry, where it is just a residual product - a nice win-win situation. Prominent growers sound the alarm because they had to contend with major shortages of external CO2 in the past year. Just our Prominent growers, with a total of 418 ha of tomatoes under glass, could dose 5,016 tons less external CO2 in the past six months due to the shortages", the producer organization reports. "This shows that this might be the biggest bottleneck for horticulture in order to make the sector more sustainable. To be able to take that step, we, as growers, really need more supply security."
CO2: problem and solution at the same time
"The CHP, the energy supply in our greenhouses, constantly amazes every group of visitors to our tomato greenhouses: a beautiful piece of technology. My presentations as an energy manager, I always start with the basic needs of a tomato plant: water, heat, light and CO2. When our visitors hear that, most of them nod in the affirmative. That you have to water plants to keep them alive, is clear. In addition, almost everyone remembers from biology class that in a plant, under the influence of light, CO2 is converted into sugars. And to make the plant feel 'at home' we occasionally make it in the greenhouse a bit warmer than outside. This way we can produce healthy vegetables throughout the year."
CHP: top system for the short term
"What most visitors do not know is that for the energy supply we have been using the CHP for more than a decade. The CHP is a large natural gas driven engine that produces electricity. Because an engine needs to be cooled, we can use the heated cooling water to heat the greenhouse. And to make the plants grow even better, the exhaust gases are as CO2 also used in the greenhouse. Top system I say. Of course our growers are aware that the quantity of natural gas has to be reduced even further."
Alternative heat sources do not provide CO2
"In the meantime all sorts of new forms of heat supply are found. For example we take heat from the underground, from biomass or from industrial neighbors. But there arises a problem with these alternative heat sources. No CO2 is released during the extraction. And that is precisely one of those essential basic needs of a plant. This means that we have to buy this CO2 from other processes that have CO2 as a residual product, and capture and purify it for us. The fact is that everything was sold out this spring ... I hear you think: "Huh, a shortage of CO2 !? We have too much of that, after all?" That's right. But because there is so much of it, and that actually it is waste product for everybody, it's not easy to capture CO2, clean it, and transport it to greenhouse horticulture companies at acceptable cost. And that means, however unbelievable this might sound, that a shortage of external CO2 becomes the biggest bottleneck for horticulture to make it more sustainable. Without CO2 the plants will not be able to grow, so if we cannot acquire it at all, it means that we cannot cultivate delicious, healthy products any more."
Shortage of CO2 bottleneck for sustainability
"And now what? Well … that’s a good question. There are currently many research projects: CO2 from waste incineration, CO2 from biomass, CO2 from outside air, CO2 from the industry, etc. However, the ultimate solution has not yet been found. Most likely, the solution will be found in a combination of all these possibilities. If the solutions do not work, I am pessimistic about the sustainability of greenhouse horticulture. The greenhouse horticulture wants to be climate neutral by the year 2040, but our growers cannot do this by themselves. That is why Prominent calls on everyone who is in whatever way involved in this issue: the Minister of LNV, national, provincial and local authorities, politics, Greenport Holland and regional Greenports, the industry, the horticultural sector and horticulture (supplying) business, research - to really get into the highest gear towards solutions. For an even more sustainable cultivation! "