In the Netherlands in the last years greenhouses are heated and powered by WKK (warmte kracht koppeling) in English CHP which means Combined Heat and Power also known as co-generation. By installing a CHP system designed to meet the thermal and electrical base loads of a greenhouse, CHP greatly increases the greenhouse operational efficiency and decrease energy costs. How does a CHP work in a greenhouse, a plant in a greenhouse in the northern hemisphere need most of the time heat, light and CO2 to grow optimal. A CHP is providing this by burning natural gas and giving electricity, heat and CO2 in return.
If you look at today’s power plants which burns natural gas still 45% is turned into heat and not into electricity this is a waste of energy because most of the time the heat is unused and therefore dumped. A greenhouse grower is burning natural gas to make electricity, one part of the electricity he is using for his grow light another part he is using to heat his greenhouse with. The CO2 which the grower is producing he feeds to his plants so they are more productive. A greenhouse has an efficiency of 90% compared to a gas powered electricity plant of around 45%
In Holland the co-generation became very popular of the current 10,000 hectare of greenhouses 6,000 hectare is using the thermal and electricity power of an CHP. Those greenhouses are producing now around 2000 Mwe and in 2011 this will be around 3000 Mwe. Currently around 20% of the total electricity demand in the Netherlands is produced by greenhouse growers and this will further grow in the coming years.
The dutch government and some NGOs like LTO Glaskracht and the Association Nature and Environment have the ambition for 2020, to have a climate neutral Dutch Greenhouse sector which is independent on high energy prices.
Down site to the success of the CHP in the Dutch horticultural sector is that it slows down innovation which is so badly further needed. The CHP is still using environmental unfriendly fossil fuel and it’s giving the greenhouses grower an income for producing electricity which inflates the price of the horticultural product they are growing such as tomato, chrysanthemum, bell peppers or cucumbers (decrease cost price). So CHP is an economical solution to keep on competing with countries which have a better climate to grow vegetables or flowers.
At this moment of the 10.000 hectares of greenhouses, 6.000 is heated with a CHP installation, so what to do with the other 4.000 hectares. Geothermal heating? At this moment it’s very popular but according to calculations of the Product Board of Horticulture Geothermal heating will only be able to heat 1.000 hectares in Holland. Another option is to burn bio fuels in stead of natural gas. Or maybe we have shouldn’t think of conventional greenhouses but look at new greenhouse concepts? We still have some time before it’s 2020.
Please comment any Greenhouse concepts or Energy solutions you think are worth investigating.