CHP at greenhouses in Belgium

The renovated and expanded tomato-growing business belonging to Geert De Breuck includes a covered area of more than 27,000 square meters (6.6 acres), making it a large business for the region of Sint-Gillis-Waas, Belgium. The facility produces about 1,650 metric tons (3.64 million pounds) of tomatoes annually with the help of an innovative combined heat and power (CHP) system designed and manufactured by Cummins Power Generation. The system uses natural gas to generate electricity, heat and carbon dioxide, which are all used to accelerate the growth of the tomatoes.
The CHP system is the result of a direct partnership between the grower and Cummins Power Generation, which provided the equipment and technical expertise for the CHP system, plus a signifi cant portion of the financial investment. With a power system that operates above 90 percent overall energy efficiency, as well as government regulations that grant CHP certificates and carbon dioxide emission permits, the project is proving to be very economical.
Power system components
The centerpiece of the CHP system is a Cummins Power Generation 1.5 MW lean-burn gas generator set. The generator is powered by a Cummins natural gas engine known for high thermal efficiency, low exhaust emissions and high reliability. The generator produces electricity that is mainly directed to the grid; less than five percent is used on site. Waste heat from the water jacket and exhaust are recovered through a heat exchanger and used to provide heat for the covered plant-growing areas year-round. A large buffer water tank stores heat produced during daylight hours. The heat can be released during the night to keep the plants warm. The generator's treated exhaust gases are also a source of carbon dioxide the plants need for photosynthesis.
Projected payback period of 3.5 years
While the financial performance of the CHP system depends on a number of factors--the price of tomatoes, the price of natural gas, the value of the electricity sold, the value of the government CHP certificates and maintenance costs--the optimized system was designed to pay for itself in about three and a half years. Given fluctuating gas prices, the selling price of electricity can be negotiated for up to three years. With today's higher gas prices, the sales of electricity alone pay back a major part of the cost of the consumed natural gas. The full case study is available to download.