Growing Greener Tomatoes
CHP greenhouse project diverts waste CO2 for plant production and is nearly 100 percent efficient
Case Study – Challenge
Houweling’s Tomatoes, a leading North American greenhouse grower with a strong environmental record, sought an ultra-efficient, combined heat-and-power system for its 125-acre greenhouses in Camarillo, California, that would generate flexible power for the local utility and establish one of the lowest carbon dioxide (CO2)-emissions and water-usage levels of any similarly sized power plant in the region.
Houweling would need to cut energy consumption and recycle waste heat and CO2 in order to achieve the goal of almost 100 percent overall efficiency in heating and powering the greenhouse.
Case Study – Solution
GE provided Houweling with two of its 4.36 MW, Jenbacher J624 natural gas engines and a CO2 fertilization system to create the first CHP greenhouse project in the U.S. that captures CO2 from combustion for plant fertilization. The CHP system furnishes 8.7 MW of electrical power and 10.6 MW of thermal power.
The greenhouses recover thermal energy in exhaust gas heat exchangers and use very low water temperatures in the heating system to cool exhaust temperatures below the dew point. With a five-minute startup capability, the plant generates enough energy to power the local grid during peak demand periods.
Case Study – Results
The CHP system’s total thermal efficiency approaches 90 percent. By condensing water from the exhaust gas, which saves about 9,500 gallons per day from local sources, and by avoiding the need to obtain and transport the CO2 from factories, the overall system exceeds 100 percent efficiency.
Also, the thermal energy produced during power generation can be sent to the greenhouse immediately when it’s cooler or kept in existing storage tanks for use at other times.