Greenhouses: Implementing High-Efficiency Power Systems to Reduce Costs, Increase Crop Yields

Greenhouse facilities can reduce operating costs by implementing a Cat^® Combined Heat and Power (CHP) system using pipeline natural gas as a fuel source. The Cat gas generator sets will provide electricity, heat and organic fertilizer created by recycling the carbon dioxide found in the engine exhaust.

Benefits from greenhouse CHP projects include:

• Over 90 percent energy efficiency
• Decreased energy costs versus separate heat and electrical generation systems
• Reduced emissions versus separate heat systems
• Increased revenue opportunities through the export of electricity
• Enhanced crop yields

Cat^® Dealers provide customized CHP package proposals, including the required mechanical equipment and controls to capture and transfer the engine thermal energy, the required exhaust emissions aftertreatment, utility grade paralleling switchgear and controls to sell excess electricity generated to the local electric grid.

How It Works

Any Cat natural gas fueled-engine can be configured for applications involving heat recovery. The engine drives a Cat generator to produce electricity, while jacket water and/or exhaust cooling circuits are fed through heat exchangers to transfer the waste heat from the engine to a hot water holding tank. That hot water is stored and used to keep the greenhouse warm.

CHP systems can also create a revenue stream for the facility. Since generator set sizing is based on heat load, the electricity produced at a greenhouse often exceeds the local demand. Many European countries offer incentives in the form of production credits for high efficiency electric power generation. In these cases, most of the electricity produced is exported to the local grid. In other parts of the world, grid unreliability and pure economics are driving greenhouse agriculture toward similar solutions.

Greenhouse operations can also use CHP systems to generate fertilizer. Oxidation catalysts can be used to remove carbon monoxide, and a urea-based SCR system is employed to reduce NOx to just a few parts per million. The result is an exhaust gas so clean it is piped to the greenhouse plants' roots as a fertilizer, boosting farmers' yields.

The total energy cost savings of such systems can more than offset the total owning and operating costs, delivering a payback in as little as two to three years, depending on local energy pricing and policies.