"Power Plant" Takes On A New Meaning

Waste heat from a 100-MW electric plant could, in theory, warm 100 acres of greenhouses. Artist rendering of greenhouses heated and enriched with CO2 using waste from a power plant. A cumulative frequency curve shows typical annual heating needs of a greenhouse used to grow tomatoes. Yields for greenhousegrown produce are about 10X that of open fields. About 15% of tomatoes consumed in the U.S. come from greenhouses, and that number is rising. One reason: Yields for greenhouse-grown fresh produce are about 10 times that of open fields. Not to mention, imported tomatoes are expensive, especially in off-season. Transatlantic shipping costs in most cases exceed the cost of the tomatoes. Then there are the growing concerns of food safety and bioterrorism associated with imported crops. Of course greenhouses require heat and (ideally) a carbon-dioxide (CO2)-rich atmosphere to accelerate growing, jobs mostly handled today by dedicated and costly natural-gas-fired boilers and, in some cases, cryogenic CO2 systems. But there is another source of CO2 and heat that is now literally going up in smoke: electric power plants. Flue gas from fossil-fuel-fired power plants is rich in CO2. The burning of 1 m of natural gas makes about 2-kg CO2 or 10% by volume, for example. A controlled amount of flue gas can be vented to a greenhouse, while waste heat from electricity generation provides heating. Greenhouses would colocate with power plants to reduce thermal and piping losses as well as tap electric power for artificial lighting, yet another requirement for growing tomatoes and other crops during winter days and feeble sunlight. That is the concept being forwarded by The (GCA), Newton, Mass. GCA plans to team with power-plant designer/builder , San Jose, and improve upon technology developed in the Netherlands. The idea of using waste heat to warm greenhouses isn't new. Since