A tomato greenhouse hooks up with an ethanol plant to save energy

 At first blush, the $21 million construction of a tomato greenhouse beside Chatham-based Greenfield Ethanol would seem to be about energy savings. But the benefits may be far rosier than the tomatoes themselves.

The Truly Green enterprise, the first in North America to hook up to an ethanol plant, is owned by the Devries family along with the Tamminga and Bultje families. President of the company Greg Devries is predicting yield increases of three to five per cent due to pumped-in carbon dioxide on top of lowering heating costs by 50 per cent using the ethanol plant’s waste heat.

“We are designing a greenhouse with competitive advantages,” says Devries. “The advantage is untethering the carbon dioxide from the heating source.”

With the first planting of tomatoes expected in early July, the construction timetable is under pressure to complete in time for a hookup to Greenfield Ethanol in September. That’s when the ethanol plant shuts down for two weeks of maintenance and when the underground connection for carbon dioxide can be made physically to the new greenhouse.

If all goes to plan, produce from 22.5 acres could be ready to market by September. Devries plans to analyze results from the first test crop, clean out the greenhouse and start with new crop next January. Eventually, the greenhouse will market 22 million kilograms of tomatoes annually, with a goal of building a complex of 90 acres during the next decade.

That’s a carbon-neutral story that can be taken straight to consumers. With a marketing agreement with Mastronardi Produce, Devries says that their tomatoes-on-the-vine and grape tomatoes are slated to qualify for a premium under the Mastronardi’s Eco-label brand. That third-party accreditation might be possible by 2014.

For Greenfield Ethanol, the advantages are also quantifiable. Angelo Ligori, Greenfield’s ethanol plant manager, supports the partnership to harness the CO2 released in the ethanol process. Greenfield will update its older technology to include waste heat recovery and a thermal oxidizer. The new technology will condense stack heat through a series of exchanger systems, allowing the ethanol plant to supply hot water to the greenhouse. The water will then be returned to the ethanol plant through an expanded cooling water loop. The changes will mean there’s no longer a visible plume from the ethanol plant.

Two years in the making, an expansion of this scope is not for the faint of heart. The Devries family has built on a relatively new entry into the greenhouse business. While they have been farming grains and oilseeds since 1948, they built their first sweet bell pepper greenhouse in 2003 which has grown to 16 acres today. In that case, natural gas boilers produce hot water and CO2 is captured from the boiler exhaust. However, they discovered that of any greenhouse-grown vegetable, tomatoes are the biggest users of C02 and that demand is greatest in the summer. The challenge is that summertime represents the least demand for heat. The bridge to the ethanol plant solves those inequities, supplying heat and CO2 on demand.

The farming operations are becoming more synergistic all the time. The Devries family grows corn, part of which is sold to the ethanol plant. At the same time, they buy the ethanol plant’s byproduct – distiller’s grains – for their feedlot, while buying the waste heat and C02 for their tomato greenhouse.

“It’s an amazing story,” he says, adding that it’s beneficial for the local economy, the farming operation, the greenhouse and the ethanol plant.

Thanks to a $100,000 grant from the Agricultural Adaptation Council and a $3.2 million grant from the Rural Economic Development Agency, Devries says these monies help make the business risk more tolerable. The Chatham region has been hard hit by the downturn in the automobile sector, so he points out that green technology is rejuvenating the area. The Truly Green operation requires 50 jobs alone for startup of phase one.

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