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Reaping a Harvest a Day PUBLIC ACCESS

Electrical and Agricultural Know-How has Created a Garden of Eden in a Central New York Greenhouse.

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Mechanical Engineering 122(05), 74-76 (May 01, 2000) (3 pages) doi:10.1115/1.2000-MAY-6

Abstract

This article reviews how agricultural facilities can harvest about two crops per year. The controlled environment agriculture (CEA) facility is a hydroponic project that began operating in July 1999. It uses computer software to control lighting, environmental conditions, nutrient balance, water pH, and other parameters to create optimal lettuce-growing conditions. The agricultural facility’s story began 10 years ago, when a graduate student at Cornell University in Ithaca found that optimizing environmental conditions enabled him to grow seedlings for nurseries in 16 days, rather than the 35 days required by conventional agricultural nurseries. NYSERDA has conducted studies examining the total energy package of conventional agriculture, from producing seed to transporting vegetables to market, and found that northeastern controlled environment facilities will use less energy than shipping produce from the West Coast or South America. Growers also can tout the fact that their produce is grown without herbicides or pesticides, a major marketing advantage to attract consumers seeking organically grown produce.

Article

For centuries, lettuce farmers have planted with the intention of harvesting about two crops per year, depending on the vagaries of nature. But, now a collaboration between academic and electrical researchers in central New York is freeing farmers from the tyranny of the seasons by producing 1,000 heads of Boston leaf lettuce every day—even in the depths of winter—at a controlled environment agriculture facility in Ithaca, N.Y.

The controlled environment agriculture, or CEA, facility is a hydroponic project that began operating in July 1999. It uses computer software to control lighting, environmental conditions, nutrient balance, water pH, and other parameters to create optimal lettuce-growing conditions.

Fifty-eight heads of lettuce a year are grown per square foot of hydroponic pond at the controlled environment agriculture facility in Ithaca, N.Y.

Grahic Jump LocationFifty-eight heads of lettuce a year are grown per square foot of hydroponic pond at the controlled environment agriculture facility in Ithaca, N.Y.

The result is a 365-day harvest in New York’s snowbelt. It is not unusual for a season’s snowfall in Ithaca to reach about 5У2 feet. From December through February, temperatures outside average in the 20s and can easily fall into the teens below zero on the Fahrenheit scale.

The agricultural facility’s story began 10 years ago, when a graduate student at Cornell University in Ithaca found that optimizing environmental conditions enabled him to grow seedlings for nurseries in 16 days, rather than the 35 days required by conventional agricultural nurseries. Louis Albright, a professor of agricultural and biological engineering at Cornell, and his colleague, Robert Langhans, a professor of floriculture and ornamental horticulture (since retired), decided to explore methods to grow lettuce faster. The duo conducted multidisciplinary research, determining the horticultural conditions needed to optimize plant growth and health, designing control software to provide economical control of those parameters, and monitoring plant growth.

The CEA growers use software to control the light and shades of their greenhouses in order to harvest lettuce during the depths of winter.

Grahic Jump LocationThe CEA growers use software to control the light and shades of their greenhouses in order to harvest lettuce during the depths of winter.

The Cornell professors’ work was sponsored by their local utility, New York State Electric & Gas Corp., as well as nearby Niagara Mohawk Power Corp. in Syracuse, the Electric Power Research Institute in Palo Alto, Calif., Empire State Electric Energy Research Corp. in New York City, and the New York State Energy Research and Development Authority in Albany. The organizations were interested in the CEA’s use of low-cost, off-peak electricity for three-quarters of the time. Syracuse, N.Y.-based Agway Inc., an agricultural cooperative, built the greenhouse and gave the grower’s perspective, while Westbrook Greenhouse Systems Ltd. of Ontario provided the greenhouse materials and assisted in construction.

In the controlled environment facility, basically a greenhouse, seeds are placed into small rock wool cubes in a totally enclosed growing room. The trays are placed on ebb-and-flow benches where pumps direct metered amounts of nutrient-laden water to the trays for specified feeding periods, and then drain away the excess.

Overhead 600-watt sodium lamps beam light onto the crops. The lamps are made by Lumenarc of West Caldwell, N.J., and are equipped with cooling jackets through which water is circulated. Water cooling the lamps lets them emit high energy to optimize growth, without the attendant infrared radiation that would harm the plants. Within 24 hours, roots emerge from the seeds, and 24 hours later, the first cotyledons, or leaves, appear.

The lamps and shades in the greenhouse are closely controlled by a personal computer containing an algorithm patented by Albright to provide the optimum amount of light needed to grow 1,000 head of lettuce, typically 17 mols of photosynthetically active radiation per square meter per day. The PC is linked to a photosynthesis measurement sensor made by LI-COR of Lincoln, Neb., to measure the amount of light at plant level. LI-COR manufactures electronic instrumentation for agricultural, ecological, and environmental research.

“Our algorithm enables the computer to determine how much more lamp energy, or how much shading, is needed to achieve the optimum number of mols of PAR per square meter, every day,” explained Albright.

After 11 days, the young lettuce seedlings are transplanted to floating styrofoam platforms on the 6,400-square-foot hydroponic ponds in the greenhouse. These are concrete walled ponds lined with plastic and filled with 11 inches of nutrient solution.

Fifty-eight head are grown per square foot of pond in a year. Each crop in the process matures in 35 days from seeding, compared to 90 days in open fields, where plants are subject to insects, molds, and sudden changes in weather. Because of the continuous flow of crops through the system, a fresh crop of 1,000 head of lettuce is harvested daily. “Our growth rate per square foot per year is 20 times that of an outdoor lettuce farm in California,” Albright said.

A check with the agricultural commissioner’s office in Monterey County, Calif., found that growers there, in the lettuce-growing capital of the world, can get anywhere from the usual 900 cartons to an extreme of 1,300 cartons of Boston lettuce per acre. Given an average of 2У2 harvests a year, the annual yield per square foot falls between 114 and almost 2 heads.

The controlled environment agricultural process does not generate any environmental discharge because its water is continuously reused. “The optimal growing conditions of CEA have given us a nutrient water supply so robust that it resists disease outbreak,” Albright explained. “A Cornell student tested this by injecting a sample of CEA nutrient water with e. coli bacteria, which can cause food poisoning. The e. coli disappeared within a few days.”

Recycling nutrient water minimizes the controlled environment facility’s water consumption. The styrofoam floaters reduce evaporation in the hydroponic ponds, and the only water lost is through transpiration by the lettuce. As a result, the greenhouses use 2У2 liters to grow a head of lettuce compared to about a cubic foot of water, or about 28 liters, per square foot in the open field.

 New Motors for New York

In addition to co-sponsoring controlled environment agriculture, the New York State Energy Research and Development Authority in Albany is encouraging energy efficiency in the Empire State through its New York Energy Smart Premium-Efficiency Motors program.

The program was launched early last year and is designed to provide New York State businesses with information on the expected costs and benefits of replacing older motors outright, instead of rewinding them.

A typical industrial electrical motor consumes 40 to 60 times its initial purchase price in energy over the course of its life. According to NYSERDA, the incremental cost of purchasing a premium-efficiency electric motor rather than a standard efficiency model is almost negligible compared to the savings in energy during the life of the motor. Companies using premium-efficiency motors can reduce their operating costs, improve motor reliability, and reduce carbon emissions to the environment.

NYSERDA works with electric motor vendors, including General Electric Supply in East Syracuse, Grainger Industrial Supply in Albany, and Kaman Industrial Technologies in Tonawanda, N.Y., as well as distributors to provide the program’s participants with tools and resources. They include the Department of Energy’s MotorMaster software, training materials, newsletters, and case studies, which assist program participants in selecting the optimum motor, performing life-cycle cost analysis, and making the decision whether to replace or repair a motor.

The New York Energy $mart program is being promoted throughout the Central Hudson Gas and Electric, Consolidated Edison, Niagara Mohawk Power, New York State Electric and Gas, and Orange and Rockland Utilities service territories.

The controlled environment approach has the potential to provide small farmers with profitable, alternative agricultural methods to fend off increasing competition from imported lettuce. In addition, the controlled environment enables electric utilities to use their resources more efficiently, because much of the electricity consumed by the hydroponic facility is during off-peak hours, at night, when there is excess power production capacity.

“CEA can provide economic development by giving farmers the opportunity to grow in the winter, when a regular harvest isn’t available. This can represent a new industry in areas where farming is very seasonal,” said Myron Jones, manager of food and agriculture programs at EPRI.

In addition, NYSERDA has conducted studies examining the total energy package of conventional agriculture, from producing seed to transporting vegetables to market, and found that northeastern controlled environment facilities will use less energy than shipping produce from the West Coast or South America. Growers also can tout the fact that their produce is grown without herbicides or pesticides, a major marketing advantage to attract consumers seeking organically grown produce.

“It’s also important to note that this lettuce always can be provided fresh, because it’s usually harvested and placed in stores within 24 hours,” said Dick Peterson, manager of agricultural marketing at New York State Electric & Gas Corp., the local utility that sponsored the project. Peterson explained that by the time field-grown lettuce is harvested and transported to stores, it is often several days old.

“The CEA facility produces some of the finest lettuce I have ever observed. Color and size uniformity are excellent,” said Chuck Sopher, director of EPRI’s Agricultural and Food Technology Alliance.

Peterson said that by producing a uniform product with a guaranteed delivery schedule, controlled environment agriculture would eliminate the price fluctuations currently caused when weather and other conditions affect crop output and transportation. This, in turn, would stabilize crop prices at appropriate market prices.

The Wegmans Food Markets Inc. grocery chain, headquartered in Rochester, N.Y., is selling the lettuce to consumers through its produce departments. “It has tremendous flavor, good shelf life, and because it is hydroponically grown, it’s free of the fine grit you often find in Boston lettuce grown in sandy soil,” said Bill Pool, manager of agricultural production and research at Wegmans. The chain operates 59 stores, with most of them in upstate New York, several in Pennsylvania, and one in New Jersey.

The lettuce is sold at the same price as other Boston lettuce in bags that identify the CEA vegetables as locally and hydroponically grown. Wegmans does its part to publicize the controlled environment agriculture project. The company mounts signs in its produce sections that illustrate the process, and sometimes has the experts in.

“The Cornell people have their own road show, taking one of their growing flats to our stores to acquaint our customers with the CEA growing process,” Pool said. “These customers tell us they find it fascinating.”

The current management of the project may be winding down its work by June 30, but the greenhouses will continue operating in any event.

“Agway is interested in taking over the facility and using it as a training center for member growers who would staff new CEA centers to be built near markets, an arrangement similar to McDonald’s Hamburger College,” said Albright. He and his Cornell colleagues are currently pursuing a grant to develop a CEA system for growing other crops, specifically spinach. They estimate that it will take about three years to develop the necessary protocols to start production. No word on how long it will take to get kids to eat that leafy green vegetable.

Copyright © 2000 by ASME
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