Controlled Environment Agriculture (CEA) is an advanced and intensive form of hydroponically-based agriculture. Plants are grown within a controlled environment so that horticultural practices can be optimized.
CEA techniques are not simpler than older systems for growing plants. Indeed, they demand sound knowledge of chemistry, horticulture, engineering, plant physiology, plant pathology, computers and entomology. A wide range of skills as well as a natural inclination to attend to details are necessary for a person to operate a successful CEA production in either a research or commercial setting.
Today's consumers increasingly demand a diet that includes fresh, high-quality vegetables free of pesticides and other agricultural chemicals. Local production is also a major factor when fresh vegetables are purchased. In many regions of the United States and the world, climate makes it impossible to meet this need year-round with only local produce. Produce imported into the United States may be from other regions of the country (California, Florida, and Texas are major exporting states) and from other countries (primarily Mexico, Netherlands, and Israel).
When fresh produce is transported great distances there can be a significant loss of quality. Furthermore, energy requirements for transport can be significant. Local production in CEA facilities can also require significant energy inputs for heating, venting, and possibly, supplemental lighting. Studies have suggested the (non-solar) energy required to grow and transport fresh produce at least 1000 miles is equivalent to the energy required for local production within CEA facilities in cold and cloudy climates such as the Northeast and upper Midwest.
Transportation relies on liquid fuels, the price of which is predicted to rise faster than the general inflation rate. Production in CEA facilities relies on electricity and natural gas, the prices of which are predicted to rise no faster than inflation. These factors suggest CEA production of fresh vegetables can become a significantly greater component of commercial agriculture in the coming decades.
Benefits to Consumers
Well-managed, local CEA operations can provide fresh produce (as well as flowers or pharmaceutical plants) of high quality and free of agriculture chemicals. Furthermore, CEA facilities can be closed in terms of discharging liquids either to surface or ground waters. CEA facilities can also be located in urbanized areas, thus not requiring the conversion of open or agricultural land to greenhouses. CEA facilities add to local tax bases and bring net income to a community.
Benefits to Agriculture
Certain sectors of the agricultural industry face increasingly difficult economic outlooks. This is especially true of the dairy industry. Diversification is one means to improve the economic stability of small farmers and CEA is an option to diversify. Furthermore, many family farms can not be divided among two or more children wishing to remain in agriculture. Adding a robust CEA facility provides the opportunity for more than one child to remain.
Benefits to Utilities
The two most important environmental variables for growing plants are temperature and light. Both parameters must be controlled to be uniform from one location the another in a greenhouse, and consistent from day to day. The only method available to achieve consistency is to use supplemental lighting. Where the climate is cloudy, electricity needed yearly for suitable lighting can be as much as on hundred kilowatt-hours per square foot of lighted area. This load is primarily during off-peak hours and can be interrupted for short periods. These features should make CEA electricity loads highly attractive to many local utilities.
A Brief History of CEA
CEA, or Controlled Environment Agriculture is a combination of horticultural and engineering techniques that optimize crop production, crop quality, and production efficiency (Albright, 1990). Dalrymple (1973) found the earliest known CEA production in recorded history was mandated by the Roman Emperor, Tiberius Caesar (between 14 - 37 A.D.). Caesar's doctor told him he needed a cucumber a day for good health. So, movable plant beds were placed outside during favorable weather, and brought indoors during unfavorable weather. During winter, on sunny days, the beds were covered with a frame glazed with transparent stone (mica) and brought outdoors.
Greenhouse production of food (again cucumbers) is next recorded in 1597. In the 1500's lantern covers were placed over small areas of ground and used to force vegetables. By 1670 greenhouse structures similar to those used today were described. These early European greenhouses utilized wood frames with either glass or oiled paper (Dalrymple, 1973).
In the United States, greenhouses were present near the time of the American Revolution. This included George Washington's conservatory at Mount Vernon, which was built in 1780. The heat source for early American greenhouses was usually from heat produced by the decomposition of manure (Dalrymple, 1973). By 1900, most greenhouse heat came from heated-water systems. Efficient boilers and improved heating systems were developed by the turn of the 20th century (Langhans, 1990). However, a critical component to year-round success was still missing.
In 1887, growers in the United States were advised in The American Florist to refrain from growing tomatoes in greenhouses until April, because "You can't make sunshine" (Starr, 1887). Making "sunshine" had become possible with the invention of the incandescent lamp by Thomas Edison in 1879, but widespread use of electric lamps did not occur until the early 1900's after many small power plants and generators were in place (World Book Encyclopedia, 1997).
The first scientific experimentation on the influence of supplemental light on a greenhouse crop was performed at Cornell University by Liberty Hyde Bailey in 1889 (Dalrymple, 1973; Bailey, 1891). The practice was termed "Electro-culture", and was documented as significantly improving crop production, but was not considered economically feasible for food production. Even today, only crops with relatively high monetary value (e.g., spinach, raspberries, tomato, specialty lettuce crops) can justify the additional production cost from the use of supplemental electric light. In the 1960's, work at the ARS Phyto-Engineering Laboratory, USDA in Beltsville, MD showed significant increases in lettuce, tomato and cucumber seedling growth through the use of plant growth chambers (Krizek, 1968).
From the mid 1980's through the late 1990's, NASA conducted plant growth chamber research in the Kennedy Space Center Biomass Production Chamber, providing state of the art levels of environmental control and monitoring of food crop production in this Martian Base prototype facility. Plant research in the NASA Biomass Production Chamber has provided evidence that the nutritive value of food crops can be as good or better than field grown crops (Wheeler et al, 1996; Wheeler et al, 1997). Other researchers have noted the increased nutritional benefits of CEA crops (McKeehen et al, 1996; Mitchell et al., 1996; Nielson et al., 1995; Johnson, 2000).
In 1999, the Cornell University CEA Program broke ground on the first commercial scale CEA prototype lettuce production facility in Ithaca, New York. The facility has a production capacity of 1245 heads of high-quality lettuce per day. The prototype facility represents the transition stage from CEA Research to commercial scale production.