Solar, geothermal wed in housing units
With the price of fuel oil and natural gas going up and up, and inexhaustible supply of energy at a fixed price may be only a dream. But is it, really? Certainly not to John Jones, a Dayton, Ohio, mechanical engineer and owner of the Jones Heating & Cooling Company.
"When solar heat is combined with geothermal heat," he asserts, "the result is an endless fund of energy at a fixed cost." He adds: "I don't know why someone hasn't tried linking these two energy sources together in residential buildings."
Mr. Jones began building small solar units more than 30 years ago while he was an engineer at Wright Air Force Base in Dayton.
After years of experimenting with alternative energy sources as a hobby related to his heating and air-conditioning business, he installed his first combined solar-geothermal system about four years ago in his own home. IT has been working without a problem ever since.
The heart of the Jones system is a water-to-air heat pump. Water is supplied to the unit from the earth at a constant temperature. Then the heat that is extractd from it is used to warm the house. The cooled water returns to the earth where it is again heated, thus continuing the cycle.
"Below ground, the temperature of the earth remains constant the year around, " explains Mr. Jones -- "anywhere from 47 degrees F. to 74 degrees F., depending upon the location. Here in the Dayton area it is 55 degrees. We can use that temperature at no cost to preheat or precool the water we use to heat or air-condition our homes."
When air conditioning is called for, the cycle is reversed. The heat pump, instead of extracting heat from the water, takes it from the house and transfers it to the water, which in turn cools the house. The heated water then returns to the earth to be cooled.
The system is not just an optimistic but untried dream. It now is being installed at Oak Creek South, a 300-home development in Washington, Ohio, just south of Dayton. In the past it has been installed successfully in 500 houses. The first comined system, the one in Mr. Jone's own home, worked so well it used 93 percent less electricity than an electric baseboard heating system installed in a similar house put up by the same builder.
Mr. Jones contends that the system will save homeowners up to 80 percent on their heating bills, compared with electric resistance (baseboard) heat, and 20 percent compared with gas heat. In the summer, the savings could be 80 percent of the cost of a conventional air-conditioning system.
In its heating mode, the Jones system gathers radiant energy from the sun in fluid flowing through solar-collector panels that are mounted on the top of a house. Heat is then transferred from the fluid to water in a 1,000-gallon underground storage tank.
"On cloudy days, when direct solar energy is unavailable, the system reverts to heat energy stored in the tank," Mr. Jones points out. "It can go about 20 days without collecting radiant energy."
Should the stored solar energy in the storage tank be depleted, the heat pump will then extract heat from groundwater. In effect, the geothermal portion of the system acts as a backup for the solar portion.
In the cooling mode, the system uses the earth's constant temperature as a heat sink rather than a heat source. In other words, with the pump operating in reverse, heat is drawn from the house and dissipated in the groundwater.
When the system is heating or cooling with groundwater, the required 20 to 30 gallons a minute is supplied by a well, lake, or some other source. However, when the flow is inadequate, a closed loop of plastic pipe is buried several feet beneath the ground. Functioning as a heat exchanger, this loop can be used independently or in conjunction with low-yield wells.
Mr. Jones recommends the use of the loop, since it eliminates the chance of contaminants getting into the system and disrupting the operation of the heat pump. It is used in most of the houses at Oak Creek South. All of the homes are two- and three-bedroom models in the 2,200- to 2,500-square-foot class and sell for $75,000 to $100,000.
Specially designed for the solar-geothermal energy plants they contain, they have low ceilings, wall-to-wall carpeting, and triple panes of glass on the smaller-than-normal windows.
Insulation, of course, is very important. Walls have 2 1/2 inches of sprayed-on urethane between the siding and sheathing. Ceilings contain 8 inches of blown-in cellulose while the 1,000-gallon storage tanks are covered with 6 inches of urethane foam and wrapped in plastic before being buried in the ground.
The smaler Oak Creek South homes have six collector panels on the roof; the larger houses, seven. Each panel measures 35 square feet and has an output of 5 ,00 Btu. Panels are mounted flat and never need adjusting, since they are manufactured for the specific latitude and longitude of the area.
Besides supplying both heat and cooling, the system also provides hot water and operates a clothes dryer. It has a life expectancy of up to 50 years and, according to the Oak Creek South builders, John Chaney and John Black, it should require 80 percent less upkeep than a conventional heating and air-conditioning system.
In a typical house, the Jones system costs $9,000 installed. A conventional heat-pump installation for the same-size house would cost about $5,000; a gas furnace, $2,500.
The payback period for the system, compared with electric resistance heating with electric air conditioning, is put at seven years. Within the next few years, however, the builders expect that rising fuel prices and mass production of the system will reduce the payback time to no more than three years.
The following figures are last winter's heating costs for a Dayton house requiring 96,905,000 Btu: Jones system $200.48 Electric heat 994.00 Oil heat 445.00 Natural-gas heat 291.00 LP gas heat 706.00
AS for cooling, there would be a first-year saving of $52.81 over a comparable electric system that did not use groundwater.
At present prices, Mr. Jones concedes that his system is not too competitive with natural gas. But that will change, he expects, as the cost of gas continuous to go up.
"If someone with natural gas calls now and wants the system, I advise them to wait," the engineer says.
When Oak Creek South is completed, it will contain 300 private homes, 80,000 square feet of commercial space, and a 194-unit condominium, all heated and cooled by the Jones system. The condominium complex, which will be the last structure to be built, will be known as "Energy Village," since it will be totally free of any power-related utility connections whatever.
"We are at the threshold of an age in which all new homes could be powered only by the sun and the earth," Mr. Jones declares. "Energy Village, I believe, is the first housing subdivision in the United States to be heated and cooled entirely by a combination of solar and geothermal energy."
Each condominium unit at energy Village will be served by this combined system. In addition to heating and cooling, it will supply power for hot-water heaters, clothes dryers, and kitchen ranges.
All electric power for the complex will be generated by a bioconversion plant that employs methane gas, which will be produced from human waste to run a turbine generator. This will be backed up by another turbine generator powered by LP gas.