Minnesota's Future 10 THE MINNESOTA VOLUNTEER

Transcription

1 ^ Fue/s fqr Minnesota's Future 10 THE MINNESOTA VOLUNTEER

2 Is Energy Possible For Independence Minnesota? ROGER AIKEN All of Minnesota's energy energy to light our homes, cook our food, run our cars, power our machines comes from fuels brought into our state. Much of our oil comes from Canada, our natural gas from Texas, and our coal from states in the east and west. Now that fossil fuels are neither abundant nor cheap, scientists have begun to look for new sources of energy. In Minnesota, several projects hold the promise of clean, abundant fuel for our energy needs. But like most good things, practical results from these efforts will take both time and money. Sun Panels. One application direct solar power for heat already provides a measure of our energy requirements. Sunshine is ideal for heating rooms and water. Black panels, usually on the roof of a home or building, absorb the heat. Plate glass over the panels minimizes its loss. Air or water between the panel and glass serves as a transfer medium to move the heat into a building or to a water heater. (In summer, the same process can air condition a home.) A number of solar heating systems operate in Minnesota. At Northview Junior High School in Brooklyn Park, 5,000 square feet of solar panels provide seven percent of the school's energy heat for water in the shower rooms and swimming pools and some room heat in winter. In the first year, the system saved $4,000 in fuel; last year, $12,500. On the University of Minnesota's Minneapolis campus, a new building housing a bookstore and admissions and records offices will be heated entirely by solar collectors. The building will be built 90 percent below ground to take advantage of the natural insulating properties of the earth. JANUARY FEBRUARY

3 Despite our cold climate, solar heating is taking hold in Minnesota. Simple, homemade solar collectors now provide supplemental heat in a growing number of homes. A pioneer project was Ouroboros South, built by the UM Department of Architecture under the guidance of Professor Dennis Holloway. A private home developer, Marvin H. Anderson has built a solar demonstration home with money from the U. S. Department of Housing and Urban Development. The home is located at 9948 Nesbitt Circle, Bloomington. Several Minnesota companies now manufacture solar collectors for homes Honeywell, Use Engineering, Sheldahl, and Solar Aire. As the cost of collectors decreases, solar energy will provide more and more of our home heating needs. An Olivia farmer, George Rauenhorst, uses solar energy to dry grain and to heat a large animal barn. Solar Electricity. Solar energy can also produce electricity. In one system, called a "power tower," mirrors focus the sun's rays on a receiver at the top of a tower. Heat absorbed by the receiver then produces high pressure steam. The steam runs turbines that generate electricity. Honeywell, Sheldahl, and UM among others are now developing this system and Sandia Laboratories is testing a prototype in New Mexico. A more direct method of producing electricity from sunlight uses photovoltaics. On spacecraft, panels of solar cells made from silicon generate electricity to power instruments. On earth, however, solar cells are not yet eco- Sun reflects off 378 square feet of solar collectors which provide energy savings in this square foot single family home on Nesbitt Circle in Bloomington, Minnesota. 1 WiV-.%. ; >' '

4 Vertical axis wind turbine at Sandia Laboratories in New Mexico has / 5-foot blades which produce about three horsepower in a 20-mile per hour wind. nomical power sources. Among other problems, manufacturing costs are too high $500,000 to $1 million per kilowatt was the price of solar cells used in the space program. The U. S. Energy Research and Development Administration is now trying to cut costs of solar cells to between $500 and $1,000 per kilo- JANUARY FEBRUARY 1977 watt. Once the cost drops, photovoltaics could become an important source of electrical energy in Minnesota. Wind Power. We are all familiar with sailboats and windmills. Boats use wind power to move through the water. Windmills harness the energy of 13

5 This simulated solar steam generator is at NSP's Riverside Generating Plant in Minneapolis. Experiment is financed by U. S. Energy Research and Development (ERDA) grant to Honeywell, Inc. air movement to drive pumps, machines, and generators. Minnesota has enormous windenergy potential. Anyone living on the western prairies or on the north shore of Lake Superior is aware of the wind potential in these regions. As the price of fossil fuels skyrockets, we are seeing renewed interest in wind-energy technology. Both ERDA and the National Aeronautics and Space Administration sponsor research on new wind power machines. The first of these machines, rated at 100 kilowatts, now operates at NASA's Plum Brooke station near Sandusky, Ohio. Two blades revolve in a 125-foot diameter circle around a hub 100 feet above ground and produce 8.15 watts per square foot of swept area when the wind blows at 15 mph. Larger units in the megawatt range are now being planned. A problem common to all solar and wind-power systems is intermittency interruptions in the flow of power to consumers. The systems need devices to store energy which can then provide power on cloudy or windless days. In the past, windmills on farms used storage batteries. But to provide a steady flow of energy to a whole community, some other storage system must be found. One of the best known do-ityourself wind-energy advocates in Minnesota is Don Marier of Milaca. Marier is co-editor of Alternative Sources of Energy magazine. In one project, he rewound a Jacobs wind generator to change it from 32 volts to a 110 volt system for his home. Marier urges development of small units and would like to see the ERDA- NASA Wind Energy Program geared up to produce small 2.5 kilowatt-rated units as well as large units for public utilities. The smaller units would provide power for homes and small factories. At the other end of the scale, Honeywell, Minnesota Power and Light, and the Vertol Division of the Boeing Company have combined to 14 THE MINNESOTA VOLUNTEER

6 study the economics of windgenerated electricity in Duluth. Their 12-month feasibility study will identify the practical applications of wind power systems for a large community. Energy from Biomass. Biomass is the term applied to all plant and animal matter, dead or alive farm crops and residues, animal manures, trees and their residues, wetland and aquatic plants, and the organic part of solid waste. The conversion of stored biomass energy into some other useful energy form either by burning it directly as a fuel to fire furnaces and boilers, or by fermentation to produce methane and alcohol fuels offers enormous possibilities. Researchers in UM's Bio-Energy Study group led by Professor Perry Blackshear estimate that agricultural residues in Minnesota have an annual energy potential of 4.3 trillion Btu (British thermal unit), 43 percent of the state's total energy demand. Furthermore, if crops were grown for energy uses as well as for food and fodder, this percentage could increase to 65 percent. Double-cropping would elevate it even more to 100 percent. From solid waste, the energy potential is some two to three percent of the total state demand. From animal manures, eight percent nearly half of which might come from feed lots and turkey farms. From forestry residues, 23 percent. Between six and seven million acres of forests could, if intensively managed, yield 10 tons of dry biomass per acre per year, sufficient to 17 meet 100 percent of the state's energy requirements. Researchers have just begun to analyze the energy potential of various plants. Apparently the common cattail exceeds all other plants in Minnesota in biomass production. One acre can produce 30 tons in one year, more than twice that of corn (at 15 tons per acre the crop that presently yields the highest residue of dry matter). If production could be increased to 35 tons per year, only 1.9 million acres of cattails could supply the biomass for Minnesota's total energy needs. What is needed to develop biomass as an energy resource? Primarily a commitment from both government and the people to make it availableafter, of course, environmental impact studies are completed. All these ways to provide energy are in the experimental stage today. But it is a near certainty that, within the next years, the sun, the wind, and growing things will provide a good share of our energy. And in time, who knows? These abundant fuels may even make our state independent of outside fuel sources. In our cold Minnesota winters, a dream worth pursuing. Roger Aiken is an Energy Research Analyst for the Minnesota Energy Agency, Research. Fellow with the Center for Studies of the Physical Environment, and a Ph.D. candidate in Mechanical Engineering at the University of Minnesota. JANUARY FEBRUARY 1977