The Future of Electricity
Why renewable fuels can't solve all our problems
The hype these days makes it sound like renewable energy will play a starring role on tomorrow's electricity generating team.
But is that really likely?
Following the progress of renewable energy sources is like watching the newest guy or gal on your favorite basketball team. There's been a lot of pre-season publicity, but can he or she deliver?
Let's take a look at some of the stats for this energy player. Then we'll check out renewable energy's potential strengths, and weaknesses.
Green power scouting report
Often called "green power," renewable energy comes from wind power, solar power, and a variety of waste products that can be burned to make steam to turn the turbines that generate electricity. Right now, only 3 percent of the electricity generated in the United States comes from renewable sources.
But among America's electric cooperatives, nearly 11 percent of the electricity sent to member-owners nationally comes from renewable sources.
Why the big difference?
A lot of it has to do with location.
Remote rural areas are often the ideal places for wind power. One hundred and fifty electric co-ops either own wind turbines or buy electricity generated at nearby independent wind farms.
Minnesota, North Dakota, Missouri, Oklahoma, and Kansas lead the way in developing wind energy. Their position is ideal because powerful winds are common across the Great Plains and Upper Midwest.
Together, co-ops in those five states generate and distribute almost 600 megawatts of wind power. But individual wind power generating stations are rather small. In Oklahoma, one wind power plant provides just 74 megawatts. That's about enough electricity to supply a city the size of Covington, Kentucky.
In rural parts of the Southwest, large arrays of solar panels work well. In that region, sunshine is plentiful over many hours for many days of the year. A solar power plant near Boulder City, Nevada, produces 64 megawatts of electricity on 350 acres. Rural areas are often the only places with enough land available at reasonable prices for such sprawling solar facilities.
Nationally, many electric co-ops are also in just the right place geographically to take advantage of biomass renewable energy sources. The waste from rural timber products operations, such as sawdust and wood chips, is a renewable fuel for boilers to make steam to turn turbines. In other rural agricultural areas, animal wastes (everything from poultry litter to cattle and hog manure) are another potential renewable power source.
Converting trash to energy often happens in rural areas, too. Gas from landfills in small and medium-sized communities in Kentucky, Alabama, Indiana, and Vermont is being used to create steam for turbines.
Renewable energy does work. But not every kind of renewable energy works well in every state. Kentucky, for example, ranks as one of the least likely states for wind energy.
If renewable energy sources are going to contribute more than just a tiny portion of our nation's electricity needs, there are big problems that must be solved, involving:
Let's start with the problem of capacity, using the example of facilities that convert waste into energy. Whether these operations use wood chips at a lumber mill or methane gases at a landfill, they generate relatively small amounts of power. They can produce two, three, perhaps as much as five megawatts of power. Coal-fired generating stations produce hundreds of megawatts. It takes a lot of small waste-to-energy facilities to match what can be generated at just one coal plant.
Connecting the power generation to the consumer is another crucial issue. While rural areas have the advantage of being close to many different kinds of renewable energy resources, that can also be a problem. Remote locations mean that more transmission lines must be built over long distances to get that renewable power to more populated areas.
The question of reliability comes up because many renewable power sources are not constant. Wind speeds vary and solar power doesn't work at night or on cloudy days. Engineers call this intermittent power, and it affects the reliability of the electricity supply.
Our nation's complex electric grid is not very well equipped to deal with some of the unique reliability problems presented by power from these renewable sources. Sudden drops in wind speed can mean that one minute a wind power plant is generating enough electricity for thousands of homes. Then 20 seconds later, there's no power at all.
Sometimes the wind can blow too hard. That means turbines must be shut down for safety, which also interrupts the flow of electricity. More steady forms of generation, such as coal, must be able to respond immediately to fill in the gap without interrupting your electric service.
Solar power isn't as variable as wind power, but it's only available during a portion of any 24-hour period. When the sun sets, some other form of electricity generation must be ready to take over until the sun rises. Large, powerful batteries could store the power for use at night, but so far nothing strong enough has been developed.
Finally, cost presents an especially high hurdle for renewable energy.
Taking advantage of many forms of renewable energy is often much more expensive than traditional methods of generating electricity. Technology available today for solar power is particularly costly--up to 15 times more expensive than coal. Figuring out how to pay for building more renewable generating capacity may limit its use.
High costs are also limiting progress with two other renewable energy ideas.
Using the Earth's heat in geothermal systems often requires extensive drilling to reach areas with the proper temperatures. A geothermal project in the very early stages of development in rural Alaska will require drilling as deep as 12,000 feet, at a cost of about $200 million.
Substituting a renewable fuel, such as biomass, for part of the coal used in a conventional power plant is turning out to be costly, too. Often these substitute fuels have a much lower energy output pound for pound when compared to coal, so more fuel must be purchased to generate the equivalent amount of power. Even with a comparable energy output, the fuel itself may cost more per pound than coal.
Solving the technical and financial issues involved in making renewable energy a larger portion of the nation's electricity supply will take time. What's practical in one region may not be suitable in another region.
In the next issue of Kentucky Living, we'll take a look at how Kentuckians are helping make renewable energy a more valuable part of America's energy team.
Next month: Kentucky's green power programs
This story makes a lot more sense if you have some idea of what a megawatt is. In fact, most any discussion of electricity calls for knowing watts from megawatts.
For example, part of this story involves comparing different ways of producing energy. What does it mean that a wind farm can produce 74 megawatts when the wind is blowing?
Watts, kilowatts, and megawatts measure electric power. A 75-watt incandescent light bulb uses, of course, 75 watts of electricity when it's turned on. A kilowatt is 1,000 watts. A megawatt is 1 million watts.
A rule of thumb for what a megawatt means is that, in Kentucky, a megawatt is enough to provide 550 homes with electricity. That number varies from state to state, and will depend on the size of the house and its consumption patterns.
But using the 550-home guideline, that 74-megawatt wind farm could produce enough electricity for 40,700 houses. That would be equivalent to a city the size of Covington.
Coal-fired power plants tend to be much larger. East Kentucky Power Cooperative's Spurlock Station near Maysville generates about 1,100 megawatts--enough for more than 600,000 homes. That's enough to supply Covington and Louisville.
What happens to that comparison when the wind isn't blowing? That's a whole other story, bringing us back to the adjoining feature, which discusses the potential and problems of renewable energy.
WHAT ABOUT WATER?
The water that provides the energy to turn turbines at a hydroelectric generating station is a renewable resource. But statistics about hydro power are kept separate from other forms of renewable energy. Why? Because the volumes of water and certain other physical factors must be just right for hydro to work. Almost all of America's suitable river sources already have dams and hydroelectric facilities in place that are operating at capacity. In some areas, changes in water flow have meant that power from hydro has actually decreased during recent seasons.
In coastal areas, some people are beginning to experiment with using the power of wave action to generate electricity, but the technology just isn't ready yet.