Wind and solar energy are very hot topics in today's energy discussion.

Wind energy has been in existence since the '70s and has many advantages over other forms of energy. The seemingly endless white stalks sprouting on the California hills along Interstate 10 in Palm Springs may offer onlookers a slight relief from the shared human guilt of our polluted environment. With no emissions and no fossil-dependent fuel, wind farms seem to be a refined choice above a carbon cap system or uranium-reliant nuclear power.

According to the EIA, nuclear energy had an average capacity factor of 91.8 percent in 2007-the average capacity factor referring to possible generation divided by actual generation, multiplied by 100. In comparison, average capacity factor for wind was 27.2 percent. TVA's Buffalo Mountain plant yields a 22-25 percent capacity factor. Solar capacity factor varies greatly by region but in 2005 it was 18.8 percent, according to UT Professor of Engineering and Head of the nuclear Engineering Department, Dr. H. Lee Dodds.

Land use is a primary concern for wind energy. Dodds says it takes 3,000 1 MW wind turbines, occupying 40-70 square miles of land, to produce the same 1000 MW of energy as one, 1/3 square mile nuclear power plant (that's upwards of 44,800 acres versus 213 acres). This figure incorporates the average capacity factor of a wind turbine.

But the development and engineering department at Invenergy LLC, the company that operates TVA's Buffalo Mountain wind farm, says that the average space taken by a turbine is about ¼ of an acre once all reclaim has been completed following construction.

A 1000 MW nuclear power plant is probably only producing 920 MW, assuming the 2007 statistic of 92 percent capacity factor.

So using this 27percent capacity factor on a 1 MW wind turbine, it would actually take (920 MW/0.27 MW) 3408 wind turbines to produce the same 920 MW of energy as one nuclear power plant.

A more common wattage for wind turbines is 1.5 MW--GE Energy has both this and a 2.5 MW model on the market. For offshore wind production, they have a 3.6 MW turbine. Twelve out of 14 of Invenergy's wind farm sites use GE's 1.5 MW wind turbines.

Using this 1.5 MW figure, it would take 2244 wind turbines (the 1.5 MW figure gets knocked down to 0.41 MW) to produce the same 920 MW of energy as one nuclear power plant.

Now for land usage. If it's true that each turbine takes ¼ acre of land, then the 3408 turbines required for a 1 MW wind farm would only take 852 acres.

1-4 percent of the land is taken up by the access roads and turbines--the rest of the land can still be used Susan Dennison, communications manager of Invenergy LLC

The 2244 1.5 MW wind turbines would take up 561 acres.

Efforts are also made to reclaim the land after construction to allow for its continual use.

"The majority of our wind sites are on. . .agricultural land. One of the things that makes wind attractive is that, depending on how the turbines are sited. . .1-4 percent of the land is taken up by the access roads and turbines-the rest of the land can still be used," said Susan Dennison, communications manager for Invenergy LLC.  "You still have the roads, but farmers can plant right up to the foundation if they wanted to."

Proper environmental management planning can reduce the incidence of wind farms ruining natural ecosystems. Buffalo Mountain's 15 Vestas-V80 wind turbines generating an expected annual output of 50,000,000 kW (enough to light 5,000,000 100-watt light bulbs for one hour) were actually built on a reclaimed strip mine-perhaps a smarter way to make use of already degraded land.

The wind turbines tower to 256 feet with blade lengths of 139 feet-that's about a 25 and 14 story building. A turbine running for 6 hours can power the average U.S. household for an entire year, using a 2001 Department of Energy approximation of 11,000 KwH per household per year.

It takes about 3-6 mph of wind to turn the blades. This speed is dependent on air density which varies with altitude (pressure), temperature, and humidity. The power available increases as air density increases-and air density decreases with increasing temperatures, altitude, and humidity. So on a lethargic summer day the massive steel structures feel lazy themselves, and a less favorable power output may be obtained.

The maximum speed is 55 mph. Once this wind speed is exceeded, the turbine shuts down to avoid system overload.

Complaints for wind energy most often revolve around noise pollution and visual and wildlife impact. Standing directly underneath the blades and looking up, there was a slight "whoosh" noise as the blades turned coupled with an audible high-pitched sound. The noise from afar was arguably hushed.

Winged animals have been a main concern for environmentalists regarding wind turbines. According to the 2008 study conducted by Erin Baerwald and his colleagues at the University of Calgary in Canada, there's a low pressure system created near the blades that fatally expands the lungs of the bats. This phenomenon is known as barotrauma. The report can be found here.

Wind and solar energy cannot be used reliably for base-load power, which is needed 24/7. As is said often, harvesting wind for energy can only work when the wind blows and the sun shines. Natural gas is the prescribed backup plan, a costly form of energy that has also negative environmental connotations. In 2006, consumption and flaring of natural gas accounted for 1187.48 million metric tons of carbon dioxide in the atmosphere, according to the EIA. 

But private ownership of wind and solar utilities is another possibility, cutting down on the need for transmission lines from possibly faraway plants. Organic farmer Leaf Myczack from Roane Co., Tenn. has a solar oven that he cooks his food in.

We get it [uranium] from Canada, from Australia, and from 14,000 Russian warheads that we've down-blended Scott Peterson, VP of Communications in Washington, D.C.

"It collects sun, and as the sun moves you go and you give it a little tweak and you turn it, and at the end of the day it's like a crock-pot," said Myczack. "You go and you take your food out, and it's all cooked."

He also has solar panels that use batteries for energy storage.

The EIA tracked that renewables accounted for the largest share of energy subsidies in 2007, nuclear falling behind refined coal and natural gas. This is frustrating to many who would like to see nuclear taking up a bigger share of the pie.

"As much as Congress likes nuclear power, it likes other technologies more," said NY Times reporter Matthew Wald at July's McCormick Specialized Reporting Institute on nuclear power here at UT. "It gets proportionally more loan guarantees and in many states it gets a guaranteed market: a quota."

But what about the supply of uranium? Is it smart to invest in yet another technology that has limited resources? According to Scott Peterson, VP of Communications in Washington, D.C. for the Nuclear Energy Institute, uranium is plentiful and there are supply reserves within America's border in case the other three sources were to fail.

Dodds says that the real future of America relies on energy diversity, including fossil fuels and renewables in addition to nuclear.

"We get it from Canada, from Australia, and from 14,000 Russian warheads that we've down-blended, taking the uranium out of those warheads and turning them into fuel for our reactors," Peterson said at the McCormick Institute. 

He continued, "The day to day application of that is that 10 percent of the electricity generated in this country comes from Russian warheads...So not only is that a cost-effective energy efficiency story, that's a tremendous non-proliferation story."

No issue is black and white, especially nuclear-there are numerous other concerns including safety, economics, environmental effects, storage of spent fuel, and transmission that still need addressing in this multi-faceted and controversial debate.

For now it is inevitable that the U.S. will continue using, and investing in, nuclear energy technology. Dodds says that the real future of America relies on energy diversity, including fossil fuels and renewables in addition to nuclear.

Germany, which Newsweek was advised to feature as the leading green nation in 2008, thinks somewhat differently.

"Germany is playing a pioneering role here," reads the Jan. 2009 "New Energy-New Thinking" pamphlet from the Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety. "It can demonstrate that even a large industrial nation can achieve economic growth and climate protection without nuclear energy."

Whether America will increase investments for nuclear in the long run is questionable, but one thing is for sure-we don't want to be left behind.