When I first began researching this story for QUEST, I was surprised that I hadn't heard more about geothermal power. It's never lumped into that renewable energy laundry list that's recited by politicians and journalists alike — you know, "…solar, wind, hydroelectric and biofuels". But it turns out that geothermal energy has really great potential.

To start, it's reliable. Geothermal is base load power, which means that the plants generate power at a constant rate around the clock. In fact, geothermal plants often have capacity factors of 86-95%, well above traditional base load generation such as coal.

It's clean. Geothermal power plants give off little or no sulfur compared to fossil fuel-fired power plants and they emit no nitrogen oxides. Emissions of CO2 per megawatt-hour are extremely low or absent for the newer flash plants. A typical geothermal plant may produce 1 lbs. of CO2 per MW hour. This figure compares with 1030 lbs. per MW hour of CO2 for a natural-gas fired plant, 1600 lbs. per hour of CO2 for an oil-fired plant, and 1820 lbs. per MW hour for a low grade coal-fired plant.

And, if the USGS assessment is accurate, and it probably is, geothermal power is abundant. According to the study:

"the power generation potential from identified geothermal systems range from 3,675 MWe (95% probability) to 16,457 MWe (5% probability); the power generation potential from undiscovered geothermal systems range from 7,917 MWe (95% probability) to 73,286 MWe (5% probability); and the power generation potential from Enhanced Geothermal Systems range from 345,100 MWe (95% probability) to 727,900 MWe (5% probability)."

So, what's wrong with it? As we touched on in the TV segment, there are several little drawbacks that no doubt should be considered. These include induced seismicity (little earthquakes that are triggered by geothermal developments), the initial expense of geothermal exploration and development, and the challenges of connecting the electricity generated by a geothermal plant to the grid at a point where there is sufficient available capacity to sell the electricity.

However, I was never really able to find a strong reason why geothermal energy should not be in everyone's renewables laundry list. And considering Obama included geothermal energy in his list during his last debate against John McCain, I would imagine we will all be hearing more and more about geothermal energy development in the months to come and beyond.

Watch the Geothermal Heats Up television story report online. And don't miss the steamy, behind-the-scenes photos for this story.

The 1992 'Peekskill' meteorite and its point of
impact in Peekskill, New York. Credit: "Pierre Thomas

The first thing I tell people is that I'm not a meteorite expert, but that I have a contact who is. This rarely discourages them from wanting to bring their rocks in for a look.

The first sample was brought in by a family who said they collected the chunk of iron from Lake Tahoe. This one actually looked promising to my mostly untrained eye: a fist-sized chuck of magnetic metal, with pits and holes and an overall melted look. I took some pictures to send off to our regional expert and told the family I'd call them to let them know what he said. The response to the pictures was pretty certain: it wasn't a meteorite, but a chunk of metallic slag. I was told that this is a common mistake; that often bits of slag from old foundries or other sources are taken for meteorites.

The second sample brought to me didn't really strike me as a meteorite, by appearance. It was metallic, but not magnetic; it was pretty heavy for its size; it didn't have any obvious signs of melting, and no real pits or holes-other than one, deep, tunnel-like hole the width of a finger. It didn't appear jagged or shrapnel-like, as fragments from an exploding metallic meteorite often do. Finally, it had wide, flat facets that looked much more like the result of natural rock cleaving as pieces of Earth's crust break apart.

I went ahead and performed a density measurement on the sample. It was pretty heavy, so our sensitive balance scales wouldn't handle the load. Instead, I resorted to our "learn your weight on other planets" scale-the one that tells you how much you would weigh on the Moon, Mars, and other planets, in addition to your Earth weight. (I found this scale useful when I had a package to mail and needed to know the weight; by selecting the Moon weight of the package, I would pay only one-sixth the normal Earth rate!)

The double-fist-sized sample was 11.3 pounds, which converted to 5126 grams. Then, I selected a graduated beaker from our lab, filled it with water and submerged the sample. Reading the difference in water level with and without the sample, I measured a volume displacement of 750 cc. So, the density-mass divided by volume-turned out to be about 6.83 grams/cc. That's twice the typical density of silicate-type rocks (stone), and fairly close to that of pure iron.

I sent the owner off with my appraisal that the rock didn't present the appearance of a meteorite, and though the density was in neighborhood of that of iron, the appearance (black, inside and out) and non-magnetic nature suggested some other metal or metal-stone mixture. As always, I encouraged him to seek an expert appraisal.

Let's face it, all rocks found on Earth are ultimately of extraterrestrial origin-though what we regard as Earth rock has been on Earth for many billions of years, and shaped, reshaped, and metamorphosed by eons of weathering and geological activity. Meteorites, then, are only the newcomers….