Yes, I got dragged into a discussion on Usenet the other day. Since some of what the poster was spewing gets repeated as gospel but has little to do with actual facts or science, I decided I should discuss it here as well.
Burning stuff to produce energy is a dying technology. Why try to resuscitate it when clean, sustainable alternatives are all around us waiting to be harnessed; technologies in which the “fuels” themselves — the Sun (wind and solar), the Moon (wave and tidal) and the Earth (geothermal) — are free and unlimited?
In any case “clean coal” schemes never turn out to be economical, even without considering the hidden and other costs and problems. They always end up requiring massive subsidies to operate. I doubt this one will prove any different.
Well, to start with, geothermal is neither free nor unlimited. It is also not without significant risk. There is a limited amount of heat trapped in the core of the earth. While many may debate about the size of that gas tank and if there are still celestial reactions happening at the core of the planet much like happen on the sun all scientists agree the sun will eventually die like every other star in the sky.I must preface this discussion by saying I used to own a Failing 1250 drilling rig and have attended their annual drilling school which is attended by drillers from all over the world.
One must be specific when they speak of geothermal. Are you speaking of TRUE geothermal or what is currently being sold in the United States for heating systems?
True geothermal requires you drill very deep or that you live on the edge of an unstable tectonic plate like Iceland. Drilling into such a plate to extract heat/steam increases the activity of the magma below by weakening the plate containing it. This leads to the volcano from Hell incidents, billions of tons of toxins and ash being spewed into the air and a cessation of all air travel for thousands of miles.
The path of “drilling very deep” through more stable plate locations has even more issues than drilling for oil. Roughnecks used to call it “Devil’s Brew.” Crude is hot, but not like that. The high heat can cause blowout protectors to cease, make everything too hot for humans to operate and lead to cascading equipment failure. It can be done but it puts every potable water vein it crosses at risk. Not all water underground is potable, meaning humans can drink it. Most of the water underground is too contaminated for current filtration/purification technology to make usable. In many areas of this country a water well of more than 800 feet either is highly contaminated with sulfur or soon will be due to increase natural gas production and storage. I life not far from one of the larger “natural domes” used for storage. The more gas they pump in the more sulfur comes out. Water veins at 800 feet used to be free of sulfur when I was a child, a statement which is not true today.
Either approach is pulling heat from the limited supply at the core of the planet causing it to cool sooner. Keep that thought in mind as it will be important later.
Early geotherm heating systems sold in the United States came in a few flavors. The one I read the most about because it was the cheapest to install was the draw & return system. This required at least 2 water wells with a total depth greater than 1500 feet. The system drew cold water (55-65 degrees depending on depth and location) ran it through the system then returned it into the second well. These systems are basically banned now. Why? They contaminated drinking water aquifers. The disposal or “return” well system is basically the same system used by the oils and gas industry. It was simply scaled down so consumers could afford it. Scaling down meant not drilling to the depth of an oil well for disposal.
Note: If you follow that link and actually read you will find most traditional geotherm as well as water from oil & gas contains a cornucopia of stuff toxic to humans. What most people fail to realize is that it also contains NORM (Naturally Occurring Radioactive Material). The presence of NORM lends credence to theories the earth’s core still has celestial chain reactions occurring. Some of those theories also go a long way to explaining gravity. Why some great big rocks in space have it and others, even bigger in size, don’t. My personal belief is:
cold core = dead rock hot core = live planet with gravity and atmosphere
“Modern” geoloop heating systems use miles of coiled tubing looped around the property with specialized heat transfer grout. Different systems go to different depths. Water based systems require some form of antifreeze. DX systems use refrigerant which will not contaminate ground water when a leak happens but it will either damage the ozone or dramatically increase green house gas effect depending on which refrigerant.
As to your “subsidies” remark, I used to live in a picturesque part of the midwest. Now I live in the middle of an ugly eyesore. I didn’t move. Federally subsidized windmills are going up. Once the government subsidy runs out it will become yet another abandoned wind farm and the fools who signed contracts letting those things get put up will find their land up for auction because it was used as collateral for the construction loans.