August 22, 2008

AltaRock Taking Geothermal Energy to the Next Level

I haven't done much research on geothermal energy, although I did a post about geothermal heat pumps a while back. But I stumbled upon a company named AltaRock Energy who believes they have a scalable geothermal solution. It looks very interesting.

As AltaRock points out on this page, the nice thing about geothermal energy is its 24x7 availability. I love wind power, but wind has a major achilles heel: the wind doesn't always blow & might not be blowing at the most critical, high demand periods. How can you rely on that? Without major improvements in battery technology (which is very expensive by the way), you can't. The same thing holds true for solar since they sun doesn't help much at night.

Geothermal's problem has been the fact that there aren't that many places that fit the conventional geothermal hot spot description. These are spots that have natural reservoirs of super-hot water deep in the ground. Think Iceland & Yellowstone National Park. We've long known we can tap into those hot water reservoirs, pump the liquid up & use the steam to spin turbines & create electricity. The issue is that there aren't enough of these naturally occurring hot spots to exploit (plus they often reside far away from populated areas).

AltaRock has a solution. They inject cold water at high pressure deep into the earth ("hot basement rock"). The water fractures the rock & essentially creates pathways & areas where the water can pool up. As the water flows through the hot basement rock, it heats up. Hot water is then pulled up to the surface via wells. This diagram below shows how the entire system works:

Underwriting this company's development are major VC firms like Khosla Ventures, Kleiner Perkins, and Google.org. AltaRock just closed a $26 million second round of financing [PDF requires Adobe Acrobat].

I couldn't find any information on costs associated with the AltaRock geothermal system, but the idea seems really interesting on the surface. Who knows? Maybe it's incredibly expensive, or maybe it's an EROEI dog ... but certainly one to watch.

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March 14, 2007

Geothermal Heat Pumps

Being fascinated by renewable sources of energy, I like to learn and read about where renewable energy is heading. I should, however, spend more time becoming familiar with the options available in the here and now. One option I know next to nothing about is geothermal energy. This article on geothermal heat pumps caught my eye, so I decided to do a little digging to find out more about this renewable source.

What is a geothermal heat pump?

A geothermal exchange heat pump, also known as a ground source heat pump or GSHP, is a heat pump that uses the Earth as either a heat source, when operating in heating mode, or a heat sink when operating in cooling mode. All geothermal heat pumps are characterised by an external loop containing water or a water/antifreeze mixture (propylene glycol, denatured alcohol or methanol), and a much smaller internal loop containing a refrigerant. Both loops pass through the heat exchanger.

Geothermal heat pumps have the ability to act as either a heat source or heat sink because the Earth's temperature below the frost line remains relatively constant.

During the winter, the fluid collects heat from the earth and carries it through the system and into the building. During the summer, the system reverses itself to cool the building by pulling heat from the building, carrying it through the system and placing it in the ground. This process creates free hot water in the summer and delivers substantial hot water savings in the winter.

Sounds pretty brilliant, doesn't it? Must be a catch ...

Ah, yes. GSHPs cost more upfront than conventional heating/cooling systems. In our two-second-attention-span, profit-obsessed society, anything that costs more money upfront - even if it pays down the line - seems to get benched in favor of the option that saves the most five minutes ago. The more you look at renewable, the more you see that the need for immediate profits is the single biggest barrier to more widespread adoption.

According to the International Ground Source Heat Pump Association, "[GSHP] Investments can be recouped in as little as three years." Plus, GSHPs are very efficient:

The GSHP is one of the most efficient residential heating and cooling systems available today, with heating efficiencies 50 to 70% higher than other heating systems and cooling efficiencies 20 to 40% higher than available air conditioners. That directly translates into savings for you on your utility bills.

GSHPs are also durable, long lasting systems:

The GSHP contains fewer mechanical components, and all components are either buried in the ground or located inside the home, which protects them from outside conditions. The underground pipe carries up to a 50-year warranty.

I'm not seeing a lot on the negative side of the whiteboard. In fact, I'm starting to fall in love with GSHPs:

GSHP systems conserve energy and, because they move heat that already exists rather than burning something to create heat, they reduce the amount of toxic emissions in the atmosphere. They use renewable energy from the sun, and because the system doesn't rely on outside air, it keeps the air inside of buildings cleaner and free from pollens, outdoor pollutants, mold spores, and other allergens.

Are you concerned about the environment and looking to reduce your energy or carbon footprint? Then maybe you should consider installing a GSHP system in your residence. For a list of available financial incentives, check this site out.

I'm going to dig for some less positive information about GSHPs. If and when I locate anything, I'll update this post.

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