Geothermal (Ground-Source) Heat Pumps (GHPs) make use of a completely different set of principles than the kind of geothermal we commonly discuss. Where the latter relies on the transfer of thermal energy from one fluid to another, like an egg placed in boiling water, the former relies on the principles of refrigeration, i.e., the evaporation and condensation of a substance in an enclosed space.

But considering that many people are unaware of this, how large an effect does public ignorance have? It’s huge, according to the U.S. Department of Energy, which dubs this effect a GHP “energy crisis” in their recent report:

The basics of GHP technology have changed very little over the decades but a geothermal identity crisis has been detrimental to fostering awareness, understanding, and acceptance of the technology. Depending on the perspective, GHPs have been cast as an energy source by many names (renewable, geothermal, solar, earth, alternative, recycled), as energy efficiency or energy conservation, or as an option within a broader category such as utility demand-side management.

There’s plenty to get excited about in GHPs, whose basic concept is that even very cold water or cold air contains an appreciable amount of energy that be extracted and moved very inexpensively.

In the coming month or two, I hope to corral GHP expert and professional consultant Mark Metzner for a webinar on the subject. I’m sure listeners will be surprised and delighted to learn how simple, inexpensive and ridiculously underused this technology is. More soon.

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• New Geothermal System Taps Heat Without Geological Risks, Firm Says
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A U.S. startup says it has developed an enhanced geothermal energy system (EGS) that engineers say can tap into heat from the Earth’s interior without any associated risks of triggering earthquakes or polluting underground aquifers.

While typical EGS processes require developers to pump liquids into deep wells at high pressure, a process that has on occasion triggered small earthquakes, GTHerm has developed an approach that doesn’t require fracturing or water cooling.

Instead, the process includes installation of a solid-state heat exchanger, or “heat nest,” at the bottom of the well that can more efficiently draw heat from surrounding rock with the help of a highly conductive grout encasing the heat exchanger.

Fluid is sent down the well in a closed loop that carries the heat back to the surface, where it creates steam that drives electricity-generating turbines. “We’re basically a heat pump on steroids,” said Michael Parrella, CEO and founder of the Connecticut-based company.

The company, which is now testing the commercial feasibility of the technology, hopes to have demonstration plants in place as early as 2012.

Article appearing courtesy Yale Environment 360.

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The most unusual place to harvest energy from the sun is perhaps also the most effective and efficient – underground. Earth absorbs nearly 50 percent of the sun’s radiation that reaches the surface and stores it as heat that can be used to warm up or cool down homes and other buildings – without polluting the environment. All you have to do is exchange it between subterranean sources and the surface with a mechanical device called a geothermal heat exchange (GHX) system.

According to the Department of Energy, GHX systems use 25 to 50 percent less electricity to operate than conventional natural gas and electric HVAC systems and move three to five times more energy than the electricity they consume because they are extracting it from the ground. The aggressive deployment of GHX in the U.S. could save $30-40 billion in energy costs annually while greatly reducing greenhouse gas emissions, according to Richard Butler of EnLink Geoenergy Services in Rancho Dominguez, Calif.

Butler outlined the design, installation and workings of GHX systems during a public workshop held at the California Center for Sustainable Energy in San Diego, Calif. He said that although GHXs are more costly to install than traditional HVAC systems, the additional up-front costs are returned in energy savings in five to 10 years. GHXs have lower operating costs because they take advantage of “the only renewable energy resource that is available everywhere, on-demand, and that cannot be depleted.”

Moving the Heat

Using geothermal sources for heating and cooling is not the same thing as geothermal power or even geothermal heating, both of which have to do with geologically hot rocks that produce heat used to generate electricity or to heat a building. Instead, a GHX system takes advantage of the fact that a few yards below the earth’s surface the ground remains at a relatively constant temperature, generally from 45°F to 75°F depending on the location’s latitude.

A GHX extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling). There are two major components – an earth heat exchanger that is buried underground and a geothermal heat pump located inside a building.

The heat exchanger is basically a loop or a series of loops of polyethylene plastic tubing buried underground through which either water or an antifreeze solution is pumped. Tubing can be installed horizontally in trenches or vertically as a series of U-shaped wells. Some systems employ copper tubing and a refrigerant to capture the heat.

Depending on the location, soil conditions and other factors, the heat exchanger may be a few yards to a couple of hundred feet deep. Because digging and drilling is costly, the heat exchanger accounts for a third to a half of GHX costs.

The geothermal heat pump is the central handling unit for the GHX system and acts much like a standard HVAC system. The heat exchanger fluid circulates through the heat pump where an electrically driven compressor and a heat exchanger concentrate the earth’s heat energy and release it inside the home at a higher temperature.

In summer, the process is reversed with the underground loop drawing excess heat from the house and allowing it to be absorbed by the earth. The system cools in the same way that a refrigerator keeps food cool – by extracting heat from the interior, not by blowing in cold air, Butler explained.

Benefits of GHX

Direct-exchange geothermal heating and cooling systems have been around for more than 60 years and became popular in Sweden in the 1970s. Their use has spread worldwide since then, with about 80,000 systems installed annually in the U.S. In addition to lowering energy costs and nearly eliminating onsite greenhouse gas emissions, GHX systems offer energy efficiencies between 300 to 600 percent, according to Butler.

“For every kilowatt of electricity consumed by a GHX system, it can deliver three to six kilowatts of energy to heat or cool your facility,” Butler said. “This translates to using 40 to 70 percent less energy than conventional HVAC systems. GHX systems are a sound investment with a guaranteed payback.”

Financing a GHX system is made easier because they are considered renewable energy and energy efficient technologies, making them eligible for incentives from multiple sources. Federal, state and local governments, as well as many utility companies, offer rebates for GHX projects.

Further Information:

GEO Trade Association

International Ground Source Heat Pump Association

Dept. of Energy – Energy Savers Information

Federal Tax Credits – 30% of cost for geothermal exchange systems

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I recently finished reading  a book I strongly recommend to anyone interested in sustainable development and energy. It is packed with figures and findings that I believe will easily start discussions among CleanTechies.

The author, David JC MacKay, is Professor in the Department of Physics at Cambridge University and was recently appointed Chief Scientific Advisor to the UK Department of Energy and Climate Change responsible for the Low Carbon Transition Plan.

One of the main findings of this book is that electrifying our cars and installing heat pumps in our buildings would enable us to cut significantly both our greenhouse gas emissions and fossil fuel consumption. Both solutions are much more efficient than the current traditional ones and could benefit from massive electrification to answer all our energy needs.

Below is a selection of the book’s key findings:

Sustainable Electricity: MacKay believes that the UK and Europe in general can’t count solely on renewables. He shows that wind, biofuels, hydro, solar PV and other energy sources don’t add up enough energy to answer our current needs and will do so to an even lesser extent in the future, once we have a strong electrified transport sector.

So we need a plan that provides additional resources, for example concentrated solar (like the Desertec project), or nuclear, or a combination of both. Clean coal may also add up enough electricity if proven viable.

North American Energy Consumption: The author notes that the continent should first and foremost decrease energy consumption from 250 kWh per person per day to the current European or Japanese levels of 125 kWh. This could enable the continent to rely solely on renewables with the installation of concentrated solar in its deserts.

European Energy Consumption: With Europeans consuming the equivalent of 125 kWh per day per person, we see a breakdown of transport accounting for 40 kWh per day, and heating for another 40 kWh. Delivered electricity amounts to 18 kWh but due to the inefficiencies of the system, this comes from 45 kWh of energy. With improved efficiency, we could go from the current 125 to around 80 kWh, a figure similar to that of Hong Kong. (This simplification for the sake of the argument doesn’t take into certain factors that are are tackled in detail in the book.)

Future Scenarios: In chapter 27, the author gives five examples for plans that add up enough electricity. The baseline plan is as follow: Clean coal 16 kWh per day per person, nuclear 16, tide and wave 5.7, hydro 0.1, waste 1.1, pumped heat 12, wood 5, solar thermal 1, biofuels 2, solar PV 3 and wind 8. The four other plans give more or less importance to each of these energy sources. In one plan, nuclear accounts for 44 kWh when in another plan, wind energy accounts for 32 kWh.

Transportation: Today, electric cars need as little as 15 kWh for 100 kilometers while models running on oil need 70 to 90 kWh. Hence, electric cars are already five times more efficient than current conventional models. (Side note: SUVs – also called spaceships by the author – need around 120 kWh…) High speed rail and other sustainable alternatives also have to be pushed forward. A full high speed train only consumes as little as 3 kWh per passenger, and biking consumes even less: 1 kWh.

Housing and buildings: The author is an advocate of both retrofitting and reducing the winter thermostat from 20°C to 17°C, which alone brings savings of 30% (page 292). By combining both solutions, David MacKay halved his heating bills. With a coefficient of performance (COP) of 4 to 5, heat pumps retrieve the heat contained in the outside air or soil and distribute it indoors. Another advantage of this solution is that it can bring air conditioning during hotter days.

The book is available for free on the official website. You can download it in one document or read it per chapter. The paper version can be bought for around $32 / €22. Published this year, it is up to date and explains simply but most effectively (and with a good sense of humor) how we can create a low carbon energy economy.

Grade : 20/20. A must read.

Readability: Maximum as it brings a lot of data.

Further information: MacKay in a recent article on the BBC – most interesting.

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Phoebus Energy unveiled its hybrid water heating system last week at the community center in Gilo, a neighborhood of Jerusalem, according to an article in The Jerusalem Post.

Phoebus Energy, founded in 2007 with $2 million in seed funding from Terra Venture Partners, has developed a hybrid heat pump system that integrates with existing oil-based systems to make them more efficient. Newly appointed CEO Yaron Tal told The Jerusalem Post that Phoebus Energy’s system saves between 50 and 70 percent of oil and reduces pollution by 80 to 90% compared to a traditional heat pump system.

“The Phoebus system is based on a complex algorithm that we developed which governs when to use the oil-based system and when to use the heat pump. It constantly monitors many parameters to decide which way is most efficient to generate heat,” Tal said. “The system measures such parameters as the temperature outside, the temperature of the water, and the price of the oil. Several of the parameters change a number of times throughout the day,” he continued.

Phoebus Energy has already installed its system in eight locations in Israel, from kibbutzim to community centers to hotels, according to The Jerusalem Post. Phoebus Energy’s solution targets medium and large water heating systems, such as those found in hospitals, hotels, factories and large apartment buildings. The company is also already in negotiations with potential clients abroad, Tal told the Post.

Heat pumps had been around for a long time as a means to heat water, Tal said. Phoebus Energy heat pumps take an ecologically safe version of freon to transfer energy to water. The freon flows at high pressure at a temperature of 5º Celsius. Air is then pushed into the freon, which heats the freon. At 12º, the freon turns from a liquid into a gas. The gas is then mixed with the water, which heats the water, Tal said. The company managed to get the pumps to heat water to 55-60º Celsius, as opposed to other models that only reached 30-40º, he said.

The use of heat pumps cut oil use tremendously, thus reducing costs and pollution, he said.

Shalom Turgeman, who runs the Gilo community center, said in a statement, “The expected savings run into the hundreds of thousands of shekels, but the real point is that we are taking a step for a greener Earth and fighting the air pollution in the Gilo neighborhood.”

Until now, the community center, one of the largest in the country, burned more than 100,000 liters of oil per year to heat the swimming pool, water for the showers and bathrooms, and the gym.

Yaron Tal, previously the President & CEO of TopSpin Medical, was appointed CEO of Phoebus Energy earlier this month. Yoav Ben Yaacov, the Founder and former CEO of Phoebus Energy, is now the company’s VP Marketing & Sales.

It was reported last month that Phoebus Energy recently completed a financing round of $1 million from Galilaea Fund.

This article first appeared on Jonathan’s blog, CleanTech Israel

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