I found this article from the Seattle Times pretty interesting. With all the talk about renewables for residential purposes I think geothermal is often overlooked especially within our region where solar and wind may not be cost effective. While geothermal may be an expensive up front cost the monthly savings could easily make up for that within 5-7 years. With efficient structures being built adding geothermal will allow for inexpensive heating and cooling and increased comfort year around.

For more information on geothermal click HERE

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HERE

Have you ever thought of using the natural heat of the earth to heat your house? It’s actually not a new idea but dates back to the time of the Roman Empire, when people used sources of hot water and steam that were near the earth’s surface to heat buildings. Because of modern technology, people can now use geothermal resources anywhere in the world to heat and cool their houses in an cost-effective way with a geothermal heat pump system!

What is a geothermal heat pump system?

A geothermal heat pump system is a heating and/or cooling system, which uses the earth either as a heat source in the winter or as a heat sink (to put the heat into the ground) in the summer. This is possible because ground temperatures remain stable throughout the year, at around 50-60 F.

This system is also known as “GeoExchange” system and “ground-source heat pump”. Geothermal usually requires a length of buried tubing on the property, a liquid pump back, and a water-source heat pump. There are both open loop systems and closed loop systems. Closed loop systems are more commonly used in households and circulate the fluid through the pipes and exchange heat between the fluid and the earth across the pipe.

Benefits

• Cut your electricity bills. Geothermal heat pumps systems save from 30% to 70% more energy than conventional systems, because they simply use electricity to move heat from the earth into buildings instead of burning fuels to generate heat. Geothermal heat pump systems thus bring in higher efficiencies, and can be up to 400% more efficient than conventional systems. Studies shows these systems can save the average family from US$400-1400/ year. In the summer, water is heated for free and only for a small cost in the winter.

• Save money in the long run. Geothermal heat pumps systems have a longer life span than conventional systems. Most loop fields are warranted for 25 to 50 years and are expected to last at least 50 to 200 years. You do not have to worry about replacing the system in the short term and once installed, systems can last twice as long as conventional systems.

• Convenient and safe. A closed loop system means no freezing of the flue vents in cold weather when you need heat the most. In addition, there are no gas lines, and therefore no potential for a gas leakage or fire.

• Friendly to the environment. The switch from fuel to geothermal reduces greenhouse gas emissions. There are more than 1,000.000 geothermal heat pumps already installed in the U.S. and the technology has reduced an estimated more than 5.9 million metric tons of CO2 annually and more than 1.6 million metric tons of carbon equivalent annually.

Cost
The initial cost of installing a geothermal heat pump system is usually two or three times than of a conventional heating system. However, some electricity companies offer special rates to customers who install geothermal systems, simply because it helps reduce their peak load due to the increased efficiency of heat pumps.

Want to know more?

• U.S. Department of Energy, Energy Efficiency and Renewable Energy (EERE)

• National Renewable Energy Laboratory, Geothermal Technologies

• GeoExchange

We are going to be installing a ground source heat pump. Which brands are the most efficient? Is it advisable to completely remove the existing furnace and air conditioner or since we live in a cold climate to keep the furnace for backup heat in case of extremely cold weather? We do have a natural gas fireplace that can assist in heating the house.

Ground source heat pumps, also called “geothermal,” are a hot topic these days.  Find the answer and learn more at the Minnesota Energy Challenge Ask the Experts section!

    The most expensive parts of our cost of living is our mortgage, food/health and our utility bill all monthly drains on our income.  In  a recent Ezine article ‘Is a risk free investment a fantasy’ I showed how to make your house a true investment and how to get rid of a mortgage quickly and increase your net worth dramatically in 7 to 12 years.  

      Now I am going to show you how to use energy that is just under your feet to decrease your heating and cooling bill.  This energy is free for your use and renewable.  The biggest reason I can think of that you may have not heard of it is that other methods worked just fine until our present concerns of the cost of oil, the environment and global warming and our national concern for how we are sending billions of dollars overseas to our enemies who control the oil and thus potentially our county’s future and security. 

       Understanding how to get to this energy is our next challenge.  Many parts of the country have already embraced this technology because of the lack of availability of fuel.    The cost of putting in a new system should not be a concern because there is approximately a 6 to 8 year return on your investment and this could be even less depending on the rising cost of fuel. 

     The temperature of the earth 6 feet down is 50 to 55 degrees Fahrenheit all year long and consistently almost anywhere in the world.  The concept for most non-technical people is the understanding the difference between temperature and heat energy and how heat pumps are able to transfer heat energy from one place to another and that the accumulation of the heat energy will produce a desired temperature.

      In the traditional furnace heater a high percent of the heat produced goes out the chimney along with CO2 and air pollution.  In a heat pump no fuel is burned so there are no emissions into the atmosphere and the heat pump produces as much heat as required. Because of how this system is designed the heat pump can be installed inside the home and because the heat pump is not exposed to the extremes of winter and summer the heat pump will last a lot longer.

      The Ground Source Heat Pump (GSHP) is not the only answer to solving the energy crisis but this geothermal energy is usually not thought of as a viable solution.  Other solutions are solar photovoltaic power, solar hot water, and wind power.  The equipment is not free but by combining the installation of any of the above with a risk free investment strategy the cost of the systems will be a lot less by decreasing the cost of borrowing other people’s money. Suprisingly the GSHP has the best return on your investment of all the above except may be windpower.     

      Another concern is how we build our homes.  If we would design our homes to be efficient users of energy the cost of heating and cooling a home would go way down.  In the future our homes could be designed to have a zero carbon foot print and require no outside utilities to heat, cool and power a home.  In the future we may consider living in earth sheltered homes that will take full use of the energy under our feet.

At first glance, the green credentials of ground source heat pumps (GSHPs) look unquestionable: because you’re harvesting free heat from the ground, you can get up to four times more energy out of the system than you put into it. Sure, it runs on electricity, which is more carbon intensive than gas, but because of this favourable ratio of output-to-input (called the COP for coefficient of performance) the system should still emit less carbon than a gas boiler – in theory.

But the claimed benefits are reliant on incorrect assumptions. A new house will emit about the same carbon using a ground source heat pump as with a new gas boiler. Here’s why:

The key factor is the carbon intensity of electricity from the grid. This is commonly stated as 0.422 or 0.43 kgCO₂/kWh. But these figures were proposed several years ago, when everyone thought the steady decline in grid intensity would continue. And it didn’t. Instead it levelled off at around 0.53 kgCO₂/kWh as shown in the graph below. (Data from BRE available here – pdf). For a realistic carbon calculation, we need to use a realistic grid intensity figure.

In addition, to maintain a high COP, GSHPs need to keep their output temperature low: around 40°C. This is why they work so well with underfloor heating. But domestic hot water should be stored nearer to 60°C, so a backup system is required to heat up the water the rest of the way. This is usually an electric immersion coil, similar in principle to an electric kettle, which requires more grid electricity - but this time without the COP advantage of a ground source heat pump.

For the purposes of comparison here’s a baseline house, using a condensing gas boiler and grid electricity.

Now here’s our house with a ground source heat pump and immersion coil backup for domestic hot water. I’m assuming the GSHP meets 60% of the DHW load.

So our GSHP house saves less than 2% of carbon relative to the baseline. That hurts, especially when you consider that installed costs for a GSHP are around £1000/kW, six to ten times as much as a gas boiler.  In addition, the above figures assume a COP of 4, but in practice the performance isn’t always as good as this. For example, Barratts recently found that the GSHPs at their scheme in Chorley Lancashire are averaging a COP of about 2.6.

So here’s an illustration of how the assumed carbon intensity of the grid affects the carbon savings of GSHP versus the baseline gas boiler system:

From the above graph it looks like the scheme at Chorley would have emitted much less carbon if they’d stuck with condensing gas boilers.

Having said that, the environmental performance of GSHPs does look better if compared against a system based on a higher carbon fuel, such as heating oil. Here’s the same table, this time compared against a baseline using heating oil at a carbon intensity of 0.265 kgCO₂/kWh:

So the GSHPs look better here. At today’s grid intensity, a GSHP with a COP of 2.6 (like the ones at Chorley) save 6.5% carbon vs. a new system based on heating oil. At a COP of 4, they save 17% (though a gas system would save 15.5% anyway since gas is so much less carbon intensive than heating oil).

Where does this leave GSHPs? The use of domestic GSHPs where gas is available is very questionable. If gas is unavailable and you’re replacing a high carbon fuel such as heating oil (and the GSHP performance is able to match manufacturers’ claims) then they do make environmental sense. But you’d need to look carefully at whether you’d get more carbon benefit by spending your money elsewhere (e.g. biomass).

And of course you could always power a GSHP from a turbine or PVs but again, you may want to look carefully at alternative heating systems that would give you more carbon savings for your money.