THE Geothermal Thread (merged)

Devil · Posted: Tue Oct 12, 2004 1:21 am Post subject:

I can possibly help. Ideally, a heatpump should have its cold end in running water or a large water body. For example, the Swiss Federal Institute of Technology in Lausanne is heated via a heatpump (or rather several) and its cold end is in Lac LÃ©man (Lake of Geneva).

Whether a pump would work from a buried heat exchanger depends on the strata. In most cases, you will be disappointed. You must have a source of heat energy at the cold end. The ideal would be where there was good heat conduction from a geothermal source, such as underlying magma or water heated therefrom. This is much exploited in Iceland, for example. However, the chances of finding such heat at a reasonable depth are negligible in most places. The only other hope is to find an inclined stratum of very porous rock through which there is an important water flow, so that your cold end is at constant temperature, no matter how much heat you extract from it.

The worst-case scenario is that your cold end becomes colder, in which case you may set up a snowball effect until the efficiency drops to near-zero, with no heating. This happened to a householder I know of (I have never met the guy). He bought a hectare of land and built his house thereon. He buried kilometres of water pipes over the whole land surface at about 1 m depth (at great expense!). Come the first winter, he started basking in the heat from his installation, working at 300% efficiency. By December, he started wondering why he was having problems keeping the house up to comfort level and by February he could not heat it above 15 deg C. The manufacturers came in, and found the water going into his cold end heat exchanger was at 4 deg C instead of 14 deg C, as it had been. Effectively, he had cooled down the ground over his hectare at 1 m depth by 10 deg C by heating his house up by a similar amount. There was no water flow through the land at that depth. It transpired later, when this became well-known in the local press, that the heat pump manufacturer had advised the guy not to do it that way, but he didn't listen.
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Devil

BabyPeanut · Posted: Tue Oct 12, 2004 7:10 am Post subject:

How very interesting. It just so happens that my house is situated right across the street from a creek. I wonder if the temperature of the surrounding land on the other side of the street from the creek will be affected enough to be a useful source of heat?

Devil · Posted: Wed Oct 13, 2004 2:11 am Post subject:

Can you put the pipework in the creek itself? That would be ideal.
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Grasshopper · Tar Sands Joined: Aug 18, 2004 Posts: 69 Location: Canada

I wonder about the riparian rights ramifications of all creekside residents taking a few calories a day through the winter from a creek. Would enough heat be taken that the water would stop flowing? Would all the heat-exchangers have to be rationed?
Seriously, I think it's a good space heating solution, which will eventually replace a lot of fuel oil and natural gas systems as the cost of fossil fuels rise. Being able to exchange heat from a large body of water, or flowing water is the most efficient approach, but if there is an aquifer (water-filled porous rock, as Devil mentioned) that you can get heat from, you are well off, too. A network of deeply trenched (more than 1 metre) piping on your own property will work, especially if there is an aquifer present (you don't have to pump the water out, just exchange heat through a loop).
You should get quotes from more than one contractor on the length of pipe and volume of system that you would need. I think I would only go this way (and I have been thinking about it) if I could install extra capacity so an especially cold or long winter would not result in the problems encountered by the bad example mentioned by Devil.
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JackBob · Posted: Wed Oct 13, 2004 9:13 am Post subject:

BabyPeanut · Posted: Sun Jan 30, 2005 9:08 pm Post subject: geothermal heating in the news

savethehumans · Light Sweet Crude Joined: Oct 20, 2004 Posts: 1541

Nice to see so many "see the light," or the heat, in this case! Smile

Backpacker · Posted: Mon Jan 31, 2005 3:03 pm Post subject:

I work as an HVAC technician. There is one development we service that has geothermal. They work very nicely. Knowing Americans, though, they will wait until peak oil hits before they decide to go geothermal and then, of course, they will all want it done right now.
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BabyPeanut · Posted: Mon Jan 31, 2005 7:56 pm Post subject:

Backpacker · Posted: Mon Jan 31, 2005 8:11 pm Post subject:

It is good that some are doing it now before the crunch hits but it is only a very tiny segment of the population. My company installs new heating systems and the ceveloppers will not even consider geothermal. They continue having us install gas and oil furnaces. When I speak to them about peak oil and how fossil fuel prices are going to continue skyrocketing they just laugh. They are not peak oil aware and are under this delusion that fossil fuels will last forever. It is going to take years to convert the majority of American homes to non-fossil fuel forms of heating. One problem is that it is so expensive but some state govts. are helping out. The state of New Hampshire offers a zero interest loan to homeowners to convert to geothermal, which is repaid over a reasonable time through your electric bill. People are notorious for waiting until the last minute. They wait till the last second then expect you to drop what you are doing, cancel your plans, and take care of them first. As peak oil hits it is going to be a gigantic bottleneck of this. I am not going to volunteer to answer the phones at that time.
FHP is a very good mfg. Their engineers will design the underground loop for you if you buy from them. Keep up with your plans. You will be fossil fuel free for you home heating before the crunch hits. If only more would think like that. Smile

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Graeme

I copied this from the IGA newsletter June 2003:
Status of Geothermal Energy Amongst the World´s Energy Sources (Part I)Ingvar B. Fridleifsson, United Nations University
- Geothermal Training Programme, Orkustofnun, National Energy Authority, Iceland
Abstract: The world primary energy consumption is about 400 EJ/year, mostly provided by fossil fuels (80%). The renewables collectively provide 14% of the primary energy, in the form of traditional biomass (10%), large (>10MW) hydropower stations (2%), and the new renewables (2%). Nuclear energy provides 6%. The World Energy Council expects the world primary energy consumption to have grown by 50-275% in 2050 depending on different scenarios. The renewable energy sources are expected to provide 20-40% of the primary energy in 2050 and 30-80% in 2100. The technical potential of the renewables is estimated 7600 EJ/year, and thus certainly sufficiently large to meet future world energy requirements.
Of the total electricity production from renewables of 2826 TWh in 1998, 92% came from hydropower, 5.5% from biomass, 1.6% from geothermal and 0.6% from wind. Solar electricity contributed 0.05% and tidal 0.02%. The electricity cost is 2-10 US/kWh for geothermal and hydro, 5-13 US/kWh for wind, 5-15 US/kWh for biomass, 25-125 US/kWh for solar photovoltaic and 12-18 US/kWh for solar thermal electricity. Biomass constitutes 93% of the total direct heat production from renewables, geothermal 5%, and solar heating 2%. Heat production from renewables is commercially competitive with conventional energy sources. Direct heat from biomass costs 1-5 US/kWh, geothermal 0.5-5 US/kWh, and solar heating 3-20 US/kWh.
Keywords: geothermal, electricity, direct use, comparison of renewables, energy prices.
1. Introduction: With increasing awareness of the detrimental effects of the burning of fossil fuels on the environment, there has been an increasing interest world wide in the use of clean and renewable energy sources. It is important for the proponents of renewable energy sources to be aware of the outlines of the world energy use. The present paper starts with a description of recent energy forecasts for the world in the new century and the increasing role that renewable energy sources are expected to play in the world energy mix. The forecasts referred to here have been initiated by the World Energy Council. The present use of energy sources is summarised. A comparison is made of geothermal
energy with other renewable energy sources based on data presented in the World Energy Assessment report [1] prepared by the United Nations Development Programme, the United Nations Department of Economic and Social Affairs, and the World Energy Council. The present paper is largely based on two review papers recently published by the author [2], [3].
2. World energy forecasts: Amongst the top priorities for the majority of the world´s population is access to sufficient affordable energy. There is a very limited equity in the energy use in the different parts of the world. Some 70% of the world´s population lives at per capita energy consumption level onequarter of that of W-Europe, and one-sixth of that of the USA [4]. Two billion people, a third of the world´s population, have no access to modern energy services. A key issue to improve the standard of living of the poor is to make clean energy available to them at prices they can cope with. World population is expected to double by the end of the 21st century. To provide sufficient commercial energy (not to mention clean energy) to the people of all continents is an enormous task.
The World Energy Council (WEC) has presented several scenarios for meeting the future energy requirements with varying emphasis on economic growth rates, technological progress, environmnetal protection and international equity. All the scenarios provide for substantial social and economic development, particularly in the developing countries. They provide for improved energy efficiencies and environmental compatibility. During 1990-2050, the primary energy consumption is expected to increase by some 50% according to the most environmentally conscious scenario and by some 275% according to the highest growth rate scenario. In the enviornmental scenario, the carbon emissions are expected to decrease slightly from 1990 levels. The high growth rate scenario is expected to lead to a doubling of the carbon emissions [5].
The scarcity of energy resources forecasted in the 1970s did not occur. With technological and economic development, estimates of the ultimately available energy resource base continue to increase. Economic development over the next century will apparently not be constrained by geological resources. Environmental concerns, financing, and technological constrains appear more likely to limit future development.
In all WEC´s scenarios, the peak of the fossil fuel era has already passed. Oil and gas are expected to continue to be important sources of energy in all cases, but the role of renewable energy sources and nuclear energy vary highly in the scenarios and the level to which these energy sources replace coal. In all the scenarios, the renewables are expected to become very significant contributors to the world primary energy consumption, providing 20-40% of the primary energy in 2050 and 30-80% in 2100. They are expected to cover a large part of the increase in the energy consumption and to replace coal.
It is a very legitimate question to ask whether these scenarios are realistic. Table IV shows the technical potential of renewable energy resources. The technical potential is the yearly availability of the renewable resources.
There is no question that the technical potential of the renewables is sufficiently large to meet future world energy requirements. The question is, however, how large a part of the technical potential can be harnessed in an economical, environmentally and socially acceptable way. This will probably vary between the energy sources. It is worth noting, however, that the present annual consumption of primary energy in the world is about 400 EJ (Table IV).
References
1. WEA(2000). World Energy Assessment: energy and the challenge of sustainability. Prepared by UNDP, UNDESA and the World Energy Council. United Nations Development Programme, New York, 508 pp.
2. Fridleifsson, I.B. (2001). Geothermal energy for the benefit of the people. Renewable and Sustainable Energy Reviews, 5, p. 299-312.
3. Fridleifsson, I.B. (2002). Energy requirements for the new millennium. In: Human development and the environment: Challenges for the United Nations in the new millennium, p 220- 233. United Nations University Press, Tokyo.
4. WEC (1993). Energy for Tomorrow's World, St. Martin's Press, USA, 320 pp.
5. Nakicenovic, N., A. Grabler, and A. McDonald, (editors) 1998. Global Energy Perspectives, Cambridge Univ. Press, 299 pp.
Hydropower 50
Biomass 276
Solar energy 1575
Wind energy 640
Geothermal energy 5000
TOTAL 7600
Table IV. Technical potential of renewable energy sources
Source: World Energy Assessment [1].
My question is: Why doesn't ASPO consider geothermal as a renewable energy source?

Devil · Posted: Sun Mar 13, 2005 2:06 am Post subject:

I can't answer for ASPO, but geothermal power, in industrial quantities, requires geological conditions that are present in only a few places in the world. It certainly cannot be considered as a general panacea for energy shortage.
However, where the right conditions exist, Iceland being the example par excellence, then yes, let's exploit it to a maximum.
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Devil

0mar · Posted: Sun Mar 13, 2005 2:17 am Post subject:

Geothermal can't be controlled and modeled for any place on earth. Rather, we have find places on earth and then build around it. It all depends on geology as Devil said. We do not have the drilling technology to create geothermal vents.
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Graeme

Here I beg to differ with the replies given because I have some expertise in this area. In addition, if you read the newsletter, the author says near the bottom of the article and in Table IV that there is considerable potential for geothermal to supply our energy needs later this century. Many countries are already exploiting their geothermal resources for electricity generation. These include nearly all countries in the Pacific Rim but also in central and eastern Europe and East Africa. This development is only going to accelerate as oil becomes more expensive. Also there is some potential in other countries to extract hot water at shallow depth for domestic heating. I am surprised that ASPO does not even consider geothermal as a renewable resource.

Graeme Scott