Engineering a solution to the energy question: 1.7. Geothermal

Something that I find interesting is the use of oil as a primary method for heating. I realize that in Australia we don't' require anything like the level of heating that is required in the North America or Europe but heating with oil went out of favour a long time ago. Primarily this was due to the cost and most oil burning heaters have now been converted to natural gas.

So the questions I raise are is the use of oil for heating due to the lack of a suitable replacement like natural gas and if not why aren't alternate cleaner and cheaper fuels used?

Hello Masu:

I live on the Eastern Seaboard of Canada (Bay of Fundy). Natural Gas IS available and competitive - but only if one fails to include the delivery charges which are charged separately for NG. The present source of gas that we use here comes from offshore Nova Scotia Fields that were not exploitable until prices became high. New local sources are coming on line now BUT we are not the target market - and market forces in New England USA dictate our pricing here. The community has broadly adopted Natural Gas for heating and process fuel. Many of the Industrial customers negotiate very sweet deals - but in other instances improvements in economy have resulted mainly from the re-engineering of obsolete heating systems,

Typical Example - a Church with an oil-fired 1.2 million BTU low pressure steam heating system and a C$35,000 per annum heating bill, too few heating zones. It is often with a single large boiler. Factor in that the place has been kept intentionally 'cool' (read "uninviting")with the hope of saving fuel.

Natural Gas (vendor) consultant comes along and re-engineers the heating system to hydronic from low-press steam, installs several condensing gas-fired boilers with a total capacity of 400,000 BTU and zones the heat either from individual boilers - or - using heating zones from parallel-sequenced boilers (by which some carry the normal load, and others kick-in when the demand is high). Modern Control Technology.

In most cases there are no dollar savings - but the buildings are more evenly heated and to a better comfort level. The capital outlay has been financed by the gas utility with the forgiveable portion often over 50% - and as high as 100%.

Most congregations accept the benefit happily.

Many congregation members order Natural Gas to be installed in their homes as a result of the 'comfort' and 'convenience' they have seen.

These smaller consumers provide much of the revenue stream for the Gas Company because of the formula by which they pay their meter charges. The charges, so I am told, can add as much as 40% to the gas charge, and sometimes higher.

A scam. And a scam blessed by the Public Utility Review Board after the Gas Company cried real tears about poor market penetration at startup and made threatening sounds about by-passing the region.

So I buy oil at 4% over New York Harbour wholesale price (delivered!)- from my choice among several suppliers. I run modern boilers and keep them clean, and I zone everything! My boilers CAN be converted quite economically - however I notice that one of my larger competitors has already begun to convert back to oil from NG with some of their apartment buildings.

Long-term forcasts from the financial industry suggest that demand for NG will result in upward pressure on NG prices for the next decade.

Thus it is demonstated yet again that going with the herd is how hamburgers are made! Don't call me pattie!

Hi Snowboy,

Thanks for the response. The pricing structure we have has a fairly small fixed charge for the meter etc. then a two price charge per Mj (Mega Joule) where the price drops after a certain level of consumption. I can't remember the figures but gas works out cheaper than electricity and seriously cheaper than oil. Actually I am not even sure if you can still get heating oil at a domestic level any more, I certainly don't know of anybody that uses it. I don't know the exact prices that we pay but if you are interested I can find out for you.

Hi Masu:

The gas company made monkeys of the first to climb on the bandwagon and government regulators helped them to do it.

However, the local realities will change in this area and NG may indeed become competitive.

My original questions in this forum was a gas question of sorts. In your experience, have you seen propane used as a refrigerant?

In so many of the CR4 forums, as elsewhere - many are reluctant to accept that we are destroying the ozone layer. However, our governments had no such problem when the most immediate cause was refrigerants and the solution had no political backlash.

Even so, as heat exchange becomes more common as a space heating solution - we will need solutions that are not only 'green', but also 'cheap'.

There is a significant market penetration with heat pumps here - mostly with air/air units -even tho these are of negligible value during peak low outside temperatures.

Ground-source heat pumps are not affected by low outside air temperatures but installation is very messy for the homeowner and much of the expense does not go to the HVAC contractors account - so they do not promote it.

There are only a few contractors who wrap the dirty work AND the refrigeration service work in a bundle for the market, and they are selling 3.5 tons for under C$20,000. installed and running. NG would come in at C$7000 and Oil at C$10,000 (ballpark figures).

The consumable is electricity (which is approx C$.12 per Kwhr here but rising) and the payback is less than a decade. Service life 20 years on the compressor/ 200 years on the buried copper refrigerant lines.

My particular question:

Can we replace the 25 or 30 pounds of R-22 refrigerant that such a 3 ton DX system will contain, with an appropriate number of pounds of butane (as R600) or isobutane R600a?

Specifically, are modern scroll compressors being used with this refrigerant in ANY refigeration applications anywhere on earth?

N-Butane and Iso butane both have excellent lube-oil solubility using petroleum based oils (like the standard oils for R-12 and R-22). THe flamability issue is not of concern so long as the exchanger is exterior to the home or in a separately vented and alarmed enclosure. (do not want toblow up the house.) Neither of these hydrocarbons has any significant global warming potential or pollution problems. You can easily design the water:butane exchanger and circulating pump system so the water side is at higher pressure. Then any leak is safe and easy to deal with.

An issure to resolve is what kind of long-term heat transfer coefficient -earth to refrigerant tubing--can be achieved. Boreholes are problematic-experience has shown gaps develop between a 'lean concrete' backfill andthe earthwall, destroying conductivity. Burried in a trench loop fields seem to work well so long as they are kept water saturated. If allowed to dry out, heat transfer drops substantially.

IF ground water is available at a reasonably shallow depth, and the water level in the well is less than 30' down, you can easily install a 2 well open loop, pumping out of one well through a heat exchanger and back down into another well. 10-15 ' spacing is enough to provide effective earth contact. The shallow water table allows a low power closed loop circulator pump once the system is primed and free of air. A deeper water level would require more lifting power than could be recovered going back down since the water column would break into a vacuum at about 34 below grade. So with a water level 60' below grade, (neglecting for a moment friction losses) the lifting work would be 60-34 , or 26'

One can reasonably expect a 10 deg F temp rise/fall in ground water without encountering scaling problems. So for 3 T of cooling (36,000 BTU/hr) water flow required is simply 36000/10*8.33 GPH. or about 7.5 GPM. Heating load is simmilarly calculated. Water requirements can be much higher than a single small bore well can supply of course, if a large buildig is being heated or cooled.

Heating loads can be several times cooling loads. 85F outside air is only 10-15 F above comfortable. -20F is 90 F below comfortable. in this simple case, heating load is approximately 8 times the cooling load.

Hi Keith:

Thanks for this response. So questions are resolved and others arise. The grout being recommended is a barite/sand mixture - the sand being used to improve thermal conductivity. Will this shrink back from the walls of the boreholes? I want to avoid open loops as the failure rate locally is approaching 100% by year ten of service due to corrosive elements in the water.

Any suggested ways to deal with the loss of conductance in the boreholes? Groundwater is at 70 feet below the surface wand will 'probably' stay that way. Would this be a positive factor?

Hi Snowboy,

It looks to me that you are looking for a cost effective system to support the heating of buildings.

Your idea was to use geothermal energy for this.

I have another approach for this: windmills.

Instead of selling the electricity to the local power grid, and getting almost no money for it, I would transfer it into heat. For this system you don't need the rectifiers. You only need the windmill with its standard generator, which you couple direct to a heating element. Some regulation could be introduced to regulate the power that you get from the generator.

There exists small rooftop mountable turbines, that generate 1 to 10 kW (rated power)

As heat storage you can use a water tank or pile of sand.

More questions? Real plans & calculations? Just let me know.

Gwen

Hello Gwen:

I would gladly install a windmill to cover my normal electric consumption for other than heat. Last month that amounted to 5475 KwHrs and I paid C$13.60 per Kwhr each taxes included. The heating requirements would be (approximate average) 25000 Kwhr per month

Windmills are not common here. Given my location in the urban core of a small city, will be noise issues or other concerns bother my neighbours and the City Council?

Do you have windmills on buildings like this in Belgium?

Also, I am located among a number of other structures and some are much taller than my buildings, so perhaps the wind would not be as reliable. And... some of our coldest days are in the middle of Arctic High Pressure zones in which the windmill would be calm, but the outside temperature will be far below the freezing mark.

What do you think? Still a possibility?

PS. I already have Solar DHW systems covering some (but not all) of the domestic hot water demands, these feed through small electric boilers (1500 watts and 3000 watts) so that there is some electric 'backup capacity'. I can envision using wind power to provide the backup electricity in the way that you describe. In that way, no battery is required and you don't simply require much other 'processing' controls or hardware.

another place where I would send windmill generated electricity is to refrigerators and freezers as these function as a form of energy battery as well.

DOes your experience with windmills go in these directions?

The noise problem is a typical issue for the horizontal axis family. Vertical Axis have less noise issues.

What I'm worried about is the ice buildup on arctic days. You will need to heat the blades.

What is the time-frame of those arctic day's (day's or weeks)

Windmills on buildings are something new, you don't see it that often yet. But there are known application.

The market is going higher and bigger (up to 10000m²), the small VAWT is a new market popping up as the big players are known by now.

This is a nice one: Quietrevolution they also explain how to evaluate your neighbourhood.

Don't take Belgium as an example on how to solve environmental problems, we started to discuss the issue, then decided that is is a regional problem. Now each region is re-discussing the whole problematic and finds out that what they want to do is still federal stuff. So again something that needs to be regionalized or regional stuff that needs to be federal. We are the center of Europe, so we are the most polluted region of it. But that is not our fault. That is a CE responsibility. So nothing happens, nothing is done and we keep on polluting. (You live in Canada, look to Quebec and multiply the issues with the size that we are smaller, imagine)

Heat can be stored easily in your cave. Freezers need again AC, which you don't have if you want to keep the cost of the installation reasonable.

Artic Highs can go on for up to a week without much wind. They occur throughout the winter season.

I saw vertical axis windmills in downtown Dublin several years ago. They greatly resembled the Canadian NRC type from 40 years ago. that windmill resembles several longbows on a common axis. As I recall, the Canadian ones had failures in high winds, and low speed performance issues as well, but I do not remember the circumstances.

Here is a present day NRC site. They have some very nice downloadable software for

www.retscreen.net

The RETScreen Clean Energy Project Analysis Software

Thanks for the QuietRevolution link - I will have a look at it.

Oh, did I mention that I have a cave. A Cave?