Editor's note: This is the first installment of a multiple part article chronicling the true geothermal district heating system at the Breitenbush Hot Springs Resort, Detroit, Ore.
A few years ago, I wrote an article that spoke about some of the true geothermal heating systems that I'd had the opportunity to look at and work with over the years. By true geothermal, I am referencing the direct use of the earth's molten core to generate steam and or super-heated hot water, as opposed to the refrigerant based systems that take advantage of the lower-grade earth heat. Most of the systems I wrote about were utilizing the heat primarily as heat sources for hot springs, swimming pools, etc.
Further investigation found that there are a lot of commercial, high temperature electrical production facilities, primarily located in the western U.S. With the demand for electricity continually increasing, and the readily availability of electricity decreasing, there are more and more commercial grade geothermal deep wells being drilled to produce steam pressures and temperatures adequate enough to generate electricity. There are a minimum of six commercial electricity producing power plant locations in the contiguous U.S., and one in Hawaii. Steam electrical production is fraught with many issues, like corrosion, dangerous gases, disposal of hot fluids and more.
Another more significant use of this resource is the heating of buildings and food production facilities. It too comes with some of the steam generation system's "baggage," but is somewhat easier to handle due to the lower temperature of operation. At present, there are 120 sites in the U.S. that are utilizing geothermal energy for heating buildings with another 218 sites utilizing geothermal for beneficial health (spas and swimming pools) operations.
Breitenbush Hot Springs near Detroit, Ore., is one of those facilities. Breitenbush was first discovered by Europeans around 1840. It was well known to the indigenous native North Americans for many years before that first "discovery." It was first commercially developed back in 1927. The property changed hands numerous times until present ownership took place in 1977. This was the beginning of the new Breitenbush experiment we know today.
The site was developed around numerous geothermal wells that were dug by the founding community members. Some wells were dusters, and some were extremely thermally and hydrologically active with the best being capable of producing a free flowing artesian capacity of 70 GPM at 220ºF discharge water temperatures. Assuming an entering water temperature from the ground of around 40ºF, this well is producing a boiler equivalent of 6,300,000 BTUs per hour. Not bad for a bunch of hippies on a yo-yo style drilling rig. This well is one of many on the property.
The developers realized early on that the naturally occurring minerals in the system represented a challenge to their operations, and opted for the use of down hole heat exchangers (DHE) to isolate their closed loop hydronic heating system from the mineral water. Well No. 4 at Breitenbush is currently their most productive well that is on line. Its DHE is 1,450 linear feet of 2-in. schedule 40 steel pipe.
The artesian capacity is used to supply flowing water to numerous hot tubs and to augment other naturally occurring hot springs in the immediate vicinity. Interestingly, in order for the well’s heat exchanger to be able to produce enough heat for the district heating systems that service the guest cabins and other buildings on the property, the artesian capacity has to be flowing in order to move the water through the heat exchanger. So there are essentially two interlocking control logics, which have been significantly updated recently with the installation of property wide Programmable Logic Controllers (PLC). This was done in an effort to optimize their efficiency and system reliability overall. You wouldn't think that "conservation" of a free energy source would really matter in a situation like this, but the mind set of all of the people working on this site is that it is a precious gift of the earth, and that it shouldn't be squandered, hence the efforts of conservation, and my being asked to come out and look at their systems for the potential of making it as efficient as it can possibly be.
I should mention at this point that Breitenbush is an "off-grid" community, with more than 140 buildings varying between small one- and two-room guest cabins and larger community buildings (main lodge, dining facilities, meeting spaces, food prep areas, etc.) that are spread out across many acres of riverside land in an ancient rainforest setting. They generate their own electricity from a small low-head hydro plant (30 kW) with additional diesel generation capacity to handle peak demands. They are a "co-op" resort community, with approximately 50 full time resident employees and their families who live on site year round.
In addition to generating their own electricity, they also treat their own water and have their own individual sewage disposal system. They have their own fire station, with many of the members and employees being on the fire-fighting force. Essentially, Breitenbush is a nearly self-sustaining community complete with all the amenities of a small city. About the only thing they have to truck in on a regular basis is food and diesel fuel, and they have a long term plan to address the food needs of the community in their long range community plan that will possibly utilize an undeveloped geothermal well, the Deer Meadow well, for supporting a year round green house operation. Breitenbush is a total vegan community, and the green house plan fits right into their theme. Their hopes are that they will be capable of providing enough food for their employees and guests, and actually create enough excess capacity to export food off of the property.
Tune in next month as we continue our journey through this amazing system. Until then, happy hot spring hydronicing!
Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303-936-7606.
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