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 It has been suggested that I start a thread on geothermal. I don't know anything about it but I will kick it off.Anyone here ever work in geothermal?

 

graph of geothermal resources of the U.S., as described in the article text

 

Geothermal is one of the main renewable energy sources used to generate U.S. electricity, even though its growth has not been as strong as wind and solar over the last three years during a big push to increase generation from renewables. Geothermal energy's greatest growth potential is in the western states (see map above).

U.S. geothermal net electricity generation totaled 10,898 million kilowatthours (kWh) during the first eight months of 2011, up 10% from the same period in 2008, according to the latest data from EIA's Electric Power Monthly report. The data in the report reflects power generation facilities of 1 megawatt or larger. Geothermal energy also provides heating and cooling for three million Americans.

Compared to all generating sources, geothermal produced just 0.4% of electricity from all sectors nationally during the first eight months of this year. However, most geothermal power plants are located in the western states (see map below) with California producing the most electricity from geothermal, about 5% of the state's total power generation.

Several factors have influenced the growth of geothermal generating capacity:

  • Technology costs. New technology, referred to as enhanced geothermal systems (EGS), which may allow greater use of geothermal resources in other areas, is now in early-development. Current cost estimates for EGS are generally higher than those for conventional geothermal plants and other more mature renewable technologies like wind power.
  • Location. Geothermal plants can be very site-specific, and have generally been limited to areas with accessible deposits of high temperature ground water.
  • Transmission access. Lack of access to transmission lines, especially in western states where the geothermal resources are highest, limits growth.
  • Completion lead times. Completing a geothermal power generating project takes four to eight years, longer than completion timelines for solar or wind.
  • Risk. Even in well-characterized resource areas, there is significant exploration and production risk, which can result in high development costs. Development is often undertaken incrementally at a site to mitigate this risk and control costs.

graph of geothermal power generation current and planned capacity by state, as described in the article text

Source: National Renewable Energy Laboratory, Geothermal Maps.

To generate electricity from geothermal resources, a well is usually drilled directly into an underground geothermal reservoir of water that can be as hot at 700 degrees Fahrenheit (371 Celsius). The trapped steam is brought to the surface to turn a turbine that produces electricity. Geothermal water is also found on the surface as hot springs or geysers, according to the Geothermal Energy Association (GEA).

Ground source heat pumps move fluids through continuous pipeline loops that are buried underground at depths where the temperature does not change much, according to GEA. Heat picked up by the circulating fluid is delivered to a home or commercial building through a traditional duct system. During the summer, the pipeline loop pulls heat out of a building and returns cooler fluid to cool the building.

The United States has significant geothermal resources. Power generation from solar facilities of at least 1 megawatt capacity was much smaller than geothermal at 1,401 million kWh during the most recent January-August period. However, EIA data shows that generation from solar facilities over the last three years grew by 111%. Generation from distributed solar facilities smaller than 1 megawatt has also risen rapidly in recent years. Wind power increased even more at 121% to 79,186 million kWh. Coal, natural gas, and nuclear remained the three biggest power generation sources at about 43%, 24%, and 19%, respectively.

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Power station types[edit]

260px-Diagram_VaporDominatedGeothermal_i
257px-Diagram_HotWaterGeothermal_inturpe
213px-Geothermal_Binary_System.svg.png
Dry steam (left), flash steam (centre), and binary cycle (right) power stations.

Geothermal power stations are similar to other steam turbine thermal power stations in that heat from a fuel source (in geothermal's case, the Earth's core) is used to heat water or another working fluid. The working fluid is then used to turn a turbine of a generator, thereby producing electricity. The fluid is then cooled and returned to the heat source.

Dry steam power stations[edit]

Dry steam stations are the simplest and oldest design. This type of power station is not found very often, because it requires a resource that produces dry steam, but is the most efficient, with the simplest facilities.[24] In these sites, there may be liquid water present in the reservoir, but no water is produced to the surface, only steam.[24] Dry Steam Power directly uses geothermal steam of 150 °C or greater to turn turbines.[2] As the turbine rotates it powers a generator which then produces electricity and adds to the power field.[25] Then, the steam is emitted to a condenser. Here the steam turns back into a liquid which then cools the water.[26] After the water is cooled it flows down a pipe that conducts the condensate back into deep wells, where it can be reheated and produced again. At The Geysers in California, after the first thirty years of power production, the steam supply had depleted and generation was substantially reduced. To restore some of the former capacity, supplemental water injection was developed during the 1990s and 2000s, including utilization of effluent from nearby municipal sewage treatment facilities.[27]

Flash steam power stations[edit]

Flash steam stations pull deep, high-pressure hot water into lower-pressure tanks and use the resulting flashed steam to drive turbines. They require fluid temperatures of at least 180 °C, usually more. This is the most common type of station in operation today. Flash steam plants use geothermal reservoirs of water with temperatures greater than 360 °F (182 °C). The hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam may be injected back into the reservoir, making this a potentially sustainable resource.[28] [29]

Binary cycle power stations[edit]

Main article: Binary cycle

Binary cycle power stations are the most recent development, and can accept fluid temperatures as low as 57 °C.[12] The moderately hot geothermal water is passed by a secondary fluid with a much lower boiling point than water. This causes the secondary fluid to flash vaporize, which then drives the turbines. This is the most common type of geothermal electricity station being constructed today.[30] Both Organic Rankine and Kalina cycles are used. The thermal efficiency of this type of station is typically about 10–13%.

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I criticized Mr. McKinsey in another discussion by saying that geothermal could potentially provide jobs for out-of-work oil drillers. But I said that wind and solar didn't sufficiently overlap the oil business. Everything below is copied from another discussion, and I don't know enough about geothermal myself. I said:

Can you start some discussions about geothermal? An article on oilprice.com ("The Oil Price Crash Could Trigger A Geothermal Energy Boom") said that oil drillers might potentially get jobs in that field:

https://oilprice.com/Alternative-Energy/Geothermal-Energy/The-Oil-Price-Crash-Could-Trigger-A-Geothermal-Energy-Boom.html

The article says: “As much as 50% of the cost of geothermal comes from drilling, so a plunge in oil prices can drop costs dramatically,” ....

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I read up on most this information you provided around 2005,  at that time almost every geothermal electric plant had been built before 1980. some and the ones we built in the 1950's are still running strong.   I had no idea so many are now currently being built.

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The Big Three

Nuclear, Geothermal, and Hydroelectric

No exceptions. 

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2 hours ago, KeyboardWarrior said:

The Big Three

Nuclear, Geothermal, and Hydroelectric

No exceptions. 

Natural gas is the best by cost/benefit IMO. Clean, superabundant, lowest cost over the lifespan. 

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So they are drilling down along the California border at the mountains. Are they trying to float it into the Pacific ocean?

graph of geothermal resources of the U.S., as described in the article text

I think it would be more efficient to frack along the San Andreas and hopefully the Democratic party problem in CA will become an island in the pacific. Far more efficient way to solve US energy problems, No need to frack the whole state off at the Sierra Nevada. 

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I believe, you'll want to include Hydrothermal mining, there's currently two companies out here whose working this that im aware of (don't quote me)... (https://dsmf.im) The Company Cited by the article, Nautilus Minerals Inc. (in liquidation) have been successfully restructured and acquired by DSMF in the course of 2019. DSMF now has full ownership of interests and rights to Solwara 1, Deep Sea Mining Finance Limited (“DSMF”) is a privately owned group aiming to become the first in the world to mine Seafloor Massive Sulphide (“SMS”) deposits commercially, starting with its high grade copper-gold Solwara 1 project (“Solwara 1”) in the territorial waters of Papua New Guinea.

Release Date: May 31, 2018

USGS oceanographer Amy Gartman and team seek to understand how and where mineral-rich deposits form in the ocean, and what effects mining them could have on the deep-sea environment.

This article is part of the April-May 2018 issue of the Sound Waves newsletter.  

Mineral-laden water emerging from a hydrothermal vent

Mineral-laden water emerging from a hydrothermal vent on the Niua underwater volcano in the Lau Basin, southwest Pacific Ocean. As the water cools, minerals precipitate to form tower-like “chimneys.” Image taken during 2016 cruise “Virtual Vents.” Photo courtesy of Schmidt Ocean Institute, ROV ROPOS

Just a handful of scientists are looking at how deep-sea mining could affect the chemistry of the ocean. USGS oceanographer Amy Gartman wants to change that.

Gartman is a member of the USGS Global Ocean Mineral Resources project, which seeks to understand how and where mineral-rich deposits form in the ocean, and what effects mining them could have on the deep-sea environment.

“Commercial deep-ocean mining will be underway within half a decade,” says the project leader, research geologist James Hein. Last September, Japan announced the successful extraction of ore from deep-water hydrothermal deposits off the coast of Okinawa. These deposits precipitate from mineral-laden water flowing out of deep-sea hot springs, sometimes called “black smokers” for the dark color of the billowing water. The deposits are attractive to nations and mining companies for their concentration of such metals as copper, zinc, gold, and silver. The pilot-scale mine off Okinawa demonstrated that “enough zinc can be recovered annually to meet Japan’s needs,” says Gartman.

Gartman recently succeeded Hein as a member of the U.S. delegation to the International Seabed Authority (ISA). The ISA is charged with implementing the Convention on the Law of the Sea, an international treaty governing the use of the oceans and their resources. The U.S. has not ratified the convention but attends ISA sessions as an observer nation. Hein, an internationally recognized expert in deep-ocean mineral deposits, has gone to yearly ISA meetings since 2000, when he began to teach workshops to ISA members. In 2007, the State Department invited him to become part of the U.S. delegation. In 2016, he brought Gartman along.

“I introduced Amy to numerous people and asked if she could take my place as scientific advisor to the U.S. Delegation to the Seabed Authority. I’m still their advisor on other matters,” says Hein.

Large auditorium with chairs and tables set up in semi-circular fashion with some people sitting.

Bird's eye view of the International Seabed Authority 24th Council, March 2018. Photo credit: Francis Dejon, IISD/ENB.

Gartman attended her third ISA meeting last March. The member nations are currently developing regulations for exploitation of seabed resources in areas beyond national jurisdictions, called “the Area.” As science advisor, Gartman helps the U.S. delegates understand the nature and locations of different types of mineral deposits, and what environmental protections might be needed if they are mined. She sits with the delegates during ISA meetings, explaining the science of the topics under discussion, and she communicates with them throughout the year.

“For instance,” said Gartman, “in December the President issued an executive order (see “Presidential Executive Order on a Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals”) on critical minerals—minerals essential to the Nation’s economy and security—and the delegates wanted to know which of those occur in the Area.”

Gartman does more than provide information to the U.S. delegates; she’s trying to grow the community of scientists studying the potential effects of deep-sea mining.

“There’ve been a lot of people who are trying, before mining commences, to categorize all the animals that live [near hydrothermal deposits], and how resilient they are,” says Gartman. Such animals include giant tube worms and snails, fish, and shrimp. “But there are not many scientists studying, for example, physical oceanography or microbiology in relation to marine mining—I think it’s important to get a broad swath of scientific expertise involved.”

Very crusty rock with tan outer layer, gray core, and bright yellow center. Man's booted foot is in background.

Cross section of a hydrothermal vent chimney from East Diamante Caldera in the Mariana volcanic arc, west Pacific Ocean, collected during a 2010 research cruise. Most of the sample is zinc sulfide. Silica lines the conduit through which the water flowed; a trace of iron imparts the yellow color. Photo credit: James Hein, USGS.

To that end, Gartman has been networking with scientists at ISA and beyond. Just before the March ISA session, she assisted in a research cruise off San Diego run by researchers from Scripps Institution of Oceanography and the Massachusetts Institute of Technology (MIT). “They wanted to figure out how the [manganese] nodule-mining plume will behave in ocean water,” says Gartman.

Manganese nodules are another type of mineral deposit, different from the hydrothermal deposits recently test-mined by the Japanese. Typically, golf-ball to baseball size, nodules sit atop sediment on the abyssal plains of the global ocean. They grow slowly, over millions of years, by the accretion of iron and manganese oxides around a tiny nucleus, such as a large grain of sand, a shark’s tooth, or an older nodule fragment. Nickel, copper, cobalt, lithium, molybdenum, and manganese are among the metals they concentrate from seawater.

The techniques envisioned for harvesting nodules would create plumes of sediment—first as a harvesting machine scoops them up, and, for some operations, later as sediment cleaned from the nodules is released back to mid-waters or the deep seabed. When the sediment particles settle down to the ocean floor, organisms, particularly immobile ones, could be covered and killed. The cruise out of San Diego sought to better understand how the plumes might behave. The team released artificial sediment plumes and then imaged them using 3D sonar techniques to track how they spread and settle.

“I went to help out with fluid sampling,” says Gartman. “If you want to know the effects of the plume, you need to not just model its physical behavior, but understand its chemical behavior.”

Collage of black nodules or rocks of varying sizes and shapes arranged next to one-inch scales, from one inch wide to 7 or so.

Manganese nodules from the deep seafloor off the Cook Islands in the southwest Pacific Ocean. Alternating black-and-white squares are 1 centimeter on a side. From paper by James Hein and others, 2015.

Gartman collected seawater samples for Anela Choy, a biological oceanographer with the Monterey Bay Aquarium Research Institute who studies deep-sea food webs. Choy will analyze the samples for carbon and nitrogen isotopes to see how plumes might affect plankton—organisms floating in the water that rely on these nutrients. Impacts on plankton, which form the base of the marine food web, could have wide-reaching effects on ocean life. 

Although the March cruise took place off San Diego, the scientists made some of the artificial plumes with mud from the Clarion-Clipperton Zone, a vast expanse of the deep Pacific seafloor that is likely to be the first area mined for nodules. Gartman obtained a container of the mud, which she plans to study in collaboration with Phoebe Lam, a geochemist at the University of California, Santa Cruz.

Gartman and Lam want to determine whether metals from seawater will attach to clay particles in mud stirred up by mining. Such “metal sorption reactions” would take metals out of the surrounding water. “But some nodules are likely to be broken up a bit during mining,” says Gartman, which would release metals. “So, it’s an open question,” she says, “whether nodule mining is more likely to add metals to seawater or remove them.”

The answer matters because metals, such as iron, “are micronutrients,” says Gartman. “You think of the big nutrients that nothing can live without—like nitrogen and carbon and phosphorous. But once those needs are met, just like people get anemic, phytoplankton can’t grow without iron.” Gartman and Lam’s study will shed light on how nodule mining is likely to affect the seawater concentration of these important micronutrients.

Lam is also involved in the International GEOTRACES program, which is mapping the distribution of trace elements and isotopes in the ocean and researching the processes that control their distribution. A GEOTRACES cruise scheduled for September will cross the western edge of the Clarion-Clipperton Zone on a long traverse from Alaska to Tahiti. Gartman notes that the cruise will “collect great trace-metal base-line data in the CCZ before mining starts.”

Container of mud from the Clarion-Clipperton Zone

Container of mud from the Clarion-Clipperton Zone, an expanse of the deep Pacific seafloor rich in manganese nodules. Amy Gartman (USGS) and Phoebe Lam (University of California, Santa Cruz) will study chemical interactions between the mud and metals in seawater. Photo credit: Amy Gartman, USGS.

In working to engage other scientists in research on deep-sea mining effects, Gartman is following in the footsteps of a pioneer deep-sea scientist at Duke University. “In 2010, I was at a meeting with Cindy Van Dover, one of the foremost hydrothermal marine biologists, and the only woman to date to have piloted the submersible ALVIN.” Van Dover had been hired by Nautilus Minerals, a company working to develop deep-sea mining capabilities, to do some background biological assessments prior to mining. She could see that the development of a marine mining industry would require scientific input, and she urged other scientists, like Gartman, to get involved.

“My Ph.D. project dealt with the oxidation of sulfide minerals at hydrothermal vents.” Sulfide minerals are crystalline compounds that combine the element sulfur with other elements, most commonly metals. One example is the mineral pyrite, or “fool’s gold,” which combines iron with sulfur (FeS2). “Iron from vents is found mainly in sulfides,” says Gartman, “and our work showed that the rate at which the sulfides oxidize [react with oxygen in the seawater] could act as a time-release, introducing the iron slowly to the oceans.”

 “I realized that my work was directly relevant to deep-sea mining, and nobody else was doing it. If we’re going to think about mining sulfide deposits, we should know the rates at which [iron and other] metals will enter the oceans, and how far these metals will travel and what the effect on life might be.”

Now at the USGS, Gartman is continuing her work on the “seafloor massive sulfide” deposits that form at hydrothermal vents. The technique for mining these deposits involves crushing them and pumping the slurry of particles up to the ship. This crushing will release a new class of particles, different from the natural ones in hydrothermal “black smoke.” Gartman is studying both types of particles, contrasting what the two types are made of and the rates at which they release metals. She is focusing on the minerals covellite, sphalerite, and chalcopyrite, the latter two being among the main minable ores in hydrothermal deposits. She's also looking at trace minerals, like bismuth-telluride and gold, that exist in low concentrations in these systems and may be toxic, technologically important, or useful as clues to how the deposits formed.

Locations of Clarion-Clipperton Zone

Pacific Ocean, showing locations of Clarion-Clipperton Zone (CCZ), the Mariana Arc, Lau Basin, and the Cook Islands. Planned path of September GEOTRACES cruise (dashed line) passes through the western part of the Clarion-Clipperton Zone. Base from USGS Coastal and Marine Geology Program Interactive Maps.

As Gartman and her colleagues advance their studies of potential deep-sea mining effects, they’ll keep trying to interest other researchers. “I think most scientists want their work to have societal relevance,” she says, “and so they tend to be pretty receptive. We just talk to people and try to engage them.”

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(edited)

14 hours ago, ronwagn said:

Natural gas is the best by cost/benefit IMO. Clean, superabundant, lowest cost over the lifespan. 

You know that I know this. Combined cycle can’t be beat by these, but as far as renewables go those are the big three. 

Edited by KeyboardWarrior
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A few examples of unconventional geothermal:

Siemens ETES. A problem with traditional geothermal is that heat flows slowly through rock. If you extract too much heat you kill your power source. Siemens brings the rock to the surface and recharges it. 

https://www.siemensgamesa.com/en-int/products-and-services/hybrid-and-storage/thermal-energy-storage-with-etes

NREL is also kicking around using depleted shale gas wells for compressed air plus thermal storage. They're also looking at recharging geothermal with solar. 

https://www.nrel.gov/news/program/2018/geothermal-technologies-could-push-beyond-batteries.html

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On 5/1/2020 at 1:20 PM, Jay McKinsey said:

Ground source heat pumps move fluids through continuous pipeline loops that are buried underground at depths where the temperature does not change much, according to GEA. Heat picked up by the circulating fluid is delivered to a home or commercial building through a traditional duct system. During the summer, the pipeline loop pulls heat out of a building and returns cooler fluid to cool the building.

This paragraph about heat pumps is basically off-topic. Sure, ground-source heat pumps are "geothermal" in the broadest sense, but their physics, geology, economics, and deployment have basically nothing to do with the rest of this thread. their geological constraints are completely different and have essentially nothing to do with the maps of subsurface heat in the article. The economics of a geothermal heat pump are more like a regular heat pump, except that they have higher installation costs and much lower running costs. They are cost-effective for a homeowner that intends to keep the house for awhile instead of selling it. Most homebuyers will not realize how cost-efficient they are, so recovering the cost at resale is an uphill battle.  In my jurisdiction, they are cost-prohibitive because of obsolete regulations about drilling near the aquifer. Drilling is needed in high-density suburbs. low-density suburbs can use trenches instead of drilled holes.

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On 5/8/2020 at 5:04 AM, Dan Clemmensen said:

This paragraph about heat pumps is basically off-topic. Sure, ground-source heat pumps are "geothermal" in the broadest sense, but their physics, geology, economics, and deployment have basically nothing to do with the rest of this thread. their geological constraints are completely different and have essentially nothing to do with the maps of subsurface heat in the article. The economics of a geothermal heat pump are more like a regular heat pump, except that they have higher installation costs and much lower running costs. They are cost-effective for a homeowner that intends to keep the house for awhile instead of selling it. Most homebuyers will not realize how cost-efficient they are, so recovering the cost at resale is an uphill battle.  In my jurisdiction, they are cost-prohibitive because of obsolete regulations about drilling near the aquifer. Drilling is needed in high-density suburbs. low-density suburbs can use trenches instead of drilled holes.

I saw a system (UK)  where a guy put 6 of these in  (see picture) which basically heated his water all year round. The late Spring -  early Autumn surplus he dumped in a ground source heat pump borehole which warmed it to about 45 degrees by early winter. . For heating this gave his system  a COP of about 6-7. It also meant he didn't need to rely on the heat pump for hot water which meant he could run the heating circuit at a much more efficient 40-45 degrees C. 

Solar panel small2.jpg

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4 hours ago, NickW said:

I saw a system (UK)  where a guy put 6 of these in  (see picture) which basically heated his water all year round. The late Spring -  early Autumn surplus he dumped in a ground source heat pump borehole which warmed it to about 45 degrees by early winter. . For heating this gave his system  a COP of about 6-7. It also meant he didn't need to rely on the heat pump for hot water which meant he could run the heating circuit at a much more efficient 40-45 degrees C. 

 

That's called a "annual cycle" system. It works if you don't need air conditioning in the summer. If you do, it gets complicated. But yes, in general thermal solar plus ground-source heat pump is usually a big win. You can even throw in hydronic floor heating, since you are already moving the heat around as hot water. All of this factors into the energy economy as spending capital to increase efficiency. If a lot of homeowners do this, the use of utility electricity and NG goes down.

Thermal solar is less flexible than solar PV. You still need electricity for the heat pump and the various water pumps, and for your electric car. This means that as wasteful as it is, it may make more sense to use solar PV and use any excess electricity that you cannot store in your battery to heat your ground source.

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34 minutes ago, Dan Clemmensen said:

That's called a "annual cycle" system. It works if you don't need air conditioning in the summer. If you do, it gets complicated. But yes, in general thermal solar plus ground-source heat pump is usually a big win. You can even throw in hydronic floor heating, since you are already moving the heat around as hot water. All of this factors into the energy economy as spending capital to increase efficiency. If a lot of homeowners do this, the use of utility electricity and NG goes down.

Thermal solar is less flexible than solar PV. You still need electricity for the heat pump and the various water pumps, and for your electric car. This means that as wasteful as it is, it may make more sense to use solar PV and use any excess electricity that you cannot store in your battery to heat your ground source.

This was Cambridgeshire (UK) so generally no need for Air Con.

That system in the picture is what I put on my roof last month. I picked up the panels very cheap and like playing around with plumbing. Id already installed a twin coil 240 litre tank. As I type at 1925 hours that 240 litre tank is at 63 degrees C - all entirely heated by solar. Even if its very cloudy tomorrow that tank will see us through till Sunday / Monday at a push. I decided heat is easier to store than electricity. My calculations estimate an annual saving on gas of about 4200kwh. 

The systems pump consumes 41watts so relatively easy to take off grid if need be. 

In a couple weeks I am going to put 3 240w solar panels on the roof and grid tie with a mini inverter (Mastervolt Soladin). That will provide for the solar pump and more. I have the kit to go off grid if necessary. 

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3 minutes ago, NickW said:

This was Cambridgeshire (UK) so generally no need for Air Con.

That system in the picture is what I put on my roof last month. I picked up the panels very cheap and like playing around with plumbing. Id already installed a twin coil 240 litre tank. As I type at 1925 hours that 240 litre tank is at 63 degrees C - all entirely heated by solar. Even if its very cloudy tomorrow that tank will see us through till Sunday / Monday at a push. I decided heat is easier to store than electricity. My calculations estimate an annual saving on gas of about 4200kwh. 

The systems pump consumes 41watts so relatively easy to take off grid if need be. 

In a couple weeks I am going to put 3 240w solar panels on the roof and grid tie with a mini inverter (Mastervolt Soladin). That will provide for the solar pump and more. I have the kit to go off grid if necessary. 

When I looked at this, I was thinking in terms of using 24VDC pumps and a DC-DC power supply from the solar panels, to skip the inverters completely. Those little pumps can operate at from about 6VDC up to about 24 VDC, so vary the flow rate by varying the DC input. To a first approximation, you don't need to pump if the Sun isn't shining anyway.

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10 minutes ago, Dan Clemmensen said:

When I looked at this, I was thinking in terms of using 24VDC pumps and a DC-DC power supply from the solar panels, to skip the inverters completely. Those little pumps can operate at from about 6VDC up to about 24 VDC, so vary the flow rate by varying the DC input. To a first approximation, you don't need to pump if the Sun isn't shining anyway.

The vacuum tubes do collect heat in cloudy conditions so the circulation will come on periodically. In all day overcast conditions I still get a temperature lift of 15 -20 deg C on that 240L tank. 

I've set up my system so the pump is energised when the panel temp is 15 degs C higher than the tank temperature. The pump continues to circulate the water until that differential drops to 5 deg C. The system usually circulates for about 10 minutes then switches off until the 15 Deg C differential is reached again. 

I have a meter which measures kwh and keep meaning to plug the system into this to see how much electricity it typically uses.

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As it generates from low-temperature(and dirty) steam,geothermal is constrained by the laws of thermodynamics to produce electricity at low efficiency. As hot rocks in Iceland and areas of California are at above the critical temperature of water,I suggest that biomass slurry could be injected down wells for hydrothermal conversion to oil. Hydrostatic pressure produced as the slurry travelled downwards would make it possible to introduce the sludge into the top of the wells at ambient pressure. A US company did carry out hydrothermal conversion of turkey wastes to oil,but with complex high-pressure equipment. The disposal of sewage sludge is an expensive problem,here in England.

 

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On 5/15/2020 at 5:46 AM, NickW said:

I saw a system (UK)  where a guy put 6 of these in  (see picture) which basically heated his water all year round. The late Spring -  early Autumn surplus he dumped in a ground source heat pump borehole which warmed it to about 45 degrees by early winter. . For heating this gave his system  a COP of about 6-7. It also meant he didn't need to rely on the heat pump for hot water which meant he could run the heating circuit at a much more efficient 40-45 degrees C. 

Solar panel small2.jpg

I was wondering about using something like this for dehumidification in the summer. Use it to evaporate liquid dessicant (salt water). But it was just a fun thought project because it would no doubt make more sense to use a typical home dehumidifier. 

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On 5/2/2020 at 12:28 PM, KeyboardWarrior said:

You know that I know this. Combined cycle can’t be beat by these, but as far as renewables go those are the big three. 

I have three patents in this area  that i will sell you my 1/2 interest plus a sucker for $1000 each.  https://patents.justia.com/patent/8281590  and https://patents.justia.com/patent/8256219 and one more and I will get the best end of the deal.

Blue Mountain https://openei.org/wiki/Blue_Mountain_Geothermal_Area and Lightning Dock https://www.theguardian.com/us-news/2019/mar/26/new-mexico-energy-geothermal-water-environment  Break even is $60/mwh with an 85% load factor.  The later is a pipe dream due to H2S issues with geothermal wells.   Geothermal needs about twice the operating subsidy that nuclear needs.

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(edited)

14 hours ago, BradleyPNW said:

I was wondering about using something like this for dehumidification in the summer. Use it to evaporate liquid dessicant (salt water). But it was just a fun thought project because it would no doubt make more sense to use a typical home dehumidifier. 

Sun based air conditioner/dehumidifier: Only thing I am bummed about is that This guy did it before me.  Had the idea floating around for decades, but no need for it in mild Western Washington.  I see no reason everyone in the world could not lower their AC load at least when sun is shining, or if you have a big hot water tank.... Should improve COP by 2X at minimum.  Why big commercial guys are not doing this I honestly do not know.... the "not invented here syndrome I guess"

 

Edited by footeab@yahoo.com

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20 hours ago, BradleyPNW said:

I was wondering about using something like this for dehumidification in the summer. Use it to evaporate liquid dessicant (salt water). But it was just a fun thought project because it would no doubt make more sense to use a typical home dehumidifier. 

I think these are best used for their intended purpose - heating water. 

You can take the glass vacuum tubes and fill them with water. Put a polythene bag over the top - in bright sunshine the water inside is boiling within an hour. 

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