14 Geothermal
It is the only other thing that you could essentially attach to the current grid, almost anywhere in the world — in fact, below current cities. It seems like science fiction, right? Drilling to the center of the earth? But it’s not. It’s a super exciting clean power generation area
Figure: U.S. geothermal resources at 10 kilometers depth
Enthalpy
Enthalpy is a property of a thermodynamic system, defined as the sum of the system’s internal energy and the product of its pressure and volume, H = U + pV. It is a convenient state function standardly used in many measurements in chemical, biological, and physical systems at a constant pressure. The pressure-volume term expresses the work required to establish the system’s physical dimensions, i.e. to make room for it by displacing its surroundings. As a state function, enthalpy depends only on the final configuration of internal energy, pressure, and volume, not on the path taken to achieve it.
The unit of measurement for enthalpy in the International System of Units (SI) is the joule. Other historical conventional units still in use include the British thermal unit (BTU) and the calorie.
The total enthalpy of a system cannot be measured directly because the internal energy contains components that are unknown, not easily accessible, or are not of interest in thermodynamics. In practice, a change in enthalpy (ΔH) is the preferred expression for measurements at constant pressure, because it simplifies the description of energy transfer. When matter transfer into or out of the system is also prevented, the enthalpy change equals the energy exchanged with the environment by heat.
14.1 Global Geothermal Power Tracker
The Global Geothermal Power Tracker (GGtPT) is a worldwide dataset of geothermal power facilities. A geothermal power plant can be composed of several units, or just a single unit. Units can consist of multiple turbines, constructed at different times and several units may make up one geothermal power station. The GGtPT includes geothermal power plant units with capacities of 30 megawatts (MW) or more, and catalogs every geothermal power plant unit at this capacity threshold of any status, including operating, announced, pre-construction, under construction, shelved, cancelled, mothballed, or retired. Various types of geothermal plant technologies are tracked in the dataset, including flash steam, dry steam, binary cycle, and others. Each geothermal plant included in the tracker is linked to a wiki page on the GEM wiki.
14.3 Deep Drilling
14.3.1 Ultra Deep Drilling
Quaise Energy Inc. has teamed with the Laboratory for Scientific Computing (LabSC) to develop computational models of the interaction of high-energy beams with geological materials. The models developed will provide understanding of the fundamental physics underlying the operation of a gyrotron-powered millimeter-wave (MMW) energy drilling system developed by Quaise, a spin-off company born from research at MIT (Massachusetts Institute of Technology) Plasma Science and Fusion Center.
This new, breakthrough technology will be used for MMW drilling to reach depths of 10-20 km below the earth’s surface, which is beyond what can be accomplished today using conventional drilling. Deep drilling will enable harvesting supercritical geothermal energy with power densities several order of magnitudes larger than wind or solar energy, thus opening the opportunity for accessing a clean, carbon-free and power-dense energy source anywhere around the world.
The successful development of a commercial system has to overcome technical challenges related to the interaction of millimeter electromagnetic waves with basement rock formations at extreme conditions and far-field transport of material.
Canary Media on Quaise
The earlier experiments at MIT produced 10-centimeter-deep holes in palm-sized slabs of rock. At Oak Ridge, Quaise has vaporized 3-foot-deep holes into larger rocks using the national lab’s more powerful megawatt-size gyrotrons. This year, the startup is planning to drill about 30 feet into the actual ground outside the Oak Ridge facility.
The company is planning to drill a 330-foot well in New Mexico or Colorado with the oil-and-gas drilling contractor Nabors Industries, which invested $12 million in the startup last year.
After that, Quaise could drill a 3,300-foot-deep hole near the Newberry Volcano in Bend, Oregon. AltaRock, which is studying the crater, has called the site “probably the biggest untapped geothermal resource in North America.” Geologists believe a shallow magma body sits only 6,500 to 16,500 feet below the surface. Drilling here would allow Quaise to validate its technology in supremely hot conditions without having to dig too far down to start.
If Quaise succeeds in demonstrating its novel approach, the startup plans to drill ultra-deep wells not just on the sides of volcanoes but primarily alongside existing power plants.
Instead of coal or natural gas, steam produced with the earth’s heat could drive turbines and generate electricity using existing infrastructure. Power plants tend to be built near population centers, reducing the need for the long transmission lines that connect remote wind and solar farms. And existing plants tend to sit atop private property, which could potentially help Quaise avoid legal challenges like those facing geothermal projects on public land.
Among the biggest risks for any advanced drilling system is seismic activity. In recent years, geothermal projects using different types of technologies were shut down in Switzerland, South Korea and France after triggering earthquakes and rattling surrounding cities.
North Sea Geothermal
Platforms in the UK North Sea could be converted to run on geothermal energy, providing power to the offshore field facilities or feeding power to markets in Europe via trans-North Sea interconnector grids.
Traditionally, once an oil or gas field reaches the end of its productive life, its production platform is decommissioned. The structure may be removed and taken ashore for recycling/reuse, or part of the platform may remain on the seabed, perhaps creating an artificial reef. However, another alternative is becoming a more viable option – re-using the platform to extract geothermal energy. If applied to redundant platforms in the North Sea, this could create a whole new industry employing thousands of workers in new productive jobs in the offshore and onshore support sectors.
Figure: UK 50 hottest geothermal gradient wells by degrees C.
The UK continental shelf (UKCS) where many platforms are situated has a relatively thin earth’s crust – around 10 km (6.2 mi) thick compared to 40-70 km (25-43 mi) thick on land – which gives the wells their high bottomhole temperatures. There are more than 50 wells in the region with a geothermal gradient more than 122°F (50°C)/km, the highest being 296°F (147°C)/km. At Total’s Elgin-Franklin high-pressure/high-temperature (HP/HT) gas condensate development in the UK central North Sea, one of the wells was drilled to a depth of 6,100 m (20,013 ft), with a temperature of 387°F (197°C) and a pressure of 16,750 psi (1,155 bar).
Heat from these wells could be employed to generate electricity on board the platform that could in turn be routed to the UK’s national grid via subsea cables. North Sea platforms have the advantage of being surrounded by cold sea water, which is at a much lower temperature than the onshore air cooling towers that are the conventional means of condensing a generating plant’s working fluids after they have passed through the turbines.
It would also be possible to re-inject waste heat remaining in the fluids back into the subsurface oil-bearing level to increase field pressure and flows, thereby enhancing secondary oil recovery and extending field life. Furthermore, discovery of further oil fields might follow when drilling to greater depths to tap the geothermal energy beneath the platforms.
Geothermal energy has huge potential when set in context against other energy reserves. All fossil fuels, i.e. coal, oil and gas, come from the earth’s crust. The crust makes up only 0.4% of the total mass of the planet, the remaining 99.6% being hotter than 932°F (500°C) within the crust, increasing to 9,032°F (5,000°C) at the core. The pressures within the earth are constantly generating this heat naturally. This means that geothermal energy is infinite in its nature, as it is naturally renewable.
Recent research carried out in Russia, in the Kola Peninsula, has revealed moving fluids and open fractures at depths more than 12 km (7.5 mi). This discovery has led to a review of current deep geological thinking and has opened the development of geothermal energy extraction for electrical power generation.
There are three types of geothermal energy. One – Geo-pressure – is where you have a high wellhead pressure, to which you can attach a hydroelectric type turbine to generate the power or electrical power from a natural gas letdown station. The twin screw turbine design from Langson Energy produces 1 MW electrical output, operating in temperatures from 350-550°F (177-288°C) and up to pressures of 600 psi (42 bar). This is already deployed by the natural gas industry to generate power, where the gas mains changes pressure to use the power instead of it being wasted. A second is created by separating the gas from the oil/water brine and using it like a diesel-type generator, i.e. burning the gas to produce power, which could provide an alternative to flaring on certain offshore installations. The third involves using the temperature, as in the high-pressure steam, steam, Organic Rankine Cycleturbine system. This approach could be applied to platforms or on a nearby support vessel.
14.3.2 Drilling Technology
Løberg (facebook ‘Geotermisk Elektrisitet’ 210123)
Ny brønnteknologi for geotermisk elproduksjon under utvikling. #regjeringen #enova I dag utvikles det meget raske og fleksible boreløsninger, f.eks en vanntrykk-hammer som ikke trenger borestreng, en kompakt drillbit under vanntrykk som borer i stål og fast fjell, som kan brushe opp casinger som er klogget, det er utviklet plasmaboresystemer som kan nå store dyp og høye temperaturer. Closed loops i gamle brønner kan bruke f.eks CO2 som arbeidsgass, og med temperatur og trykk på 4500 meter kan gassen bli superkritisk, slik at den kan trekke til seg store mengder varme. Det er kjent kunnskap (CO2 har vært brukt i kjøleskap etc i 20-30 år). Det er gjort prototyper som har testet CO2 i lukkede sløyfer/closed loops, og det er gjort beregninger på potensialet. Det er flere selskaper som spesialiserer seg på closed loop-systemer. Norge er faktisk med på dette også, som på Island, Indonesia etc. Vi kan gjøre det på Svalbard, og fase ut vårt kullkraftverk, som nå skal gå på diesel som er fraktet dit med skip. Hva med naturgass i mellomtiden, før det fases over til geotermisk el og varme?
Det finnes mye info på våre sider om dette. Skal vi få geotermisk el og varme opp i bevisstheten, må vi sette oss inn i elementene jeg har nevnt i denne posten. Bare studer linkene under og del med de som bør oppdatere seg:
Hammergy, norsk utviklet boreteknologi
Drillbit utviklet av Fraunhofer IEG i Bochum og Fraunhofer-Chalmers Research Center for Industrial Mathematics FCC i Sverige.
High-Temp 330C Drilling System (pdf)
Plasmakutting kan brukes ned til 10 000 meter med temperaturer på 300-400 grader.
Drilling/smelting med millimeter-bølger
Roterende vannjet Liu (2017) (pdf)
Closed loop selskap, EAVOR
Gjenbruk av en brønn med closed loop og CO2
Les rapporten her (pdf)
Se en informativ film her Lær om ulike geotermiske systemer og closed loop
14.4 Enhanced Geothermal
The startup (Fervo) uses horizontal drilling techniques and fiber-optic sensing tools gleaned from the oil and gas industry. Technicians create fractures in hard, impermeable rocks found far below earth’s surface, then pump the fractures full of water and working fluids. The super-hot rocks heat those liquids, eventually producing steam that drives electric turbines. The idea is to create geothermal reservoirs in places where naturally occurring resources aren’t available. Gallucci (2023) America’s first ‘enhanced’ geothermal plant just got up and running
Canary Media
Companies and U.S. agencies are increasingly turning to “enhanced” geothermal approaches, which, broadly speaking, aim to create their own geothermal reservoirs instead of relying on naturally available resources. Technicians drill into hard, impermeable rocks found thousands of feet below the earth’s surface to create fractures, which they pump full of water and working fluids. The super-hot rocks then heat those fluids, eventually producing the steam that drives electric turbines.
A recent Department of Energy analysis found that enhanced geothermal projects could provide potentially 90 gigawatts of power to America’s grid by 2050, enough to meet the power needs of more than 65 million U.S. homes. To do so, companies will need to develop and significantly scale up technologies that today exist mainly as pilot and demonstration projects. They’ll also need to move carefully to avoid triggering earthquakes and causing potential damage in the process of drilling and fracturing rocks.
Fervo, which has raised over $180 million from investors, began drilling at the Blue Mountain geothermal field in Humboldt County, Nevada in early 2022.
The startup’s team drilled two wells that reach 7,700 feet deep and then connect with horizontal conduits stretching some 3,250 feet long. During the well tests, which took place in May, the startup flowed fluid into the reservoir, where the liquid reached temperatures of up to 376 degrees Fahrenheit and achieved a flow rate of 63 liters per second, that translated to 3.5 megawatts of power.
When you think about the metrics to be successful for geothermal, it comes down to how much flow rate you have and how much reservoir volume is there, so that your fluid can stay down there long enough to get hot. Going horizontally, instead of just a simple vertical well, completely changes the game in terms of how effective you can be on a per-mile basis.
Canary (2023) Startup claims breakthrough in turning the earth’s heat into clean power
14.5 History of Geothermal
Thomas
Three key ingredients are necessary to build a traditional geothermal power plant: heat, permeable rock and water. The geothermal industry quickly learned that while there’s a nearly infinite amount of heat beneath the earth’s surface, naturally occurring permeable rock and water are rarer.
But the key phrase there is “naturally occurring.” If it were possible to create fissures in the rock beneath our feet and then pump water through them, a vast amount of energy would suddenly be available.
Enhanced geothermal began as a side project at Los Alamos.
The fracking boom was a disaster for the environment and many people living near projects. But if there was a silver lining, it was the fact that much of the technology could also be used to create enhanced geothermal systems.
Fervo Energy’s milestone is important, but whether or not the system can scale and move down the cost curve is still an open question.
Geothermal developers will also face a challenge unique to their technology. On public land — where most wells are likely to be drilled — environmental reviews take between seven and 10 years. By contrast, oil and gas companies, which are granted a categorical exclusion from these lengthy reviews, can permit new wells in just a few years’ time.
The geothermal lobby doesn’t have the same sway in Washington as fossil fuel companies.
But if enhanced geothermal can overcome these barriers, it could transform the energy industry in America and globally. In the most optimistic scenario in Ricks’ recent study, he shows how the technology could provide enough power to supply up to 45% of the electricity needed in some regions of the U.S. In this scenario, the cost of wholesale electricity would also fall by 25%.
Thomas (2023) Harnessing the heat beneath our feet: Geothermal’s past and future
14.6 US - Nevada
CanaryMedia
Fervo, which raised a $28 million Series B round in April, aims to make geothermal more competitive by applying advanced drilling technologies from the oil and gas industry. Horizontal drilling and underground fiber-optic sensors already make oil and gas drilling more efficient, but they can reduce costs and increase productivity for geothermal as well.
Small modular nuclear reactors require years of regulatory vetting before they can be built. Long-duration energy storage needs to be tested, at small scales and usually for years, before customers will trust it. But advanced geothermal doesn’t involve any radically different technology, so its path to market could be swifter. Geothermal doesn’t have to reinvent the wheel.
The partnership with Google extends beyond power delivery and into data crunching as well. Fervo will work with Google’s cloud analytics and artificial intelligence capabilities to study the data collected while drilling. One objective is to understand how to optimize geothermal plants as flexible resources,
Geothermal currently supplies just 0.4 percent of U.S. electricity. But a Department of Energy study suggests this 24/7 renewable resource could reach as much as 120 gigawatts installed by 2050, delivering 16 percent of the country’s electricity, if technological improvements take hold and gain traction.
14.7 China
Smelror (in Norwegian)
I gjennomsnitt øker temperaturen nedover i dypet med rundt 3° C for hver 100 m. Geologiske variasjoner som varmeproduksjon og termisk konduktivitet kommer først inn som en viktig faktor ved 1000 m og dypere. Her vil varmeproduksjon fra nedbryting av radioaktivt materiale ha mye å si for den geotermiske gradienten.
Geotermisk energi i dag ikke dekker mer enn 1 % verdens totale behov for energi. 10 av de 15 landene med høyest andel geotermisk energi utviklingsland (inkludert El Salvador, Guatemala, El Salvador, Filippinene og Kenya).
Et av de landene som satser sterkest på å utnytte geotermisk energi er Kina. Målet er å produsere 560 000 GWh elektrisitet innen 2015. Selv om dette ikke vil dekke mer enn 1,7 % av landets totale energiforbruk, vil dette tilsvare et forbruk på 68,8 millioner tonn standard kullekvivalenter. Det er beregnet av bruken av grunn geotermisk energi i de 287 største byene vil kunne tilsvare en produksjon på 2,8 millioner GWh elektrisk strøm. Fratrukket nødvendig strømbruk til utvikling og drift av varmepumpene, vil dette tilsvare et forbruk på 250 millioner tonn kullekvivalenter, noe som igjen vil tilsvare 500 millioner tonn redusert utslipp av karbondioksid. I tillegg vil Kina produsere geotermisk energi fra 12 ulike områder med varme kilder, tilsvarende et forbruk på 4,52 millioner tonn kullekvivalenter, tilsvarende et redusert utslipp av karbondioksid på hele 1,3 milliarder tonn.
Potensialet blir ennå mer overveldende hvis man også tar i betraktning muligheten for utnyttelse av dyp geotermisk energi på en regional skala også utenfor de 12 høytemperatur-områdene. Dette vil kreve en storstilt satsning på energibrønner boret ned til mellom 3000 m og 10 000 m. I følge nyere beregninger kan man få ut energi tilsvarende 860 trillioner tonn kullekvivalenter, noe som tilsvarer mer enn 7 trillioner GWh elektrisk strøm, og som er nok til å dekke Kinas totale årlige energiforbruk 260 000 ganger.
For å kunne utnytte potensialet for geotermisk energi må det framskaffes ny geologisk kunnskap. Vi må kjenne til løsmassemektigheter, ha kunnskap om hydrogeologiske forhold i undergrunnen, kjenne til porøsitet og permeabilitet i reservoarene dypt nede i undergrunnen, vi må kjenne til varmeproduksjon og varmeledningsevne i de ulike bergartene, og vi må vite hvor store rom i undergrunnen de geotermiske reservoarene strekker seg over. Bærekraftig energi for alle handler mye om geologi. De som ønsker å gjøre en forskjell ved å bidra til en verden med økt bruk av miljøvennlige energikilder, gjør klokt i å velge en utdanning som gjør at de kan omsette gode intensjoner til konkret handling. I så måte er kunnskap innen geologi et godt og nødvendig fundament.
14.8 US
In this paper, we identify the technological, economic, and political reasons that the United States has failed to exploit its geothermal resources. We provide actionable policy recommendations to sustainably and economically utilize the vast energy reserves under our feet.
Geothermal Everywhere: A New Path for American Renewable Energy Leadership