|Posted by Winnipeg Chapter on January 15, 2017 at 11:30 PM|
The fossil fuel industry has left behind thousands of abandoned wells in Alberta. The wells have the potential to produce enormous amounts of geothermal energy that is clean, green, and sustainable. Using abandoned oil wells to reach some of Canada’s abundant geothermal energy means producers wouldn’t have to pay for expensive drilling: the wells are already there. They’re a nearly perfect transition tool, a made-to-order piece of the reject, reduce, reuse, recycle puzzle that clean energy advocates are assembling from the wreckage of fossil fuel use.
Chapter member and scientist Dennis LeNeveu explains the basics of geothermal energy and how it could work here in Canada.
Glossary of terms:
Enhanced Geothermal System (EGS) is a man-made reservoir, created where there is hot rock but insufficient or little natural permeability or fluid saturation. In an EGS, fluid is injected into the subsurface under carefully controlled conditions, which cause pre-existing fractures to re-open, creating permeability.”
Capacity factor of a power plant is the ratio of its actual output over a period of time, to its potential output if it were possible for it to operate at full nameplate capacity continuously over the same period of time.
Dennis LeNeveu, a retired biophysicist who is deeply concerned about tar sands and pipeline expansion, is an active member of the Council of Canadians Winnipeg Chapter. This is the second in a series of blogs by Dennis addressing various issues that are too often overlooked in media coverage of pipelines.
D.M. LeNeveu - 16 December 2016
Imagine an affordable, inexhaustible electrical power source with an over 90% capacity factor, minimal environmental impact and a tiny surface footprint. This source is geological heat reservoirs, something Canada has in abundance. In 2011, Natural Resources Canada (NRCAN) released a Geological Survey of Canada report that looked at geothermal potential in Canada. The report is clear: despite obstacles to developing many of the sources, deep geothermal power is available and would offer a significant benefit for Canada’s transition to clean energy.
- “Canada's [deep] geothermal power exceeds one million times Canada's current electrical consumption, although only a fraction of this can likely be produced.”
- “As few as 100 projects could meet a significant fraction of Canada’s base load energy needs.” 1
Deep geothermal power is not to be confused with shallow geothermal heat systems. Shallow systems use heat pumps to take advantage of constant shallow subsurface temperature. Deep geothermal power uses boreholes to extract heat from hot brine reservoirs found at a depth of from 700 to 4000 m in many areas of Canada. In a few locations, primarily in BC, shallow hot springs could be used. 2
Geothermal power is a developed technology that is used worldwide. 3 Most would think of Iceland, a country that uses abundant near-surface volcanic heat for power generation and heat. Other power plants include the over fifty-year-old 835 MW Geyser power plant in California that uses steam from 350 wells to turn turbines. Withdrawn water is recharged by injecting wastewater from regional wastewater treatment plants.4
Binary Cycle Power Plant (Figure 1)
More advanced “binary cycle systems” use a closed loop. Heat from hot brine in turn heats a second liquid (an organic fluid) to turn it to steam. The steam is used to drive turbines to produce power. Both the brine and the second liquid remain in their own closed loops and are reused. (Figure 1). 5
- The hot brine is pumped to the surface and circulated through a heat exchanger to vaporize the organic fluid,
- The organic fluid) is used to drive a power turbine,
- The brine is reinjected to the reservoir,
- The organic vapour is liquefied in cooling towers or in heat exchangers cooled with surface water,
- The organic fluid returns to the brine heat exchanger to be re-vaporized and continue the cycle,
- The boiling point of the organic fluid can be much lower than that of water, allowing for the use of reservoirs with temperatures less than 100 °C, 6
Alternatively, the organic fluid can be pumped through a borehole to the deep, hot reservoir. Heat can be withdrawn from the reservoir from a heat pipe that vaporizes the organic fluid at depth. The hot vapour is returned to the surface to turn turbines, liquefied in a heat exchanger, and pumped through the closed loop back to the heat pipe to continue the cycle. 7
Image: U.S. Department of Energy (Figure 2)
In the binary method, potential contaminants from the deep reservoirs (such as brine and heavy metals) are returned to the deep reservoir; with the heat pipe method, contaminants remain in place. There is a very small potential for environmental detriment from contaminants in the brine from a leak in the primary loop.
Distribution of geothermalpotential in Canada based on end use. (Figure 3)
As shown in Figure 3, significant deep geothermal resources occur in B.C. Alberta, the Yukon, southwestern N.W.T, Saskatchewan, southwest Manitoba, the Gaspe peninsula, and New Brunswick.1 These resources are virtually ignored and remain undeveloped in Canada.
B.C., which has the highest grade potential geothermal power, already has abundant hydroelectric power. The recent investment in the site C dam leaves little opportunity for exploitation of geothermal power. Some studies have shown the equivalent power from geothermal could have been done more cheaply with far less environmental impact. 8
Impediments to large scale geothermal exploitation in Canada include: 9
- Geothermal reservoirs in the Yukon and N.W.T. are remote from power infrastructures.
- Geothermal reservoirs in the Western Canadian Sedimentary Basin coexist with substantial oil and gas deposits that have a higher energy density and a greater short term return on investment. Oil companies with the technology to drill deep are invested in and have the expertise for the fossil fuel extraction, not geothermal.
- Geothermal reservoir development has significant up front costs and risk with a long payback period.
- Hot brine could be lost through leakage into formations disabling the resource.
- Similar to new promising oil and gas reservoirs, geothermal reservoirs can prove to be inadequate.
- Government support comparable to the fossil fuel industry is usually unavailable, and regulatory and permitting impediments exist.
The current tiny geothermal investment in Canada includes a 15 MW plant to be constructed in 2017 at Laytong hot springs about 10 km south of Terrace B.C. A consortium of Kitselas First Nation and Borealis Geopower has purchased for $100,000 the subsurface rights to develop the geothermal power. 10, 11
In 2010 Saskatchewan a start up company, DEEP, received a $2 million funding commitment from NRCAN and the government of Saskatchewan to develop geothermal power from a vast three kilometre hot deep aquifer near Estevan. 12 The first well, to be drilled in 2017, is expected to produce 5 MW of power with further development expected. 13
This can be compared to the 1.4 billion in government funding swallowed up by 110 MW coal fired carbon capture boundary dam power plant in Saskatchewan. This plant is billed as clean coal even though the captured carbon dioxide is to be sold for enhanced oil recovery that will generate more carbon dioxide through the burning of the recovered oil. 14 The waste streams from the toxic amines used in the process and the recovered sulphur from the coal are conveniently ignored.
Similar chemicals used in removing carbon dioxide and hydrogen sulphide from natural gas have already poisoned drinking water in Alberta and elsewhere. 15, 16 It is claimed that the sulphur recovered from the coal will be sold to generate a profit. 17 This is hard to imagine given the massive mountains of sulphur already stockpiled from the Athabasca bitumen sands and from sour oil and gas processing plants all over Western Canada. 18
Many oil and gas wells over the Western Canadian Sedimentary Basin, including the Bakken, inject huge amounts of hot produced wastewater into deep reservoirs. 19 These hot fluids could be potentially used to generate electricity in coproduction with the oil and gas. This is undeveloped technology that is viewed as having uncertain and comparatively small returns on investment so remains moribund.
Abandoned Oil and Gas Wells
Similarly, some of the thousands of abandoned oil and gas wells that are now a significant liability could be used for geothermal power. The high cost of drilling could be avoided by developing these wells. 20, 21
To realize the full potential of deep geothermal power would require initiatives by both the public and government. If the full environmental costs of fossil fuels were born by the industry, and global emissions curtailed to combat climate change, market forces could drive an explosion of geothermal power.
Measures to enable this transition would include a price on carbon, polluter funded fossil fuel waste treatment and disposal, double walling of pipelines and hard caps on emissions. Waste treatment would include industry funded treatment and isolation from the environment of the huge volume of toxins in the bitumen waste impoundments in the Athabasca sands.
The injection of sulphur waste in the form of acid gas containing deadly toxic hydrogen sulphide gas into oil and gas fields that will eventually leak should be stopped. 22 Alternatives include dissolution of the acid gas in produced waste water and stabilization of the sulphur in the form of sulphur salts such as calcium sulphate. 23, 24
Governments often react and follow rather than lead. Public awareness and advocacy for this valuable and environmentally benign resource might help to get the ball rolling. The most feasible economically viable option for large scale uninterruptible low carbon power is geothermal power. Geothermal power can be introduced incrementally well by well each having a relatively low cost and low environmental impact compared to large scale hydro, nuclear power or carbon capture. 25
What are we waiting for Canada? Get on board and be a world leader in geothermal power. Make us proud to be Canadians once more rather than shameful purveyors of climate, clean air and fresh water destroying, oil, natural gas and bitumen.
Categories: No Energy East Pipeline