Monday, 30 August
US Geothermal Energy 50 years old and still growing
Last week the US Geothermal Energy Association recognised the 50th anniversary of utility-scale geothermal power in the United States.
The construction started 50 years ago on a 11-MWe plant, The Geysers. The Geysers geothermal development has come a long way since then and presently is producing enough electricity to power a city the size of San Francisco.
California is no longer alone in geothermal production. The GEA notes that approximately 3,086 Megawatts of installed capacity is produced by 77 plants in nine states, with seven new plants brought online last year. Currently 188 projects in 15 different states are in consideration or under in development. Those developing projects could triple the US geothermal capacity over the next decade.
“These numbers are impressive,” said Karl Gawell, the GEA’s executive director. “In the past 50 years, geothermal energy has blazed the trail for renewable power in this nation. But this industry has not yet peaked; the growth potential for geothermal energy is incredible.”
Calpine's "The Geysers" geothermal power plant
The success of the geothermal energy sector in the lat 50 years in USA will be showcased in the 2010 Geothermal Energy Expo being held this year in in Sacramento, October 24-27.
Friday, 26 August
Paving the way for clean geothermal energy production
The passing of the Geothermal Bill by the Queensland Parliament last week provides motivation to resume my blog, which I have had difficult to maintain in the last couple of months.
In a press release earlier this week, Mr Robertson reiterated the commitment of the Bligh Government to renewable energy and said that geothermal power was a key element of the State's clean energy future.
The Minister notes that Queensland already operates Australia's only geothermal power station at Birdsville and the Government is investing up to $4.3 million to upgrade the existing 80 kilowatt power station there. Our Centre is given due notice in the press release. As the readers know, the Queensland Geothermal Energy Centre of Excellence was established by a $15-million grant from the Queensland Government. The Press Release provides a short summary of our research objectives and states the expectation that "this investment will help position Queensland as a global hub for research and development of geothermal technology."
It is pleasing to see that both the discussions noted in the Hansard and the statements in the Minister's Press Release show strong commitment from the Government towards geothermal energy in Queensland. We agree that Queensland is well placed to capitalise on geothermal energy and I continue to quote from the Press Release:."The geothermal energy industry has the potential to create many jobs in rural and regional Queensland as well as providing a viable energy source for some isolated rural communities and mines. It's an ideal energy source to help us tackle climate change. It has the potential to make a significant impact on the Federal Government's national renewable energy target of 20 per cent of Australia's electricity supply to come from renewable energy sources by 2020. The Government has also(in addition to the above investment in Birdsville Power Station expansion and the Queensland Geothermal Energy Centre of Excellence) committed $5 million to the Coastal Geothermal Energy Initiative."
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| Birdsville plant is the first and only (presently) geothermal plant in Australia. In my June 2009 blog entry, I had noted an announcement by the Mines and Energy Minister Stephen Robertson earmarking $4.3m to upgrade the Birdsville geothermal plant. The government investment is to subsidise a major upgrade by the plant owner, Ergon Energy, to increase the capacity to several hundred kilowatts from its present 80-kW installed capacity. |
Monday, 31 May
RESEARCH TO UNLOCK THE GEOTHERMAL SECRETS OF QUEENSLAND
The Queensland Government expects 250 MWe to be generated from geothermal energy in Queensland by 2020. The Geothermal Energy Bill was tabled with the Queensland Parliament on 19th May 2010. Following the passage of the bill, a significant increase is expected to occur in geothermal exploration activities through the State.
The geology program of the QGECE is focussed on better understanding of the Queensland geothermal resource. In a new project, the QGECE PhD student Alex Middleton and his supervisors Drs Tonguc Uysal and Masimo Gasparon are aiming to develop a new exploration method for hot rock geothermal resources.
This pioneering study is starting from the premise that any deep geothermal resource is bound to produce some alterations at the surface through its interaction with the deeply-circulating surface fluids. QGECE's Dr Tonguç Uysal tells me that "the analysis of near-surface mineral alterations and geochemistry is a well-established method in mineral exploration but has not been used yet in exploring hot rock geothermal resources." QGECE is one of the few groups in the world working in this area. We all know that those granite types highly enriched in elements (uranium, thorium and potassium) whose radioactive decay produces a significant heat source can offer substantial geothermal energy potential if they are insulated beneath thick sedimentary succession. The interesting thing is that, in spite of such insulating layers (which are essential to preservation of the radiogenically generated heat), there would still be relatively short instances in the geological past in which the radiogenic granite would interact with deeply circulating sub-surface waters. Water interacting with such granites would pick up their geochemical fingerprints and carry them to shallow sedimentary rocks along fault and fracture zones. It is exactly the detection of these fingerprints that the QGECE research is aimed at. Drs Uysal and Gasparon and their students are developing techniques to identify and quantify these fingerprints and use them to estimate the potential subsurface geothermal resource.
One of the outcomes of the project will be more precise knowledge on where hot geothermal resources are likely to be found in Queensland without having to drill deep exploration holes. Obviously, the existence of such knowledge would substantially increase the chances of success in future geothermal projects and would increase the commercial viability of geothermal electricity. The QGECE PhD student Alex Middleton is planning to analyse samples from the Galilee Basin, Innot Hot Springs region, Hodgkinson Province, Styx Basin, Maryborough Basin and North d'Aguillar Block, Wandilla Province. The above map of Queensland shows some of the target areas.The granites in these areas were generated between the Late Devonian to Triassic representing a geologic time span from 370 to 230 million years ago . The preliminary research indicates significant promise of hot rock geothermal energy in these areas. As readers of this blog would remember from past postings, the Galilee Basin is of special interest to the QGECE as it directly overlies the Drummond Basin, which is known to harbour Devonian-Carboniferous granitic igneous rocks abundant in uranium and thorium, providing a significant potential for hot rock geothermal systems. Similar expectations apply to the other target areas.
Thursday, 27 May
News from Panax Penola Project
It has been over a week since Panax issued a news release on the results of the Salamander-1 drilling. So the following is not exactly news hot off the press. But I suppose late is better than never.
Panax results are important not only for Panax but also as the first HSA result in Australia, for future of Hot Sedimentary Aquifer developments.
The temperature measured at the bottom of the hole is 171.4 oC, which means the prediction by HDRPL was spot on (they apparently had a prediction of 171 oC based on their modelling -- clap your hands loudly for Graeme Beardsmore and the good people of HDRPL).
The above image shows the Panax planning for future development in this project. The production from the two-well project will of course depend on the transmissivity of the medium between the two wells. The same Panax press release also provides transmissivity estimates. These were provided by Down Under Geosolutions (DUGEO) based iin Perth. DUGEO estimates that the transmissivity in the open hole section of Salamander-1 well range from 6.7 Dm to 13.5 Dm.
To put these numbers into perspective, let me provide a bit of background on reservoir transmissivity. Please skip the rest of the blog if you are not interested to learn about different ways to express geothermal reservoir transmissivity.
At least for a first pass analysis, it is common practice, to simulate the fluid flow through a geothermal reservoir as a problem of fluid flow through an idealised porous medium of packed granular material as shown in the following sketch.
This is the so-called Darcy flow problem. Darcy tested (1856) the flow of water through a bed of sandy material and, based on his tests, he developed the following expression for the pressure gradient across a porous plug in a pipe:
The above equation was the original equation reported by Darcy. The effect of viscosity was later incorporated into this equation by other people to obtain the equation which has become the Darcy's Equation:
which is usually expressed as
Here, K is called the permeability for the porous medium. In SI units, it is m2 but it is usually expressed in terms of D or darcy (1 darcy = 9.87 x 10-13 m2).
The viscosity of water is highly dependent on the temperature as shown in the following chart:
Let us take the viscosity of the water at the bottom of the Salamander - 1 hole as roughly 0.2 cP. The cP or centipoise is a unit of viscosity and can be converted to SI units as 1 cP = 0.001 N-s/m2. Substituting this into the above equation and recognising that the flow through the reservoir is Q=uA, where Q is the flow rate and A is the flow area, we get
The first term in brackets on the right represents all the known unknowns about the reservoir: the permeability (K), the flow area(A), and the length of the flow path( Dx). This term is sometimes referred to as the K-h factor for the reservoir and its unit in SI units is m3 but it is cooler to refer to it as darcy-meter. One darcy-meter is of course 9.87 x 10-13 m3, following on the definition of darcy given above.
After this background information, we can now comment on the transmissivity values reported by Panax. A range of 6.7 Dm to 13.5 Dm was reported, let us say it is 10 Dm. If we substitute KA/Dx = 10 x 9.87 x 10-13 in the above equation, and after some manipulation and further unit conversion, we should get
This means that to get 1 liters/s from the production well, we need to have a pressure forcing of 0.02 MPa. This is from the virgin reservoir with no stimulation yet. For stimulated EGS reservoirs, this ratio is known to change between 0.1 and 1 MPa-s/l. For the Cooper Basin hot rock resource, it was reported as 0.71 (Wyborn, 2009 AGEC, Brisbane). We will report on future progress as more reports come out of Panax. Watch this space.
Thursday, 20 May
US Government funds National Geothermal Institute in Reno
This is fast becoming a weekly blog. Too busy.
The Department of Energy announced on Monday of $1.2m awarded to the University of Nevada, Reno, to develop and operate the National Geothermal Institute. The institute will be a consortium of geothermal schools, including the Massachusetts Institute of Technology, Cornell, Stanford, the Oregon Institute of Technology and the University of Utah.
Officials say the new venture will effectively be the first university training program of its kind in the country. The National Geothermal Institute's goal is to educate and train the next generation of scientists, engineers, plant operators and policy makers. The plan is to start offering classes as early as February 2011.The geothermal program is expected to offer a series of eight one-week courses with additional field trips and a project. Courses could include: Introduction to Geothermal Energy Utilization; Geothermal Business Principles; Public Policy, Permitting, and Environmental Issues; Exploration; Reservoir Engineering and Management; Power Plant Design and Construction and Direct Use.
It looks like this is going to be a coursework Master program. It will be interesting to see how this is going to develop in terms of the student interest. The $1.2m award should be enough to start a program but unless sufficient enrollments are realised the consortium would find it difficult to sustain such a program.
It has been suggested in the past that Australian universities should get together to offer a similar program. The experience of the US Institute may be useful in that context.
Thursday, 13 May
Massai protesting against Olkaria Geothermal Plant Expansion
South African Times reported yesterday of Massai tribesmen blocking the drilling of four geothermal wells in Kenya's Rift Valley region to protest environmental and health damage. According to the news article, around 100 protesters stopped engineers from KENGEN, the country's electricity generation firm, from working on the wells near the town of Naivasha. "We have for many years suffered under KENGEN and this time we shall not allow the drilling of more wells near our homes," Natata Kisotu, the protest leader said. They complained about the toxic fumes coming out of the wells, the noise from the steam gushing out, and the contamination of surface water that their cattle drink. The KENGEN Project manager Geoffrey Muchemi said the locals would be relocated and explained that an environmental assessment had been done and approved by a government regulatory body and the World Bank which is financing the project.
The existing literature suggests due diligence had been followed in previous developments in the Olkaria field. Readers of this blog may remember a previous posting about this field. In that posting I concentrated on the technical issues. A quick search after reading the Times article ended up with several references on environmental management in Olkaria fields.
The existing Olkaria III is a binary plant with the condensers being cooled by wet cooling towers. The geothermal fluid is being reinjected to minimise water pollution. A paper from KENGEN presented at the Reykjavik International Geothermal Conference in September 2003 reports on comprehensive environmental management practices. The geothermal fluid contains H2S with concentrations in the steam plume coming out of the wells varying between 0.15 - 1.25 ppm. The Report also states that the H2S levels around the camp vary between 0.02 and 3.4 and 4.4 PPM at the power station. The measurement of 4.4 PPM near the power station is coming from the H2S released from the steam separator. These numbers are significant but appear to be well below the Kenyan maximum occupational exposure limit (reported as 10 PPM).
The purpose of this posting is not to pass judgment on the quality of environmental management at Olkaria nor on the validity of the Massai claims. I wanted to make the point that if the contribution geothermal energy increases in the future, the geothermal energy sector will have to deal with these environmental issues. All countries that have significant geothermal installed capacity have these issues, e.g. Iceland, New Zealand, California.
Concentrating on the noncondensables, it looks to me that there are two options to deal with nasty non-condensables: (a) scrub the emissions as in coal-fired power plants using FGD(Flue Gas Desulphurisation); or (b) send the gases back to the reservoir with the reinjected fluid. The former adds to the expense and may not work with all non-condensables. The second option requires the geothermal fluid to be circulated at a pressure high enough to keep the non-condensables in solution. Thinking further along these lines, higher pressures would be easier to handle in a binary plant using a supercritical cycle. In fact, it would probably make it easier to design such a plant if the brine-side pressure is similar to the cycle pressure. This is one more motivation for working towards supercritical cycles in geothermal binary power plants.
Wednesday, 12 May
Support for Renewable Energy in the Federal Budget
The industry insiders have been noting how it became more difficult to get finance for new renewable power investment, including investment for geothermal plants, after the federal government decision last month to delay an emission trading scheme. Therefore, the inclusion of a Renewable Energy Future Fund in the Federal Budget 2010 would have to be welcome by the geothermal industry. Maybe but probably not quite.
This is probably going to be fleshed out in greater detail by the government in the future but my first reading of the budget document is disappointing in terms of geothermal energy: I copy below from the budget web site:
- The Government will invest $652 million over four years in a new Renewable Energy Future Fund (REFF). This will form part of the Government's expanded $5.1 billion Clean Energy Initiative.
- The REFF will support development and deployment of large and small scale renewable energy projects, including wind, solar and biomass..
- The Fund also complements existing support through the Government's expanded Renewable Energy Target (RET), which dictates that 20 per cent of Australia's energy comes from renewable sources, such as wind, solar and geothermal.
- The tax reform package provides support for geothermal energy by expanding the definition of exploration expenditure to include geothermal exploration for the purposes of the new Resource Exploration Rebate.
My disappointment is on the second bullet point where wind, solar and biomass are spelled out as would-be recipients from the REFF but geothermal is left out. This is in spite of the latest projection from ESAA (copied in a previous blog) that marks geothermal as the cheapest source of renewable electricity in Australia. One may hope that this is an oversight and will soon be fixed, but on the other hand the omission of geothermal from the REFF looks deliberate because in the next two bullet points support for geothermal energy is said to come through the RET and also through the Resource Exploration Rebate in the Henry Tax reform . (HG on 20 May -- I learn from an AGEA announcement that REFF will cover geothermal even though the budget document does not include geothermal in the list of the technologies targeted by this program)
The Resource Exploration Rebate is significant. As I understand from an accompanying media statement, a company that spends $1m on exploration will get a rebate of $300,000. I am not clear if this is cash-in-hand or if it is a deduction from the company tax. My reading is it is the latter but I am certainly not qualified to pass that judgement. I will leave it to people with more experience in tax matters. But, if it is the latter as I think now, it is not clear if this is useful to most geothermal companies who are yet to declare income. It is also stated that the rebate program will start from 1 July 2011.
While skimming through the budget document, I noticed that one of the savings announced involves withdrawal from the FutureGen Alliance. This is a public-private partnership between the United States Department of Energy and a consortium of international energy and resource companies, including companies from Australia, which was formed to develop a near zero emissions coal power plant. This does not mean loss of commitment to "Clean Coal". The budget statement notes that the Government has committed $2.0 billion in funding to the Carbon Capture and Storage Flagships program to support the construction and demonstration of large-scale integrated carbon capture and storage projects in Australia and also committed $400 million over four years from 2008-09 to the recently launched Global Carbon Capture and Storage Institute in order to accelerate the worldwide commercial deployment of at-scale carbon capture and storage. The withdrawal from FutureGen saves $15m in 2009/10.
Thursday, 22 April
Official Opening of the Geothermal Plant on the OIT Campus
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Oregon Institute of Technology’s Klamath Falls campus reports on the official opening of its geothermal electric power plant generation demonstration plant. I remember a presentation by Toni Boyd (the Assistant Director for OIT's Geo-Heat Centre, which is responsible for this project) on planning for this in last year's Stanford Geothermal Workshop. |
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The brine is produced using line-shaft pumps with variable-frequency drives placed at about 170-m depth. Prior to the the construction of the power plant, the geothermal fluid was being used for heating. The fluid out of the well was first piped into a central heat exchanger building where its particulate matter (mostly sand) is removed in a settling tank. From there the water is gravity fed into the various buildings on campus.
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Toni Boyd with the new OIT Demo Plant. The new power plant is based on a UTC Pure Cycle unit. The plant is fed by geothermal fluid that boils the cycle fluid (a refrigerant) at 91 oC.
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Initially the geothermal water was used directly in the heating systems, but due to ammonia and 2 ppm (2 mg/L) of hydrogensulfide which attacked the copper and solder in the radiators, this introduced maintenance problems. There was a range of failures including failure of the 50/50 tin/lead solder connections; rapid failure of the 1% silver solder; wall thinning and perforation of copper tubing; control valve failure where brass plugs were crimped on stainless steel stems (threaded vaves experienced no problem); and control valve problems associated with packing leakage. To address these issues, isolation plate heat exchangers had to be installed in each building. These used 316 stainless steel plates with Buna-N gaskets and a picture was included in Toni Boyd's paper and I copy below.
The 316 stainless steel was not suitable for the heat exchanger that was used for swimming pool heating due to the chlorine in the pool water and titanium plates had to be used there.
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Tuesday, 20 April
Technology for larger EGS wells
An article in the New Scientist last week was reporting on a proposal that is being discussed in the USA for future disposal of nuclear waste. What has this got to do with geothermal energy you ask. Just read on.
After abandonment of the Yucca mountain nuclear waste storage project, for a while, the hottest proposal to dispose of nuclear waste is to bury it deep in the basement rock. Holes to hold the nuclear waste canisters need to be half a meter wide. The hole will need to penetrate at least 3-km into the basement rock. Canisters of spent fuel lowered into the borehole would end up stacked one on top of the other, filling the bottom 2 kilometres. This stack would then be sealed in place with a cap of clay, asphalt and concrete.
A brainstorming meeting between Sandia and MIT groups on 15 March apparently discussed this proposal but it is not clear where it goes after that. This idea is not new but it looks like it gained new wind after Yucca Mountain. A government-owned British nuclear waste disposal consultancy company, Nirex, issued a report in 2004, on "Deep Borehole Disposal Concept for Radioactive Waste". This Report, accessible off the web, reviews past proposals in this area. One of the proposals considered in the report is shown in the following figure:
The capability to drill to 6000 m with a bottom hole diameter of 20 in (0.6 m approx.) was claimed to be within current drilling capabilities. According to one of the studies quoted this report, the maximum depth was constrained by the stability of the borehole, with a borehole containing heavy weight drilling mud being unstable in crystalline basement below a depth of approximately 6000 m.
A 1989 study by Juhlin and Sandstedt mentioned in the Nirex report examined the drilling technology and the costs at that time. Three different options were considered in this study:
- Option A: a borehole with an ID of 800 mm in the disposal zone where waste would be emplaced in a zone from 2 – 4 km.
- Option B: a borehole with an ID of 375 mm in the disposal zone where waste would be emplaced in a zone from 2 – 5.5 km
- Option C: a borehole with an ID of 375 mm in the disposal zone where waste would be emplaced in a zone from 2 – 4 km.
Option A was thought to be the most suitable for the purpose of nuclear waste disposal but also the one with most challenges, especially in the area of casing design. Nevertheless, Juhlin and Sandstedt thought that the technology existed that the borehole could be drilled, the waste emplaced and the borehole sealed in less than three years. The costs for one such borehole were estimated to be 388MSEK (approximately £30 million) at 1988 prices.
In our studies into the feasibility of the supercritical CO2 geothermal siphon, the friction up the production well turned out to be a major loss factor. This is not as much an issue with water but with the higher flow rates required for the CO2 the pressure drop gets very substantial. One solution is to have a larger-diameter well. That is why I got interested in the New Scientist article and the development in the deep borehole waste disposal proposals. If the technology is developed in that sector, it may have spin-offs for the hot rock geothermal industry.
Wednesday, 13 April
Renewed Geodynamics Confidence
Geodynamics announced yesterday that the company is back on track with an updated work program for the next three years, including Jolokia 1 stimulation; commissioning of the new and heavier drill rig 200; drilling of the Habanero 4 and 5 doublets (which will power the 1-MWe power plant to be commissioned by early 2012); new Jolokia 2 well with the new rig; and the final decision on the commercial demonstration plant by early 2013.
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| The Jolokia 1 was drilled in 2008. Geodynamics is hoping to start the hydraulic stimulation and testing of a fracture zone in granite, as soon as the current flooding recedes and the roads re-open. Successful stimulation and testing of Jolokia-1 will demonstrate that favourable reservoir conditions experienced in he Habanero wells extend across the tenement area and will increase the "Measured Resources". This will also be the last task for the Drill Rig 100. Following the stimulation of Jolokia 1, the Rig 100 will be assigned to the Innamincka-Shallows work program. This is also a Geodynamics-Origin Energy joint venture operation, but with Origin Energy as the operating partner. |
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Following Jolokia 1 stimulation, the Innamincka Deeps JV will return to the Habanero site to drill two new wells: Habanero 4 and Habanero 5. The Habanero site is of course the start of the Cooper Basin project where Geodynamics proved the concept and demonstrated the flow through the fracture reservoir in 2008/2009. The 1-MW power plant infrastructure is locate at Habanero with power lines built to the nearby town of Innamincka. The Habanero site was not flooded.. |
The new rig, Rig 200 is currently under construction in Canada and will be delivered in October 2010. It is being built by National Oilwell Varco to the Geodynamics specs and, when delivered, it will be the heaviest drill rig in Australia. In December 2009, Geodynamics had announced that the Rig 200 was being constructed under a new standard resulting in a substantially heavier mast. One reported advantage is that Rig 200 will feature greater wind loading capacity, a requirement for the extreme desert conditions of central Australia. The two new wells (Habanero 4 and 5) to be drilled by this new rig will power the 1-MW plant. This puts the timing of the 1-MW power plant subject to the completion of the two new Habanero wells and this is scheduled to occur by early 2012.
As the reader will remember, the company was awarded $90m late last year through the Commonwealth's Renewable Energy Demonstration Program (REDP) to build a 25-MWe power station in Cooper Basin. The decision for the Commercial Demonstration Plant is expected to be made by early 2013 following 12 months of successful operation of the 1-MW power plant. The commissioning of the 1-MW power plant is therefore a very important milestone and the Gerry Grove-White, the Geodynamics CEO, says that they will investigate all avenues to accelerate the timeframe for commissioning the 1-MW power plant. The following is the forward work program at this stage:
Innamincka 'Deeps' and Innamincka 'Shallows'
Innamincka 'Deeps' is the original JV between Origin Energy and Geodynamics and its focus is on higher temperature Enhanced Geothermal Systems (EGS) in the basement rock (starting at approximately 3500 m depth). The participants in the JV are Geodynamics Limited at 70% and Origin Energy Geothermal P/L (a fully owned subsidiary of Origin Energy) at 30%. The operating partner is Geodynamics.
Innamincka 'Shallows' is the new JV established earlier this year and its focus is on exploration of shallow Hot Sedimentary Aquifers (HSA) above approximately 3500-m depth. The JV participants are Origin Energy Geothermal at 50% and Geodynamics Limited at 50%. The Origin Energy Geothermal is the operating partner in Innamincka 'Shallows' and will probably be pursuing HSA interests elsewhere in Australia.
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