Monday, 30 May

Deep Drilling Project in New Zealand

Last week a Taupo workshop discussed how New Zealand can access its deep and very hot geothermal resources. These are resources that are about 5 kilometers below the surface and hold geothermal fluids in excess of 400^oC. “Scientists conservatively estimate that deep geothermal resources in the central North Island could provide 10,000 megawatts for over 100 years for New Zealand,” said GNS Science Senior Geothermal Scientist Greg Bignall, a convenor of the Taupo workshop. The total installed capacity in New Zealand at the present is 9000MWe, about 730MWe of which come from geothermal resources. If deeper resources can be accessed, they would be able to provide all of New Zealand's electricity needs with capacity to spare (to be sold to Australia through a future subsea transmission link? Iceland is contemplating a 1900-km subsea link to sell geothermal electricity to Scotland. A 2100-km link from North Island to Sydney should be in the same league).

Greg Bignall had a presentation about this at last year's World Geothermal Congress in Bali. As noted in that paper, a barrier to the commercial development of deep geothermal resources is the ability to identify zones of permeability that could be tapped by deep drilling. It appears that last week's workshop was another milestone in the Taupo Volcanic Zone - Deep Geothermal Drilling Project (TVZ-DGDP); a proposal to the International Continental Scientific Drilling Program (ICDP). The current work is being conducted under the heading of the Hotter and Deeper Geothermal Program, funded by the New Zealand Foundation for Research, Science and Technology by a grant of undisclosed amount over three years covering 2009-2012.

The objectives of the current program are

• Improved understanding of the deep structure and dynamics of the Taupo-Reporoa Basin; New Zealand’s most intense area of deep-seated geothermal manifestations (geological and geophysical mapping) and the focus of significant existing or anticipated proposed geothermal energy development for electricity generation.
• Greater understanding of the physical and chemical nature of the deep fluids and their flow pathways to be encountered during production (chemistry and modelling).

At the depths considered, the fluids are expected to be near the critical point and neither the transport properties nor the interaction with the host rock are well understood in such regions. While the concept is exciting the challenges are also enormous as the Icelandic Deep Drilling predict found out. Therefore, it was appropriate that two people from that project were expected to be at the New Zealand Workshop last week. I have not been able to attend the Workshop but I will read the proceedings with interest if they are published.

Wednesday, 25 May

Queensland Geothermal Energy Workshop (Presentations are posted below)

On Monday, we had the Queensland Geothermal Energy Workshop. This was an event jointly hosted by the Office of Clean Energy and the Queensland Geothermal Energy Centre of Excellence (QGECE).

The workshop was well-attended with 81 delegates. We had our first Stakeholders Workshop last year where we presented our research program and asked feedback. The Centre research strategies were reconsidered and modified based on that feedback in consultation with the QGECE Advisory Board and the Technical Advisory Committees. The Workshop this year was an occasion where we reported to our stakeholders on the progress in our research projects.

It was also an occasion for the Queensland Government to reaffirm its commitment to the development of geothermal energy. This commitment is evidenced through its allocation of $5 million to the Coastal Geothermal Energy initiative under the direction of the Geological Survey of Queensland and of up to $4.3 million to Ergon to upgrade the only operating geothermal power station in Australia at Birdsville. The passage of the Geothermal Energy Bill in 2010, with accompanying Regulations to be forthcoming in 2011 is also expected to provide added incentive and certainty for exploration and investment in the development of the geothermal resources of Queensland. Finally, it was the $15m grant from The Queensland Government that made it possible for the University of Queensland to establish the Queensland Geothermal Energy Centre of Excellence (QGECE) in 2009.

Presentations

The morning of the Workshop was dedicated to presentations that related progress under these headings to the Workshop participants:

• Welcoming Addresses by Professor Trevor Grigg, Chairman, Queensland Geothermal Energy Centre of Excellence and Benn Barr Executive Director (Policy) Office of Clean Energy, Queensland Department of Employment, Economic Development & Innovation
• Geothermal Energy Challenges and Opportunities and Update on the QGECE Research, Hal Gurgenci, Director, QGECE
• Update on Birdsville Geothermal Plant Expansion, Bashir Gabriel, Ergon Energy
• Progress in the Coastal Geothermal Initiative Project, Behnam Talebi, GSQ
• Geothermal Energy Act 2010, Myria Makras, Manager, Legislation Unit, DEEDI
• Geothermal Energy Framework Implementation, Kerrie Musgrave, Project Manager - Implementation

The afternoon was dedicated to group discussion where the workshop participants discussed the following questions:

1. How could the QGECE help the geothermal industry?

• Work with the companies to develop proposals for Queensland geothermal energy projects.
• Work with the Government and Geosciences Australia to explore new resources in Queensland.

2. The following three objectives were acknowledged by speakers in a recent US Workshop as requirements for commercial deployment of EGS geothermal energy:

• reduce the drilling costs by 20%
• double the production flow rate; and
• increase power conversion efficiencies by 20%.

Do you agree with these objectives? How do you see the QGECE work as relevant to these objectives?

3. How can Government assist Industry?

• What are the impediments for industry in getting projects up?
• What is the business model that will work for Queensland?
• Given the current funding constraints what is the role of Government in developing the geothermal sector?

The reported from each group reported the outcomes to the audience. These were recorded and will be compiled into a short report as the Workshop Outcomes.

 

Wednesday, 18 May

QGECE Work on Metal Foam Heat Exchangers

The QGECE seminar of this week was from Ampon Chumpia on "Improving the performance of air-cooled condensers by using metal foams."

Mr Chumpia presented the results of his work over the past year towards his PhD objectives of testing metal foam heat exchangers. Metal foam heat exchangers are being considered by the QGECE as an alternative to conventional finned tubes. Their perceived advantage over the conventional alternative is achieving the same heat transfer rate at lower pressure drop. This advantage has been identified by numerical analysis by Mostafa Odabaee, another QGECE post-graduate research student. His work has shown that the heat transfer rate from a single cylinder in cross-flow can be increased by an order of magnitude by adding a metal foam layer to its outer surface. While this increase comes at the expense of a higher pressure drop, the increase in pressure drop is small enough to promise a significant potential for this novel heat heat exchanger technology. Mostafa's numerical results for single tubes have already been published in Transport in Porous Media (86:911-923, 2011).

Ampon is now trying to validate these numerical predictions by testing metal foam wrapped tubes and tube bundles in our wind tunnel at air speeds representing the air flow over condenser tubes in natural-draft and forced-draft cooling towers. He will be testing single tubes and tube bundles and compared the results for the finned and foam-wrapped tubes between themselves and against numerical results. The following image shows examples of foam-wrapped and finned tubes being used by Ampon in his experiments.

Tuesday, 10 May

This Week's Seminar was on Scroll Expanders

The QGECE seminar of this week was from Braden Twomey. Braden's Post-Graduate research topic is modelling of the dynamic behaviour of the QGECE/Verdicorp Portable Test Plant. The QGECE/Verdicorp Portable Test Plant is expected to be ready for testing by the ned of the yuear. In the meantime, Braden has been developing his modelling and testing skills using a scroll expander.

Scroll compressors are used in small air conditioning systems. They are mass-produced and therefore are relatively inexpensive. Running a scroll compressor in reverse, one gets a cheap expander. In fact, if one has access to a hot spring and a pond for cooling the condensers, it is easy to build a small homemade geothermal power plant using a second-hand scroll compressor and heat exchangers. Scroll expanders are positive displacement expanders and the fluid is expanded by being passed from one chamber to another as one scroll rotates within a fixed scroll. This is shown in the following figure, which is the reverse animation of a scroll compressor.

As an introduction to his Thesis, Braden Twomey has been modelling a scroll expander for the last several months and recently he ran some tests to compare against his modelling. Today he talked about his results. His first series of runs was with compressed air to expeirmentally identify a number of geometric variables about his particular scroll expander. He wil be running a refrigerant loop next in a true simulation of a small geothermal power plant.

Monday, 9 May

Origin Energy expands to Chile

Origin Energy announced today that it acquired a 40% stake in the leading Chilean geothermal exploration company, Energia Andina S.A. (EASA). The remaining 60% of the company will continue to be owned by Antofagasta Minerals S.A. (AMSA). Origin acquired the 40 per cent stake in EASA from Empresa Nacional del Petróleo (ENAP) following a competitive bidding process run by ENAP.

Origin Chief Development Officer, David Baldwin said, "With this investment in EASA we have further expanded our geothermal portfolio. We look forward to working with AMSA and contributing Origin's geothermal experience to successfully develop EASA's portfolio of geothermal exploration projects." In addition to its investment in EASA, Origin was awarded the Sorik Marapi geothermal concession in Indonesia last year with Tata Power of India, in consortium with PT Supraco Indonesia (See my 6 September 2010 Blog Entry for information on this). Through its 52 per cent interest in Contact Energy, one of New Zealand's largest producers of geothermal electricity, Origin has exposure to 290 MW of geothermal generation and 364 MW of geothermal development. Origin also has interests in a number of geothermal exploration joint ventures located in the Cooper Basin, South Australia, including its partnership with Geodynamics in the Innamincka Deeps and Innamincka Shallows Projects (see my 13 April 2010 entry for more on these projects).

EASA, which was founded in 2008, has established a portfolio of eight geothermal exploration projects in the Northern and Central regions of Chile, covering a total of 553,400 ha. The following is a picture I copied from their web site. It looks like a nifty chopper.

Chile is located on the Pacific 'Ring of Fire' and has considerable prospective geothermal hot spots, estimated to make up 60 per cent of the total Latin American geothermal resources. Preliminary assessment of the geothermal potential of Chile indicates a possible 16,000 MW of resource available.

Tuesday, 3 May

QGECE Weekly Seminars

The QGECE holds weekly seminars every Tuesday. These are public seminars and all interested are welcome. Last week it was the Easter break and we did not have a seminar. The week before, it was Hugh Russell talking on the use of shallow aquifers for power plant cooling.

Hugh is doing his Masters in this area. For the last six months he has been collecting data on water resources in the Eromanga basin. He is targeting depths up to 130 m. While the data is patchy at such shallow depths, it looks like the layers above the Winton formation may provide the permeability to serve as heat dumps for a geothermal power plant., The idea was first raised by Bob Collins in 2009 and Hugh took it up as his master Thesis.

This was the QGECE Seminar two weeks ago. Today's Seminar was by Tonguc Uysal, the leader of our Reservoir program. Tonguc talked about the likely sources of Australian geothermal heat.

This was a very interesting talk and it looks like, in addition to radiogenic granites, there are old magmatic events (or possibly even new in certain areas) that may be contributing heat eat to the geothermal reservoirs. Two mechanisms were mentioned, namely magmatic plumes and lithosphere thinning. It looks like this is still work in progress but the results should be of great interest to the geothermal community, especially for those searching for new resources closer to the population centres.

Click here for the QGECE Weekly Seminar Schedule

Click here for the rest of the blog

 

Friday, 29 April

Geothermal Energy at the State Library

Next Wednesday (4th May), Doone Wyborn (Geodynamics) and I will be at the State Library. Quoting from the State Library web site:

Join Michael Duggan in conversation with Professor Hal Gurgenci (the University of Queensland) and Geodynamics' Chief Scientist Dr Doone Wyborn, as they discuss how geothermal energy works, how it affects our daily living, its advantages over other sources of energy, and the future of geothermal energy in Australia.

When Wed 4 May, 6pm
Where slq Auditorium 1, level 2
Tickets Free, bookings required
Bookings qtix [new window] 136 246 or The Library Shop

Opening of the Centre

We had the official opening of the Queensland Geothermal Energy Centre on 20 April. The Centre was opened by the Energy Minister Stephen Robertson.

Mr Robertson said the government's $15 million investment in the QGECE represented the largest investment in geothermal energy research in Australia, "helping position Queensland as a leading technology provider in the growing international geothermal energy sector".

Here are some pictures from the Opening Day:

Peter Jacobs (on the right) explaining how the geothermal reservoir and the rest of a geothermal power plant are represented in our turbines laboratory. At the back, after me, we have Jason Czapla (a PhD student), Minister Robertson, and Paul Greenfield (the Vice Chancellor of the University of Queensland).

The rig at the back is an application of metal foams to manufacture better fuel cells (an ARC spin-off from Centre research by Mostafa and Kamel)

The big inlet on the right sucks in air for our heat exchanger bundle tests.

Kamel Hooman relating our Heat Exchanger research program to the Minister and the VC.

Handshake after unveiling the plaque that commemorates the Opening Day.

Friday, 15 April

HSA or EGS ?

The term Hot Sedimentary Aquifer or HSA has been coined together in recent years in Australia. I am not sure who is the first user and so has the naming rights. In spite of the increasingly common usage of the term by the industry practitioners, a formal definition does not exist. For example, the Australian Geothermal Lexicon, which is an industry initiative to standardise the way resources and reserves are reported, uses the term HSA but does not offer a definition. The name implies a geothermal resource that has natural permeability, as opposed to an EGS reservoir that needs to be stimulated. I reported in an earlier blog (15 March) that the proposed US Geothermal Technologies program 2012 budget is allocating $6m to "Permeable Sedimentary Resources", which very much sounds like our HSA.

In Australia, the argument has been that an HSA development will yield lower temperatures compared to a deeper EGS reservoir but this will be compensated by much higher flow rates.

The conventional wisdom on upper crust permeability is summarised by the Manning-Ingebritsen Geothermal/Metamorphic curve:

Permeability [m2] = -14-3.2 log z[km]

which I plot in the following chart (below on the left):

Measured EGS and estimated HSA permeabilities and the general crust permeability curve	The general crust permeability curve by Ingebritsen and Manning (1999)

According to this curve, the permeability of the upper crust is 10^-16 to 10^-15 m² in the depth range 1 km to 5 km. On the same curve, I also plotted the permeabilities measured at some past EGS experiments. These are values measured during hydraulic tests and induced seismicity experiments in those sites (cited in Townend and Zoback, 2011). There is no data on HSA permeability. Barnett(AGEC 2010) offers some estimated values for the Koroit reservoir based on the petrophysical relations between rock porosity and permeability. These are plotted as squares in the above chart. They suggest permeabilities much higher than what can be predicted by the Manning-Ingebritsen curve at those depths.

The fact that the expected HSA permeabilities are two orders of magnitude higher than the general crust permeability curve should not mean that the expectations are unreal. The data used in generating the Manning-Ingebritsen curve has a relatively large spread. I copy from one of their papers above (above on the right) where the data in the first five kilometers of crust cover a wide range from 10^-13 to 10^-17 m². In fact, compared against this spread, the three EGS data points shown in the left-hand figure are astonishingly close to the Ingerbritsen-Manning curve. In any case, the deviation from their best-fit curve is no reason to suspect the Barnett(2010) predictions or high HSA permeabilities expected by other players in this area.

So, the answer to the question in the title has to be both.

However, and this is the main point of this blog entry, it does not look like there will be many HSA reservoirs with such high permeabilities and for companies chasing after HSA resources it will be important to locate such resources before they start drilling. This is in contrast to the EGS reservoirs which suggest a reasonably close fit to the curve as shown above and have higher predictability. If the geothermal electricity is to make significant penetration into the electricity generation, it will have to be through EGS. This is why it is important to solve the three challenges facing the EGS today as identified in the Hedberg Geothermal Conference last month:

• Drilling costs must be reduced by up to 20%
• Production flow rates must be doubled to 60-80 kg/s
• The power conversion efficiency (kWe per kg/s of brine) must increase by 20%

Thursday, 29 March

The Bright Future of Deep Geothermal Energy (also known as EGS)

My posting two weeks ago was from Napa Valley attending the Hedberg Geothermal Research Conference organised by American Association of Petroleum Geologists(AAPG), Society of Exploration Geophysicists(SEG) and Society of Petroleum Engineers(SPE). Hedberg Conferences are organised by the AAPG. According to the AAPG web site, from time to time the AAPG Research Committee selects a topic for critical examination. They invite scientists from various disciplines (geology, geophysics, reservoir engineering, etc.) to discuss state-of-the-art concepts, methodologies, case histories, and future directions relating to this subject. The conferences are held in informal settings with a maximum of 80-100 attendees. This particular one fit that mold.

Overall, it was a good Conference and was worth the trip. My presentation was on how increased power plant productivity would help EGS commercial viability. This is summarised in the following two charts. For both of these charts, the y-axis is my estimate for the levelised busbar cost of electricity ($/MWh) and the x-axis is the geothermal fluid production flow rate. Three curves correspond to the three different well preparation costs, $10m/well, $15m/well and $30m/well.

Figure 1 - Levelised EGS Electricity Cost at Present Power Plant Productivity	Figure 2 - Levelised EGS Electricity Cost at 50% Higher Present Power Plant Productivity

The chart on the left plots the costs at the typical present power plant productivity and the chart on the right plots the situation that would arise if the current QGECE project on supercritical turbines succeed. The goal of this project is to achieve a 50% increase in power plant productivity. Other parameters are listed in Table 1 below. The main lesson to draw from these charts is that a concerted effort is required to make EGS viable and advances are required on at least three fronts: drilling costs; production flow rate; and power plant productivity. The pleasing outcome of the Hedberg Geothermal Conference was that this was generally acknowledged by the participants. Joel Renner in his presentation expressed the DoE expectations that the following was required to make EGS commercially viable: (a) 20% reduction in driling costs; doubling the flow rate from 40 l/s to 80 l/s; and 20% increase in power plant productivity. Gary Isaaksen of Exon Mobil in his presentation listed the same three requirements as the preconditions which in his view needed to be satisfied before Exon Mobil would become interested in the technology.

Parameter	Value for Chart 1	Value for Chart 2
Plant productivity in terms of the generator output shaft kwe per kg/s of brine flow (after accounting for the pump)	84	126
Life of plant, years	25	25
Parasitic losses (cooling circuit and reinjection), % of generator output	16%	16%
Capacity factor	90%	90%
Unit plant cost, $/kWe	$3500	$3500
Number of wells	2	2
Discount rate (not meant to be realistic; for the purpose of this exercise I did not bother to look up the formula that uses the discount rate)	0%	0%

We in the QGECE have good reasons to believe that we could do much better than 20% increase in power plant productivity. In fact our supercritical turbine project is aiming to increase the binary plant productivity from a 250-^oC resource by 50%. The following two charts compare the expected productivity of a supercritical CO₂ cycle against a conventional steam Rankine cycle.

Figure 3. Binary power plant using supercritical CO2 cycle	Figure 4. Binary power plant using steam Rankine cycle

We know other research teams are working towards the first two criteria stated by Joel Renner above, namely the drilling cost and the flow rate and they have good reasons to believe that they will succeed too. In other words, the next five years may be the period which will make it possible for the EGS to fulfill its potential promise of cheap virtually unlimited and energy without emissions nor significant environmental hazards.

Tuesday, 15 March

Today was the first day if the Hedberg Geothermal Conference addressing the challenges facing the EGS industry today.  The commonality of interests with US and Australian EGS efforts is interesting.  It is also pleasing that the DoE Geothermal Technologies Program budget continues on the uptake since it hit bottom in 2007.  The following shows the Program budget changing through the last 35 years:

The total GTP Budget request for 2012 is $101m divided into the following subprograms:

• Enhanced Geothermal Systems - $61.5m
• Innovative Exploration Technologies - $15m
• Low temperature co-produced resources - $14m
• Permeable sedimentary resources(known in Australia as HSA) - $6m
• Systems Analysis - $5m

The size of the program indicates the importance for the Australian sector to maintain the watch on what is happening here in the States.

I have a presentation scheduled tomorrow and here is a PDF copy of my presentation:

Presentation to Hedberg Geothermal Workshop

 

Thursday, 10 March

Ambitious plan to build the world's longest undersea cable to bring a remote geothermal resource to Europe

While we are quibbling in Australia about the cost of transporting geothermal electricity over a thousand kilometers of flat mostly unoccupied land, it is interesting to note that much larger distances across much more difficult terrain are seriously being contemplated elsewhere.

Iceland's biggest utility company, Landsvirkjun, has announced a plan to build the world's longest undersea cable at 1,180 miles long to carry up to five billion kWh of electricity a year to European countries. If you divide five billion kWh or five million MWh by the number of hours in the year, you get the capacity of the line as 600 - 1000 MWe, which is about the level it would take the the Cooper Basin geothermal resource to the Queensland grid. The mooted Icelandic cable however will be twice as long stretching over 1900 kilometers and it will be under the sea. "The idea is to meet demand during peak hours in Europe, as well as some base load," said Ragna Sara Jonsdottir, a company spokeswoman. The final decision on the project is likely to come within five years.

At current power prices in Europe, five billion kilowatt-hours corresponds to between 250 and 320 million euros ($350-448 million) at a unit cost of about 6 euro cents per kWh. Once the cost of the cable is amortised, this will be a significant ongoing export item for Iceland, a country still reeling from the effects of the Global Financial Crisis, which hit the country at the end of 2008.

Landsvirkjun is currently producing electricity from geothermal and hydrothermal resources, including the 60-MWe Krafla geothermal power station shown below.

Friday, 18 February

Why does Australia need to start manufacturing renewable power plant equipment?

There is a point that is usually ignored when discussing renewables in Australia. This is the relation between renewable investment and the current account deficit of the nation. At a small rate of investment in renewables, the effect of such investment on the current account deficit is negligible. However, if come to a point when all or most of the new capacity increases are expected to come from renewables, then this will have a detrimental effect on the current account deficit. This will be an effect no government will be able to ignore at that time. This is true even if the levelised or life-time cost of renewable electricity becomes the same as the levelised cost of fossil-fuel electricity.

The reason is the difference in the capital investment requirements. In renewable electricity, the bulk of the levelised cost is due to the cost of the capital. For gas-fired electricity, only a small part of the levelised cost is due to the capital investment. In other words, most of the cost electricity from a gas-fired plant is recovered from the customer at the time when the electricity is generated. The initial cost fraction is higher for coal, even higher for brown coal and the highest for renewables. This is seen in the following chart:

Now let us look at a scenario that in the next ten years the concerns on climate change will be serious enough so that all or at least most of new investment in the electricity sector after 2020 will start coming from renewables. I do not think this is an implausible scenario. Let us see what the implications will be for the national current account deficit.

The annual Australian current acount deficit was $43b in 2009. In the same year, Australia consumed about 242000 GWh of electricity, 95% of which is produced by burning coal and gas. The total generating capacity in that year was about 50000 MWe. This generating capacity needs to be increased at a rate of about 2% every year to meet the increasing demand. In 2020s, if the current trends continue, the country may need to increase the installed generation capacity by about 1500MWe every year. In this scenario, we are assuming that all of this new increase will come from renewables. Let us also assume that this is going to be at a cost of $10m/MWe in 2009 dollars.This means a capital investment of almost $15 billion dollars per year. If all of the capital investment comes from overseas, this is an addition of $15b to the current account deficit, or an 30% increase. Moreover, this will not be a one-off component but a structural increase in the national deficit that will be repeated every year. In other words, all other things being the same, the current account deficit for the nation will increase as in the following chart:

I think this is a very strong argument for the country to start planning to manufacture some of the equipment for future renewable plants domestically. Otherwise, no future government will easily stomach the national deficit to increase at this rate.

NOTE 1: When I raised this point in a meeting last week, some people rejected it and called me an alarmist. Their argument is that we do not manufacture gas turbine plants either so what is new? The response is obvious but worth spelling out. In gas-fired electricity, the main part of the levelised cost of electricity is distributed over the life of the plant and is due to the cost of the fuel. As long as we do not have to import the fuel, this means the bulk cost of electricity will be coming from domestic sources.In renewable electricity, almost all of the cost is at the outset. People aware of this is as a constraing on capital raising but in this blog entry I wanted to draw attention on its macroeconomic implications.

NOTE 2: In this scenario, I assume only the new investment coming from renewables. The situation will get increasingly worse when we start replacing the existing fossil-fuel fired capacity.

 

Monday, 7 February

Growing Evidence for a Large Asteroid Hitting Cooper basin 300 million years ago

Four months ago I reported a summary of the preliminary findings by the QGECE Reservoir Program leader Dr Tonguc Uysal and his research collaborator Dr Andrew Glikson that suggested a large asteroid hitting the Cooper basin 300 million years. They had a presentation at the AGEC 2010 on this topic and they have been working about it since then. Today I received an e-mail from Dr Glikson reporting on their recent work. It seems like their original conclusions are being supported by his work since then:

1. Investigation of drill holes in Adelaide during 3 - 14 January indicates that the shock metamorphism of the East Warburton Basin sediments and volcanics extends over an area at least 220 km NS and 150 km EW. This implies a buried impact structure larger than 300-km in diameter.
2. Seismic tomography research indicates the existence of a sharp crustal low velocity anomaly under the East Warburton Basin (Saygin and Kennett, 2010), in addition to the marked gravity and magnetic anomalies below the basin (Meixner, 1999, 2000).
    

I am excited about this study because it bears potential implications for the origin of radiogenic K-U-Th enrichment and high temperatures, such as measured under a 3.5–4.5 km-thick insulating sedimentary cover in the Nappamerri Trough between Moomba dome and Innamincka. As the readers of this blog would know very well, this is the region where geothermal gradients as high as 55-60^oC/km were measured (Middleton, 1979; Wyborn et al., 2004; Radke, 2009). In this region temperatures of ~225^oC occur at 5 km depth over an area about 79,000 km² large. The presence of a highly radiogenic basement within 3-4 km of the surface is consistent with upward migration and reconcentration of large ion lithophile elements associated with an impact generated hydrothermal cell, as is the case in some impact structures, including Woodleigh (Glikson et al. 2005b), Shoemaker impact structure and Yarrabubba impact structure (Pirajno, 2005).

An interim report on the work of Glikson and Uysal is posted on our web site. Click here to download a copy. While this is a relatively long report, it makes very interesting reading. Glikson and Uysal are condensing it to a size which can be published asa scientific paper.

I should emphasise that this is still work in progress and while the evidence for a large impact is getting stronger every day still more research is needed. This work does not need to be limited to Cooper basin drill cores. An impact of dimensions indicated in this report will result in major ejecta fallout units and tsunami deposits, such as are likely preserved in drill holes and outcrops in the entire central Australia and beyond.

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