Cleaner coal? The answer lies below
Just over two years ago, I concluded an article for Business Spectator with the rather flippant remark that if the executives of emissions-intensive generators were really serious about reducing emissions, then they’d reverse their BMWs and Audis out of the executive car park and drill down to tap into the geothermal resources that lie beneath.
It turns out it wasn’t such a silly idea.
Professor Behdad Moghtaderi, the deputy-Director of the Priority Research Centre for Energy at the University of Newcastle, has filed patents over a new system that would allow coal-fired generators to use geothermal power to pre-heat water and improve the thermal efficiency by as much as 30 per cent – with corresponding reductions in coal use and emissions.
Moghtaderi says most coal-fired power stations are situated in areas that have good geothermal resources. The coal deposit often acts as a thermal blanket over hotter rocks below. The sort of heat necessary to make this system work – around 120°C to 150°C – can probably be found at relatively shallow depth using conventional technology.
Coal-fired power stations create electricity by boiling water and creating steam to drive a turbine. To try and improve the efficiency of that system, some of the steam is diverted to “pre-heat” the water. Moghtaderi suggests using geothermal heat to replace that diverted steam. He says this could add another 12 per cent to the normal rate of thermal efficiency at these plants – from around 35 per cent to the high 40s.
“That is a massive increase,” he says. It would also lower the emissions profile of some coal-fired power stations down towards those of gas-fired generators. Some initial estimates prepared by Moghtaderi and his partner in the concept, Brad Mullard, the executive director of mineral resources, industry and development within the NSW government, suggest major reductions of CO2 and sulfur dioxide and nitrous oxides, as well as heavy metals.
The numbers suggest a 10 per cent gain in thermal efficiency across the NSW industry would avoid 89 million tonnes in CO2 emissions over 10 years, 250,000t of SO2 and 175,000t of N2O, as well as delivering coal savings of $1.44 billion, and $2.24 billion in carbon credits. A 20 per cent gain in thermal efficiency would double those achievements.
Moghtaderi says it is a relatively simple concept and – despite the cost of drilling and of retrofitting plants – it is likely to be much cheaper than some of the other alternatives, particularly carbon capture and storage, where coal-fired producers are also likely to need to burn 30 per cent more coal to make the system work.
The idea is similar to the solar-booster technology that is installed at the Liddell power station in the Hunter Valley, and is about to be repeated at a larger scale at the Kogan Creek power station in Queensland. The advantage of geothermal over solar is that it can operate all night long – the experience at Liddell is of less than 25 per cent capacity – and probably at significant lower cost.
Indeed hybridisation – be it solar/coal, geothermal/coal, solar/gas – seems to be all the rage. Some green groups and advocates of 100 per cent renewable technology don’t like it, but it’s generating a lot of interest in the industry because it lowers costs, means that existing assets retain value, and also exploits resources such as solar and geothermal that do not yet have the operating cost profile to flourish on a stand-alone capacity.
Moghtaderi is generating interest not just from generators but also some coal miners. It seems that now a carbon price is to be introduced, rather than sitting on a stranded asset and bleating about it, some are now keen on taking proactive action. He hopes to secure seed funding for the concept soon, and then begin proving it. Once that is done, the actual implementation of a project could take less than a year.
There may be another incentive for coal suppliers – many provide coal to local generators at a significant discount to the export price – if they can satisfy the local demand with less coal, it frees up more to be exported overseas.
Last year, a survey by geothermal consultants based on oil and gas drilling in the Latrobe Valley suggested an extensive resource of geothermal energy – with temperatures of 150°C or more – lies beneath the massive brown coal generators and the 400m of brown coal reserves. Hot Dry Rocks also plans to pilot a small-scale 500kW geothermal power plant in the Latrobe Valley, using technology developed by Melbourne-based car air conditioning specialist Air International Thermal Systems to build cheap plants that can tap into shallow aquifers heated to around 80-90°C.
The nature of the technology means that it will work best where coal-fired power stations are located adjacent to their coal deposits, and therefore the geothermal resources. Moghtaderi estimates that up to 30 per cent of US coal-fired plants may be similarly located above geothermal resources, with around 20 per cent in China and 15 per cent in India. That still equates to around 15 per cent of global coal-fired generation assets.
Comments on this article
A lot of maybe.
Suppose the geothermal boost works to lower emissions to that of gas power stations, and could be done for all existing coal power stations, and will function ok for the long term. Then total the emissions reductions achieved will still be very unambitious, relative to what is actually required world wide, unless total fossil fuel burning is considerably reduced.
A lot of maybe.
Suppose the geothermal boost works to lower emissions to that of gas power stations, and could be done for all existing coal power stations, and will function ok for the long term. Then total the emissions reductions achieved will still be very unambitious, relative to what is actually required world wide, unless total fossil fuel burning is considerably reduced.
Re: To every action exists its ex'tr'act opposite
Allan, how is this different to what is currently going to happen? Any coal fired station closed is just going to end up exporting that coal instead. And I'm including brown coal, India will by anything that burns.
Re: Just add a little science
Peter,
Not sure you understand the huge significance a 10% improvement in efficency is. It's taken 100 years to get coal plants from 5% efficiency to 35%. In terms of reduced costs / fuel reduction, this is huge. Roll this out on all our coal plants and you would smash our current emission reduction target. This is why you have an emissions trading scheme. So the cheapest offsets can be found.
geo thermal hybrid
nothing to do with carbon tax just good business practice to cut costs its somthing they have been looking into for a long time
Sublimely Simple
I have to agree with Rory, this is exactly the kind of outcome the carbon tax is designed to achieve. It is inevitable that coal fired power stations will produce the bulk of Australia's energy needs for some time yet but any impetus to improve their efficiency and reduce their CO2 output in the interem has to be applauded.
The owners of these power stations have known they were living on borrowed time for some years now just waiting for a government with the courage to implement a price on emissions so they should be eager to embrace initiatives like this.
A Constitutional Blackout
If State owned generators of electricity are to be significant payers of the carbon tax, then the Commonwealth could be in for an unwelcome surprise. Relevantly s. 114 of the Constitution provides that the Commonwealth shall not… ‘impose any tax on any property of any kind belonging to a State’. In short, these emissions belong to the States and hence are not liable to be taxed by the Commonwealth.
To illustrate from page 17 of its 2010 Annual Report, Macquarie Generation would on my reckoning have emitted 23.3 million tonnes of carbon dioxide. Taxed at $23 per tonne this would create a liability of $536 million, (Bayswater at $324 million and Liddell at $212 million). Equal to roughly half of its revenue of $1.2 billion and turn its profit before tax of $269 million into a loss of $267 million.
Happily for Macquarie and other state owned
electricity generators, s.114 of the Constitution would seem to exempt them from this proposed tax.
Bryan Pape
26 July 2011
A Constitutional Blackout?
Dear Alan,
If State owned generators of electricity are to be significant payers of the carbon tax, then the Commonwealth could be in for an unwelcome surprise. Relevantly s. 114 of the Constitution provides that the Commonwealth shall not… ‘impose any tax on any property of any kind belonging to a State’. In short, these emissions belong to the States and hence are not liable to be taxed by the Commonwealth.
To illustrate from page 17 of its 2010 Annual Report, Macquarie Generation, would on my reckoning. have emitted 23.3 million tonnes of carbon dioxide. Taxed at $23 per tonne this would create a liability of $536 million, (Bayswater at $324 million and Liddell at $212 million). Equal to roughly half of its revenue of $1.2 billion and turn its profit before tax of $269 million into a loss of $267 million.
Happily for Macquarie and other state owned electricity generators, s.114 of the Constitution would seem to exempt them from this proposed tax.
Bryan Pape
26 July 2011
Innovation through cost of carbon?
Philip,
Is it directly stimulated through the carbon tax? I think not. A quick search of the Newcastle Uni website shows an ongoing engagement with Granite Power - a geothermal company that also has technologies around waste heat recovery. There must have been an anticipation of a cost of carbon to come (even though you might not believe it with the current noise) - by the people who invested in the development of the technology, and by the power generators who surely must have been doing some scenario planning. I'd expect that the business case that deals with the additional investment for the heat recovery technology will look at both the revenue from increased MWh output, and the removal of the cost of emissions.
Geothermal hybrid: Giles Parkinson
Is this an example of innovation stimulated by the carbon tax on polluters ?
If it is , this example should be shouted from the chimney tops for all to hear.
Carbon Tax will harm
To John Bennett’s: II have actually worked as the Environmental Manager for a large coal mine for many years. One of the most frustrating issues was to get resources to control spontaneous combustion. It seemed the environment was regarded as a side issue. I was at a meeting when manager of the mine stated in front many workers that “the environment is NOT important”. Spontaneous combustion does occur on stockpiles and you are right, these events are usually far faster controlled then overburden fires. Fires in old underground mines can burn for hundreds of years and often cannot be put out. I know of instances where overburden fires have been burning for decades. The issue of “clean coal” requires cultural changes as much as more targeting resource allocation. Yes, the “bonus” system remains an issue and will cause the delay of “non-essential” expenditure such as for pro-active environmental works. I also know of very well managed mines with responsible mamagers. The carbon tax will hit the well managed mines as hard as the badly managed operations.
Commonsense at last
Great to see direct action that delivers cheap baseload power, business incentive and pollution reduction. Taxing in order to subsidise inefficient rooftop solar won't achieve any of these. Liddell is now teaching the US and China how to get more megawatts per tonne of coal to turn their steam turbines. This delivers the Greens' stated environmental goals, but not its real agenda, and this is why the Greens are not endorsing these magnificent efficiencies.
Intermediate solution
There are a few reasons why this is a good idea for NSW: the availability of the geothermal resource in the Hunter, the absence of any credible geological storage for CO2 in NSW - should that route to reduce emissions be attempted - , the high reliance on coal fired generation and the age of the power stations relative to e.g. those in the LaTrobe. I don't think this is about "clean coal" but an intermediate step to reduce emissions, and one that will give the power generators the chance to learn about geothermal power in the process. Geothermal projects have had great difficulty attracting start-up funding and there is a need to prove the concept in order reduce the risk and attract investors. Here is an opportunity to do something that is simpler than generating power from geothermal resources, and that will allow us to learn about and optimise the sub-surface engineering that is required.
A cost on emissions will help the business case for the required investment. And whilst the route from Melbourne to Ballarat will definitely not be via Sydney, going via Geelong might make some sense.
Clean coal is a myth!
It's not just the CO2 emitted, it's all the dangerous compounds that burning coal emits that actively damages the health of our populations!
Here are just a few of the byproducts created by burning coal: nitrogen dioxide, sulphur dioxide, soot, mercury, ash and clinker (the ash often contains traces of heavy metals such as cadmium, lead mercury and arsenic).
Clean coal is a myth!
To every action exists its ex'tr'act opposite-
Giles, domestically, for Australia, and perhaps some other countries also, it's a very good idea, but unless enough of the particular countries where that envisaged extra exportation of freed up coal is destined for also follow suit with the geothermal/solar preheating process then we will have merely exported our prior contribution to global pollution overseas along with its means. Will those coal-importing countries emulate the preheating process and have they the means to do so? That's the 'burning' question!
Just add a little science
If you want to go directly from Melbourne to Ballarat, you don't go via Sydney. And if Australia wants to reduce its emissions by 90-95% - the amount required for it to equitably contribute to a significant reduction in global emissions by 2050 at the very latest - then you use the most direct means available. Why would you use geothermal for minor increases in the efficiency of coal-fired power generation and achieve only small decreases in emissions? Use it as a source of baseload power which, in combination with other renewable sources, can replace coal altogether... hopefully creating alternative jobs in the power generation sector in regions like the Latrobe Valley at the same time.
solar thermal/geothermal hybrid
Is there any plans for such a hybrid?
Let the market decide ....
The advantage of these kinds of hybridisation is they can be determined by the plant owners as to the financial viability (cost of hybrid plant against reduction in coal use and carbon costs).
It means the government doesn't need to pick winners or subsidise the implementation which they seem keen to do for non-hybrid geothermal or solar plants.
Let the market decide!
Beat Odermatt is spouting nonsense
Beat is just plain wrong with his assertions. I'm no friend of CO2, but let's at least stick to the facts.
CO2 from spontaneous combustion in stockpiles? Where are these stockpiles, I wonder. Yes, nuisance spon-com does happen. When it happens, it is quickly extinguished. Nowhere does a whole stockpile, or even the major part of one, burn.
Ditto underground and open cut mining, where the objective is to sell the coal, not to burn it in situ. Sure, there are fugitive emissions and these are unwelcome and environmentally damaging, but they are nowhere near as significant as the actual burning of coal in furnaces.
Exaggeration of these matters does not help to win arguments, only to derail them.
Continuing from above
The whole purpose of this "tax" is to make polluting more expensive, and so forcing highly polluting industries to invest in technology that will make them less polluting - and more efficent if they are smart about it.
In all truth, I can even see that there is a huge advantage to this sort of measure that can do completely without the "climate change" and all the conflict that ensues.
It makes perfect sense for the government to lean on industry to be less poluting. That is in the benefit of the entire country, not only to the environmental health, but also to the future of the economy. By imposing this en-mass, certainly innovation will come out of it - innovation that can lead to Australian companies selling innovative polution-reducing technology overseas.
Then the there is the fact that a large part of the tax proceeds will go to help renewable energy products. These will lead to a diversity of generation, both in terms of type as well as in terms of location, and this is always a benefit to the grid and the population it serves. And again, as more renewable projects come online, innovation a knowledge will come out of these, which will help pusho Australia into the clean-tech sector, which has been booming all over the world (and surprise, especially in China!) except over here.
Well said, and I totally
Well said Rory, and I totally agree. Excellent article for those of us who aren't scientists and are simply interested in knowing what technology already exists, or can be implemented straight away. Again good article, restored my faith in climate spectator.
Wraping the whole deal into one side-point
To Mr. Beat - it seems you have put the entirety of the effects of the carbon tax into one relatively minor effect of the coal industry. And funny enough, you actually say that the "increased" emissions stem from the existing bonus policy.
As you read from your comment, these emissions already exist, and so not fixing the issue would not lead to an increase in CO2 emissions, but a non-reduction of these, which is quite diferent.
Secondly, the effect of the carbon tax will be quite a bit more overarching than to affect only the coal manager's short term expenditure.
Interesting bridge technology
Interesting concept to use renewables as a booster for coal. If the time to market for these types of things is short they maybe a useful bridging technology for legacy power while renewables stand-alone grow their market penetration. And using geothermal with coal plants opens up the possibility of an interesting segue from coal to geothermal within the one plant - that might significantly ease the capital impact of coal plants becoming stranded assets.
Sublimely Simple
This is one of the most interesting articles I have seen for a long time. Not being scientific personally, I find it hard to understand the concerns or dissatisfaction of green groups to this idea and please feel free to educate me.
Any use of geothermal heating must surely increase the effectiveness of any of the many renewable technologies that are being developed surely ? and specifically to to coal powered energy generation as mentioned in the article.
As a starter and so long as the costs are viable, the idea that the water arriving in a power plant could be x degrees higher has got to be good news even if its not the ultimate solution
I can only see the positive in the idea and look forward to results or a future update. If such a 'quick' technique could help over say the next 20 years well that gives us time to increase the efficiency of new technologies.
Well done Professor Behdad Moghtaderi and thank you Mr.Parkinson for the article.
Carbon tax will lead to a massive increase of greenhouse gases!
The dream of “clean coal” may remain a dream for a very long time. The main problem with coal mining is not necessarily the CO2 emission at the power plant. It is often caused by spontaneous combustion, which may occur in open cut as well underground mining, in coal and or overburden stock piles. In some mines, the “fugitive” emission may be higher than the actual greenhouse gas emission at power plants, especially of the loss of methane and other gases are included.
Most of the spontaneous combustion can be controlled, but it costs money and the current system of “bonuses” does not reward good management. The “bonus” system rewards managers and workers to defer “non-essential” expenditure such as rehabilitation and control of spontaneous combustion into the future. A carbon tax will put many mine managers even under greater pressure to take short-cuts and to delay the implementation of fugitive emission control. The carbon tax will cause a considerable increase in the emission of greenhouse gases in the coal mining industry.