Physical Insights

An independent scientist’s observations on society, technology, energy, science and the environment. “Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.” – Carl Sagan

Posts Tagged ‘energy systems

Blog Action Day

with 3 comments

Well, long time no post. I hope all my readers are well.

So, apparently today is something called “Blog Action Day“, and this year the topic of interest is anthropogenic forcing of the climate system, and mitigating the potential thereof.

So, OK, I thought I’ll write a blog post about it. The day is supposed to be about action, as the name suggests, so let’s talk about specific actions, with a view towards making a significant mitigation, in a realistic way, of Australia’s anthropogenic carbon dioxide emissions.

Australia’s brown coal (lignite) fired electricity generators have by far the highest specific carbon dioxide emissions intensity per unit of electrical energy generated, since they’re burning relatively high moisture brown coal. They are the most concentrated point contributors to the anthropogenic GHG output. Therefore, these are the “low-hanging fruit” – a very valuable target to look at first and foremost if we want to make the greatest realistic mitigation of the country’s carbon dioxide emissions in a practical way, followed by black coal-fired generators.

Australia’s total net greenhouse gas emissions in 2006 were 549.9 million tonnes of CO2 equivalent.

If we look at the three main sets of lignite-fired generators in the Latrobe valley in Victoria, they represent a very concentrated point source of CO2 output, so they’re a very good case to focus on specifically.

In 2006, Hazelwood generated 11.6 TWh of electrical energy, and 16,149,398 tonnes of carbon dioxide to atmosphere.

In 2006, Loy Yang A generated 15.994 TWh of electrical energy sent out to the grid and 19,326,812 tonnes of carbon dioxide to atmosphere.

I’ll exclude Loy Yang B from this list for the moment, since its numbers are eluding me.

In 2006, the Yallourn power station generated 10.392 TWh of electrical energy sent out to the grid and 14,680,000 tonnes of carbon dioxide to atmosphere.

If you look at the the total contribution of just those three brown-coal-fired plants combined, you’re looking at 9.12 percent of Australia’s total anthropogenic carbon dioxide emissions. If you replace those with clean technology that can deliver an equivalent electricity output, you get a 9.12 percent reduction in Australia’s CO2 emissions. (When you include Loy Yang B, I think it’s approximately 11-12%.)

That’s not a bad target for Australia to implement for the relatively short term for a real reduction in CO2 emissions. It can actually be done, if the real political will exists to do it.

Now, I’m not interested in this “100% renewable energy by 2020” business from the extremist any-excuse-for-a-protest Socialist Alternative set, because it is nonsense.

Replacing all the coal-fired and gas-fired generators in this country inside 10 years (and presumably only using wind turbines and solar cells, not nuclear energy of course since it doesn’t fit their para-religious ideology)? That’s complete bullshit, of course, because in the real world it cannot be done.

There’s a difference between setting a challenging target and setting a nonsense target. Unless you’re only trying to implement a political bullshit stunt instead of actually trying to hit your targets.

Of course, you don’t just close down the coal-fired generators. You’ve actually got to build their clean replacements first. So what do you use that can realistically replace a coal-fired power station? Nuclear power, of course.

Now, again, to be realistic, we probably can’t build LFTR/MSR, PBMR/HTGR, IFR/PRISM or any kind of nuclear fusion based generation capacity on a large scale to generate grid-connected energy right now. That’s not to say that pilot-scale research and development on those very cool technologies shouldn’t continue, but right now, getting more nuclear energy on the grid means advanced light water reactors – or maybe heavy water CANDU-type things, or conventional sodium-cooled fast reactors maybe. The most practical thing for serious deployment in the relatively short term is advanced LWR technology. In the slightly longer term, there is certainly a place to be encouraging both Gen. IV and fusion.

To get the same amount of energy as the total output from those coal plants, as above, which we’re talking about replacing, we need 4.56 GW of installed nuclear capacity, assuming a 95% capacity factor.

With 4 x 1154 MWe Westinghouse AP1000s, with a 95% capacity factor, you’ve got 4.62 GW, which is a little more than what’s needed.

You can easily have four nuclear power reactors integrated into one nuclear power plant.

Now, how much does it cost?

On March 27, 2008, South Carolina Electric & Gas applied to the Nuclear Regulatory Commission for a COL to build two AP1000s at the Virgil nuclear power plant in South Carolina. On May 27, 2008, SCE&G and Santee Cooper announced an engineering, procurement, and construction contract had been reached with Westinghouse. Costs are estimated to be approximately $9.8 billion for both AP1000 units, plus transmission facility and financing costs.

That gives you an idea of how much a nuclear power plant costs today, in the current financial environment, in the current regulatory environment.

If we double that figure of USD$9.8 billion, it’s AUD $21.4 billion. There will be some saving since we’re considering building four reactors at one plant, not two independent two-reactor plants.

How much that saving will be, quantitatively, I don’t really know. If the cost is reduced by 30%, we’re looking at 15 billion Australian dollars.

How long would it take? If the real political will exists to do it, 10 years is heaps of time. We could probably do even more in that timeframe if we really, really wanted to. AP1000 construction takes 36 months from first concrete poured to fuel load, if you ignore any political protest rubbish.

This is really just a base-line relatively achievable “base case”. After this decade, of course, the rate of nuclear power deployment – and related GHG emissions mitigation – could foreseeably accelerate.

What about the uranium input? About 600 tonnes of natural uranium per year total, for all four reactors. Australia’s present production, off the top of my head, is something like 10,000-11,000 tonnes. Australia’s present uranium production can very, very easily provide for Australia’s total electricity production even without expansion of uranium production – again, considering the inefficient once-through use of low-enriched uranium in conventional LWRs.

What about the so-called “waste”?
Roughly 80-85 tonnes of used uranium fuel per year. 96% of that is unchanged uranium, so that 76.8 tonnes of uranium can be seperated and re-used. It’s just uranium, so it’s not going to hurt you.

The remaining 3200 kg is made up of the valuable, interesting and unique byproduct materials from a nuclear reactor – unique resources with all kinds of different technological applications, which aren’t all radioactive, which you cannot get anywhere else.

Anyway, that’s one scenario which I happen to think has a lot of merit.

Maybe you don’t agree – but if you don’t agree, I’d love to see you elucidate an alternative scenario which can deliver the equivalent greenhouse gas emissions mitigation – shown to be accurate in a quantitative way – within a comparable timeframe and within a comparable cost.

It will not be inexpensive, and it will not happen overnight – but I have yet to see any scenario which can honestly do the same job faster and cheaper, when some real quantitative analysis is applied.

Written by Luke Weston

October 15, 2009 at 12:45 pm

Fischer-Tropsch fuels and carbon dioxide mitigation.

with 7 comments

“The good news is that there is no need to build new nuclear power plants to provide for the projected energy needs of the future. Indeed, it would be possible, using other forms of electricity generation, to close down most of the existing nuclear reactors within a decade. Many kinds of alternative solutions are currently on the drawing board because of the extreme urgency of countering global warming. For instance, the conversion of coal to a synthetic fuel, which can be used for transportation and which would contribute much less to global warming than petroleum, is actively being championed by Governor Brian Schweitzer of Montana.”

That’s a quote from the perhaps infamous Nuclear Power is Not the Answer. However, this post isn’t really a criticism directed at Caldicott, specifically. The bold is mine.

The production of synthetic of petroleum-like liquid hydrocarbon fuels through Fischer-Tropsch synthesis using coal as a feedstock is not environmentally sound at all, it is not an efficient use of energy resources and it is not at all a useful technology in the slightest degree to contribute towards the mitigation of anthropogenic carbon dioxide emissions from energy systems.

The first step in Fischer-Tropsch synthesis of liquid fuel from coal is the reaction of coal, which is mostly carbon, with steam under elevated temperatures and pressures, to yield a mixture of gaseous carbon monoxide and hydrogen, known as synthesis gas. This requires mining the coal, adding water, and supplying a significant input of thermal energy, intrinsically reducing the efficiency with which the energy content of the coal can be utilised – where does the thermal energy come from?
From burning more coal?

C(s) + H2O(g) –> CO(g) + H2(g)

We may wish to consider the small amount of hydrogen, about 4% by mass in typical bituminous coal, giving the coal an empirical chemical formula of something like C2H. However, the presence of this small amount of hydrogen in the coal makes essentially negligible difference, other than to marginally increase the H2:CO ratio in the synthesis gas mixture.

2 C2H(s) + 4 H2O –> 4 CO(g) + 5 H2(g)

It’s essentially the same as the previous reaction, above.

For the sake of simplicity, we might ignore, for now, the presence of sulfur, hydrogen, oxygen, nitrogen, metals and heavier elements in the coal, and focus on the carbon content. One notable advantage of Fischer-Tropsch fuels, however, is that the sulfur content of the fuel can be removed altogether, resulting in a fuel, such as diesel fuel, with negligible sulfur content, and hence with negligible emissions of sulfur dioxide into the atmosphere when the fuel is burned.

At the heart of the Fischer-Tropsch process is the use of an appropriately engineered catalyst and reaction conditions to convert the synthesis gas mixture back into a mixture of liquid hydrocarbons with an average molecular weight and composition which is usable as a fuel for vehicles. Suppose, for example, that we’re interested in the production of petrol for passenger cars – however, you could apply the same analysis equally to diesel fuel, for example, or any other particular kind of liquid petroleum fuel that you’re interested in.

Typical liquid hydrocarbon fuels, such as petrol or diesel fuel, contain about 13-15% hydrogen by mass – significantly greater than any possible abundance of hydrogen in the coal. As such, the addition of additional hydrogen into the reaction is necessary. Suppose that we’re interested in the production of petrol for passenger cars. For the sake of simplicity we can say that octane, C8H18, is representative of the overall chemical composition of the petrol.

When the coal is reacted with water to form synthesis gas, the synthesis gas is then reacted with more steam in order to increase the H2:CO ratio in the gas mixture, using water as the source of hydrogen, and producing carbon dioxide. This gas mixture can then be used to form the desired heavier hydrocarbons, using a Fischer-Tropsch catalyst.

25 C(s) + 25 H2O(g) –> 25 CO(g) + 25 H2(g)

9 CO(g) + 9 H2O(g) –> 9 CO2(g) + 9 H2(g)

16 CO(g) + 34 H2(g) –> 2 C8H18(g) + 16 H2O(g)

Hence, we have an overall chemical reaction which is equivalent to this:

25 C(s) + 18 H2O(g) –> 2 C8H18(g) + 9 CO2(g)

Traditionally, we extract crude oil from the ground, fractionate and refine the oil into products like petrol, and run our cars on the petrol. If we combust 2 mol of octane in an engine, we’ve emitted 16 mol of fossil-fuel-derived carbon dioxide into the atmosphere. However, if that 2 mol of octane is produced from coal via a Fischer-Tropsch process like we’ve elucidated above, then 25 mol of fossil-fuel-derived carbon dioxide is emitted into the atmosphere, for the same amount of energy output in the car’s engine. Does this “contribute much less to global warming than petroleum”?

Absolutely not – quite the opposite, in fact.

Even if all the carbon dioxide created during the synthesis was captured at the Fischer-Tropsch plant, liquefied, and sent to geological sequestration – which assumes that geological sequestration of the enormous quantities of carbon dioxide associated with fossil fuel energy systems is practical, which is extremely doubtful indeed and is at best completely unproven – then, at best, assuming that none of the additional energy inputs into the process come from fossil fuels, then the combustion of the synthetic fuel is associated with exactly the same quantity of carbon dioxide emissions as the
combustion of fuel derived from petroleum.

Synthetic fuel production, as exemplified by the Fischer-Tropsch process, is not advocated for reasons of the mitigation of anthropogenic carbon dioxide emissions – it is advocated by people including but not limited to Brian Schweitzer as a means to contribute to a secure domestic supply of liquid petroleum for the United States – helping to end the United States’ present dependence on foreign oil.

Fischer-Tropsch chemistry provides a particularly attractive means to keep our petroleum-fuelled vehicles in operation, using abundant, ubiquitous and secure domestic supplies of coal, where the security of foreign oil supplies are threatened by strategic or geopolitical considerations – as was the case in Nazi Germany and in South Africa under Apartheid, where Fischer-Tropsch fuel production was first well developed on a large, industrial scale.

Of course, perhaps it’s also possible Schweitzer also wants to see Montana’s abundant lignite coal utilised for the production of these synthetic fuels – bringing income into the state, and perhaps helping to keep the coal extraction industry in business in a society where it is increasingly widely accepted that coal is our number-one environmental enemy. That’s no secret.

Written by Luke Weston

November 25, 2008 at 1:21 am

Thinking about Better Place’s EV infrastructure proposals.

with 2 comments

For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.
— Richard Feynman

Better Place has attracted a lot of publicity recently, including on the Today Show and in the New York Times, following their agreement with AGL Energy and Macquarie Capital Group to raise one billion Australian dollars (about USD $665 million) to build a network of electric-vehicle battery infrastructure across Australia.

Better Place’s model offers a network of battery stations, just like petrol stations, at which an attendant will swap out an electric vehicle’s discharged Li-ion battery for a newly recharged one.

Drivers belonging to a monthly subscription service gain unlimited access to Better Place stations and fully-charged batteries for their cars. While electric-car owners can still charge their cars at home, a series of stations gives them more flexibility to travel long distances despite a battery’s limited range.

These are the biggest challenges to electric vehicle adoption – even the very best electrochemical batteries give a relatively low limit to the maximum range, they take a long time to recharge, there’s no infrastructure for recharging on the go, the batteries have finite lifetimes, and they’re very expensive. There’s only so much energy you can store in a given amount of battery of any particular chemical composition, and there’s a limit to the rate at which you can pour energy back into the battery in practice – these barriers are not things you can easily get around with politics and marketing.

The Tesla Roadster, as an example of one of the few battery electric vehicles on the consumer market today for which plug-to-wheel energy consumption data is easy to find, consumes 199 Watt-hours per km. In February 2008, Tesla Motors reported that, after testing a Validation Prototype of the Tesla Roadster at an EPA-certified location, that those tests yielded a range of 220 miles (354 km) and a plug-to-wheel efficiency of 199 Wh/km. (Admittedly, the Tesla is probably sacrificing a little energy efficiency for the sake of performance, meaning that it could probably be possible to deliver better energy consumption in a vehicle designed with that consideration in mind.) I’ll use the Tesla Roadster as a specific example, mainly because such technical details of it are easy to find.

The battery in the Tesla takes 3.5 hours to charge from zero charge, and stores 53 kWh of energy. Efficiency of the charging electronics is 86%, so 62 kWh of electricity is needed for a single charge.

If you just plug in the vehicle to charge it, and it consumes 62 kWh to charge the battery, and charges in 3.5 hours, then the line power supply to the charger must supply 74 A at 240 V (AC RMS) or 144 A, on a 120 V grid. Those are very large currents, far in excess of the maximum capacity of 10 to 15 A or thereabout that we associate with standard domestic power circuits.

If you were to just plug in such a vehicle into a household electricity line socket to charge it, (at 10 A at 240 V), then a 12 hour charge would correspond to a range of 164 kilometers, or a round trip of 82 kilometers.

If you need to travel further than that in a day, then clearly “charging stations” like the Better Place model, or some kind of provision for high-current power supplies to charge the vehicles, needs to be available. In principle, at least, the Better Place business model sounds like a good idea.

The service also saves drivers time, according to the company, since Better Place attendants can swap out a battery in about three minutes, versus the few hours it takes to recharge a battery.

Keeping in mind that electricity is only as clean as its energy source, Better Place claim that their stations will purportedly recharge their stocks of batteries using electricity from renewable energy systems.

Better Place proudly proclaims that “We will build an electric vehicle network capable of supporting the switch of Australia’s 15 million gas cars to zero emission vehicles.” and that “AGL will provide all of the renewable energy—from wind and other sources—needed to power the electric vehicles and work with Better Place to optimize the network.”

The total ‘renewable’ electricity generation in Australia in 2007 was 20.964 TWh, almost all of which (14.722 TWh) is hydroelectricity.
[Source]

So, if all of Australia’s current renewable energy generation, across all energy utilities – which is already used, already traded for “carbon credit”, and sold to “green power” customers – was used to power Australia’s 15 million passenger cars, assuming that they were all replaced by battery electric vehicles, then there is only enough renewable electricity generation at present for each car to travel an average of 19.2 kilometers per day, assuming that only “renewable” energy, i.e. hydroelectricity, and solar, wind, tidal or biofuel generated electricity was used to power 15 million BEVs, and that every bit of electricity generated from these systems in this country was dedicated exclusively to this use.

In 1991, cars in Australia travelled an average of 14,600 km [source], or 40 km per day. If this level of car use was maintained today (unfortunately I cannot find any newer statistics), then total renewable energy generation would have to be multiplied 2.1 times from present levels – assuming all cars were replaced with BEVs and that all the renewable electricity generation was used exclusively for charging the BEVs, and no fossil-fuel-generated electricity was used. I don’t think I really need to convince anybody that any real expansion of hydroelectricity is not something that is at all foreseeable nor really practical in Australia.

Simply muttering the magic word “renewables” three times and clicking your heels, or something, isn’t grounds for conjuring up an arbitrarily large quantity of cleanly generated electrical energy – the infrastructure has actually got to be put in place to generate that corresponding quantity of energy.

The entrepreneur wasted no time comparing the east coast of Australia, where Better Place will build “electric highways” connecting Melbourne, Sydney and Brisbane, to the West Coast of the U.S. where Agassi would like to do the same between L.A., San Francisco and Seattle. The greater Melbourne-Sydney metro area will require 200,000 to 250,000 charging stations, Agassi said. Better Place plans on deploying some 500,000 charging points for the whole of Israel.

Under the plan, the three cities will each have a network of between 200,000 and 250,000 charge stations by 2012 where drivers can plug in and power up their electric cars.

If you have 250,000 charging stations (I’m not sure if they mean 250,000 total for the east coast, or 200,000 to 250,000 each in each of those three cities.) and 21 TWh per year of renewable energy, then that’s only enough for each charging station to be able to recharge three batteries per day, which is obviously completely insufficient. (1 day * (21 TWh per year) / (250,000 * 62 kWh) = 3.7)

In practice, burning one litre of petrol in an automotive engine results in emission of 2.32 kilograms of carbon dioxide per litre. Obviously, better fuel economy means better CO2 emissions economy per kilometer.

In Australia, the average GHG emissions intensity for electricity generation is 1000 gCO2/kWh. (In Victoria, it’s obscene, about 1300-1400 gCO2/kWh.) The Tesla Roadster has a plug-to-wheel efficiency of 199 Wh/km. Therefore, the equivalent CO2 emission for the Tesla Roadster is about 20 kg CO2/100 km.

So, if you can have a petrol-burning IC engine car with a fuel economy equal to 8.62 L per 100 km or better, then in terms of CO2 emissions, it is equally as good as, or better than, such an electric vehicle. In brown-coal-powered Victoria, the point of equivalence is about 11 to 12 litres per 100 km – which basically all cars surpass, at present.

8.62 L per 100 km is 27.3 miles per gallon – so that’s approximately equal to the old CAFE standard for cars in the USA, which I’m pretty sure was 27.5 MPG, and significantly worse than the newer standard of 35 miles per gallon. It is totally practical to build cars with such a degree of fuel economy.

Whilst in principle electric vehicles are a good idea particularly in the long term, we have to realise that right now, given the current state of electricity generation in Australia, the number one priority, in terms of mitigating excessive anthropogenic emissions of greenhouse gases, has got to be the replacement of fossil fuel based electricity generation with non-polluting systems.

While we’re implementing that, I also think that improving the fuel efficiency of ICE cars and vehicles is just as easy, probably more cost effective, and capable of delivering an equal degree of improvement in the environmental intensity of the transport sector, at least in the near term, until the coal-fired electricity generators start being replaced.

Robert Merkel over at Larvatus Prodeo posted a good post on the same topic recently.

I’ll leave you with a quote from Merkel – I couldn’t agree more with this:

If I were a government minister receiving a visit from Better Place and its partners for some kind of government incentive, I’d look very long and hard at the environmental benefits we’ll get for the dough they’re asking for.

Just like solar panels, I’d expect the answer to come back – lots of money for bugger-all environmental gains. And that should be the bottom line, not slick PR campaigns that suck in a gullible mainstream media.

Written by Luke Weston

October 29, 2008 at 8:31 am

ThermoGen: When “Green” energy doesn’t add up.

with 3 comments

I’ve been looking at some of the claims on the website of Thermogen recently.

In short, what Thermogen claim is that they can supply a domestic solar thermal energy installation whch provides an electrical power output of 5 kWe, and that that power output is accessible 24 hours a day via energy storage in tanks of high-temperature water.

The Thermogen is designed to supply it’s rated output 24 hours per day, cloudy or sunny weather e.g. a 5kW system will supply 120kW per day. [sic] It has a three day design storage for inclement weather.

Of course, if a 5 kW system can supply 5 kW of power for 24 hours, then that’s 120 kilowatt-hours of energy. I’m a little bit wary of a company selling energy technology when they can’t tell the difference between a unit of energy and a unit of power.

This heated water is then stored in 1000 litre insulated tanks at 150-200 °C. These tanks are a solar energy storage system designed to store enough energy to provide the following services for up to three days without sunshine:

For a 5 kWth system to be able to store energy up for three days, then 360 kWhth of energy must be stored in the system. We’ll come back to that in a minute.

They explain that:

Each panel measures 2.4m wide and 2m up the roof. It is expected that you will need 7 of these panels for the Thermogen system.

That’s a collector area of 33.6 m2. A little less than that, actually, since not 100% of the panel’s dimensions will be usable solar collector area.

For comparison, a standard large two-panel Solahart hot-water system has a collector area of 3.5 square metres.

Now, if we look at BOM’s map of average daily solar exposure across Australia, we see that the average daily solar exposure is, in the sunniest parts of nothern Australia, 21 megajoules of solar energy per square meter per day.

If there is one idea to keep in mind when considering solar energy, that is it. Irrespective of what sort of collector technology you have, there is always a very finite limit to the amount of energy you can collect from a solar collector of a given area. That energy flux is the maximum that there is to be utilised, no matter what technology you use to harvest it.

So, anyhow, we have 21 MJ/m2/day, and a rooftop solar collector of 33.6 m2. We’ll be conservative here and assume (a) you live in Townsville or Alice Springs or Darwin and (b) the entirety of the surface area of those collectors is active area. So, the power output that you get is a maximum of 705.6 megajoules per day.

The most efficient evacuated-tube solar thermal energy collectors, like the ones proposed by Thermogen, manage a gross efficiency of energy collection of about 60%. So, now we’re down to 423.36 MJ per day.

This thermal energy is then converted into electrical energy in a heat engine. In this case, the engine that they’ve pictured on their webpage – without attributing it’s source – is a Freepower 6 [PDF link] 6 MWe Organic Rankine Cycle powerplant.

Some of the images on the Thermogen site appear to depict the FreePower 6 organic Rankine cycle engine / generator as well as a Rotartica absorption chiller, with no credit given to the peope responsible for these components.

(An organic Rankine cycle is simply a Rankine cycle engine using an organic chemical as the engine’s working fluid, such as a fluorocarbon liquid, a fluorocarbon gas like a refrigerant type material, or some type of liquid with a lower boiling point than water, as the engine’s working fluid. Such engines are commonly used to recover low-grade heat from industrial processes, and as geothermal electricity generators, since they’re designed to operate with low temperatures.)

Now, let’s look at the specs of the FreePower 6 engine. It requires a heat source of 180 °C, returns the cooled oil at 123 °C, and requires a thermal power input of 70 kWth, to generate an electrical power output of 6 kWe. Since the Thermogen system is supposed to generate 5 kWe, I presume 1 kWe is consumed to drive the hot water pumps.

Therefore, the engine only has an efficiency of 8.6% – seemingly very low efficiency indeed. That seems like a terribly low efficiency, but the maximum efficiency – as per Carnot’s theorem – at these temperatures is only 11.6%, so the efficiency realised in practice isn’t too bad. At least these guys aren’t trying to flog off a perpetual motion machine.

Now, if we’re putting 423.36 MJ into the engine, and our electricity output is uniform day and night, then at this efficiency, we have a thermal input power of 4.9 kW, and we’re getting an electrical power output of 421.4 Watts.

I suppose that might be where they’re getting their claimed of “5 kW” from, given that they’re putting an average power of about 5 kW thermal into the engine?

Furthermore, cooling water is required to dissipate the engine’s 60 kWth of waste heat, at a flow rate of up to about 0.8 L/s and a maximum outlet temperature of 55 °C. I’m afraid that yes, in this house, we obey the laws of thermodynamics. Perhaps you need to build an artificial pond next to it or something? But that’s good, right? Lake Anna attracts lots of tourists, doesn’t it? 😉

So, we’re left with 421.4 Watts. Jump for joy; your energy needs are solved forever.
That’s, what, enough energy to run a handful of incandescent light bulbs?

We have an electricity output of 10.11 kWh per day, then.

The energy requirement for an average home is 10kW per day (See Synergy website), so the additional 110kWhrs of electricity may be supplied to the grid.

For example, a 5kW Thermogen system will generate 120kW per day while the average Australian home uses between 10kW to 30kW per day.

Average Australian household electricity consumption is about 15 GJ per household per annum – 11.4 kWh per day.

If you have a small household, or an energy-efficient household, then such an installation can realistically meet all your household electricity needs. Probably. If you live in northern Australia. If you live in Melbourne, Sydney or Adelaide, forget about it. Even if you could supply all household demand for electricity, however, there will be little or none left to sell into the grid.

They claim that the power generated from a domestic Thermogen installation “will supply a revenue stream of up to $20,000 per annum at current rates which will pay the mortgage on most homes in Australia”.

It won’t.

If we really did want to generate 120 kWh of electricity per day, what would be required? You’d simply need 400 square meters of collector panels. That won’t fit on your roof. It would be the kind of system that lives up to what they’re claiming, though.

This is before we even start thinking about the energy storage tanks of a couple of thousand litres of water at 150 to 250 °C – superheated water at pressures exceeding 200 psi. If you’re standing around the tank and it ruptures, it will cook you to death. Do you really want this engineered and installed in homes by people who can’t tell the difference between power and energy?

For a 5 kW system to be able to store energy up for three days, then 360 kWh of energy must be stored in the system.

If the initial temperature of the water is 180 °C, and the final temperature of the water is 123 °C, then the storage of 360 kWhth to supply three days worth of energy requires 360 kWh / (4.184 Jg-1K-1 * 57 K * 1 g cm-3) = 5434 L; 6 quite large 1000 L storage tanks.

How much does all this cost, anyway? There is not one word of it on the site thus far.

There’s nothing especially malicious or ill-intentioned about Thermogen – although I would not invest in them under any circumstances. They simply appear to be another trendy, hopeful “Green” enterprise that simply can’t count.

The illustrious Dan Rutter has more in a similar vein, here.

Written by Luke Weston

October 11, 2008 at 11:55 am

Water and cooling requirements for large thermal power plants.

with 2 comments

I was involved in a bit of discussion recently about the cooling of large thermohydraulic (i.e. heat engine) generatng stations, their use of water, and the like. I was thus inspired to to a bit of thinking, research and writing about the issue. The little essay or discussion piece that I’ve put together can be found here, and I encourage you to please have a read if you’re interested and tell me what you think. I’ll keep it online in that PDF since it’s a little long, and I’ve used a little math typesetting which is a hassle to transcribe across to the blog post.

Written by Luke Weston

September 5, 2008 at 4:54 pm

Energy from Heaven and Earth

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Has anyone read this book? If not, I recommend it. It’s one of those books that, despite being nearly thirty years old, seems to remain astonishingly relevant to this day.

For some readers, depending on what you may think of or know of the famous or slightly infamous Edward Teller, some of the points of the book may come across as a little surprising. Energy conservation is not enough. Coal is not enough. Nuclear energy is not enough. … turn down the thermostat… we can reduce our energy requirements for heating by wearing sweaters or warm underclothing. In fact, there are parts of this book where you’d be forgiven for thinking you’re reading the contemporary works of Romm, or Lovins, or Caldicott, where issues like domestic energy use is discussed.

From the origins of petroleum and fossil fuels, to the origins of fission fuels in the collapse of heavy stars, to the oil embargo and OPEC, to the expected detailed treatment of nuclear fission and fusion energy systems, to an impassioned call for reductions in domestic energy use – it’s all here, it’s all fully relevant today, and it’s all very interesting.

ENERGY FROM HEAVEN AND EARTH — Edward Teller — W H Freeman, 1979, 322 p., illus., “In which a story is told about energy from its origins 15 billion years ago to its present adolescence — turbulent, hopeful, beset by problems and in need of help.” Past, present, near and distant future uses of energy are discussed, together with energy policies. A model for the future is included.

A recommended piece of reading.

Written by Luke Weston

September 5, 2008 at 9:35 am

Switching off Victoria?

with 5 comments

I was quite impressed with myself to discover, the other day, that everybody’s favourite opinionated newspaper columnist, Andrew Bolt, had linked to and cited one of my recent posts.

That’s probably responsible, at least in part, for the significant increase in traffic I’ve seen on this blog over the last week or so – and I’m grateful for that.

Sometimes Bolt is absolutely on the money – but not always.

Here’s a recent blog post of Bolt’s which is somewhat agreeable, but still gets on my nerves a little bit. It’s worth reading, anyhow.

It’s utterly unbelievable that the Rudd Government should be contemplating making bankrupt the stations that provide more than 90 per cent of Victoria’s power:

Yes – it is extremely worthwhile and important to close down the extremely polluting and greenhouse gas emissions intensive brown coal fired power stations that provide more than 90 percent of Victoria’s electrical energy. That does not mean making the energy companies bankrupt – we still need that energy, it just has to come from a different source.

However, I too would have a hard time believing that Rudd would or could actually make it happen.

Although careful to respect the Federal Government’s process, Victorian Energy Minister Peter Batchelor appears increasingly nervous in his public comments. Asked if one of the state’s brown coal generators will be forced to close prematurely, he said: “It depends on the nature of the emissions trading scheme (introduced).”

The purpose of a GHG emissions trading scheme is to mitigate anthropogenic greenhouse gas emissions from our industries. Its purpose is not to raise more government revenues or to create more paperwork – its purpose, its reason for existing, is to reduce industrial, anthropogenic emissions of carbon dioxide.

Therefore, if the “mud-burning” Latrobe Valley stations are not the very first things to close down under an emissions trading scheme, then clearly the scheme is not working.

If it’s one like Garnaut actually recommends – with no compensation to power stations for wiping billions off their value – the generators are cactus. And here is Kevin Rudd’s modus operandi writ large and destructive: process over purpose. What possible good could there be to cause such an economic catastrophe in this state?

But Rudd’s guru has a solution of the kind the Soviet Union would have suggested:

In his report, Professor Garnaut said $1 billion to $2 billion of the emissions trading scheme proceeds should be invested in clean coal technologies, matched dollar for dollar by the companies. If clean coal worked, he said, the Latrobe Valley would heave a “prosperous and expansive future”. If it didn’t, money from the scheme should be used to help retrain workers and to help the valley community survive the brave new world of zero emissions.

Hey, let the Government spend a couple of billion of taxpayers’ money, and another couple of billion of the bosses’, on a yet-to-be proved “solution” many experts say is pie in the sky. And then, $4 billion later, let’s give the unemployed some handouts.

Warning: These people now have their hands all over your jobs and paypackets.

Whilst I’m interested – and many others are interested – in seeing the coal fired plants closed down, that doesn’t mean that the electricity utilities are out of business – we still need the electricity, and we will continue to need the electricity.

Ideally, what we would see happening is the construction of new lower-emissions or zero-emissions electricity generators of an energy output comparable to the coal power plants, followed by the decommissioning of the coal-fired plants. [Of course, we don’t decommission the coal plants until after the new ones are online.]

The electricity utilities are still operating lower-emissions or zero-emissions generators, there are still people employed, and we’re still getting the energy needed to support developed civilisation. This is where we need to transition to, and where an emissions trading scheme – if it’s done right – might help us transition to.

I agree that investing many billions of dollars in CCS research and development, which is considered by many to be pie in the sky, is a grave mistake. Instead, we need to consider the energy generation technologies that are mature technologies that are available and proven right now, that can replace coal-fired power plants, generating energy at a comparable scale, for less GHG emissions.

Those options are large hydroelectricity, natural gas fired turbines, and nuclear fission.

In Australia, expanding the use of large hydroelectric installations above and beyond what we’ve already got is really not a practical proposition, so we’re left with two options that really could replace coal-fired generators in the Latrobe valley, under an emissions trading scheme – natural gas and nuclear energy. Certainly, what is absolutely not sensible at all is arbitrary, unfair and exceptional, scientifically unfounded legal prohibitions on the development of nuclear power plants by the energy companies who are willing to invest in zero-emissions replacement for coal, especially when their investments may be kick started by billions of dollars in the government’s ETS revenue, which clearly needs to be put back into these zero emissions or lower-emissions technologies.

If power plant operators wish to pursue either of these options, which will finally actually put a stop to the ever-expanding use of coal-fired generators, and finally put a real dent in GHG emissions, then they are to be wholeheartedly encouraged in doing so.

Obviously the nuclear energy option is completely superior to natural gas in terms of greenhouse gas emissions – however, in practical terms, one must grant that gas turbines are already in widespread use in Australia today, and they are more politically acceptable in some political circles than nuclear power – however that may change as concern over greenhouse gases, even at the somewhat reduced levels from natural gas generators, grows.

However, that said, given the importance of making real cuts in GHG emissions within the next 3-10 years, if the generators want to build combined-cycle natural gas turbines, technologies with which they’re more familiar, straight away, then they shouldn’t be discouraged. Natural gas could offer some benefit as a stopgap measure for last-ditch replacement for coal fired plants in the absence of nuclear power.