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

Archive for the ‘fossil fuels’ Category

Not-really-clean-coal for Victoria.

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Just two days before the Garnaut report on climate change is handed down, the Victorian Government has given the go-ahead to a new brown-coal power station in Latrobe Valley.

Environmental campaigners said it was “complete madness” to approve the $750 million plant, but the Government said the station would use new technology that would slash greenhouse gas emissions.

The project is a joint venture between consortium HRL and Chinese power giant Harbin Power, and will receive funding of $100 million from the Federal Government and $50 million from the Victorian Government.

“The $750 million HRL plant will use technology which has been developed right here in Victoria and is part of the new generation of clean coal power stations designed to slash greenhouse gas emissions,” said the Energy Minister, Peter Batchelor.

“The project uses a process called integrated drying gasification combined cycle (IDGCC) which can reduce emissions of CO2 from brown coal-fired power generation by 30 per cent and reduce water consumption by 50 per cent, compared to current best practice for brown coal power generation in the Latrobe Valley.”

Robert over at Larvatus Prodeo actually reported on this at length last year, when the project was first announced, and there’s a good body of details of the project and discussion to refer to there.

Typical generators burning Victorian brown coal generate 1175 g CO2e per kWh of electricity generated.

The IDGCC plant will reduce carbon dioxide emissions by 30% – so, that’s about 823 g CO2e/kWh.

For a good supercritical black coal burning plant you’ve got about 863 gCO2e, and 751 g for natural gas, or 577 g for combined cycle natural gas – which is about the absolute lowest you’ll get for a fossil fuel.

The carbon dioxide emissions are still high as all hell. It’s basically the same as a black coal fired power plant – in absolutely no way is it low in greenhouse gas emissions. All that the IDGCC technology is really accomplishing is to turn a plant powered by brown coal – the most especially inefficient and carbon dioxide intensive form of coal – into the emissions equivalent of a more conventional black coal fired plant. Make no mistake – the entirety of that dangerous fossil fuel waste is being discharged straight into the environment, as per business as usual.

But there’s one aspect to this which I find interesting, in particular.

This plant is slated to cost 750 million (Australian) dollars, and will have a nameplate capacity of 400 MW.
That is; $1875 per kilowatt of nameplate capacity.

The US nuclear energy industry is aiming to build new nuclear power plants for a cost of $1500 to $2000 per kW capacity.

The General Electric ABWR was the first third generation power plant approved. The first two ABWR’s were commissioned in Japan in 1996 and 1997. These took just over 3 years to construct and were completed on budget. Their construction costs were around $2000 per KW.

Westinghouse claims that the AP1000 power reactor will cost $1400 per KW for the first reactor and fall to as low as $1000 per KW for subsequent reactors.

I don’t know what kind of capacity factor is to be expected from an IDGCC plant – but at best, it’s comparable to that of nuclear power. If the capacity factor is significantly less, then this decreases the economic competitiveness of the coal plant relative to nuclear power still further.

We’re looking at the construction of a coal-fired power station that is not mitigating its carbon dioxide emissions in any meaningful way, emitting about 823 g CO2e/kWh straight into the atmosphere, along with all kinds of other dangerous coal byproducts, where the construction of a new nuclear power plant is already likely to be directly competitive, if not superior, on construction cost terms, even in the absence of any kind of emissions trading scheme, carbon dioxide ‘price’, carbon dioxide capture and storage or carbon dioxide sequestration.

What’s up with that?

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Written by Luke Weston

July 3, 2008 at 4:52 am

A little coal-fired satire.

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If the embedded video above doesn’t work properly on your web browser, use this link.

Written by Luke Weston

April 30, 2008 at 3:23 pm

Natural gas

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Have you ever wondered they call it natural gas, anyway? Is it anything more than an attempt to invoke association between the word natural and a “clean and green”, ”good” source of energy? We don’t refer to natural coal or natural oil, do we? How about natural uranium? Well, granted, the latter term is not uncommon, in a different context.

Can you imagine the outcry if the energy industry started marketing their energy systems as natural oil, or natural coal? It would be derided as a misleading stunt by the energy companies (not to mention the Amory Lovins brigade), to give their environmentally dangerous fuels a clean image!

Just to make it really clear to everyone what it really is, perhaps we should refer to it as fossil gas?

Written by Luke Weston

April 2, 2008 at 9:01 am

Earth Hour, candles and carbon

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There’s one thing in particular that bothers me about Earth Hour – these people who electric lights and then go and light up candles, and think that they’re helping do something about anthropogenic forcing of climate change.

The widespread practice of misguided eco-Luddites turning off their lights for Earth Hour and burning candles as a source of light is grossly misguided and actually contributes to increased carbon dioxide emissions.

Yes, I know candles are nice and romantic – but you’re taking paraffin wax, in the form of a candle, and burning it, very inefficiently, at a low temperature. This stuff is pure hydrocarbon – it’s a heavy alkane fraction distilled straight off crude oil. This stuff is getting so scarce that nations are prepared to go to war just to secure it, remember?

A candle flame burns at a low temperature – so it’s a thermodynamically very inefficient source of energy – and most of the energy released in a candle is wasted as heat, anyway.

Even if 80% of your electricity comes from coal and fossil fuel fired power stations, as it does in Australia, burning candles is very polluting and certainly very greenhouse gas and carbon dioxide emissions intensive, even more so than electric lighting.

If you need to do something that requires light – then leave an electric light on – just one. It’s far more efficient, less carbon dioxide emissions intensive and better for the environment – not to mention much safer than using hazardous candles.

If you want the romance of a candle, try looking for candles that you are certain are made from pure “carbon neutral” beeswax or tallow – not from crude oil in the form of paraffin wax.

Can’t we just put science, reason, rationality, education and reason ahead of trendy politics and trendy dogmas – before it’s too late?

What Earth Hour should not be about is the notion that we want to have a civilisation without artificial lighting – this is absolutely ridiculous. Lighting up the darkness was one of the most useful technological achievements in human history – why would we give that up?

Using electricity for lighting is far more efficient and environmentally sound than the primitive technologies, burning fossil fuels dirtily, at ambient pressure and relatively low temperatures, that came before electrification.

The use of electricity, and the use of electric lighting, is part of our way of life, in a developed, technological first-world society – I, for one, am not prepared to give that up, not the least because we don’t have to.

Light bulbs don’t produce greenhouse gases – burning fossil fuels to generate electricity does.

Let’s focus our efforts on moving away from fossil fuel based electricity generation, and expanding the use of non-greenhouse gas intensive hydroelectricity, nuclear energy, and wind energy, to solve our problems with anthropogenic greenhouse gas emissions.

Earth Hour should be about doing everything that you can to reasonably, sensibly limit your demand for electricity – and we can do this every hour of every day, of course. It makes sense for everyone – after all, you pay for the electricity.

I guess I have a problem with the idea that Earth Hour symbolises something.

It might symbolise something, but it doesn’t actuallydo anything.

The only thing it symbolises is primitive society.

I’d much rather see people spend their Earth Hour doing something that really does count for something.

Instead of spending your Earth Hour bearing with an uncomfortable, dark lifestyle, use that hour to think about the things that we can all do every day to limit electricity consumption, that we will actually bother to do every day, that are compatible with the fact that, yes, in our developed first-world society, we actually use electricity, and we work after the sun goes down. Think about the things that are compatible with our sensible lifestyles in the developed world, and do them, and it works out better for everybody!

Now, let’s consider just how much, quantitatively, this use of candles during Earth Hour is responsible for increased emissions of greenhouse gases.

Postulate I: A typical candle produces about 13 lumens of visible light, from a total power output of about 40 W, most of which is heat.
Postulate II: A 40 W electric incandescent light bulb consumes 40 W of electric power, and produces approximately 500 lumens of visible light output.
Postulate III: The overwhelming majority of candles are made from petroleum, in the form of paraffin wax. Paraffin wax has a heat of combustion of approximately 42 kJ/g, and can be assumed to consist, chemically, entirely of pentacosane – \mathrm{C_{25}H_{52}}.
Postulate IV: The average greenhouse gas emissions intensity for electric power generation in Australia is about 1000 g \mathrm{CO_{2e}}/kWh, and electricity is transmitted with transmission losses of about 7%.

\mathrm{C_{25}H_{52}(g)\ +\ 38\ O_{2}(g)\ \to 26\ H_{2}O(g)\ +\ 25\ CO_{2}(g)}

\mathrm{M(C_{25}H_{52})} = 352.68 g/mol;

\mathrm{M(CO_{2})} = 44.0 g/mol.

Thus, we know the emission of carbon dioxide from burning candles:

\mathrm{\frac{40\ W/candle\ \cdot\ 25\ mol/mol\ \cdot\ 44\ g/mol\ \cdot\ 3600\ s/h}{4.2\ \times\ 10^{4}\ J/g\ \cdot\ 352.68\ g/mol}\ =\ 10.69\ gCO_{2e}} – per candle per hour.

And the rate of carbon dioxide emissions from the electricity generation corresponding to the use of 13 lumens worth of lighting – the equivalent of one candle – for one hour:

\mathrm{\frac{13\ lumens/candle\ \times\ 1000 g/kWh\ \times\ 107\%\ \times\ 40\ W\ \times\ 10^{-3}\ kW/W}{500\ lumens}\ =\ 1.11\ gCO_{2e}} – per candle-equivalent of electric light per hour.

Therefore, for every candle that is burned to replace electric lighting during Earth Hour, greenhouse gas emissions over the course of the one hour are increased by 9.6 g of carbon dioxide.
If the light output from a 40 W light bulb was to be completely replaced by candles, this will lead to the emission of an extra 295 grams of carbon dioxide per over simply using the electric lights – if the equivalent of one thousand 40 W bulbs are replaced by candles, that’s an extra 295 kilograms of \mathrm{CO_{2}} emitted.

In places where a greater proportion of the electricity supply is generated by nuclear energy or hydroelectricity, this increase in greenhouse gas emissions is even larger.

Written by Luke Weston

March 31, 2008 at 5:13 pm

Electric cars and fossil fuels.

with 3 comments

I’ve recently heard a bit of debate centred around the question of electric cars – in a society such as Australia, where essentially all electricity generation comes from extremely polluting, carbon dioxide emissions intensive coal-fired plants, is there any environmental benefit to using electric vehicles?

First and foremost, of course, petroleum is one of our most finite and limited energy resources – concerns about the limits to conventional petroleum extraction are oft discussed, and the geopolitical insecurity associated with dependence on foreign oil also needs to be taken into account.

Gasoline/petrol has an energy content (calorific heating value) of 44.4 MJ/kg, and a mass density of about 737 g/l, and therefore a heating value of 9.1 kWh per litre.

A typical small car uses about 7 litres/100 km at an average of 90 km/h in highway use, and about 8.5 litres/100 km in city use.

In highway use, the engine uses about 1 litre of fuel – 9.1 kWh – to generate 1.7 kWh at the wheels – 18.7% efficiency. In city use, due to frequent braking, this overall efficiency in energy consumption is greatly reduced – let’s say 5-10%.

Averaging out highway and city use, let’s take – just rough approximations, remember – an overall efficiency of 12%, giving 1.48 kWh generated at the wheels per kilogram of fuel.

With an electric car, assuming 90% efficiency in the charger, and 90% efficiency in the control electronics, combined with regenerative braking, then we need to input 1.83 kWh of electricity from the grid, to get 1.48 kWh at the wheels. For 1 kg CO2 equivalent per kWh of electricity generated – this seemingly very high figure is typical for Australia – we have 1.83 kg of CO2 generation, for the equivalent of the use of 1 kilogram of fuel in a gasoline engine.

If we assume that the fuel is a mixture of only octane and its isomers (a rough assumption, but it will do), then the complete combustion of 1 kg must generate 3.08 kg of carbon dioxide – clearly the electric car is significantly ahead in this regard.

Electric cars are a technology we should at least give full, rational scientific thought to. Whilst the burning of coal to generate 80% of our  electricity needs is clearly unacceptable and cannot continue, as we replace the coal-fired base of the grid with  cleaner technology, maybe electric vehicles are potentially a technology where, in theory at least, benefits are to be had, especially if combined with a scalable, high-capacity, strong power grid, powered by clean nuclear electricity.

Written by Luke Weston

December 17, 2007 at 5:33 am