Sunday, August 16, 2009

The Limits to Growth

Folks in an apocalyptic frame of mind will sometimes consider what would happen if everyone in the entire world were to adopt a lifestyle which consumed resources at the rate of those of us in western countries. To keep this blog post short, I'll not address the entire problem, but I would like to point out that carbon emissions need not be a problem.

I'll take as my example the French. French people live a pretty good life on about 6.1 tonnes CO2/person/year, which is the lowest of the countries in the G8. The French low consumption is possible because their electric sector doesn't emit significant CO2 or burn significant fuel and has stable prices (it's 85% nuclear and 10% hydro). So as gasoline prices have gone up (mostly taxes, but large increases in crude costs too), folks have switched to electrified mass transit. Their electric-powered TGV trains carry almost as much traffic as their domestic airlines.

Is French low consumption really a result of nuclear electric production? Yes. Consider Germany at 9.8 tonnes CO2/person/year. That would be 5.9 tonnes CO2/person/year if their electricity sector was nuclear, which is about the same as France.

[Update: for comparison, the United States would be at 11.3 tonnes CO2/person/year if we replaced all our coal and gas fired powerplants with nukes. If we replaced half our air transport with electric trains, it would help a bit more, but I think less than 1 tonne CO2/person/year.]

My point is that the French example can be applied to many countries. Now here's an interesting thought. What if the entire world were to adopt the French lifestyle, including the carbon-free electric system? How catastropic would the emissions be?

The world population is now 6.7 billion, so at 5 tonnes/person/year, that'd be 33.5 billion tonnes/year. Compare that to our current emissions of 28.4 billion tonnes/year. It's larger by 18%. Something to work on, not a catastrophe.

Obviously, it's not quite so easy. Right now, a fair bit of the carbon going into the air comes out of the ground in solid form. If the entire world were to use nuclear electricity, coal production would nearly stop (it's still needed for steelmaking), and all that carbon would be coming from petroleum and natural gas. That would take a fairly drastic increase in production capacity for both, leading to a rapid depletion of existing stocks.

The summary: anti-growth doom and gloom is unnecessary in the electricity sector, so long as folks are willing to follow the French example.

Side note: French reactors are almost all inland and cooled by river water. This is perhaps an example best not followed. The French have laws which prohibit those plants from releasing back into the river water which is too warm. So, during a heat wave two years ago, some power plants reduced generation in order to reduce their output temperature, right as electricity demand was spiking.

Seawater cooling is much more reliable, and doesn't use up fresh water either. Some day, when we have high-temperature molten salt reactors, we will be able to air cool our nuclear plants, and then this will not be an issue. Until then, we should probably build the majority of nuclear power plants near the coast.


  1. Hi Ian - -

    I just wanted to point out this recent paper by Meinshausen et al (www.nature,com/nature/journal/v458/n7242/abs/nature08017.html), which finds that in order to exceed 2 C warming with 50% likelihood, global cumulative emissions would need to be 1440 Gt CO2 from 2000-50. This works out to be 28.8 Gt CO2/year, or 4.25 t CO2/yer/per (current-day) person. For comparison, the US, at 5.75 Gt CO2/year uses an alotment of 18.9 Gt CO2 per person per year.

    So if we emit our fair share of this 1440 Gt for the next 50 years, we would emit 0.304 billion people * 4.25 Gt CO2 * 50 years = 64.46 Gt CO2. In other words, we will blow through our share in a few years. The implications of this is that we, the US, would need to completely decarbonize the economy post haste to avert warming that we know will cause bad things. That's going to require changes not just in fuel substitution (nuclear, wind, CSP, PV, etc), but end-use efficiency in buildings and industry, and as you say transportation infrastructure. Probably some negative emissions would be required to make this emissions target. Nope, as you say, not easy.

    There is another recent interesting paper on individuating global CO2 emissions by individual income (no surprise, richer people emit more . . but following a power law with diminishing returns) Turns out we can solve the carbon problem if we all emit as though we made $40,000 a year!

    - - Adam

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  3. The US has about 25 gigawatts of wind turbines, which cost between 30 and 40 billion dollars, and displace around 30 million tonnes of CO2 per year, primarily by displacing gas turbine power. The same money would have purchased 3 or 4 Palo Verde nuclear plants (the whole facility, not just one unit), each of which displaces 25 million tonnes of CO2 per year. Obviously 3 or 4 would displace a lot more CO2.

    If the US did what the French have done (nuclear generation and fast trains), we'd be down around 10 tonnes/person/year. To get down to French levels, we would need, in addition, to switch to more fuel efficient cars, and change our long-distance freight from trucks to electrified trains. I don't have exact numbers yet, but I think that gets us to 8 tonnes/person/year. After that it gets a lot harder.