Friday, October 28, 2016

70% of US CO2 Reduction Due Simply to Cheaper Natural Gas

US annualized CO2 emissions peaked in January 2008, at 6.01 gigatons of CO2 per year.

The latest US EIA data shows that July 2016 had annualized emissions of 5.12 Gt CO2/yr. 

("Annualized" just means the moving sum of the latest 12 months.)

That's a 15% decrease, and it's not trivial, especially in just 8+ years. Per capita emissions are down an impressive 29% from their peak.

How much of this decline is due to fracking, versus deliberate efforts to reduce our CO2 emissions? 

I estimate about 70% of this decline is due to exchanging coal power for power from natural gas, for electricity generation. Some of this is due to fracking, some due to simple economics of power plants, if indeed there's any difference. 

Oil emissions are up in recent months because oil prices are down. 

The result is

where the energy delivered from coal + natural gas hasn't changed much for about 15 years

indicating the difference in emissions isn't due much to reduced energy usage, but from switching from coal-genereated power to natural gas-generated power.

(The units energy engineers use suck. 1 Quad = 1015 BTU = 1.055 exajoules. 1 BTU = 1,055 Joules.)

The latest numbers say that the total change in CO2 emissions is down 896 Mt CO2 from its peak, whereas the change in CO2 emissions from coal + NG is down 634 Mt CO2 from its peak. 

So coal + NG makes up 71% of the decline. What remains -- less than 1/3rd -- is due to slightly more efficient cars, perhaps more efficient lighting, etc. 

But the bulk of the decline has come without individuals, or Obama, doing much in the way of CO2 reductions. Instead it's mostly from the switch of generating power via coal to generating power from natural gas. Because natural gas is now cheaper. 

So that reduction could well not hold if the relative prices of natural gas and coal, per BTU generated, stop holding or reverse.

So we, or Obama, don't really deserve a lot of credit. 


William M. Connolley said...

You sound somewhat disappointed. As though reductions from NG aren't as good as reductions from people choosing differently. Because you want people to become "better"? Isn't the lesson of this that making people "better" is really hard, so we should do easier things instead?

> So that reduction could well not hold if

Maybe on the short term but not on the long. Coal plants that are shut won't be readily re-opened.

PaulS said...

Can't speak for David, but from a pessimistic perspective all that's occurred is an increased availability of fossil fuels for burning. That it happens to be a relatively low carbon-intensive fossil fuel is fortunate, and at least in the short term there is the obvious benefit of reducing CO2 emissions by replacing higher carbon-intensive fuels.

Whether or not that's a situation which will persist is the question. There is a historical precedent. Coal consumption in post-WW2 USA plummeted, apparently largely due to replacement by oil and gas alternatives. However, from 1960 to the early 2000s coal consumption more than doubled, high above previous peak levels.

Jon said...

"Isn't the lesson of this that making people "better" is really hard, so we should do easier things instead?"

In the event that there aren't enough easier things to do to produce the desired effects, it would be helpful if we, as a species, had a track record of being motivated enough to solve this particular problem to do less easy, even hard things in pursuit of that goal.

David Appell said...

William Connolley said...
"You sound somewhat disappointed. As though reductions from NG aren't as good as reductions from people choosing differently"

I don't think they are equivalent.

People didn't lift a finger for NG from fracking. They would have been just as happy burning whatever the NG replaced -- coal, mostly.

The reduction required nothing on the part of users. They just, as always, bought whatever was cheaper, still ignoring its negative externalities.