A recent article in The Independent, suggested that:
A golf-ball-sized lump of uranium would supply the lifetime’s energy needs of a typical person, equivalent to 56 tanker trucks of natural gas, 800 elephant-sized bags of coal or a renewable battery as tall as 16 “super” skyscraper buildings placed one on top of the other.
I tend to disapprove of these types of statistics because they don’t compare apples to apples. So, I decided to make some simple estimates for average American use (note that this is close to double an average European’s use).
This is a little tricky because as I discussed in The basics of energy, each energy type is different. However, the EIA has been converting back and forth regularly for many years. The idea is to work backwards from electrical energy to get the amount of heat energy. For a typical coal or nuclear plant this is roughly 1 part electric = 3 parts heat (based on thermal efficiency).
First, let’s look at historical usage rates from the EIA and use a few guesses to estimate future usage. I include two linear trend lines. One suggests growth over time, while the other suggests a slight decrease over time.
If we assume the average life expectancy is 80 years and that the person is 40 years old in 2015, our typical energy user lives from 1975 to 2055. After plugging these values into the trend line equations, we can calculate total emissions by just using the formula for a trapezoid (A = b * (h1+h2) / 2).
That means our estimate for cumulative use by an average American is between 26,700 and 29,600 million Btus. Checking the MIT_conversion sheet, the heat content of several fuels are:
- coal is 21.5 million Btu / ton
- natural gas is 50 million Btu / ton
- uranium is 379,000 million Btu / ton mined
High estimates are therefore (and low):
- coal: 1,377 tons (1241)
- natural gas: 592 tons (534)
- uranium: 0.078 tons mined (0.070)
Now of course, each material has a different density, but this comparison seems more useful. And if these numbers seem too big to picture easily, it’s easy to pick a smaller time-frame. For instance, fuel use over an average week during the lifetime:
- coal: 728 pounds
- natural gas: 313 pounds
- uranium: 0.04 pounds mined
The article suggests that a golf ball sized uranium slug could provide power for a lifetime, but with different assumptions we arrive at 78 kg or the average weight of an American. Since uranium is very dense, that volume is just slightly larger than a gallon of milk. Still pretty impressive compared to other fuels.
But you might be worried about nuclear for other reasons. In the coming weeks I’ll be comparing electricity generation from coal and nuclear. Post in the comments if there are specific issues you want me to talk about.