Energy usage

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<TR><TD>Finished petroleum products, other</TD><TD align=right>2,220</TR> <TR><TD>Finished petroleum products, other</TD><TD align=right>2,220</TR>
<TR><TD>Total</TD><TD align=right>20,731</TR> <TR><TD>Total</TD><TD align=right>20,731</TR>
-<TR><TD><B>Total (barrels/year)</B></TD><TD align=right><B>7.6 million/yr</B></TR>+<TR><TD><B>Total (barrels/year)</B></TD><TD align=right><B>7.6 billion/yr</B></TR>
</TABLE> </TABLE>

Revision as of 14:44, 25 October 2005

Contents

Current total energy use

These data are compiled from the U.S. Department of Energy Energy Information Administration.

It's disappointing that the DOE EIA doesn't have more recent information on all-around energy consumption. I think this data is more useful in that it gives us an order-of-magnitude approximation of current energy usage, even if the data are for ten years ago.

The data on petroleum usage, however, are recent (2004), and I've attempted to quantify how much energy (in units of energy) we derive from the petroleum we use. The following figures are from the Wikipedia gasoline page[1]:

Fuel10^3 Btu/gal
Gasoline125.0
LPG95.5
ethanol84.4
methanol62.8
gasahol (10% EtOH, 90% gasoline)120.9

I'm unsure whether these figures represent the useful energy derived from fuel's combustion or the theoretical energy derived from 100% efficient combustion. It appears as though it's the former: the value given for ethanol is about 20% lower than the theoretical value based on ethanol's heat of combustion.

So assuming these figures represent useful energy, we can calculate, in joules, how much useful energy is consumed in petroleum consumption each year. (I'm assuming that, based on the table below, the about of petroleum that is combusted dwarfs the amount of petroleum that is used to make plastics, lubricants, etc.)

7.6 million barrels of petroleum per year
= 318 million gallons of petroleum per year (this is on the same order of magnitude as Briggs' estimate [2] of 180 million gallons per year of gasoline and diesel together)
= 3.97 x 10^13 Btu per year
= 4.20 x 10^16 joules per year

This final figure may be a useful number in determining for ourselves how much of any energy source would be required to replace petroleum in the U.S.

Note: 1 barrel = 42 gallons, 1 short ton = 2,000 lbs, 1 Btu = 1,055 joules.

Petroleum consumption

Data [3] from 2004.

ProductConsumption (10^3 barrels/day)
Natural gas liquids (NGLs) and Liquefied petroleum gases (LPGs)2,264
Finished petroleum products18,497
Finished petroleum products, finished motor gasoline9,105
Finished petroleum products, finished aviation gasoline17
Finished petroleum products, finished jet fuel1,630
Finished petroleum products, kerosene64
Finished petroleum products, distillate fuel oil4,058
Finished petroleum products, residual fuel oil865
Finished petroleum products, asphalt and road oil534
Finished petroleum products, other2,220
Total20,731
Total (barrels/year)7.6 billion/yr

Residential

Data [4] from 2001.

FuelConsumption (10^15 Btu)Total consumption
Electricity, primary11.63 (53.2%)1,140 (109 kWh)
Electricity, site3.89 (17.8%)
Natural gas4.84 (22.1%)4.708 (109 ft3)
Fuel oil0.71 (00.3%)5.105 (106 gal)
Kerosene0.05 (00.2%)348 (106 gal)
LPG0.38 (01.7%)4,121 (106 gal)
Wood0.37 (01.7%)18.7 (106 cords)
Total (excl. primary electricity and wood)9.86 (45.0%)

End useConsumption (10^15 Btu)
Space heating4.62 (46.9%)
Lighting and other appliances2.40 (24.0%)
Water heating1.68 (17.0%)
Electric air conditioning0.62 (06.2%)
Refrigerators0.53 (05.4%)
Total9.86 (100%)

Commercial

Data [5] from 1999.

FuelConsumption (10^12 Btu)
Electricity, primary9,352
Electricity, site3,098
Major fuels5,733
Natural gas2,023
Fuel oil179
District heat433

Industrial

Data [6] from 1998.

FuelConsumption
Electricity, net (10^6 kWh)889,474
Residual fuel oil (10^6 barrels)57
Distillate fuel oil and diesel fuel (10^6 barrels)23
Natural gas (10^9 ft3)6,469
LPG and NGL (10^6 barrels)38
Coal (10^6 short tons)51
Other (10^12 Btu)6,248
Total (10^12 Btu)17,695

Transportation

Data [7] from 1994.

UseConsumption (10^9 gal)
Total90.6
Motor gasoline, total88.3
Motor gasoline, unleaded87.0
Motor gasoline, unleaded regular59.9
Motor gasoline, unleaded intermediate11.7
Motor gasoline, unleaded premium15.4
Gasohol0.9
Diesel1.2

Projected future energy usage

Projected world energy consumption. Figure copyright DOE EIA.
Projected world energy consumption. Figure copyright DOE EIA.

In order to determine how much biodiesel we might need, we need to estimate what future energy needs will be. The most recent analysis by the DOE Energy Information Administration projects that world energy consumption will increase to 645 quadrillion Btu/year by 2025, up from 412 quadrillion Btu/year in 2002.

Vaclav Simil, a professor at the University of Manitoba, argues in Perils of Long-Range Energy Forecasting: Reflections on Looking Far Ahead (2000) that future energy forecasts have generally been failures due to a variety of reasons, and that we should create scenario-specific models instead.

Both studies, and it seems the majority of the work on the subject, seem to be forecasting actually energy consumption, which is particularly difficult given the unknown availability of energy resources in the future. I think a far better problem to model is the demand for energy in the future, independent of the projected energy supply. Economists should stop me now if this is impossible to do, but I'll outline a few considerations I think this model should take.

I'm not an economist, but I'll feel free to stop you anyway. Demand for a good is not independent of the long-term supply of it. There's no worldwide demand for flamberol, because it doesn't exist and never has. A less silly example might be something like whale meat, for which (to my naive knowledge), there's essentially zero demand in North America for, because its supply had dwindled and was then forbidden. People have replaced whale meat with other goods. Likewise, while energy broadly is necessary for economic activity and indeed for life, if energy becomes more scarce, then people can (could?) adapt, and reduce the demand for it. --Jleith 05:38, 25 October 2005 (EDT)

A model of energy demand

We should take the following factors into account, for each will have an impact on energy demand. Please feel free to modify this model, for this is back-of-the-envelope logic.

  • Population growth. This, in itself, is difficult to model. Furthermore, population growth is, to some extent, probably dependent on the availability of energy, which in turn is dependent on past energy demand and usage. Reasonable estimates for the next 50 years are given by the UN World Population Prospects Database [8], which are summarized on Wikipedia's world population page [9].
  • Energy usage per capita. There are two opposite forces at work here: improvements in appliance efficiency (such as better fridges, hybrid cars, etc.) and economic development. The former leads to a decrease in energy usage per capita, the latter to an increase, at least historically. Therefore, energy usage per capita is dependent, in turn, on two variables that change over time: some appliance efficiency factor, which measures how efficiently individuals use energy, and some economic development factor, which is, roughly speaking, the percentage of individuals worldwide living under a mature economy (which is a rough proxy for the amount of energy they will consume).

This alone should be sufficient to forecast future energy demand. Note that it makes a few assumptions:

  • There is virutally unlimited energy available. Or, in economic terms, the price of energy is low enough that demand is nearly independent of price.
  • Energy generation does not produce harmful wastes that inhibit population growth over a large time scale. Otherwise, any sufficiently harmful source of energy could keep population levels constant, and energy demand would like cease to increase.