U.S. Energy Consumption - the Big Picture

Tracking energy consumption

It's an oft-quoted statistic: the United States is the world's largest energy consumer (for now, at least - China is forecast to overtake the U.S. in 2010). On a per-capita basis, U.S. energy use is double that of some European countries. Just where is all that energy going?

As it turns out, answering that question isn't difficult. The Energy Information Administration (EIA), an agency of the U.S. Department of Energy, was created expressly to track American energy statistics. A visitor to their website will find thousands of tables, graphs and reports covering various aspects of energy supply, prices and consumption patterns.

The goal of this article is to focus on the EIA's consumption data, distilling it into a few graphs that should give even the most rushed reader a basic understanding of the layout of the American energy landscape.

The four sectors

Before getting into the details, a quick explanation of energy sectors may be helpful.  When accounting for consumption, the EIA converts each energy expenditure to a common measurement unit (BTU's) and assigns it to one of four broad sectors, defined as follows:

• Transportation - any equipment used to move people or materials, via land, water, or air.
• Residential - private living quarters. Includes single-family homes, apartments and mobile homes. Hotels, dormitories and other commercial/institutional living quarters are not included.
• Commercial - service-providing facilities. Included are both government and private sector buildings, such as offices, stores, restaurants, churches, hospitals and libraries.
• Industrial - facilities used for producing and processing goods. This sector is dominated by manufacturing operations, but also includes nonmanufacturing enterprises such as agriculture and mining. Another separate category within this sector is feedstocks, which refers to fossil fuels used as raw materials for manufacturing (e.g. petrochemicals, asphalt, etc.).

Special consideration is made for the energy consumed by electrical power plants. Factoring in generation inefficiencies and transmission losses, only about a third of the fuel energy consumed by the average electricity producer is actually delivered to the end user. Rather than creating a separate consumption sector, the EIA adjusts end-use electricity consumption estimates to reflect the actual energy required to produce that power, not just the amount delivered. (For example, 1 kilowatt-hour delivered to a home air conditioner is counted as 3.18 kilowatt-hours of "primary energy" in the Residential sector's air conditioning category.)

Visualizing the data

gasoline
Some people may be surprised that gasoline isn't a more dominant presence on the consumption map. While gasoline-powered transportation is certainly the chart's biggest single element, it only constitutes about 17% of national energy use. So why does gasoline get the lion's share of attention from the press?  Some likely explanations:

1. Gasoline is the energy source whose cost is most visible to Americans on a daily basis.  Other energy costs are seen only in monthly utility bills or as a hidden part of the prices of goods and services.
   
2. Oil and gas prices have fluctuated dramatically in the past two years.
3. Unlike natural gas, coal, nuclear and other fuel sources, the U.S. depends on foreign imports for most of its petroleum.  Gasoline supplies and prices are therefore more vulnerable to political instability abroad.

lighting
In what has become an annual event, Earth Hour encourages people to turn off their lights for an hour to conserve energy and show they "care about the living planet".  This well-meaning effort to raise consumer awareness may actually be misleading people about where their homes' energy use lies.  As is apparent in the consumption map, lighting is actually the fourth-highest consumption area in a typical American home, behind heating, air conditioning, and water heating.  Targeting consumption in those areas is plainly as important as lighting (or more so), but it won't be as simple as flipping off a light switch.  Reductions in space conditioning and water heating expenditures require more basic sacrifices, such as spending money on weatherization, living with less comfortable thermostat/water-heater settings, or even moving to a smaller home.

electronics
The residential "electronics" category, which includes computers and televisions, has grown steadily in recent years, but it is still a fairly minor piece of the energy picture. An energy-conscious consumer may look with suspicion at all the boxes plugged into their home entertainment system, but it's a safe bet that in most homes the majority of energy consumed somehow involves heating (furnaces, water heaters) or cooling (air conditioners, refrigerators).  Even the incandescent light bulb is essentially a heating device - the filament is heated to the point that it emits light as a by-product.

Energy consumption and climate

Global warming studies have suggested that the world's energy consumption (i.e. burning fossil fuels) is adversely affecting global climate. But the converse is also true: climate affects energy consumption.

This is readily seen in an EIA study that estimated household energy use on a state-by-state basis. The results of that study are mapped below:

Other factors may also be in play.  California, Arizona, and New Mexico are sufficiently arid to allow the use of evaporative air conditioners (aka "swamp coolers"), which consume up to 75% less electricity than refrigerated air conditioners.  It's also worth noting that the Pacific Coast and Southwest states have seen the largest population growth in the past few decades, thus their housing stock is probably newer and more energy-efficient than in the Midwest and Northeast.

Comparing the U.S. to other countries

References

Companion knol: U.S. Energy Sources