Energy Efficiency

The energy we don’t use

The energy we don't useOf all currently available energy resources, one stands alone when it comes to affordability, clean power, and job creation. That resource? Efficiency.

We can’t realistically meet our needs for energy by mining coal, pumping and piping natural gas and petroleum, or even building wind farms. Technologies that use less energy to do more work are cheaper and produce less pollution than even the most modern wind turbines or slickest solar panels. Efficiency is the workhorse of a technologically advanced, clean, and economical energy system.


Efficiency measures can be implemented in every sector of the energy economy—electricity production, buildings, industry, and transportation.

Comparing the cost: new electricity sourcesElectricity production
It takes energy to make electricity. At the most basic level, electricity is most often generated by turning a turbine. You can turn a turbine with water, or you can turn it with steam from burning coal, burning natural gas, or splitting atoms. You can also turn a turbine by putting it on a tower in a windy place.

The amount of energy used in each of these technologies varies widely, as does the amount of energy wasted. Consider coal. It must be mined with petroleum-fueled machinery before it’s transported (sometimes hundreds of miles) to a coal plant, where it’s finally burned to create electricity. The most efficient, modern coal plants are able to convert coal to electricity with approximately 37 percent efficiency, meaning that for every unit of useful coal energy, nearly two are lost up the smokestack as wasted heat. Add that to the energy used in mining and transportation and lost in transmission, and coal’s efficiency is closer to 25 percent.

Now consider wind. Once the machine is in the ground, the turbines turn when the wind blows, and electricity is generated. No energy is wasted. Plus, there’s no pollution, no waste storage, and the fuel is free.

Buildings: residential and commercial
We use electricity and fuels like natural gas or propane to light, heat, and cool our homes, office buildings, schools, medical centers, shopping malls, factories, and all the other buildings we’re in and out of every day. Plus, it takes energy to run our appliances, electronics, and equipment. Of all the energy in the United States, almost 25 percent is used in American homes and 19 percent in commercial buildings.

People who want to save money in their homes can take simple actions like weatherizing, purchasing efficient appliances, and installing energy-efficient light bulbs. Those efforts matter. But imagine how much less energy (and money) is used when buildings are constructed with the best insulation, highly efficient windows and doors, fewer air leaks, and advanced heating and cooling systems. The building itself becomes a partner in energy savings.

The industrial sector accounts for approximately one third of all energy use in the United States. The massive equipment employed in this sector—boilers, steam systems, furnaces, heat exchangers, compressed air systems—uses a colossal amount of energy. The financial goals of increasing value and decreasing expenses make efficiency innovations very attractive. For instance, a system called combined heat and power (or cogeneration) recovers the heat created by conventional electricity generation and puts it back to use, almost doubling the efficiency of the system.

If you’re like most Americans, it’s a rare day that you don’t use some sort of gas-powered vehicle to get where you need to go. Currently, the transportation sector uses approximately 28 percent of the country’s energy. According to efficiency expert Amory Lovins, only 0.3 percent of the energy consumed by your car goes to moving you, the driver. (That’s not very gratifying after 100 years of automotive engineering, he adds dryly.) We can use energy better by constructing vehicles that use dramatically less energy to go the same distance, whether those vehicles are powered by petroleum or electricity. Electric cars are substantially more efficient than cars run on gas because the electric motor is much more efficient than its internal combustion counterpart. That difference is largely due to simplicity— electric motors have many fewer moving parts than gas ones—and heat.

It’s also essential to address the efficiency of the transportation system as a whole. A great deal of energy can be saved through smart land-use planning that makes it possible for people to travel shorter distances and avoid using energy (other than their own!) to get where they need to go. Public transit also increases system efficiency, especially in congested areas.


Energy efficiency is an energy resource, just like wind or coal. The amount of energy we’ve been able to save is so significant, in fact, that utilities and utility regulators are starting to understand that and to include energy efficiency in their investment plans for the future. Unlike the rising prices of fossil fuels, utility efficiency programs are a stable, predictable investment. Efficiency is an essential ingredient in the American energy system and will be even more so in the future. It’s the cheapest, most benign, least controversial power plant available.

Of all currently available energy resources, one stands alone when it comes to affordability, clean power, and job creation. That resource? Efficiency.

Add a comment 2 comments

  1. dave bryan


    “only 0.3 percent of the energy consumed by your car goes to moving you, the driver.” Shouldn’t that be 30% ?

  2. Jenna


    Dave, our executive director Michael Noble saw Amory Lovins speak recently, and 0.3 percent is the number he quoted. Shocking, right? But here’s an example Michael gives to illustrate: if a 200 pound man is in a 6,000 pound SUV, his body weight is about 0.3 percent of the SUV’s weight, and if the efficiency of an internal combustion engine is as bad as this infographic suggests (, you get a better idea of the inefficiencies involved.