Almost two-thirds of the potential energy embedded in our energy sources ended up wasted in 2017. See the latest American energy use, in one diagram.


Spring brings new growth, new possibilities, and, best of all, a new spaghetti diagram from Lawrence Livermore National Laboratory (LLNL) at the Department of Energy.

Every year, LLNL produces a new energy flow chart showing the sources of US energy, what it’s used for, and how much of it is wasted. If you’ve never seen it before, it’s a bit of a mind-blower.

Behold US energy in 2017:


So much information in so little space! (It’s worth zooming in on a larger version.)

Before digging through a few of the more interesting details, let’s get terminology out of the way. LLNL measures US energy consumption in “quads.” What’s a quad?

Well, a British thermal unit (BTU) is a standard unit of energy — the heat required to raise the temperature of a pound of water by 1 degree Fahrenheit. If you prefer the metric system, a BTU is about 1055 joules of energy.

A “quad” is one quadrillion (a thousand trillion) BTUs. Here, according to Wikipedia, are a few things equivalent to a quad:

  • 8,007,000,000 gallons (US) of gasoline
  • 293,071,000,000 kilowatt-hours (kWh)
  • 36,000,000 metric tons of coal
  • 970,434,000,000 cubic feet of natural gas
  • 25,200,000 metric tons of oil

So a quad is a lot of energy. The US consumed 97.7 quads in 2017, an amount that has stayed roughly steady (within a quad or so) since 2000.

With that out of the way, what can the diagram show us?

We waste how much now?

Perhaps the most striking feature of the spaghetti diagram — what everyone notices the first time they see it — is the enormous amount of “rejected” energy. Not just some, but almost two-thirds of the potential energy embedded in our energy sources ended up wasted in 2017. (And note that some scholars think LLNL is being too optimistic, and that the US is not even 31 percent efficient but more like 13 percent.)

What’s more, the US economy is trending less and less efficient over time. Here’s the spaghetti diagram from 1970 (LLNL has been at this a long time): Back then, we only wasted half our energy!

llnl energy spaghetti, 1970

What to make of this?

It’s important to put this waste in context. It is not mainly about personal behavior or inefficient energy end use — keeping cars idling or leaving the lights on, that kind of thing. That’s a part of it, but at a deeper level, waste is all about system design.

The decline in overall efficiency in the US economy mainly has to do with the increasing role of inefficient energy systems. Specifically, the years since 1970 have seen a substantial increase in electricity consumption and private vehicles for transportation, two energy services that are particularly inefficient. (Electricity wastes two-thirds of its primary energy; transportation wastes about three-quarters.)

There is loss inherent in any system that converts raw materials to usable energy, or transports or uses energy, of course. That follows from the second law of thermodynamics. And it’s true both narrowly (a car is an energy system) and broadly (a city is an energy system). It’s not possible to achieve perfect efficiency, or anything close to it.

But surely we can do better than 31 percent! Sixty-six quads is a truly mind-boggling amount of energy to vent into the atmosphere for no good purpose.

It really highlights the enormous potential of better-designed systems — especially better electricity and transport systems, along with better urban systems (i.e., cities) — to contribute to the country’s carbon reduction goals. We could double our energy use, with no increase in carbon emissions, just by halving our energy waste. 

Electricity is changing: coal and natural gas down; wind and solar up

Let’s look at some more recent changes in electricity. Here’s the spaghetti diagram from 2010.

llnl energy spaghetti, 2010(LLNL)

If we toggle between this one and the one from 2017, a few changes jump out.

Electricity generation is down by 2.8 quads since 2010. The big loser there is coal, which is down from 21 quads to 14. The big winner (thanks to the fracking revolution) is natural gas, up by 3 quads. Notable runners-up: wind, up by 1.44, and solar, up by 0.63.

To focus in even closer, here are some changes in the past year, from 2016 to 2017:

  • Coal: down 1.4 percent to 14.2 quads
  • Natural gas: down 1.7 percent to 28 quads
  • Wind: up 7 percent to 2.35 quads
  • Solar: up 32 percent to 0.775 quads

As you can see, wind is growing fast, as is solar.  In short, US electricity is slowly but steadily decarbonizing. The sector’s carbon dioxide emissions fell by just under 1 percent in 2017. 

Time to focus on transportation

US transportation, however, isn’t. It is just as dependent on petroleum as it was in 2010, or 1970. Its energy consumption and carbon emissions are only rising.  This has led to a fateful intersection (as Umair Irfan reported this year): In the US, in 2016, for the first time in decades, transportation emissions were higher than electricity emissions.

eia emissions by sector 2016(EIA)

This is largely reflective of the broader world’s efforts to constrain carbon emissions: Most of the successes have come in electricity. Transportation is a huge, looming, and almost entirely unsolved climate problem.

Watch for advocates, activists, and policymakers at the state and city level (the feds are useless right now) to begin taking transportation more seriously as part of the climate fight — to start pushing policies that can be as effective as renewable portfolio standards have been in the power sector.

Bonus state charts

LLNL periodically makes spaghetti charts for US states, most recently in 2014. Just for fun, let’s look at a study in contrasts.

Here’s West Virginia:

llnl energy spaghetti, WV, 2014(LLNL)

Not much of anything else, but a lot of coal!

Here’s California:

llnl energy spaghetti, CA, 2014(LLNL)

Almost no coal, lots of natural gas, and lots of oil. On the way to its ambitious carbon goals, California is going to see its carbon fight become a transportation fight.

More info on the claim that all but 13% is wasted…

Photo  We could save 20 percent of the industrial energy we are using now just by breaking the utility monopoly that prevents it,” says Robert Ayres, co-author of “Crossing the Energy Divide.”

According to Robert Ayres and Edward Ayres, brothers and co-authors of the recently published book, “Crossing the Energy Divide,” the American economy uses energy with only 13 percent efficiency.

This means for every unit of fuel burned, only 13 percent of the potential energy is actually converted as useable output to power machines, and illuminate and heat buildings.

Most of the remaining energy is discarded, typically in the form of waste heat that, with the right application of technology, could be used for electricity generation or space and water heating.

(As just one example of the potential, two large American steel companies together generated 190 megawatts of electricity from recycled waste heat in 2005. This was more than the entire United States production of solar-photovoltaic electricity that year.)

By recycling this waste energy resource, the United States could double the energy efficiency of its economy, which would also effectively double the nation’s energy supply. In the process, “we would reduce carbon emissions and boost economic growth during the next several decades,” the authors say.

But widespread adoption of efficiency measures like this faces obstacles, which the authors describe as “ideological blind spots, structural barriers, bad habits and outdated laws.”  

Green Inc. discussed these topics with Robert Ayres, a physicist and environmental economist and professor emeritus at the European Institute of Business Administration.

Excerpts from this conversation follow.

Q.  How widespread are the technologies that you describe in the book?
A. We estimate that 1,000 U.S. companies are producing electricity by harnessing waste-energy streams, but these companies account for only 10 percent of the national waste-stream potential.
Q. For the other 90 percent, why aren’t they using this waste energy?
A.  It’s not the technology that’s the obstacle; it’s the regulations. For example, PURPA, [the Public Utility Regulatory Policies Act of 1978], was intended to encourage the use of co-generation by obligating the utilities to buy energy from outside producers at prices set by the state utility commissions. But because the utilities have such tight control over the regulators, they are able to set the prices so low it becomes uneconomic for most companies to build these projects.  Also, PURPA is federal law with no teeth because it defers to the states to implement the mandate, and not all states have taken an interest.
Q. If the state utility commissions are setting the prices so low, why can’t these companies with co-generation systems find another market for their surplus electricity?
A. Actually, in a number of states, it’s illegal to sell electricity to anyone but the utility. And all 50 states have laws making it illegal to cross the streets with wires carrying electricity from anyone other than the area utility.  So for many companies, it isn’t worth building a co-generation plant because they don’t use enough of the electricity, and they can’t sell the surplus they create to anyone but the utility at a set price.  Our estimates show we could save 20 percent of the industrial energy we are using now just by breaking the utility monopoly that prevents it.
Q.  What are some of the most inefficient uses of burning fossil fuels?
A.  Using fossil fuels to produce only heat is extremely wasteful because you can easily get heat as a by-product of producing electricity.  Using combined heat and power systems, or C.H.P., for example, you can produce electricity in small power plants in apartment buildings, hospitals, schools or commercial buildings. By not getting your electricity from the utility’s large steam generation plant, you save the transmission losses (usually about 10 percent), and you also can use the captured heat for space or water heating in the buildings. A C.H.P. plant can reach 50 to 80 percent efficiency.

Over the next 20 years, we should eliminate the use of fossil fuels for producing only heat, but we need greater investments in this area.  Unfortunately, the Recovery Act provided little support for energy recycling or C.H.P.   We also support legislation to require utilities and electric power–distribution companies to purchase an increasing percentage of power from decentralized C.H.P. and other small private-power sources.  But as an economist, I would prefer a system where the price is set by the market rather than by a legislature.

Q.  What else will need to change to get businesses to become more energy efficient?
A.  The biggest problem with industry today is the obsession with growth over other types of investments. They think if they grow bigger then that will take care of profits.  Profits will come with size and less competition. So they are less focused on becoming competitive, but more focused on eliminating competition. They miss a lot of opportunities for energy conservation, which could be quite profitable.  And the banks are more inclined to loan money for projects that involve expansion, especially if they can have the security of a building or other hard asset. They are less interested in loaning money for energy efficiency measures that can reduce costs.  I think this is another important reason why energy efficiency hasn’t taken off like it should. If we are serious about increasing the economic productivity we get from the energy we use, we are going to need to change this type of thinking.