Consumer Technology

Published on August 26th, 2013 | by Guest Contributor


US Wastes 61–86% Of Its Energy

August 26th, 2013 by  

Originally published on Outlier, Opower’s blog.
by Barry Fischer, Opower’s head writer

An updated analysis published last month by the Lawrence Livermore National Laboratory suggests that the USA is just 39% energy efficient.

Put another way, more than half (i.e. 61%) of the energy that flows through our economy is ultimately wasted.

US energy waste UK

The predominance of inefficiency is conveyed by the energy-flow diagram below: it shows the country’s energy fuel inputs (e.g. coal, natural gas) on the left side, and end-use energy consumption (e.g. residential, industrial, transportation) on the right side.

Of the 95.1 quadrillion British Thermal Units (known as “quads”) of raw energy inputs that flowed into the US economy in 2012, only 37.0 quads were constructively used at the end of the day (as “energy services”). The other 58.1 quads were, in essence, wasted. This waste, summarized in the top right of the diagram, is euphemistically classified as “rejected energy.”

US energy production waste

Lawrence Livermore National Laboratory (July 2012)

As has been the case for decades, most of the economy’s energy waste stems from electricity generation (because most power plants are relatively inefficient) and the transportation sector (internal-combustion vehicles are also notoriously inefficient, but they are getting better).

One should not expect any economy, power plant, or car to be 100% efficient. Indeed, the Second Law of Thermodynamics tells us that achieving perfect thermal efficiency is as possible as unscrambling an egg. But 39% efficiency? It certainly leaves some major room for improvement.

And some experts argue that even 39% efficiency is painting a rosy picture: defining energy as the “capacity to do useful work” (rather than strictly as a commodity measured by its energy content), physicist Robert Ayres and his colleagues estimate that the true energy efficiency of the US economy is closer to 14%.

So how does Lawrence Livermore National Laboratory’s 2012 energy flow analysis compare to its analyses in recent years? Strikingly, their findings suggest that 2012 was the most energy-wasteful year in more than a decade (and the third most profligate year since LLNL began producing these studies in the 1970s). By LLNL’s historical calculations, the amount of energy wasted annually has hovered between 50-58% during the last ten years. But in 2012, their waste calculation shot up to 61%.

Why? AJ Simon, a senior researcher at LLNL who leads the energy flow studies, told Opower that the increased waste number stems in part from updated assumptions about the end-use efficiency of vehicles and household appliances. Specifically, a pair of recent analyses of overall energy consumption in the transportation and residential sectors prompted LLNL to adopt more realistic engineering estimates for 2012.

Simon’s team now estimates that US cars, trains, planes and the like are on average 21% efficient (rather than 25%, as previously surmised) and US household energy uses like heating, cooling, and lighting are on average 65% efficient (rather than 80%). Holistically, these estimates may yet still be overly optimistic, in that they don’t reflect behavior-related energy inefficiencies, such as over-drying one’s clothes or leaving the A/C running in an unoccupied house.

Feeling nostalgic for a time when the US economy used more energy than it wasted? You’ll have to go back to 1970, in the days when LLNL’s diagrams weren’t so colorful. In that year (which also featured the first Earth Day celebration), the country eked out a slightly better than 50% efficiency performance, wherein 31.1 quads of “useful energy” eclipsed 30.6 quads of “rejected energy.”

US energy use waste 1970

Lawrence Livermore National Laboratory (November 1973)

Since 1970, however, the substantial growth in energy use for electricity and transportation — sectors that, as mentioned above, are historically poor at turning fuel into work — has caused energy waste to gradually prevail over energy productivity.

Fortunately, though, the nation is seeing a promising wave of technological advancesutility-sector innovation, behavioral science approaches, and policy breakthroughs that are helping to make energy productivity not just a serendipitous achievement in 1970, but an enduring reality for the decades ahead.

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Note: Comparison between US energy waste and UK energy consumption is based on 2012 US waste of58.1 quads and 2012 UK consumption of 8.456 quads

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  • patb2009

    Here’s teh 2014 version

    If we switch to renewable energy and Electric vehicles 75% of that will be solved.

  • Ed Pell

    Folks, to convert heat energy into mechanical motion we have to use a heat engine. The fraction of energy converted into energy of useful motion is set by the equations derived by Carnot in 1824. Higher temperature give higher efficiencies. As soon as humankind invents new materials that can survive at the super high temperatures needed to improve heat engine efficiencies then we will have higher efficiencies.

    • patb2009

      or just switch to PV

  • Jack

    This is a grave misunderstanding of thermodynamics. There’s no such thing as 100% conversion efficiency, so it’s misleading to term heat rejection as waste, when in fact it’s an unavoidable part of conversion systems. Please research your claims more thoroughly.

    • Bob_Wallace

      So what?

      All you are saying is that it is impossible to get to 100% efficiency. See anyone making the claim we can?

      Heat rejection is waste. It’s more of a problem with some approaches than with others. The task at hand is to figure out how to do what we want to do in the most efficient manner. Identifying systems that have the highest heat waste problems tells us where gains are likely to be easiest.

      Ditching the internal combustion engine in a no-brainer. Getting rid of fossil-fuel thermal, another.

  • Great Insight – Love the Sankey Diagram

  • dirt coach

    if something confusing or to complicated the simplist explanation is your stupid

    • Altair IV

      It would be much easier to agree with your pronouncement if it didn’t include at least five blatant grammar, spelling, and punctuation errors.

  • jburt56

    Yes the waste is staggering. Behold Robosaurus!!

    Happy Monday 😉

  • peleve

    A confusing graph. Too busy.

    • Doug

      I like the graph – and find myself thinking of how to better organize the information. If I had a complaint about the article, it would be that there is no benchmark for energy efficiency – so I don’t know if the US is better or worse than other countries.

    • Bob_Wallace

      First time I saw one of these graphs I had trouble making heads or tails out of it.

      Try clicking on it and zooming in so it fills your screen. Start on the left with one of the categories and follow it to the end.

      Once you get the hang of them, there’s a tremendous amount of information in them.

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