RED | the new green: thoughts on ways to reduce greenhouse gas emissions

How much energy does the U.S. waste?

Posted by Sean Casten on September 14th, 2009

More on C02 | energy | energy recycling

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At the broadest level, everything we can do to address climate change/national security/energy balance of trade and just about any other meaningful social question associated with our energy use falls into one of three categories:

1. Use less downstream energy. Turn down the thermostat, ride your bike to work, move to a smaller home, etc.

2. Switch upstream fuels. Favor coal in the name of national security. Favor nuclear in the name of CO2. Favor wind in the name of green jobs. Etc.

3. Use less upstream energy. Insulate your home, build CHP plants, recycle your plastic and aluminum waste, etc.

All three have a critical role to play, but note that only the third creates social benefits and can be guaranteed to increase our overall standard of living. In the famous Amory Lovins-ism, no one gives a damn about how much coal, oil or gas they use — they care about how hot their shower is and how cold their beer.

Ergo, we ought to make maximal use of anything that fits into that third bucket as a matter of public policy. Which raises the question: how big is that third bucket? Or, framed another way: how much energy does the U.S. currently waste? Any increase in our efficiency of energy conversion (from upstream fuel to downstream energy) is implicitly a reduction in our energy waste. Tell me how much we waste and you will tell me the maximum size of that third bucket.

How Much do we Consume?

As it turns out, there’s very little good data on how much energy we waste. DOE estimates that we use about 100 quadrillion btus (“quads”) of primary energy per year. But they too often present that data in charts like this one that seem to assume a perfectly efficient economy. As that great philosopher Homer Simpson said, “In this house, we obey the laws of thermodynamics!” And I’m pretty sure thermo says that you can’t get 100 percent of the energy you put in out in a useful form. DOE charts to the contrary notwithstanding…

Nonetheless, this does bound our analysis. If we put 100 quads of primary energy in, we must get 100 quads out somewhere. At the very least, it implies that there can’t be more than 100 quads of wasted energy presently available in the system.

Solid Waste

EPA estimates that the average American produces 1,130 lbs of trash per year.  At 4,500 btu/lb and just over 307 million people, that’s 1.6 quads of energy in our trash.  Add in 6.5 million metric tons of solid waste in our sewage per year at 10,000 btu/dry ton and that’s another 0.1 quads.  So in total, all our solid waste is about 1.7 quads of total energy waste, or 1.7 percent of all our primary energy use.

Industrial Waste

Lawrence Berkeley National Lab has estimated that the US could produce 96 GW of electric power from energy that is currently wasted by the US industrial sector.  (This waste includes a host of different materials, from paper sludge to waste heat.)  RED‘s internal analysis suggests that this may be conservative, but let’s use the LBNL data.  Assuming 25 percent fuel-to-power generation efficiency (and assuming further that this represents 100 percent of all energy wasted by the US industrial sector, and not simply the economically recoverable/LBNL-identifiable fraction) that works out to an additional 11.4 quads.

Power Generation Waste

In 2008, we generated 3,806,611 GWh from fossil-fired thermal power plants. Those plants, on average, operate at 33 percent fuel efficiency, meaning that for every 1 unit of electric power generated, 2 units of waste heat were thrown away in cooling towers, rivers and streams. That’s 2 x 3,806,611 GWh of wasted heat, or 26.4 quads up in smoke.

Transportation Waste

The total US transportation sector uses some 28.6 quads of fuel per year. For rather obvious reasons, there’s not a lot of good data on how much of that goes out the tailpipe vs. a more productive use. But conservatively, let’s assume that we get 30 percent of the useful energy out of that fuel (this is considerably higher than a passenger car over normal driving cycles, but probably low for rail, shipping and long-haul trucking on an efficiency per ton-mile basis.) Clearly, this is the least accurate of the numbers, but even at 30 percent, that implies an additional waste of 0.7 x 28.6 or 20 quads of waste, going into tail pipe exhaust, hot brakes, burnt tires, etc.

Total Identifiable Waste

Add those all up and we’ve got 100 quads of primary energy and 60 quads of waste energy. For all the reasons noted above, the waste energy is probably much higher, but even at this level, it is a massive opportunity. Recovering just half of this total would reduce every issue associated with fossil fuel use by one third with no detriment to our standard of living. Getting this waste out of the system ought to be a priority of our national energy and environmental policy.

Note: This first appeared on Grist.

2 responses to “How much energy does the U.S. waste?”

  1. Wendell Ellison said on August 10th, 2010 at 12:22 pm

    I agree, this is a great opportunity. We will continue to accumulate waste, whether we extract energy from it or not. So, why not put it to use?

    I don’t hear, or read much about methane gas extraction. It would seem to be an obvious choice for the majority of municipalities to pursue. Why is this not the case? Am I missing something?

    Also, I did have a couple of questions pertaining to this technology;

    1. Are there high initial capitol investment and/or operating costs for gas extraction, processing and transmission?

    2. Can the gas be used “as-is” from the landfill, or must there be additional processing to make is “useable”.

    3. Are there any industry accepted calculations to determine the percentage of methane extracted?

  2. Sean Casten said on August 10th, 2010 at 12:33 pm

    Wendell,

    I assume you are referring to landfill gas recovery? We are not subject matter experts in that field, although you are right – it is a significant waste source with recoverable potential. Do be aware though that the amount of energy that is theoretically available from such sources is constrained by the amount of energy in our solid waste (which then bio-degrades to methane when stored in a landfill). As noted at the start, that works out to 1.7 quads of total opportunity, or 1.7% of total US energy use. Not a small number, but not nearly as large as the other big energy waste streams either.

    Generally speaking, it is a pretty easy gas to recover – it is a very clean gas, amenable to combustion without additional processing in off-the-shelf generation with comparatively low capital costs (reciprocating engines, gas turbines, etc.)

    The challenges relate primarily to collection, both in time and in space – from a business perspective, it more closely resembles an oil/gas play than a power play since you have to “drill” and collect the gas, bring it to a common location for the power generator and then have a good understanding of the lifetime of the gas production curve (since the landfill will eventually stop producing gas).

    We are well beyond our expertise to provide much more detail, but hopefully that answers your high-level question?

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