Slides from wonderful "engineering climate change" talk

Here's a slide deck to accompany Saul Griffith's incredible talk on engineering solutions to climate change from the O'Reilly Emerging Technology Conference earlier this month in San Diego. The talk was the highlight of the conference for me, dealing as it did with the engineering affordances of carbon, climate, and energy sources of all kind, and coming to a humane solution that invites us to live luxuriant high-quality lives that nevertheless massively reduce our carbon footprints to a sustainable level. Link (Thanks, Avi!)

See also: Engineering approach to global climate change


  1. Not impressed with that second formula, it’s unnecessarily complicated. You have kW HOURS, so to get kW, just find the number of hours, and divide by it – that leaves you with the kW. Say there are 30 days in a month, that makes 30×24=720 hours. So: ( 122 kWh / 720 hrs ) = 0.170kW = 170 W

    Oh, and how many days are there in a month? If I convert that seconds figure to days, there are apparently 34.167 days in a month. (Must be a typo, the result is still correct.)

    I hope other slides have an explanation of where those figures come from. 140MJ per km? 120kWh per month? My last electricity bill had about 3X that, thanks to an all-electric flat (incl. heating). =8-/

  2. The 1.4MJ/km looks as though it may have come from Wikipedia’s information on the 747 (see the 747 and Orders of Magnitude (power) articles), with 140MW average power consumption, 400 passengers, and an average cruise speed of Mach 0.85.

    More strikingly, 168,000 km/year of flying seems absurdly high, considering that it’s slightly more than 4 times the circumference of the Earth, or enough to take a flight between New York and London every other week, and then be left with 14,000 more miles to go.

    I also must note that the conversion from kWh to W here is probably the worst example of unit conversion I’ve ever seen.

  3. It is nor fair to bill one passenger with the footprint of the entire flight. If you calculate it this way, the footprint of a car travel would much less then taking a bus or a train. You must divide the result by the number of passengers in the same plane.

  4. The slide show is somewhat confusing to scientifically literate people, because he talks about “energy footprints” but refers units of power.

    It appears that what he’s done is to define a new unit of energy, which is watt-years, though he mostly refers to this as just “watts”. This is why his flight calculation gets so convoluted: instead of just multiplying the energy per km by the total number of km flown, he has to then divide this by the number of seconds in a year.

    If you’re going to calculate your “energy consumption”, wouldn’t it be simpler to calculate it in units of, you know, energy, rather than power?

    (The absurdly high rate of flying is from the speaker’s own 2007 travels, apparently…)

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  6. Victor Bogado @ 3:

    I think the intent was to calculate the energy use per passenger.
    The only reference on the slides is to an “Ask the Pilot” column at,
    though that column quotes estimates of gallons of aviation fuel used per passenger, not energy.

    The transatlantic flight values quoted in the “Ask the Pilot” column work out to about 0.036 liters/km of aviation fuel burned, per passenger (which is almost identical to the value of 3.5 liters/100 passenger km quoted here).
    If we assume 3 kg of CO2 emitted per liter of aviation fuel (a round number from various places on the web), then his total CO2 emissions from air travel in 2007 would be about 19,000 kg. In another slide, he gives the figure of 18,500 kg/year — so I suspect he’s doing the math more or less correctly.

  7. The distance between New Yok and San Francisco is 2563 miles. Flying back makes it 5126 miles. Does anyone ever fly 105,000 miles? I guess if you go from New York to San Francisco 20 times in a year.

  8. There’s some good material here, if a bit rough.

    Let’s hope this helps more people be more responsible about managing their waste intelligently, without succumbing to Global Warming hype and the growing backlash against it.

  9. To bring up another aspect of the talk is a bottom up solution to climate change possible/desirable? Doubtless a change in consumption trends will be necessary in the next ten years, but it would be a bit out of character for people to choose to change their consumption. The problem is so massive that solving it will be the largest social engineering problem of all time.

    Industry is currently lobbying government to set up restrictions, since donating to green causes is all well and good, but they cannot change their production methods until somebody steps in and makes all industry change, sort of like a massive game of chicken, with factories instead of cars, and global meltdown instead of a cliff. But for the US government to set up trade restrictions, and muscle other governments to set up trade restrictions goes so far against its philosophy of the last fifty years, one wonders if it will ever happen. In England, one can easily predict someone like John Reid coming into power in the next decade and setting up a basically Stalinist government to precede over the crisis; the hegemony is basically already in place. But the prospects of the US are even more frightening.

  10. Bottom-up is the only thing that’ll work. Top down is just fascism in action.

    Legal changes, like the tax code changes proposed by the Ontario Green Party, will still be required, but they will only work when the majority of individuals recognize that we need to take better care of the future. Any attempt to fix things from the top down on environmental issues will devolve into hypocrisy almost instantaneously for the simple reason that it is unsustainable (to say nothing of morally bankrupt) to try to make people better. You wind up putting all kinds of effort into enforcement, which is a dead-weight loss that more than eats up any environmental gains you might make.

    It is wonderful, however, to see someone arguing for “a humane solution that invites us to live luxuriant high-quality lives that nevertheless massively reduce our carbon footprints to a sustainable level”. This is the kind of thing that will separate the Greens from the Puritans.

  11. Tom,

    You mean governments are instituting more and more authoritarian policies for nothing? The dead weight of enforcement, as you called it, already drives the US economy.

    I would argue that the main role of changing consumption patterns is ideological, rather than actually helpful, since production is a greater problem. I must, however, disclose that I’m having trouble loading the slide show and subsequently talking out my arse. Will rejoin if I find a better connection.

  12. #7 MikeSum32, not to argue with your logic, but your example assumes an entirely USA-centric presumption. Many people fly to other countries on a regular basis for work, leisure, etc. I will admit that the 105,000 mile figure is excessive, but it does seem a little bit more reasonable when figuring in flight distances to London, Cape Town, and/or Beijing from either of the two cities mentioned.

  13. @4

    He calculated his energy consumption in watts, just like he says. Consumption is a rate of energy use, so calculating in units of energy makes no sense, unless you specify a unit of time over which that energy was used. Thus, you need units of power, one of which is the watt that he used.

    The years unit comes from calculating consumption on a yearly averaged basis. So, for example, he needs to find out how much energy he used in a year of flying. This 168207 km/yr * 1.4 MJ/km = 235490 MJ/yr. But notice that this is itself a unit of power, because it contains the time basis of the average, 1 year. Since this unit is used by no one, he converts to watts by dividing by the number of seconds in a year and multiplying by 1000000 for MJ to J.

    He has not created the watt-year you suggest unless you want to consider his values as given in watt-years per year, which is just a watts…

    One thing I do quibble with, though, is that he quotes 1^10 ZJ in several places as the stored nuclear energy available. But 1^10 is just 1. If you look at the gcep exergy charts he references at, he means 1E10 or 1×10^10 ZJ. For comparison, this is enough energy to support out current total energy consumption rates for the next 20 billion years, 4 times longer than the sun will last!

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