World saved by the Wii

Sorry folks. Another title tease. Patience.

When I wasn’t at the STFC Community Forum on Thursday, I was instead at a really good seminar about renewable energy, given by David Mackay from the Cavendish. He gave a hard headed look at UK requirements and what various renewable schemes can deliver. (David has a marvellous book called “Sustainable Energy without the Hot Air“). The main conclusion was that if you insist on European or US levels of consumption, then any successful renewable scheme has to be country sized – cover Wales with photocells etc – which isn’t practically or politically possible for the UK. This didn’t surprise me. Before STFC politics took over this blog, my most read post was about how extrapolated world energy requirements will get uncomfortably close to the solar input. However, David was more optimistic than I was there, suggesting that if we take an international approach, we really can solar-farm several Wales-areas in the North African desert and fuel Europe and Africa. So its possible in principle but still politically kinda tricky… Alternatively of course you can do it the Roger Angel way. Mirrors in Space.

That evening I had dinner with David, Alan Heavens, and Stephen Salter, a well known Edinburgh engineering genius. In the 1970s he invented the wave duck, and now he is having another go at saving the world – global cooling with albedo control. All we need is a fleet of two thousand automated ships, that drift around the oceans, hoover up sea water, and shoot a fine spray of particles up to the clouds. The idea seems to be that this (err somehow) changes the way cloud particles nucleate, and so changes their size distribution, making the clouds more reflective to incoming visible and UV, but without changing the reflectivity for IR on the way up. We make the clouds whiter folks. This takes very little energy cost. I haven’t read his paper, which is in press in Phil Trans, but there is a BBC news item on it.

Back to energy. Of course if we can just cut our consumption … David said that our energy consumption is about equal amounts transport, heating, and making stuff. Of course we can insulate our drafty Victorian Edinburgh homes better, but we can also turn down the thermostat. David said (I think… this was after a few glasses of wine..) that in the 1950s the average household temperature in the winter was 12C, compared to 20C now. Part of the problem is, we are all so sedentary… but things are changing !

When I were a lad we watched TV all day. My kids of course have spent years playing on the Playstation or checking Bebo. But since Christmas – things have changed ! We have a Wii and now the whole damn family leaps about playing imaginary tennis and so forth. Much less heating needed.

There. You knew I’d get there.

20 Responses to World saved by the Wii

  1. Michael Merrifield says:

    I hope your Wii Fit is on order…

  2. Martin E. says:

    Don’t you remember how bloody COLD it was in 1950s British houses! frost on the blankets (well, almost). fuggedaboutit, we gotta find a way to stay warmer forever.

  3. andyxl says:

    How could I remember Martin – I was only a toddler. Oh yeah, I forgot, you are SLIGHTLY older than me.

  4. Martin E. says:

    now wait a minute… our energy production ain’t that big, even if everyone consumes at current US rates… i had some notes stuffed in a drawer about it somewhere… ah, yes. h
    here you go, 4May2004. step by step…

    Insolation at Earth
    ==============
    Lsol = 3.8e33 erg/s [AQ]
    AU = 1.5e13 cm [AQ]
    Erad = 6.4e8 cm [AQ]
    A(E) = 1.29e18 cm^2
    fsol = Lsol/(4pi AU^2)
    = 1.34e6 erg/s/cm^2
    insol= fsol x A(E)
    = 1.73e24 erg/s
    = 4.10e31 erg/yr = THE BOTTOM LINE
    ————

    Now then… human energy production on Earth
    =====================================
    World energy output = 1.001e10 TOE (Tonnes of Oil) [Economist World in figures 2004]
    population = 6.1e9
    per capita = 1.64 TOE

    US
    energy consumption = 2.29e9 TOE (Tonnes of Oil) [Economist World in figures 2004]
    population = 2.85e8
    percapita = 8.04 TOE
    So, World energy consumption if at current US rates = 4.9e10 TOE
    [Only a factor 5 increase! I thought we were worse than that. Did I mess up?]

    Energy density of petroleum = 45 MJ/kg
    [The Physics Factbook, http://hypertextbook.com/facts/2002/KarolShepelsky.shtml%5D%5D
    1 tonne of oil = 4.5e10J = 4.5e17 erg
    E(4.9e10TOE) = 2.21e28 erg/yr
    = 5.4 e-4 total insolation.
    [currently = 1.11e-4 ]

    Since we are not done growing our energy consumption per capita in the US,
    we could expect another factor 10 say, which would bring us to 0.1%.

    What do you think? Is this a big number or a small number?

    Let’s compare that with the changes in insolation around the Earth’s orbit:
    Earth orbit:
    perihelion = 0.983 AU [AQ]
    aphelion = 1.01 AU [approx 3% above perihelion, USNO web site]
    eccentricity, e = (a^2 – c^2)^0.5/a = 0.0167 (1970) [AQ]
    i.e. 3%, near to the minimum value.
    Leads to 6% difference in insolation between ap- and peri-helion.

    So compared with this change 0.1% is not important.
    But it is a systematic positive change, so perhaps not unimportant.

    fuel for thought.

  5. andyxl says:

    ergs Martin ? does harvard still have rulers marked in inches ???
    … will try to work through this later .. right now am in Euston station on way to one of the famous consultation exerccise ad-hoc panels …

  6. Martin E. says:

    rulers in inches? Actually, yes. It’s really hard to find metric rulers here. dumb.
    But, really, astronomy is a hopeless place for units: parsecs, Hubble times, solar luminosities and masses… We _could_ use proper SI for all of this, but no-one does. Why do we say 10,000km/s, not 10Mm/s? I think it’s familiarity, not just ‘cos ‘this is how we always did it’ (well partly that), but because we need to tie in to useful units to keep our perspective on what numbers are significant.
    keep doing the exercises!

  7. Omar Almaini says:

    I remember once explaining cgs units to a student, and in particular that an erg was 10^-7 J. He paused thoughtfully for a moment, then said: “So astronomers measure the power output of quasars, the most luminous objects in the Universe, in units of butterfly farts?”

  8. Martin E. says:

    poetic, Omar, very poetic.
    But really “10^12Lsol” is about as meaninglessly large compared with the unit as “10^45erg/s”. All our attempts to get convenient units tend to fall down, and that does stick us with loads of silly ones that make the field unnecessarily hard. Guess I should become a SI fundamentalist after all . (and so i contradict what i said earlier!)

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