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Re: [carfree_cities] New carbon-free city about to break ground

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  • Warren Weisman
    Agreed that the city is unlikely to be carbon neutral, however, it is a positive step in the right direction that I for one enjoy seeing take place. Our
    Message 1 of 10 , Aug 6, 2007
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      Agreed that the city is unlikely to be carbon neutral,
      however, it is a positive step in the right direction
      that I for one enjoy seeing take place.

      Our Sporeprint mycoplex at http://www.sporeprint.org,
      which we just unveiled our first model this
      weekend---the pictures are up on our forum at
      http://groups.yahoo.com/group/mycoplex_forum will go
      beyond carbon neutral and benefit the environment,
      since we will be relying on biogas (the ONLY energy
      source that contributes zero greenhouse gas
      emissions---since the CO2 released during burning is
      the same amount that would be released naturally
      during decomposition). Biogas will be used in the
      summer, and rainwater dropping off the living roof
      will generate electricity in the winter. Might not
      sound like much, but 1" of rainfall over a 5000 sq.ft.
      roof will produce 250 cu.m. of water, dropping 13.5 m.
      will potentially generate 30 MJ or 8 MW of power.
      Enough to light 4,000 homes.

      We should not promote carfree cities and then complain
      when they begin to arrive.

      --- Jym Dyer <jym@...> wrote:

      > > ... the world's first carbon-neutral city.
      > > ... a zero-carbon city ...
      >
      > =v= Whose measurements back up the terms "neutral"
      > and "zero"
      > that CNN bandies about so casually here?
      >
      > =v= Existing carbon-trading schemes seem to neglect
      > calculations
      > that encompass full-lifecycle considerations in
      > favor of those
      > that provide a handy price-point (TerraPass'
      > USD$29.95 a year
      > comes to mind). Until some more relevant accounting
      > underlies
      > these words, the media shouldn't be reprinting
      > marketing copy.
      > <_Jym_>
      >
      >



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    • Jym Dyer
      ... =v= They deserve credit for being carfree, straight up. That doesn t mean they should be immune from criticism when something else they do is questionable.
      Message 2 of 10 , Aug 6, 2007
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        > We should not promote carfree cities and then complain
        > when they begin to arrive.

        =v= They deserve credit for being carfree, straight up.
        That doesn't mean they should be immune from criticism when
        something else they do is questionable. By trumpeting the
        use of very dubious carbon offset schemes with marketing
        doublespeak like "carbon-neutral" and "zero-carbon," they
        undercut their own project.

        =v= Bear in mind that these schemes are currently a leading
        form of greenwash whose biggest market is specifically to
        co��nable wasteful individual car use.

        > ... biogas (the ONLY energy source that contributes zero
        > greenhouse gas emissions ...

        =v= Sorry, but this is also bogus wording. Biomass still adds
        carbon to an atmosphere already overburdened with it, and it
        stays there and has an impact for a lag time. It definitely
        has a distinct advantage over fossil fuels in that its lag time
        is much shorter, but tallying it up as "zero" is inaccurate.
        <_Jym_>
      • Warren Weisman
        ... I did not say biomass---which does release greenhouse gases, since it is not covered and captured---but instead work with biogas, or natural fuel gas,
        Message 3 of 10 , Aug 7, 2007
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          >
          > > ... biogas (the ONLY energy source that
          > contributes zero
          > > greenhouse gas emissions ...
          >
          > =v= Sorry, but this is also bogus wording. Biomass
          > still adds
          > carbon to an atmosphere already overburdened with
          > it, and it
          > stays there and has an impact for a lag time. It
          > definitely
          > has a distinct advantage over fossil fuels in that
          > its lag time
          > is much shorter, but tallying it up as "zero" is
          > inaccurate.
          > <_Jym_>

          I did not say biomass---which does release greenhouse
          gases, since it is not covered and captured---but
          instead work with biogas, or natural fuel gas, which
          does not contribute any net greenhouse gas emissions,
          since it relies on an anaerobic environment that
          prevents gases from escaping---and creates better
          fertilizer by trapping the nitrogen, too. Since the
          methane is burned during combustion and the CO2
          released is the same amount released during natural
          decomposition, it is more than offset by the plant
          matter growing in the first place. Meaning I am
          perfectly accurate in using the word "zero". Your
          skepticism is defying science.



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        • J.H. Crawford
          Hi All, ... First of all, 8 MW is power, not energy. Energy is power * time, so 8 MW for one hour is 8 MWh. 5000 s.f. x 1 inch = 417 ft3, which is about 26,000
          Message 4 of 10 , Aug 7, 2007
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            Hi All,

            A recent post claimed that:

            >... rainwater dropping off the living roof
            >will generate electricity in the winter. Might not
            >sound like much, but 1" of rainfall over a 5000 sq.ft.
            >roof will produce 250 cu.m. of water, dropping 13.5 m.
            >will potentially generate 30 MJ or 8 MW of power.
            >Enough to light 4,000 homes.

            First of all, 8 MW is power, not energy. Energy is
            power * time, so 8 MW for one hour is 8 MWh.

            5000 s.f. x 1 inch = 417 ft3, which is about 26,000 lbs.
            13.5 m is about 45 feet. 26,000 lbs falling 45 feet
            does 1,170,000 ft-lbs of work. At 33,000 ft-lbs/min
            for one horsepower, this is 35.5 HP-minutes. One
            HP is 746 watts, so this is 26,500 watt-minutes or
            440 watt-hours or .44 kWh. If it rains 40 inches a
            year, you get 18 kWh per year, or about enough to
            power .002 of a house for a year at the once-commonly-used
            value of 1 kW continuous will power one house. (I think
            maybe 2 kW is the new number, but I'm not sure.)

            So, this calculation is off by a factor of 4000/.002
            or 1,986,704, give or take a few gnats' whiskers.

            We really have to be numerate in these discussions.
            What this really highlights, though, is that people
            have NO conception of the amount of energy we are
            using. The notion that a little rainwater falling off
            a roof could power 4000 homes is truly discouraging.

            And doesn't anyone study physics any more?

            Regards,

            Joel








            ----- ### -----
            J.H. Crawford Carfree Cities
            mailbox@... http://www.carfree.com
          • dawie_coetzee
            I was about to ask for more information about that system: thanks for saving me the trouble! I was slightly sceptical, because one of the great advantages of a
            Message 5 of 10 , Aug 8, 2007
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              I was about to ask for more information about that system: thanks for
              saving me the trouble!

              I was slightly sceptical, because one of the great advantages of a
              living roof is the cooling effect of plant transpiration,
              particularly useful in hot, moist climates. This tends to reduce the
              volume of water that comes off the roof as stormwater considerably.
              Because I live in a warm, dryish climate my own plans limit living
              roofs to those that are readily accessible, and include a
              considerable area of steeply-pitched conventional roof for the
              purpose of gathering rainwater. Even so, at the annual rainfall of
              750mm the site area is not great enough to supply the entire water
              needs of the occupants at the projected density, but such things as
              using grey water to flush the toilets can reduce mains water
              consumption considerably.

              Indeed the calculations required to project the power consumed by an
              electric pump to pump grey water to a roof-mounted cistern, which
              delivered a surprisingly low figure, only reinforced my suspicions.

              I've been considering supplemental wind power for the same project,
              notwithstanding the losses in efficiency due to a turbulent, truly
              urban roofscape. Here's a useful resource for this sort of thing:
              http://www.otherpower.com I enjoy their combination of common sense
              and dogged low-tech independence.

              The figure of 9000kWh per year is mentioned somewhere on that site as
              being slightly profligate. It corresponds to about 1.22kW continuous.
              My own calculations produce a slightly lower figure if one excludes
              electric cooking, so I suspect that 1kW continuous is not unrealistic
              if one steers clear of silly things like water taps that need
              electrical connections that allow them to change colour (they're
              actually made!), or the facility of running a bath over the internet
              from another country.

              Best regards

              Dawie Coetzee

              --- In carfree_cities@yahoogroups.com, "J.H. Crawford" <mailbox@...>
              wrote:
              >
              >
              > Hi All,
              >
              > A recent post claimed that:
              >
              > >... rainwater dropping off the living roof
              > >will generate electricity in the winter. Might not
              > >sound like much, but 1" of rainfall over a 5000 sq.ft.
              > >roof will produce 250 cu.m. of water, dropping 13.5 m.
              > >will potentially generate 30 MJ or 8 MW of power.
              > >Enough to light 4,000 homes.
              >
              > First of all, 8 MW is power, not energy. Energy is
              > power * time, so 8 MW for one hour is 8 MWh.
              >
              > 5000 s.f. x 1 inch = 417 ft3, which is about 26,000 lbs.
              > 13.5 m is about 45 feet. 26,000 lbs falling 45 feet
              > does 1,170,000 ft-lbs of work. At 33,000 ft-lbs/min
              > for one horsepower, this is 35.5 HP-minutes. One
              > HP is 746 watts, so this is 26,500 watt-minutes or
              > 440 watt-hours or .44 kWh. If it rains 40 inches a
              > year, you get 18 kWh per year, or about enough to
              > power .002 of a house for a year at the once-commonly-used
              > value of 1 kW continuous will power one house. (I think
              > maybe 2 kW is the new number, but I'm not sure.)
              >
              > So, this calculation is off by a factor of 4000/.002
              > or 1,986,704, give or take a few gnats' whiskers.
              >
              > We really have to be numerate in these discussions.
              > What this really highlights, though, is that people
              > have NO conception of the amount of energy we are
              > using. The notion that a little rainwater falling off
              > a roof could power 4000 homes is truly discouraging.
              >
              > And doesn't anyone study physics any more?
              >
              > Regards,
              >
              > Joel
              >
              >
              >
              >
              >
              >
              >
              >
              > ----- ### -----
              > J.H. Crawford Carfree Cities
              > mailbox@... http://www.carfree.com
              >
            • J.H. Crawford
              OK. Lance Armstrong pedalling a bike-driven generator can produce about 350 watts and he can probably keep this up for about 3 hours. That is, roughly, 1
              Message 6 of 10 , Aug 8, 2007
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                OK.

                Lance Armstrong pedalling a bike-driven generator can
                produce about 350 watts and he can probably keep this
                up for about 3 hours. That is, roughly, 1 kilowatt-hour.

                If Lance drives to the gym in a Prius and he travels
                10 miles round trip, he uses an average of about 10 HP
                for a period of 10 minutes (assuming an unlikely average
                speed of 60 MPH). At 746 watts/HP, this is 74,600 watt-min:

                10 min * 10 HP * 746 watts

                74,600 watt-min is 1243 watt-hours or 1.243 kWh

                So, in ten minutes of driving, Lance uses more energy than
                he can produce in 3 hours of pedalling.

                Now, if it's YOU on the treadmill, how many watts continuous
                can you produced for three hours?

                If you power your car by pedalling a generator to charge
                its batteries, you're going to have to pedal for, say,
                one working shift in order to drive 10 miles back and
                forth to work. Or, you could ride your bike for, say,
                40 minutes each way.

                We MUST get our heads around the notion of just how much
                energy we are consuming. It's truly incredible. Think in
                terms of reducing your energy consumption 10-fold in
                your lifetime. Even THAT is probably not sustainable.

                The fix we're in is so much worse than people think it is,
                simply because they think it's quite normal to put 10 gallons
                of gasoline in the car once or twice a week. The energy
                content of that gasoline is just incredible; only since
                the start of the industrial era have people been able to
                consume energy at this rate. This has only been possible
                because we have been burning fossil fuels created over a
                span of millions of years during the course of a century.

                Rainwater falling off the roof is not going to power your
                next flight to Disneyworld. It's not going to get you to
                the airport. In fact, it's barely going to get you out
                of the driveway.

                Life is going to change. Get used to it. Then figure out
                how to enjoy it. That's not hard. Just imagine carfree cities.

                Joel




                ----- ### -----
                J.H. Crawford Carfree Cities
                mailbox@... http://www.carfree.com
              • Doug Salzmann
                Joel s post is an extraordinarily elegant explanation of the brutally simple math that underlies our inescapable energy crisis - and gives the lie to so many
                Message 7 of 10 , Aug 8, 2007
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                  Joel's post is an extraordinarily elegant explanation of the brutally
                  simple math that underlies our inescapable energy crisis - and gives
                  the lie to so many facile and fantastic claims about "solutions" thereto.

                  If anyone here is unfamiliar with such calculations, PLEASE correct
                  that deficiency. Truly understanding the magnitude of the fix we are
                  in is essential, if there is to be any chance of survival for our
                  civilization.

                  -Doug



                  --- In carfree_cities@yahoogroups.com, "J.H. Crawford" <mailbox@...>
                  wrote:
                  >
                  >
                  > OK.
                  >
                  > Lance Armstrong pedalling a bike-driven generator can
                  > produce about 350 watts and he can probably keep this
                  > up for about 3 hours. That is, roughly, 1 kilowatt-hour.
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