[extropy-chat] Moving on (was CF research)

[Keith Henson]

At 03:31 PM 2/14/2007 +0100, Eugen wrote:

>On Tue, Feb 13, 2007 at 10:45:12AM -0500, Keith Henson wrote:
>
> > There are critical industrial processes that just don't lend themselves to
> > distributed solutions.
>
>Yes, but residential energy production (whether a methane motor generator,
>a methane fuel cell, a wind turbine, or a roof/facade PV array) is a problem
>space which profits exactly from decentralisation, and in situ production.
>In case of heat-power coupling, the transport losses are easily avoided,
>and ditto applies to low-voltage, high-current PV power, which otherwise
>would need up-transformed for transport, with conversion and transport
>losses.

You are thinking of single family suburban housing, not city apartments 
which start off much using much less energy.

>The most real advantage is that's a low-threshold technology.
>Very different from terrestrial (nanotube) or lunar (aramide) tethers,
>linear mass drivers or even cheap LEO launches. While I like them,
>nothing helps like low-tech like insulating a house, using heat
>pumps and high-efficiency burners, installing solar gardes,
>thermal solar collectors, and similiar.

I do many of these things, including insulating plugs for the windows at 
night.  While you are right about it being low-threshold technology, it is 
beyond the vast majority of people.

> > Consider aluminum as an example.  An aluminum pot line uses 250,000 
> amps at
> > 800 volts.  That's 0.2 Gw, if the plant has 5 pot lines, it eats a
> > Gw.  (Metalic aluminum represents about 40 kwh/kg.)  Or consider
> > cement.  Last time I looked, grinding clinker to dust was taking 1.5 to 2
> > percent of the total US generation.
>
>Concrete production along with aluminum (and air nitrogen fixation)
>are a major sinks of energy, and large-scale producers of CO2
>(doubly so, if you calcinate carbonates). I don't find these
>processes particularly sexy, and would frankly wish we would
>substitute them with something more hi-tech, and greener.

If you have any ideas . . . .  Short of Nanotechnology, I don't.

> > And when you are talking about solar cells, remember the cost of the
> > support structures.  I have seen 100 nm films and let me assure you that
>
>You'll notice that houses are typically built to withstand most weather,
>hail included. It is of course rather expensive to retrofit houses (starting
>with north-south alignment, for instance, difficult to fix after the fact),
>but buildings which have designed for energy efficiency and integral power
>generation do need to be that much more expensive. Consider that most
>current PV panels are waranteed for 25-30 years, that's a reasonably good
>life time for a building facade without renovation.

I was talking about 100 nm films, not current PV panels.

> > one hail storm would be the end of them.
> >
> > You also have the problem of collecting the current from solar
> > cells.  That's something I have been concerned with recently.  There are

>Um, collecting the power is a solved problem. Off-the shelf power
>electronics for some 3-5 k$ will generate your AC phase-synced to
>the rest.

Collecting, not converting.  In the context of a 100 nm thick cell, you are 
going to be looking at fusing currents for the conductive element before 
the cell gets very large.

> > also serious difficulties with storage.
>
>Conventional power plants have a large thermal inertia, which along
>with nocturnal demand lull is the reason there's a major overcapacity
>during nighttime. The demand peak is during day, so if you dump things
>into the grid you would only need very marginal nocturnal capacities
>without requiring storage (which is not a huge problem, whether central
>(reverse hydro, air-pressure cavities) or decentral (electrochemical
>energy sources, e.g. such as a water electrolyser built into a pressure
>tank along with a hydrogen/oxygen fuel cell which dumps direcly into
>the electrolyser -- low efficiency maybe, but if PV is an order of
>magntude cheaper than solar efficiency for a storage cycle is not
>that important).
>
> > Now, much of this goes away with nanotechnology, but if you are talking
> > near term it's a hard problem.
>
>Sufficiently near-term about everything is a hard problem. Redesigning
>infrastructure towards sustainability is a major effort, and takes time
>and lots of resources.

Given the replacement times involved, the energy and carbon crisis isn't 
likely to hold off long enough.

Keith