Re: H2

["John S. Denker" <jsd@AV8N.COM>]

On 10/21/2003 01:08 PM, Frohne, Vickie wrote:
> Turns out that solar power isn't the cure-all and end-all of
> long-term energy shortages

Well, the way I figure it, solar power is the worst form
of power in the whole world ... except for all the rest.
                       -- apologies to W.S.C.

In particular, if present trends continue, all fossil
fuels will be exhausted 75 years or so ... much less if
everybody in Bejing starts driving an SUV.

That includes all the oil, all the natural gas, all the
coal, and all the U235.

Some people imagine that coal is abundant and will solve
all the world's problems, but the numbers seem to not
bear this out.  Some people imagine that U235 is abundant
and will solve all the world's problems, but the numbers
seem to not bear this out.
  http://www.av8n.com/physics/fossil-resources.htm

> because the energy density, availability duty cycle, and collection
> efficiencies are all low.

Low compared to what?  Compared to, say, electricity from
gasohol from corn, solar photovoltaics are efficient.
Solar-powered steam engines are comparably efficient
(indeed arguably more efficient) relative to photovoltaics,
and can produce power overnight.

> Furthermore, it's not clear to me that the energy required to
> manufacture a photovoltaic cell, from raw materials to finished
> product, would be recovered over its operation lifetime.

Years ago that was a problem -- a fatal problem -- but
since then manufacturing has gotten more efficient and
the product has gotten more efficient.

It is unnecessary to calculate the energy-gain ratio
separately;  it suffices to denominate the calculation
in dollars.  That is, calculate whether solar cells
are economically viable, making self-consistent assumptions
about the buying-price of energy to fabricate them and the
selling-price of the energy they produce.

> IMHO, using sunlight to make H2 will be a commercial success only if
> photovoltaics are not involved,

Producing renewable energy is hard enough.
Producing it in the form of H2 is an additional
constraint, and I'm skeptical that H2 will ever
work out.

> when, not if, the energy shortage becomes acute enough to drive the
> price way up

The way I figure it, solar electric power is within a factor
of two of being competitive with the wholesale price of
present-day fossil-fuel electric power.
    http://www.av8n.com/physics/fossil-resources.htm