I would like to see a good engineering comparison of the following two
things:

A) A field of some size planted with some plant that grows over some time
and is then harvested, fermented to alcohol or oil extracted and that
resulting product burned to move a car down a road.

B) A field of the same size covered in solar panels or other means of
electric power generation and that power stored in batteries and used to
move a car down a road.

Which one:
1. is less costly to implement?
2. moves the car further over some set time (say 1 year)?
3. is more repeatable / renewable?

???

My guess is that A is cheap but doesn't move the car very far and that B is
more expensive both in terms of the generation field and the required
modifications to the car, but puts out more actual work.

So... We need either a GMO crop (more expensive seeds) that produces much
more oil or alcohol OR a less expensive method of generating electricity
from the sun even if it is a bit less efficient coupled with lighter, more
efficient batteries or even (shudder) hydrogen.

Russell will now assert that the GMO crop will end up killing us all.

I will now assert that we should chuck both issues and just build a nuke
plant. (that does still leave the need for better batteries)

Someone else will assert that Hydrogen is the answer and someone else will
assert that Hydrogen is a joke.

Now that the extremes have been preemptively addressed, maybe there are some
others who would like to comment on the mid ground?

---
James.
 
 

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Peter
> Sent: 2005 Sep 15, Thu 14:55
> To: Microcontroller discussion list - Public.
> Subject: Re: [OT] Vegetable oil in a diesel engine... Was: 
> [EE] ROHS ~ lead free soldering - reality strikes.
> 
> 
> On Thu, 15 Sep 2005, Russell McMahon wrote:
> 
> >> I saw someone claim (on piclist a long time ago?) that if you 
> >> calculate the delivered efficiency of biomass (So much 
> solar flux per 
> >> km^2 yields so much energy in sugar, alcohol, or carbon), 
> there is no 
> >> way you can even support the worlds current appetite for 
> energy, much 
> >> less projected energy demand.  IIRC, I didn't buy all their 
> >> assumptions, but it's a sobering thought; one doesn't 
> think of plant 
> >> efficiency compared to solar cell efficiency (for 
> example), but the 
> >> number is there somewhere and apparently it's not all that 
> impressive 
> >> :-(
> >
> > I too disbelieve it in its more extreme forms, but the claim was in 
> > fact that ALL terrestrial energy sources which may be considered to 
> > replace finite lifetime hydrocarbons, failed to deliver a 
> net energy 
> > gain and that " we're
> 
> What is a 'net energy gain' ?! You can think in terms of 
> man-energy (paraphrasing LeCorbusier who got some flak for 
> that at the time). 
> Estimate how much joe average needs and find a way to cover 
> that. Of course you can just about forget about street 
> lighting and things like immense billboards shining at night.
> 
> My probably incorrect calculations show that a man who has 
> about 50m^2 of solar panels and a windmill in a temperate 
> zone will make enough power to sustain himself and to store 
> some for maintenance and even some development. Of course if 
> the panels will be low tech (homemade) he will need 500m^2. 
> The large size comes from the need to run ovens and power 
> tools to make things with.
> 
> > solar" chemical energy sources or "new solar" sources such 
> as wind / 
> > waves / hydro/ biomass / ... but instead uses very-very-old 
> solar-like 
> > nuclear processes. ie All energy sources available to us 
> have come (as 
> > far as we can
> > tell) from stars, but using nuclear processes gives you a leg up.
> 
> Maybe we should wait until this is tested at least in a 
> one-off trial ?
> 
> Peter
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