I have a question that some of you might be able to shed some light on.
As well as having an interest in biofuels, I also have an interest in
Third World development issues and other technologies, including Solar
energy collection and storage. So when trying to find an 'energy
solution' for a remote village for example, there are a number of
possible options. Of course, you have to ask, "what problem are you
looking to find a solution for?" For the purposes of this post, I will
assume that we are trying to provide electricity to power
refrigerators, lighting, miscellaneous equipment such as telephones and
computers (even remote villages can have satellite connections to the
internet these days!). This would be a light load and not include
industrial use nor electrical heating/cooking.
So I will propose two solutions, both of which are used in various
places:
1) Grow an oil crop, use it to power a diesel generator
2) Install photovoltaic solar panels and use a battery system to store
the energy overnight
Now I'm trying to get an understanding of the pros and cons of these
two approaches, and which would be better for a particular location.
The issues I have thought of so far are the following:
--
Photovoltaics and batteries are expensive in terms of capital outlay,
whereas biofuels are cheap to 'install'.
Photovoltaic systems have a conversion efficiency of ~10% of the solar
energy, whereas biofuels have a conversion efficiency of about 1%
Photovoltaic systems require more specialist knowledge to maintain,
whereas biofuels require less.
Photovoltaics require low labour input once they are installed, whereas
biofuels require planting, harvesting, processing etc..
Photovoltaic systems can store only small amounts of energy over short
timescales, whereas you can store large quantities of oil for a long
time
Photovoltaics make less sense when sunshine levels are highly
unpredictable, whereas biofuel crops are not significantly affected by
a few gloomy days
Photovoltaics require less land to install than oil crops, because of
their higher conversion efficiency.
--
I realise that this is an oversimplification of the issues, and I'm
trying to gain a deeper understanding of the secondary issues. So my
specific questions are:
1) What are the implications of manufacturing Solar collectors,
batteries, electronic control equipment and so forth in terms of energy
use, toxic materials (e.g. lead in batteries), sustainability? How does
this compare with manufacturing a diesel generating system?
2) Biofuels are often produced from crops that are grown in an
unsustainable manner. What are the effects on biodiversity of this? How
can this be counteracted? Are there any comparable environmental issues
in the manufacture of solar systems?
3) Do the levels of expertise required to install and maintain a solar
system make it inappropriate for use in remote villages?
4) Am I correct in assuming that the best (cheapest over all) solution
for a Diesel generator in such situations is to use SVO (straight
vegetable oil) with a preheating system, rather than converting it to
biodiesel?
5) What are the effects on electricity usage patterns for each type of
supply? For example, if people know that their battery system can only
store a fixed amount that won't be replenished until the next day, are
they more efficiency conscious than if they know their supply won't be
replenished until next year's harvest?
My gut feeling is that due to the higher conversion efficiency of solar
panels, these would make a better overall solution for providing
electricity than growing biofuels, with less environmental impact
overall. However the high capital cost may rule this solution out for
smaller villages. (Of course if you are using the energy for transport,
then biofuels are much better because the energy can easily be stored
and transported over long timescales. But that is not what I'm
interested in here).
Does anyone have any other information, opinions, experience of these
types of systems? Have I overlooked any significant arguments on either
side?
I may soon have an opportunity to visit a remote solar installation
that is backed up with a Diesel generator (as far as I know using
petrodiesel) so wish to find out as much as possible beforehand.
Regards,
Donald
=====
--
43 - slightly more than the answer to life, the universe and everything.
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