Harness Lake Nyos
The geyser of water and gas from Lake Nyos represents wasted energy
(24 March, p 36).
This energy could be harnessed to spin a turbine, rotate
machinery, generate electricity.
A practical realisation poses some interesting engineering challenges. How
much power can be generated continuously and renewably, for instance? And should
the turbine be driven by liquid, gas or both?
The fountain is running fast enough to run a 10-kilowatt power
generator鈥攅nough, at least, for the research camp. But there are no power
lines in the area, and there are other, more plentiful sources of energy, like
the waterfall at the end of the lake.
People have also considered using the gas to supply a cola bottling plant or
study the effects of elevated CO2 on plants鈥攂ut
at the moment there’s no easy way to separate the water and gas鈥擡d
Letter
Your researchers seem to have missed a more intriguing effect of the
Lake Nyos explosion. In Britain, only 15 years have passed since 1986,
yet in the vicinity of lake Nyos, according to the introduction to your article,
25 years have passed.
Was this a hallucinatory effect of inhaling high concentrations of CO
2, or is it a genuine temporal abnormality? If so, there may be a more
sinister cause for the explosion.
Sorry for the typo鈥擡d
Sex and science
Your cover of 17 March asks: “Sex sex sex. Will science take control?”
I was under the impression that chemistry already had a substantial role to
play.
It takes vision to fuel the future
Mick Hamer’s report on vehicle fuels
(17 March, p 18)
seemed a little discouraging at first reading, as it placed the hydrogen-powered
internal combustion engine at the top of the polluting table, ahead of the petrol
engine.
However, his last paragraph makes it clear that the study is based on “as is”
technology, and the output of greenhouse pollutants includes those formed by the
conventional generation of hydrogen from natural gas.
If the hydrogen were generated electrolytically, using photovoltaic trapping
of solar energy in deserts and other arid regions, the hydrogen fuel cell would
emit only a fraction of the 100 grams per kilometre of greenhouse pollutants
quoted for the natural gas fuel cell. The technology effectively exists, but it
needs serious political will to finance it, given our energy economy, which is
so dominated by fossil fuel.
The British government has placed photovoltaic hydrogen on the back burner by
describing it as a “very long term” technology. The people responding to the
recent consultation document, New and Renewable Energy Sources, have
already drawn attention to this potential error of judgement.
We should pursue the photovoltaic hydrogen option vigorously, and not solely
for pollution control. Otherwise the world will be forced back to nuclear power
as fossil fuels become depleted.
Stealing the wind
Andrew Walker wonders if wind power will affect the weather
(31 March, p 52).
A wind turbine will, just like a tree, slow the wind down a small amount.
Since we have cut down millions of trees and constructed only thousands of wind
turbines, I imagine each new turbine goes a little way towards mitigating the
effects on wind speed of removing all that woodland.
Letter
Andrew Walker worries about the term “renewable energy”. He is right to say
that it is meaningless if taken literally, but that is hardly the point. The real
issue is renewable energy sources. We can’t “renew” energy itself, but we can
certainly renew (and also destroy) the sources that make energy available in a
useful form.
Swill on the fields
You report that feeding pigs with swill may be banned
(17 March, p 11).
There are already stringent regulations on kitchen waste, covering collection,
premises, inspection, records and processing (which has to take place at 100
掳C). The product must not be consumed by cattle.
However, some authorities are even now advocating that the same material be
collected by waste management licensees and subjected to large-scale centralised
treatment at temperatures up to 65 掳C. They intend to spread the resulting
product on agricultural land or urban landscaped areas as a soil
conditioner.
There are no comparable specific statutory regulations regarding such a
process.
Moreover, this aerobic process adds to the health risk by multiplying and
distributing the ubiquitous pathogenic and allergenic fungi. There are more
sustainable localised methods of composting available that make a safer and
better product. Surely the same level of precaution should be exercised to
protect livestock and people from this crude, hazardous procedure.