Examination of Witnesses (Questions 80
- 88)
WEDNESDAY 8 DECEMBER 2004
PROFESSOR DAVID
POWLSON, PROFESSOR
ALASTAIR FITTER
AND DR
AUSILIO BAUEN
Q80 Alan Simpson: That is helpful,
because the idea of micro energy systems, as much as micro energy
markets, is a whole untapped or unexplored area of greenness.
It is the post bigness era. What I was intrigued about, though,
is in a sense the pathway through the green exchanges. In a sense
it was the Chairman who brought us back to the notion that you
could pursue a carbon emissions reduction agenda that was not
remotely the same as ecological footprinting. If we went entirely
nuclear it could be carbon free, but it would be one hell of a
stump on the eco-systems for centuries to come. What I was interested
about is the connection between the two of you, because it takes
us into a much more complex set of analysis. At another point
you talked about soil sequestration; and it seems to me that there
is an immediate trade-off: if we wanted to produce biofuels, whatever
the intensification of the current agricultural system, it would
automatically have a counter effect, from what you are saying,
on the soil's ability to sequestrate it. Is that not the case?
Professor Powlson: No, if you
go the liquid biofuels route and grow rape seed or wheat, and
the like, and make ethanol or biodiesel, that is exactly what
we are doing now, so that is sort of neutral in terms of soil,
if you like. If you go the route of growing perennial crops like
short rotation coppice of willow or miscanthus, which are perennial
crops, all of the admittedly small amount of evidence that we
have on them so far suggests that those are going to sequest additional
carbon in the soil. They are plants that put a lot of organic
matter through their roots into the soil, and, because they are
perennial, they are not ploughed up every year, so you appear
to retain more carbon in the soil. It is a bit like converting
arable wheat fields into grass. We think that going that route
is, in a small modest way, beneficial in terms of sequestration.
Q81 Alan Simpson: Can I ask you to
set that against the comments from both the Tyndall Centre and
the Soil Association about agricultural policy and the impact
on carbon emissions and carbon sequestration by the soil? One
suggests that the current agriculture and trade policy of the
EU conspires to encourage emissions from agriculture, and the
Soil Association say that there is evidence that past and ongoing
declines in soil carbon levels is due to changes in agricultural
practice. I want you to take us into that area, because it is
important, I think, for us to talk about the capacity of nature
to absorb and use carbon and also how some of our current practices
have worked to minimise or to undermine that process?
Professor Powlson: I will try.
A soil which is under woodland or grass, which the whole of the
UK was under trees more or less at one time in the past, will
have a large amount of carbon in the organic matter in the soil.
When you chop those down or plough them up and go into arable
agriculture growing wheat or whatever, the inputs from those plants
are less than the inputs from the grass or the trees. Therefore
the balance between inputs and outputs for the carbon in soil
goes down, so the stock of carbon in soil, it is true, probably
since the Second World War in this country, has gone down because
a lot of former grassland has been ploughed and gone into arable
cropping so that has been a net release of carbon from our soil.
That is completely true. In principle, you could reverse that
by putting it all back into grassland or trees, but then you would
not do any farming. There are, of course, middle ways where you
can put some of it back into those things, and again we do have
as a starting point our set aside land. You cannot use the same
land twice, of course. You have to make choices. In principle,
you could start by saying, "Let us put some of our set aside
into biofuels, some of it into new forests, and we have the new
National Forest in the Midlands area"—those sort of
schemes should be very beneficial in terms of sequestering carbon
both in the trees, but probably in the soil in the more longer
term, and they have other amenity and wildlife habitat benefits
as well; so there is a win-win if you do that sort of land use
change.
Q82 Mr Mitchell: On balance, is agriculture
a net emitter or a net sequestrater?
Professor Powlson: Most agriculture
will be a net emitter at present. You cannot get away from that.
You can do things to decrease it. I should say, though, that agriculture
can be an emitter because of all sorts of things—using fuel
in tractors, and so on, you are manufacturing fertiliser and the
like. The soil itself often will get to equilibrium and be in
balance with inputs and outputs, so it is zero.
Professor Fitter: It is worth
adding that globally soil is still absorbing a fair quantity of
carbon, several thousand million tons of it. Can I add another
thing in terms of the use of land? Another of the reasons why
land has lost carbon from stores is drainage on a large scale.
Drainage also is a major antagonist of biodiversity in many areas
of land; so there is another win-win to be got there if we could
reduce land drainage. Obviously for productive agriculture it
is important; but if you are not going for productive agriculture,
you can gain on soil carbon sequestration and you can gain in
diversity terms.
Professor Powlson: Can I indeed
agree and add to that. I have been talking about agricultural
soils, ones that have got low in carbon because they have been
in arable production. There is some potential to increase them,
either through taking them out of agriculture, or a smaller potential
through changes in management within agriculture. There is potential
there and we have got figures on how much it is, but soils which
are peaty or have been under grass for a very long time have got
a huge stock of carbon in them. They will probably not go up much;
the danger is they will go down; and drainage can do that; even
planting trees on wet peats in Scotland is very likely to be causing
a net release of carbon. So with those high carbon stock soils,
you want to just preserve them and make sure they do not become
a source, but with the ones that are low, you might be able to
make them into a slightly bigger sink.
Q83 Chairman: Moving from the land
to paragraph 16 in your evidence, you talk about solar and tidal
wave energy and you say that this has received less government
attention. You also say, "Unfortunately the Government has
failed to support such development and companies have gone to
Germany and Holland to develop their products." Why the lack
of take up? Why the lack of interest?
Dr Bauen: You are talking about
bio-energy generally and the use of land.
Q84 Chairman: I am talking specifically
about paragraph 16 of your paper which was about solar and tidal
wave energy. You say that this has received less government attention,
and you say that those who wish to develop this technology have
gone elsewhere?
Professor Fitter: What you are
receiving is evidence from the Biosciences Federation. We represent,
and I can be corrected, but of the order of 30 different organisations
who have all contributed to this submission. We can supply you
with the evidence, unless Dr Bauen you have got it at your fingertips.
Dr Bauen: I think investment in
renewable energy technology in the UK has not been not at the
level of other countries, and in other countries it has been,
in parallel, stimulated by very strong uptake through procurement
programmes. I think that has been the case typically for wind
and solar in the past. When we talk about wave and tidal, we are
talking about earlier stage technologies today. I think there
has been a realisation in the last few years in the UK that innovation
in these areas is fundamental, and I think very important steps
have been made, in particular with regard to wave and tidal. There
are research programmes, but also the Carbon Trust accelerator
programme, for example, which is supporting the development of
companies and their technologies. So I think there has been progress,
but I think historically the track record is not very good.
Q85 Alan Simpson: Would you send
us the details of more effective uptake policies in terms of solar
or renewable energies. I think that would be very helpful to us.
Earlier on in today's session I asked whether this breakthrough
in terms of the way energy markets work would be helped if we
had a new building and planning obligation that said every new
building that now goes up, whether domestic or commercial, has
to generate 25% of its own energy consumption.
Dr Bauen: The building sector,
I think, in the UK has also been neglected compared with other
countries like Switzerland or other countries which have stronger
norms. Also some countries today are starting to implement efficiency
obligations and efficiency certificates which they call "white
certificate". I think this is possibly also an interesting
option to look at and to pursue. Their implementation may be more
complex than for a renewables obligation, and I think some countries
have started implementing that, such as Italy, so it is something
worth looking at. With regard to solar wave and tidal, I will
refer you to a colleague of mine who has better expertise. That
is not my area.
Chairman: Mr Mitchell wants a tiny postscript.
Q86 Mr Mitchell: The problem is enormous.
Methane makes more of a contribution to global warming than CO2,
and cows fart a lot. What is the contribution of agriculture and
forestry to methane emissions and what can be done about it?
Professor Fitter: Methane, molecule
for molecule, is a bigger contributor to global warming, but not
actually in terms of its contribution at present.
Professor Powlson: I have got
some figures from a colleague at a sister institute.
Q87 Mr Mitchell: I keep seeing figures
that cows are a bigger threat than cars?
Professor Powlson: No, not bigger.
Apparently around 30% of UK methane emissions do come from agriculture,
I understand. Most of the rest is from leakages from gas pipes
and disused coalmines, I think. Methane does come from ruminant
animals. Apparently, I am told, more from the front end than the
back end, so it is burping more than farting, I am reliably informed!
Things can be done about this in terms of the feed mix that you
give to animals and trying to alter the microbes in the ruminant,
and work is actively going on to find ways of feeding them so
that you get less methane per litre of milk or per pound of meat.
Q88 Chairman: Right.
Professor Fitter: The concentration
of methane in the atmosphere is tiny compared to that of CO2.
At the moment CO2 is the problem, not methane.
Professor Powlson: But per molecule
it is very powerful.
Chairman: As you can see, we do get down
to the basics in this Committee! Thank you very much for the benefit
of your evidence, both written and oral, and we look forward to
your further contribution: you are going to send us some other
information. Thank you very much indeed.
|
