Re: Solar heated hot water

[Bruno Prior <bruno@xxxxxxx>]

Scott,

There are several problems with PV at the moment: financial,
environmental and practical. The environmental problem relates to the
energy/materials cost in producing the panels. I can't say I'm much of
an expert on it, but I have heard it said that the environmental cost of
the energy and rare materials required to produce the panels is barely
compensated by the environmental benefit of using them. But this is only
hearsay - a PV expert may be able to refute this.

I am more familiar with the financial arguments. At the moment, the
electricity produced from PV needs to be worth around 10 times more than
the lowest retail electricity prices to get any reasonable payback on
the investment. The German government recognised this (and the practical
problems, which I will come onto below) when they introduced a special
"feed-in" tariff, available only to small-scale PV generation, at
a
price equivalent to around 25p/kWh. That was the price they calculated
householders needed to earn on their excess generation to encourage
significant numbers to invest in the technology, and even then they
expected the payback period to be 10 years or more - not something most
businesses would invest in.

The practical problem is simple - the pattern of output from solar
panels does not remotely match your pattern of consumption. They
generate least in winter - you use most in winter. They produce their
maximum output in the middle of the day, when your demand is at its
lowest. Their output is ebbing and waxing as your demand is waxing and
ebbing. And they produce nothing in the evening after dark, which is
when you have your periods of highest demand. That was the other reason
the Germans introduced the "feed-in" tariff - they knew that
without a
means of selling this excess in the middle of the day, much of the
energy would be wasted, and no one would bother.

At least with solar, the output is predictable and consistent. This
lends itself to storage technologies. Remember the guy in the wood in
Grand Designs, with his car batteries hooked up to his solar panels?.
But storage technologies aren't really there yet. That guy had pretty
minimal electricity demands and still had a fairly large collection of
batteries. If you want to use solar to power a HA house, you are
probably going to have to fill your garage with batteries! The great
white hope is fuel cells, but (a) they're not really there yet
commercially, and (b) they're really just batteries with a fancy name.
They're still going to take up a lot of space if you want to store
significant amounts of power. And if you're using batteries, you're
going to have the AC/DC issues to contend with.

In contrast to solar, wind power is neither predictable nor consistent.
This is the big reason why wind is the least green of all renewable
forms of energy. Were you aware that even wind advocates quote an
expected availability for onshore installations (outside areas with more
extreme climates, such as the upper reaches of the Scottish highlands)
of 30% (i.e. the number of units you will generate in a year is 30% of
the number of units that would have been generated had the turbine run
full-whack all the time)? In practice, availability last year was even
lower (around 27%), which the wind people say is because last year was
not a windy year. But (a) they would say that wouldn't they, and (b)
people didn't consume less electricity just because there was less wind.

That is the fundamental point about electricity - it's bloody difficult
to store (the only major contender is pumped-storage hydro, and there is
little possibility of any more of that in the UK), so generally you have
to produce it when you need it. Large-scale development of wind farms
will make sense on the day that large numbers of people are prepared to
watch TV and turn the lights on only when the wind blows! I can't see
that day coming any time soon.

And even if storage technologies like fuel cells become practical and
economic, they are not likely to benefit wind. You can probably imagine
a battery farm to support an energy source with predictable short-term
variation in output, such as solar or tidal power, where you only need
storage capacity for 12 or 16 hours before they can start charging
again. But can you imagine a battery farm for an energy source that
might produce constantly for a fortnight and then nothing for a month
(not an improbable scenario for wind)? It would have to be immense, and
most of the capacity would only be used 10 or 20% of the time, which is
hardly going to make it economical. In reality, it doesn't happen, and
it won't happen any time soon.

So where does the electricity come from when the wind isn't blowing? For
local small-scale (embedded) installations, it is probably from the old
diesel generators maintained by the former regional electricity
companies. And for larger installations, it will mostly come from
coal-fired generators (our electricity industry is in a "Looking
Glass"
world at the moment, so the more flexible gas-fired generation is mostly
running baseload, while the older, less flexible coal-fired generation
is providing the variable supply). So if wind energy takes off
significantly in the UK, this will only entrench our reliance on the old
fossil-fuel generation technologies. Is it a coincidence that wind
energy is the one renewable technology being talked up by the big
fossil-fuel generators?

Have you noticed how many current adverts by the big electricity
suppliers have lots of pictures of windmills? You'd think they were
backing renewables to the hilt. Actually, wind constitutes only around
30% of the new renewable electricity output in the UK. And new
renewables (i.e. excluding old, large hydro installations, which provide
another 1.5% of domestic supply) constitute only around 2% of our total
output. And a decent proportion of what little wind power has actually
been installed, was installed by small, entrepreneurial businesses, not
by the big boys. The total capacity of renewable projects actually built
by the big boys is derisory. When you hear yet another discussion on
renewables focus almost exclusively on wind, remember that this focus is
mostly paid for out of the large budgets of the big boys, who are "all
mouth and no trousers", and who would like nothing better than to see
us
continue to depend on large, dirty generation plant for the foreseeable
future.

Having said all that, everything has its place. The high cost of PV may
be a small price to pay in places like much of Africa where the absence
of any grid connection means you have no other source of power to keep
your medicine cool or run the lights. Wind is not as unpredictable in
other parts of the world as it is in the UK. There are reliable thermal
winds in Spain, Greece and elsewhere which may make wind more practical
for those locations. But the best technologies are the ones that you can
control. And in the renewables world, that primarily means biomass.

As a company, we are investing in and researching into technologies for
the anaerobic digestion or combustion of energy crops and waste
materials. I strongly believe this is the future for a large part of our
energy needs, and a solution to the plight of our farmers and the
pointless food mountains that they are paid to produce. But although we
would like to do this on a small, local scale, it will probably never be
small enough for domestic applications (although a digestor in every
house to produce energy from your own sewage, food and garden waste is a
nice dream). But domestic-scale stoves, ovens and boilers running on
wood or pellets are widely available now, and if you go for the right
type of equipment, you can get a grant to help you along.

Besides biomass, I would also look at heatpumps and solar hot water. But
all of these are for heating rather than electricity. If you really want
to produce your own electricity, you will have to look at PV or possibly
wind (if you are in a suitable setting). I'm not saying that you
shouldn't use these technologies, just that they are likely to be more a
labour of love than an economic investment. Then again, if you get a 50%
grant, maybe that will make your payback period more sensible.

And to answer your initial question, who knows which way technology will
go? PV is an immature technology, so one would expect significant
improvements in the economies, but nowadays we have a countervailing
force, which is the ever-upwards movement in standards (environmental,
safety, quality etc.), which tend to have an inflationary effect on
prices. I would guess that PV will get significantly better value than
it currently is, but may nevertheless remain uneconomic by dispassionate
standards.

It's good to hear of someone who actually "puts their money where
their
mouth is" on renewables. unit[e] have struggled hard (without great
success) to carve out a green niche in the UK. Perversely, the new
mechanism to encourage renewable generation (introduced last year by the
government) has the opposite effect on the domestic market for green
electricity. All electricity suppliers are now obliged to buy a certain
proportion of their electricity from renewable sources. But as they are
incentivised to do so, they are prevented from then selling this
electricity on at a green premium. The only British electricity which
can be legitimately marketed as green is principally the old Scottish
hydro plants (paid for in taxes by you and I in the days of the CEGB),
which are not a part of the new renewable market. And this output is
largely controlled by a couple of the big boys - Scottish & Southern
and
Scottish Power. Plus, as all the suppliers now have to buy renewable
power, they can all now claim to be green, which makes it harder for
companies like unit[e] to differentiate themselves. And as they all have
to buy only a small proportion (currently 3%) from renewable sources,
companies who want to buy more than that have to be quite clever to
avoid losing out to those who buy mostly cheaper "brown" power.
It can
be done, but it is an unfortunate contradiction in an otherwise
excellent policy that the same mechanism that is providing a genuine
boost to renewable generation is working against the development of a
retail market to sell that generation. That's why it's particularly
important that people like you take a principled stand to buy their
electricity from a company that is genuinely trying to do the right
environmental thing.

Please forgive the lecture (you can probably tell that it's something I
am passionate about) and thank you for supporting renewables.

Cheers,

Bruno


Scott Crowther wrote:
> Hi Bruno
>
> Are you saying that PV may improve over time?
>
> And if that's no good now, what should the average homeowner look at,
as
> well as solar hot water?
>
> I was considering PV because of the good grants available, but if its
not
> worth it...
>
> Currently I get my power from unit-e, so I s'pose I'm as close to
having my
> own renewable energy system as I can get without the actual
hardware!!!
>
> Ta
>
> Scott
>
>
>
>
> -----Original Message-----
> From: Bruno Prior [mailto:bruno@xxxxxxx]
> Sent: 01 April 2003 01:26
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] Solar heated hot water
>
> Now would be a great time for people to investigate this sort of
thing.
> The government has just introduced a grant scheme called Clear Skies
> (www.clear-skies.org) to encourage people to install small-scale
> renewable energy equipment.
>
> I'm putting a heatpump (from Kensa Engineering -
> www.kensaengineering.com) in my barn conversion which will give me 3
> units of heat (or cooling) for every unit of electricity used. I'm
also
> looking at putting in a wood pellet burner. The government should give
> me £1200 towards the heatpump and another £800 if I go for the burner.
> Would have looked at solar hot water, but (a) it's a listed building,
so
> we can't put it on the roof or anywhere else that would impact the
> appearance, and (b) you can only get grants for upto 2 qualifying
> technologies per installation.
>
> For what it's worth, I run a business generating renewable
electricity,
> and my opinion is that solar hot water can be a good idea, PV (i.e.
> electricity from solar) is not worth it (at the moment). And don't
fall
> for the myth that renewable = wind. Wind power is actually one of the
> least practical forms of renewable energy (although, like every source
> of energy, it has its applications).
>
> Cheers,
>
> Bruno Prior