RE: Solar heated hot water

["Brian G. Reynolds" <brian.g.reynolds@xxxxxxx>]

Very well done Bruno, a good read.

Thank you,

B.

-----Original Message-----
From: Bruno Prior [mailto:bruno@xxxxxxx]
Sent: 02 April 2003 03:15
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Solar heated hot water


Scott,

There are several problems with PV at the moment: financial,=20
environmental and practical. The environmental problem relates to the=20
energy/materials cost in producing the panels. I can't say I'm much of=20
an expert on it, but I have heard it said that the environmental cost of=20
the energy and rare materials required to produce the panels is barely=20
compensated by the environmental benefit of using them. But this is only=20
hearsay - a PV expert may be able to refute this.

I am more familiar with the financial arguments. At the moment, the=20
electricity produced from PV needs to be worth around 10 times more than=20
the lowest retail electricity prices to get any reasonable payback on=20
the investment. The German government recognised this (and the practical=20
problems, which I will come onto below) when they introduced a special=20
"feed-in" tariff, available only to small-scale PV generation, at
a=20
price equivalent to around 25p/kWh. That was the price they calculated=20
householders needed to earn on their excess generation to encourage=20
significant numbers to invest in the technology, and even then they=20
expected the payback period to be 10 years or more - not something most=20
businesses would invest in.

The practical problem is simple - the pattern of output from solar=20
panels does not remotely match your pattern of consumption. They=20
generate least in winter - you use most in winter. They produce their=20
maximum output in the middle of the day, when your demand is at its=20
lowest. Their output is ebbing and waxing as your demand is waxing and=20
ebbing. And they produce nothing in the evening after dark, which is=20
when you have your periods of highest demand. That was the other reason=20
the Germans introduced the "feed-in" tariff - they knew that
without a=20
means of selling this excess in the middle of the day, much of the=20
energy would be wasted, and no one would bother.

At least with solar, the output is predictable and consistent. This=20
lends itself to storage technologies. Remember the guy in the wood in=20
Grand Designs, with his car batteries hooked up to his solar panels?.=20
But storage technologies aren't really there yet. That guy had pretty=20
minimal electricity demands and still had a fairly large collection of=20
batteries. If you want to use solar to power a HA house, you are=20
probably going to have to fill your garage with batteries! The great=20
white hope is fuel cells, but (a) they're not really there yet=20
commercially, and (b) they're really just batteries with a fancy name.=20
They're still going to take up a lot of space if you want to store=20
significant amounts of power. And if you're using batteries, you're=20
going to have the AC/DC issues to contend with.

In contrast to solar, wind power is neither predictable nor consistent.=20
This is the big reason why wind is the least green of all renewable=20
forms of energy. Were you aware that even wind advocates quote an=20
expected availability for onshore installations (outside areas with more=20
extreme climates, such as the upper reaches of the Scottish highlands)=20
of 30% (i.e. the number of units you will generate in a year is 30% of=20
the number of units that would have been generated had the turbine run=20
full-whack all the time)? In practice, availability last year was even=20
lower (around 27%), which the wind people say is because last year was=20
not a windy year. But (a) they would say that wouldn't they, and (b)=20
people didn't consume less electricity just because there was less wind.

That is the fundamental point about electricity - it's bloody difficult=20
to store (the only major contender is pumped-storage hydro, and there is=20
little possibility of any more of that in the UK), so generally you have=20
to produce it when you need it. Large-scale development of wind farms=20
will make sense on the day that large numbers of people are prepared to=20
watch TV and turn the lights on only when the wind blows! I can't see=20
that day coming any time soon.

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

So where does the electricity come from when the wind isn't blowing? For=20
local small-scale (embedded) installations, it is probably from the old=20
diesel generators maintained by the former regional electricity=20
companies. And for larger installations, it will mostly come from=20
coal-fired generators (our electricity industry is in a "Looking
Glass"=20
world at the moment, so the more flexible gas-fired generation is mostly=20
running baseload, while the older, less flexible coal-fired generation=20
is providing the variable supply). So if wind energy takes off=20
significantly in the UK, this will only entrench our reliance on the old=20
fossil-fuel generation technologies. Is it a coincidence that wind=20
energy is the one renewable technology being talked up by the big=20
fossil-fuel generators?

Have you noticed how many current adverts by the big electricity=20
suppliers have lots of pictures of windmills? You'd think they were=20
backing renewables to the hilt. Actually, wind constitutes only around=20
30% of the new renewable electricity output in the UK. And new=20
renewables (i.e. excluding old, large hydro installations, which provide=20
another 1.5% of domestic supply) constitute only around 2% of our total=20
output. And a decent proportion of what little wind power has actually=20
been installed, was installed by small, entrepreneurial businesses, not=20
by the big boys. The total capacity of renewable projects actually built=20
by the big boys is derisory. When you hear yet another discussion on=20
renewables focus almost exclusively on wind, remember that this focus is=20
mostly paid for out of the large budgets of the big boys, who are
"all=20
mouth and no trousers", and who would like nothing better than to see
us=20
continue to depend on large, dirty generation plant for the foreseeable=20
future.

Having said all that, everything has its place. The high cost of PV may=20
be a small price to pay in places like much of Africa where the absence=20
of any grid connection means you have no other source of power to keep=20
your medicine cool or run the lights. Wind is not as unpredictable in=20
other parts of the world as it is in the UK. There are reliable thermal=20
winds in Spain, Greece and elsewhere which may make wind more practical=20
for those locations. But the best technologies are the ones that you can=20
control. And in the renewables world, that primarily means biomass.

As a company, we are investing in and researching into technologies for=20
the anaerobic digestion or combustion of energy crops and waste=20
materials. I strongly believe this is the future for a large part of our=20
energy needs, and a solution to the plight of our farmers and the=20
pointless food mountains that they are paid to produce. But although we=20
would like to do this on a small, local scale, it will probably never be=20
small enough for domestic applications (although a digestor in every=20
house to produce energy from your own sewage, food and garden waste is a=20
nice dream). But domestic-scale stoves, ovens and boilers running on=20
wood or pellets are widely available now, and if you go for the right=20
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=20
all of these are for heating rather than electricity. If you really want=20
to produce your own electricity, you will have to look at PV or possibly=20
wind (if you are in a suitable setting). I'm not saying that you=20
shouldn't use these technologies, just that they are likely to be more a=20
labour of love than an economic investment. Then again, if you get a 50%=20
grant, maybe that will make your payback period more sensible.

And to answer your initial question, who knows which way technology will=20
go? PV is an immature technology, so one would expect significant=20
improvements in the economies, but nowadays we have a countervailing=20
force, which is the ever-upwards movement in standards (environmental,=20
safety, quality etc.), which tend to have an inflationary effect on=20
prices. I would guess that PV will get significantly better value than=20
it currently is, but may nevertheless remain uneconomic by dispassionate=20
standards.

It's good to hear of someone who actually "puts their money where
their=20
mouth is" on renewables. unit[e] have struggled hard (without great=20
success) to carve out a green niche in the UK. Perversely, the new=20
mechanism to encourage renewable generation (introduced last year by the=20
government) has the opposite effect on the domestic market for green=20
electricity. All electricity suppliers are now obliged to buy a certain=20
proportion of their electricity from renewable sources. But as they are=20
incentivised to do so, they are prevented from then selling this=20
electricity on at a green premium. The only British electricity which=20
can be legitimately marketed as green is principally the old Scottish=20
hydro plants (paid for in taxes by you and I in the days of the CEGB),=20
which are not a part of the new renewable market. And this output is=20
largely controlled by a couple of the big boys - Scottish & Southern
and=20
Scottish Power. Plus, as all the suppliers now have to buy renewable=20
power, they can all now claim to be green, which makes it harder for=20
companies like unit[e] to differentiate themselves. And as they all have=20
to buy only a small proportion (currently 3%) from renewable sources,=20
companies who want to buy more than that have to be quite clever to=20
avoid losing out to those who buy mostly cheaper "brown" power.
It can=20
be done, but it is an unfortunate contradiction in an otherwise=20
excellent policy that the same mechanism that is providing a genuine=20
boost to renewable generation is working against the development of a=20
retail market to sell that generation. That's why it's particularly=20
important that people like you take a principled stand to buy their=20
electricity from a company that is genuinely trying to do the right=20
environmental thing.

Please forgive the lecture (you can probably tell that it's something I=20
am passionate about) and thank you for supporting renewables.

Cheers,

Bruno


Scott Crowther wrote:
> Hi Bruno
>=20
> Are you saying that PV may improve over time?
>=20
> And if that's no good now, what should the average homeowner look at,
as
> well as solar hot water?
>=20
> I was considering PV because of the good grants available, but if its
not
> worth it...
>=20
> 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!!!
>=20
> Ta
>=20
> Scott
>=20
>=20=20
>=20=20
>=20
> -----Original Message-----
> From: Bruno Prior [mailto:bruno@xxxxxxx]=20
> Sent: 01 April 2003 01:26
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] Solar heated hot water
>=20
> Now would be a great time for people to investigate this sort of
thing.=20
> The government has just introduced a grant scheme called Clear
Skies=20
> (www.clear-skies.org) to encourage people to install small-scale=20
> renewable energy equipment.
>=20
> I'm putting a heatpump (from Kensa Engineering -=20
> www.kensaengineering.com) in my barn conversion which will give me
3=20
> units of heat (or cooling) for every unit of electricity used. I'm
also=20
> looking at putting in a wood pellet burner. The government should
give=20
> me =A31200 towards the heatpump and another =A3800 if I go for the
burner=
.=20
> Would have looked at solar hot water, but (a) it's a listed building,
so=
=20
> we can't put it on the roof or anywhere else that would impact the=20
> appearance, and (b) you can only get grants for upto 2 qualifying=20
> technologies per installation.
>=20
> For what it's worth, I run a business generating renewable
electricity,=20
> and my opinion is that solar hot water can be a good idea, PV (i.e.=20
> electricity from solar) is not worth it (at the moment). And don't
fall=20
> for the myth that renewable =3D wind. Wind power is actually one of
the=20
> least practical forms of renewable energy (although, like every
source=20
> of energy, it has its applications).
>=20
> Cheers,
>=20
> Bruno Prior



http://www.automatedhome.co.uk=20
Post message: ukha_d@xxxxxxx=20
Subscribe:  ukha_d-subscribe@xxxxxxx=20
Unsubscribe:  ukha_d-unsubscribe@xxxxxxx=20
List owner:  ukha_d-owner@xxxxxxx=20

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/=20