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jema

Another nail in the home wind turbine coffin

http://www.theregister.co.uk/2008/08/07/rooftop_wind_turbines_eco_own_goal/

I don't think anyone here needed more convincing though.
vegplot

I'd like to see the end of micro wind turbine propaganda, it's a form of self harm for the renewable energy movement.

They're great in the right environment but not in suburbia.
earthyvirgo

The B&Q 'pop one on the side of your house' promotion was just a farce.

Not all publicity is good publicity.

EV
jema

I wonder how many people here could accurately say where they could best spend money on their property in terms of the environment?

We have finally booked cavity wall insulation (it was meant to be done previously, but fell through) which is probably a pretty good bet.

I expect as for most people the best bet for us next would probably be mundane things like even more loft insulation and individual radiator thermostats.
James

I recently calculated the energy I was likely to get from the wind at around 3m above ground level in my urban area (for the purposes of making a small domestic turbine).

The calculations were an eye opener.

The database described in that article lists my house as having a wind speed of 6.5 mph close to surface (I cant remember what the lowest alititude was, but I used this). I then dropped it further to account for urban condititions and being closer to ground: I assumed an average wind speed of 5mph.

At that speed, a 5 blade horizontal axis wind turbine with 2.5ft length blades (larger than most of the domestic turbines) would have trouble starting and would easily stall with a very small load applied. A 3 blade turbine wouldn't stand a cat in hells chance of starting, . In reality, I'd need consistently higher wind speeds with lower turbulance to make it worth pursuing

Vertical axis turbines work better in turbulent low wind speeds and have often proved worthwile in urban areas. So my calculations moved onto the most efficient design of these- the LENZ2 HAWT. I calculated that with a 1m x 1.5m horizontal axis 'LENZ2' turbine, I probably wouldn't even have the energy to power a 6 volt battery charger under average wind- I'd need at least 6 to 6.5mph and a voltage doubler to charge a 6v battery with some degree of confidence.

To go for a 12v system (enough to power one small domestic electrical item for a short time) would involve many, many meters of square area- a very large turbine that would have to be perfectly balanced atop a very tall pole- not very easy to achieve.

So to power a whole household is totally impractical.

The amount of electricity that can be generated is proportional to the cube of the wind speed. So low wind speeds mean REALLY low electrical production. And turbulence means noise, vibration and damage to property.

Its a great shame that these things have been touted as 'free' energy.
vegplot

jema wrote:
I wonder how many people here could accurately say where they could best spend money on their property in terms of the environment?

We have finally booked cavity wall insulation (it was meant to be done previously, but fell through) which is probably a pretty good bet.

I expect as for most people the best bet for us next would probably be mundane things like even more loft insulation and individual radiator thermostats.


Insulate, insulate, insulate. Smile Deadly dull but highly effective.
James

A trombe wall is another concept I've been considering.
Its a passive solar gain device that can be retro-fitted to the a south facing wall to heat air. A narrow space is created by installing a glazed frontage to the wall. The air behind the glazing heats up which in turn heats up the wall. The wall acts as a massive heat sink (stone walls are obviously better here). After a while, enough energy is being released to create a thermal current, sucking cool air in at the base of the trombe wall and discharging warm air at the top.



They're very easy to install, have no moving parts and have been proved to work in northern England (Bebbington, near Liverpool apparently have some bungalows with trombe walls).

On a much more mundane level, a large amount of energy is lost drying walls out after rain (think wind-chill). Re-pointing your brickwork can greatly reduce the dampness of the outer course of bricks, and therefore save quite a bit of energy (...its on the list...)
lottie

My postcode is ideally situated for a domestic turbine----hardly suprising as I can see 2 windfarms as I'm sat here----the problem is the initial cost of a worthwhile turbine Sad What if I don't live long enough to recoup my outlay Laughing
vegplot

lottie wrote:
My postcode is ideally situated for a domestic turbine----hardly suprising as I can see 2 windfarms as I'm sat here----the problem is the initial cost of a worthwhile turbine Sad What if I don't live long enough to recoup my outlay Laughing


The payback time for wind turbines is anything thing from 5 to 25 years most within the 15-25 year bracket. As fuel prices increase above inflation payback time shortens. The bigger the turbine the better the payback - as a general rule which is one of the reasons why the big generators use big turbines. When we go fully micro renewable it will be for independence and convenience rather than payback.
MikeB

As we have an average wind speed of 27mph we could avail ourselves of some “free electricity” but have decided to use the wind to move water around the land to where we need it, as well as making a few nice water features without it costing us in electricity to pump water
RichardW

You could do both.

When you say you are using wind to pump water is this with a wind driven pump or a wind turbine making electricity & then powering a electric pump (which seems to be much more common & cheaper now days)?


Richard
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