The Great Winter Heating Experiment

[biffvernon]

No problem with your browser, Worms, it was a communication from elsewhere.

Load factors on installed capacity for wind farms are typically just under 30%. Been a bit higher for the last couple of months but spring and summer this year were poor. Jane may well have been feeling pretty cosy recently. My windmiller friend tells me he's ground more grain this December than since records at his mill began.

Actually 30% is not as bad as some people think it sounds. Big power stations also have surprisingly low load factors when planned maintenance and unforeseen shutdown events are included.

 

[Jane Smith]

I've had a look through this thread but can't find your post, which you quoted. Can you give me a link to where it is, so I can read it in context? Then I'll be able to reply properly.

Ah but

It’s a nice story but the numbers don’t add up. There is no way a 6kW wind turbine can displace £3,000 a year of heating oil without something else going on.

Lets be really generous and give the turbine a 30% activity factor – that means it generates 15.8MWh per year or an average of 43.2kWh of energy per day.

Fuel oil is around 30 pence per litre so £3,000 buys 10,000 litres - the energy density of heating oil is 38.7 MJ/L so that’ll be 387 GJ per year or 107.8MWh – lets say the combination of diesel generator and boiler are only 50% efficient on average that still leaves 53.8MWh compared to the 15.8MWh from wind. It’s worse than that though as some of that wind energy will be lost due to the wind blowing in the summer when the batteries are full, the battery charge discharge cycle will suck up at least 5-10%, the inverters and cable loss will take a few %...

I expect there is closer to 10MWh per year of energy service coming from the wind turbine compared with 50MWh from the oil system.

It may well pay back in ~7 years... but that doesn’t include the 80% energy discrepancy.

Maybe you can explain, Jane?

By the way, we do a lot better than the usual 30% of rated output that most wind turbines average. I think the last time we worked it out it was up in the 40s, but that didn't take in a whole summer so would have been slightly higher than it should. We do get a whole lot of wind up here.

As far as the payback goes: remember we're off-grid so HAVE to have some way of generating power, and we needed a new system as the old one was dying. If it hadn't have been the turbine it would have been a new diesel generator, which would have had a far higher impact on the environment if you allow for both use and manufacture.

 

[Jane Smith]

First off, thanks to Biff I've noticed an important detail I missed out. Our annual oil bill includes the oil we use to run the Aga, which is of course on all the time. I don't know how much it consumes. So the turbine hasn't completely replaced our oil use, but has taken care of a lot of it.

The next point is that our house is huge, old, not completely renovated (which is a polite way of saying it's a wreck) and very draughty. When we have the central heating on the pipes run right round the house and although we don't have all the radiators switches on, the pipe lengths must lose considerable heat, whereas all our dumploads and electric heaters are only on in the rooms which we use.

At this time of year we would routinely have the heating on for 3-5 hours a day, and my life would be severely restricted as I have Reynaud's disease (fancy name for bad circulation) and get a lot of pain if my hands and feet get even a bit cold. I tended to heat the house when the boys were home and then huddle by the Aga when I was home alone (so I couldn't work much--I write stuff--during the day as my computer is in the bedroom, which gets ferociously cold). We had the heating on for an hour or two around Christmas, but I don't think it's been on since. And I'm not only plenty warm, I also have the door slightly ajar so that the cats can come in and out without shredding the carpet.

When we first got our turbine it put out 9kW of energy in high winds despite only being rated at 6kW. Proven had to send an engineer to loosen the springs which hold the rotors, to adjust it down. I'd have liked to have left it as it was but it would have killed the inverters, sadly. We have had just about the highest output possible from it: far more than we expected, having spent several years calculating what a wind turbine would do up here.

There's a poor picture of our house and turbine here:

http://www.sustainergy.net/index.php?id=16

Scroll down to the pictures of the house belonging to David Barnard in the Peak District. That's it. Doesn't show us off to our best advantage nor does it show just how isolated and windswept we are, but it's something.

 

[NT]

When we first got our turbine it put out 9kW of energy in high winds despite only being rated at 6kW. Proven had to send an engineer to loosen the springs which hold the rotors, to adjust it down. I'd have liked to have left it as it was but it would have killed the inverters, sadly.

If the turbine is able to handle it, but the rest of the system cant, it would not be too hard to add an extra dummy load that loads the turbine when it sees high enough rpm, and thus makes use of the extra power.


NT

 

[Jane Smith]

If the turbine is able to handle it, but the rest of the system cant, it would not be too hard to add an extra dummy load that loads the turbine when it sees high enough rpm, and thus makes use of the extra power.
NT

It might not be too hard for you but it's way beyond me!

We do have four dump-loads (three storage heaters and a convector heater) installed all ready, and have provision for a fifth one which we've not yet got around to installing: they come on when the batteries are full and we're not drawing sufficent load from the system to absorb the incoming power. Do you mean we could add more of those, or am I barking up the wrong tree again/as usual? I do like the idea of getting too much power out of our turbine. You should have seen it belting round again today. Lovely!

 

[Lime]

It sounds like you are sitting on a gold mine.
Buy some more of those turbines and get connected up to the mains and make your fortune.

 

[Gervase]

With that sort of surplus power you could be making your own hydrogen, or starting an electroplating business. Maybe you could even bottle it and sell it to the tourists. Or invest in a hunchbacked assistant called Igor...

 

[Jane Smith]

I hear the sound of hollow laughter blowing across the moors.

1) We're in the Peak Park so I can't see that we'd ever get permission for a 60m turbine.

2) The last estimate we got for connection to mains electricity was £165,000 plus VAT. They refused to give us a quote, as they said the cost was likely to vary upwards.

3) Our house cost less than that. (But we did turn down a very impressive offer a few weeks ago and are still amazed that we said no.)

 

[Jane Smith]

I do quite like the sound of an assistant called Igor, though. Does he do floors?

 

[skier-hughes]

Looks a mighty fine house, is the turbine next to the tree?

How did you find sustainergy as a company?

 

[Penners]

We do have four dump-loads (three storage heaters and a convector heater) installed all ready, and have provision for a fifth one which we've not yet got around to installing: they come on when the batteries are full and we're not drawing sufficent load from the system to absorb the incoming power.

I'm finding an increasing number of forum threads that remind me how little I know about anything. It's very depressing.

Jane - do I understand the above to mean that the turbine mustn't operate with no electrical load? Does this damage it? If so, why isn't there a system whereby you can lock or feather the blades so that it doesn't rotate when you have no need of it?

I'm just wondering what you do on warm, windy days, when you don't really want power or heat.

 

[biffvernon]

why isn't there a system whereby you can lock or feather the blades so that it doesn't rotate when you have no need of it?

There probably is but that's wind wasting. When I worked at a windmill we had a lad helping to change the flour sacks and such jobs. He would always complain if we were slow starting on a windy day. "Windwasters", he would mutter.

 

[Penners]

But if the wind is only being used to generate unwanted heat, doesn't that amount to the same thing? Indeed, isn't it actually worse - since unwanted heat is rather what the planet is suffering from?

 

[Jane Smith]

To answer all those questions, in no particular order:

Dump-loads are designed as places to dump electricity that's generated when the batteries are full. If the house is pulling a lot of power out of the system then the dump loads stay off even if the batteries are full (for example, if I'm running the washing machine and tumble dryer). If the dump-loads are full (as ours sometimes are, as three of the four are storage heaters which are limited in how much heat they can absorb) then there's a metal coil in the controller room which acts as a further dump load, worth 1.5kW. If that all heats up and the system can absorb no more power then the turbine switches to free-wheel, and really belts around. So there are two fail-safe devices in operation. I just don't want them to ever operate, as I want ALL THE POWER FOR MYSELF.

When the wind blows very strongly and threatens to drive the turbine too fast, the rotor blades furl away from the hub (the back of the hub points into the wind) like the petals of a flower closing. That limits the speed it turns at without the need for a gearing system, as gears cause noise and wear out quickly.

Bob Robarts of Sustainergy was fantastic, and I cannot fault him. I would recommend him to everyone. Not only was he cheap, he was meticulous in his attention to detail, he made us laugh AND he involved our two boys (now 6 and 11, then 5 and 9) by explaining to them what he was doing and letting them do Real Stuff. He knows his subject inside and out. And, when we had several problems (which all came down to Proven, not Bob) he worked hard to sort them out and gave us a crate of Champagne as an apology. My kind of man.

The turbine is next to a bank of rhododendrons, a good way away from the trees. I'll see if I can post a photo or two here, if you like. The house will be mighty fine when it's finished. For now we have a two up, two down buried in the middle of it, and the rest is a bit haphazard.

 

[Lime]

The generation and storage of unused and waste electricity is a key factor with most forms of "green" electricity.
While Jane Smith is very fortunate to have a surplus of electricity storing all the power is a problem.
Batteries cost a fortune, do not have a particularly long life, are limited in capacity, occupy space and weigh a ton.
Nearly all other forms of electricity/heat storage are much more expensive and/or impractical.
Perhaps an electric car should be high on the list of must-have purchases?

 

[Jane Smith]

We'd love an electric car. But bearing in mind that we live a mile off the road up a really rough track I don't think we could get one close enough to charge it up. David once wrote off his Clio by driving up at speed: a stone flew up, hit the wheel arch, and all the airbags went off. While the car didn't even slow, the airbags burst out all over the place, even out through the upholstery of the seat he was in, and although he was still driving at 40mph he was blinded by a lot of puffy white stuff, and had no idea what was going on.

 

[Jane Smith]

Don't know if this will work or not. If it does, you should be able to click on the picture to enlarge it. Let's see:

 

[Lime]

The picture works well.
It looks a lovely house in a wonderful position.
I envy you except when you have to walk to the shops.

As for the electric car perhaps a long cable running to the where you park up?
Failing that an electric land Rover.
There must be some nut prepared to make one!

 

[biffvernon]

There's an article in this week's New Scientist about vanadium flow batteries. They can be built as big as you like to store as much power as you want. All rather experimental as yet but there's a promising future.

 

[Gervase]

...and, as if by magic: http://www.evparts.com/about/rover.html