Saturday, December 05, 2009

All change on renewables

In my October post, I gave the impression that the case for the wind turbine was all cut and dried. It wasn't, as it turned out, and was a lesson to me on accepting real data as real. I had very much wanted a turbine for two reasons: 1. when the wind blows strongly, it's generally the time you need energy; 2. our location in NW Wales should have been pretty good for windiness. This latter assumption was strongly backed up by the two national databases of wind speed averages and predicted power output. The latter, as it turns out, was wildly optimistic.

NIMBY neighbours do us a favour: We had a tense meeting with our downwind neighbours, arranged to test the waters before formally applying for planning permission. They were implacably opposed to anything visible or audible and I found myself having a little sympathy with their views such that we agreed to go back to the drawing board and see if there were alternative sites or just alternatives. So, Val and I had another look at the results for the average wind speed yielded by the anemometry; the real data. I had previously suspected the anemometer of under-recording wind speeds and, with this in mind, we had checked its calibration by holding it out of the car window at different speeds on a calm day. It was spot on.

And the real average wind speed? I had two results from the anemometer read-outs. One was the average wind speed and the other was the average gust speed. I had - wrongly as it turned out - assumed that the true average would be the average of these two averages (the 5.1m/s figure I quoted in the earlier post). I was always worried about this assumption and had made efforts to find out the correct position, so I posted a question of Green Building Forum and Val phoned an anemometer company and discussed the issue with an expert. The upshot of Val's chat was that we should totally ignore gusts! So that means that the windspeed on my best exposed site in windy north Wales is a paltry 3.58m/s, averaged over almost 12 months! So a wind turbine is out for the best reason of all: there really isn't enough wind on this site. The anemometry and neighbours' complaints saved us from jumping to the conclusion, fostered by the databases I mentioned above, that windpower was for us. So we are saved from acrimonious disputes and almost inevitable planning rejection, from appeals and from building a 25k pound white elephant!

So we're now looking at photovoltaics for which no planning consent is needed. Feed in tariffs of around 36 pence/kWh make this a viable option.

The moral of this story: If you're thinking of putting up a turbine, do the anemometry and believe the results!

Tuesday, October 20, 2009

Planning for wind

This is a 6kW Proven turbine on a 15m mast, courtesy of Proven. The little girl is not one of my grandchildren!

I have just written to our local planning officer to find out how the land lies for a full planning application for our intended Proven 6kW turbine.

Why a wind turbine? As you may have read in earlier posts, we propose to install a small wind turbine on our farm in Llangybi, north west Wales. We have two reasons for wanting to undertake this project: firstly we feel we have to do what we can to help combat climate change and are already doing what we can. We have grandchildren and are concerned about the world they will inherit. In this windy area, a turbine is easily the most practical way for us to more than neutralise our carbon footprints. As we approach the critical United Nations Climate Change Conference in Copenhagen, our own government exhorts us all to take action (Act On CO2). This we want to do. Secondly, the turbine should generate a useful income (particularly with Feed In Tariffs) and thus become an additional diversification for our main farm business of growing vegetables in a co-operative for our local box scheme. Details of this environmentally friendly scheme are available on the Llangybi Organics website.

The Site: This is to be in the centre of our land, as far from neighbours as possible whilst consistent with being appropriate for turbine location. You can also view the site on a Google map (a pin marks the spot and the high-resolution satellite imagery shows the hedgerows clearly ).

Windspeed data: A viable average windspeed for microgeneration is generally taken as 5m/sec. How do we best know what our average windspeed actually is?

  • NOABL (BIS) database gives 5.3 - 5.6m/sec for 10m above ground level (agl) (grid squares SH4341 and 4241 in which the turbine will actually be located) and 6.1 - 6.3m/sec at 25m agl. Turbine hub height of 15m agl should receive an average of 5.7 - 5.8m/sec.
  • Carbon Trust Wind Yield Estimation Tool gives 6.0m/sec at 15m hub height with anticipated 13,885 kWh/y generation potential with corresponding CO2 saving of 7.456 tonnes/y
  • Anemometry from October 2008-October 2009 on exactly the planned site with anemometer 11m agl has given average wind (in a year with long periods of blocking anticyclones) at 5.1m/sec based on 147,331 data points. For a description of this, see my previous post. [By the way, this complete set of equipment is now for sale so if you're interested, let me know by way of a comment with your email address. This includes the data logger base station, anemometer and everything needed to connect to a PC including software and cables, the 11.5m mast and supporting gear. I have even calibrated the anemometer. About 100 pounds for the lot!]

Distance from neighbours

Cae Du (upwind for the prevailing southwesterlies) c.160m
Llwyn Helyg (downwind) c.200m
Brongybi (to west) completely shielded by intervening woodland

Turbine details: Proven 6kW on 15m mast (high enough to avoid turbulence from hedgerows and a serious reduction in performance). The installation will be about 60m from our house where it will be connected to the grid via an inverter. Its slow rotation speed and direct drive (no gearbox) means that this turbine is both reliable and the quietest on the market in its class (e.g. 45dBA at 5m/sec). The result is that noise from the turbine is reduced to the swish of the blades turning in the wind, virtually unnoticeable compared with

background sound. See and hear examples from our intended installer's website. And yes, we have been and stood underneath these turbines and they really don't make much noise. The more the wind blows, the more noise there is from the wind in the trees and hedges which tends to drown out the increased whooshing of the turbine.

We await the planner's views before we pay something like 300 pounds just to ask for permission. In this day and age, you'd think every small farm like ours would be encouraged by government to put up turbines. It may come as permitted development rules change and the urgency for tackling climate change finally sinks in.

Sunday, March 29, 2009

Earth Hour in Llangybi

Celebrating Earth Hour by candlelight with Spanish wine and olives, Llangybi-style! Yes, we celebrated Earth Hour on Saturday night. I previously had thought it pointless but the WWF-inspired campaign has gone from strength to strength this year.

So even if it didn't help cause a dip in energy demand (signalling a 'vote' for low-carbon alternatives), it was somehow good to be sitting in front of our logburner with only its flames for light plus that of a beeswax candle. We thought of all the other thousands of people around the world who were doing the same thing at 8.30pm, from time zone to timezone as the planet rotated. There was a sense of solidarity and connectedness and, yes, voting for an end to the Age of Stupid fossil foolishness!

By the way, we used a beeswax candle because paraffin wax candles are made from oil products and we have to be purist about this, don't we! The carbon-neutral logs are from the farm with not even 1 wheelbarrow mile on them. Kosher, eh? Smug, no.