Saturday, 24 April 2010

Would a turbine work on my land?

We're never short of enquiries from folk asking about whether their site might be suitable for wind power, and we're always happy to help out if we can. The recently announced Feed in Tariff however has generated a huge surge in interest in the small wind turbines sector, the tariff structure now making home-made power a viable prospect for many householders, whether from solar PV roofs in urban areas or standalone wind turbines on farms and small holdings.

But before being taken in by the claims of equipment manufacturers and suppliers, it is always prudent to check the reality of your renewable energy resource to avoid dissappointment a couple of years down the line due to poor energy yields, and thus a much longer payback than first expected.

With PV this is fairly straightforward. Our 1.08kW system at East Cambusmoon (central/west of Scotland) has produced around 800kWh per annum over each of the last 6 years; the same setup would probably priduce 10-20% more on the south coast of England. In other words, expect around 800kWh per kW of solar PV capacity installed in the UK; a bit more in southern England, a bit less in northern Scotland! This assumes the panels are facing south and tilted at an angle of 20 degrees less than your position of latitude (eg. if you're at 56 degrees north, the panels work best tilted at 36 degrees from the horizontal - conveniently the pitch of many a roof!). It goes without saying they shouldn't be in shadow by any nearby obstructions!

But the wind is a bit more tricky. At any one time it's fickle, inconsistent, and above all very site specific. On the plus side a few things are predictable; it's windier near to the coast and high on the hills, it tends to blow harder during the day than at night, and more often in winter than in the summer. These patterns also loosely correlate to energy use, such that a wind turbine is more likely to generate electricity when its needed.

So how do we work out whether a site is any good? The 'near-to-coast' and 'high-as-possible' rules are a good start, followed by a quick check on the well-worn NOABL database which provides the estimated annual mean windspeed on each 1km square of the UK. The database however carries a long list of health warnings, as it takes no account for local topography and obstructions, and simply boils down to a computer model.

The best way is to measure and record the windspeed and direction where the turbine is intended to be installed. For 'big wind' we go to great lengths to do this, using superbly engineered wind-tunnel calibrated instruments mounted at several levels on a mast which needs to be at least 2/3 the intended hub height of the turbines. The recorded data - typically wind speed, direction, temperature, and sometimes humidity and rainfall - are transmitted daily via the cellphone network to the office for collection and analysis.
Whilst the high cost and complexity of this kit is prohibitive for the prospective home-generator, working out whether to invest the equivalent cost of a high-end family car in a wind turbine warrants somewhat more than poking a wet finger in the air.

Enter the Power Predictor, a new device on the market which combines th measurement of windspeed, direction and solar energy with a data loggr in a package for around £150. We've been testing one at East Cambusmoon since last Autumn, and both performance and useability have so far been impressive, even through our severe winter.

Data is recorded onto an SD card, which can be removed from the logger and the data uploaded every few weeks or so to a website which provides an analysis of the results, thus requiring no specialist analytical knowledge. Wind geeks can also pour through the raw data by downloading to Excel.

Wednesday, 10 February 2010

FiT for purpose?

The Department for Energy and Climate Change (DECC) last week ended years of lobbying, months of anticipation and a few weeks of anxiety for the micro-generation sector by announcing the rules and tarriffs for a new system of supporting small and micro-scale renewables, the Feed-in Tarriff (FiT).

FiT's work by offering a Government-backed and guaranteed price for electricity generated from power producers, a system which has been successfully used for at least a decade in other countries to stimulate growth in renewable energy development.

In the UK, commercial scale renewable energy has been supported by the Renewables Obligation (RO) since 2001, a 'carrot & stick' approach which requires electricity supply companies (ie. the folk who send you the bill!) to supply a set percentage of electricity from renewable sources to consumers. As such it is in the supply companies' interest to contract to buy electricty from renewable generators or develop their own green capacity, which is why the big utilities are the major developers in the market.

Small projects (typically less than 5MW installed but down to domestic solar panels and wind turbines) have also been supported under the RO alongside a mish-mash of capital grant schemes, but neither have really provided sufficient market stimulus or caught the public's attention at a scale beyond dedicated early adopters and self builders. The FiT is therefore game-changing for this sector, being ultimately designed to yield a ca. 5-8% tax-free return across the various technologies supported - a relatively low risk investment which many a financial adviser might struggle to match in the current market.

Take solar PV. A retrofitted 4kW system might cost £20k to install, yet produce around 3,200kWh of electricity per year - not far short of the UK average domestic electricity consumption. For this the FiT would pay 41.3p for each kWh generated, giving a 'FiT' annual income of £1,322. About 60% of the electricity generated would by used within the property, avoiding the use of 'imported' electricty at 10p/kWh, so this is worth £192 annully. The remaining 40% is exported at guaranteed price of 3p/kWh, worth £38. So the annual total is £1,552; not bad for a £20k investment, plus an uplift in the value of the house.

Expect your local electricity supplier to offer to install solar PV panels alongside a new electric shower and a house re-wire in your next bill...!

Details of the FiT can be found here on DECC's website.

Friday, 15 January 2010

Merkins Wind Farm - First Public Meeting

Consultation and public engagement are so very important to good planning, whatever the subject matter. Over the past year greater direction has come from the government on the requirements for public consultation for larger schemes, including proposed wind farms over 20MW in size. Pretty much all the developers we know in the wind industry carry out consultation and engagement activities in excess of the guidelines and usually apply it to schemes under 20MW as well. Its a matter of best practice and good professionalism.
Last evening the first public information evening in respect of the Merkins Wind Farm proposal took place in Gartocharn. Despite the inclement weather conditions some 30 people attended to hear Steve's presentation on the project, the work undertaken so far and our plans to be in a position to complete the Environmental Impact Assessment and submit a planning application in Summer 2010. A lengthy and interesting Q&A session followed the presentation. We shall also be carrying out similar public information in neighbouring communities.

Wednesday, 6 January 2010

Beauly-Denny green light...

BBC Radio Scotland ran a phone in this morning over the long awaited Beauly Denny power line upgrade decision which was made today. Of course opponents jammed the lines, the debate often transgressing to the well worn (and discredited) rants against onshore windfarms and renewable energy policy in general.
I didn't get this is what I wanted to say to if I had:

Myth 1: Wind doesn't work when we most need it, ie now!
Answer: From the actual output data of operating windfarms I am involved with, they certainly have been generating lots of electricity during the recent cold spell! This myth is often rolled out by objectors at times of crisis, but nobody in our industry is advocating wind as the sole source of our energy needs; the balancing capacity is already there and will continue to be there.

Myth 2: We need's most reliable.
Answer: Since when was uranium mined in Scotland? The UK? At risk of opening this can'o'worms, let's just say the Scotland givernment is currently saying no to future nukes; it's not on the agenda north of the border. And why should it be when we are blessed with our own natural resources to generate more power than we need?

Myth 3: Let's build big hydro again to meet our renewable needs!
Answer: Good idea, but fraught with environmental difficulties. Let's not forget that onshore wind capacity built in the last decade now produces more eletricity than hydro capacity built in the last century...but we do need both.

The decision is a good one for the renewables industry and shows real political action over rhetoric. As far as the undergrounding question goes, the Scottish Government in its statement on the decision makes it clear that it has no legal powers to enforce undergrounding - so why the apparent confusion?