Why we only offer a 2.5kw turbine
We have decided to offer a 2.5kw turbine as a modest turbine that most people can afford, and which will make a meaningful dent in their energy bills
There are some cheap 5kw machines out there, but they are usually Chinese made and are simply not designed for our climate. At the other end of the scale, the 6Kw machines that are well made are costing about €32,000 installed. That is still more expensive per watt than our turbine.
However, there are other issues with larger turbines;
Planning Permission and Turbulence
The planning exemption for domestic turbines is a total height to the tip of the blade of 13m. With our rotor diameter of 3m, the tip of the blade is never less than 10m off the ground. This means that the blade tip is not exposed to turbulence at lower levels.
A 6kw turbine with a rotor diameter of 5.5m can only have a tower height of 10.25m. The blade at the bottom of its stroke will be 7.5m off the ground. This means that the blade tip (which does most of the work on a wind turbine) will suffer a lot more turbulence from surrounding hedgerows.
Effect of the new tariff
The new feed in tariff is set at 9c per KwHr for electricity exported, with a subsidy of 10c for the first 3,000KwHrs per year. Most of the extra power generated by a 5 or 6 kw machine will be exported at a price of 9c, whereas most of the power produced by a 2.5kw turbine will be either exported at 19c, or used by the householder at 16c.
The return on investment for a larger turbine is considerably lower as a result.
How much electricity do you use?
You can look at your ESB bill to see how many units of electricity you use. Of course, you won’t use these at exactly the same time that your turbine is producing, so electricity is constantly being bought and sold seamlessly. But in round terms, you can expect the following production from a 2.5kw turbine on your site, depending on the local wind speed. This assumes that you use 40% of the output from the turbine and export the other 60%;
|
Mean Wind Speed (metres/sec) |
5 |
5.5 |
6 |
7 |
8 |
|
Annual Output (KwHr/Yr) |
3877 |
4871 |
5866 |
7854 |
9643 |
|
Units exported |
2,326 |
2,923 |
3,520 |
4,712 |
5,786 |
|
Units exported at 19c |
2,326 |
2,923 |
3,000 |
3,000 |
3,000 |
|
Units exported at 9c |
- |
- |
520 |
1,712 |
2,786 |
|
Units used at home at 16c |
1,551 |
1,948 |
2,346 |
3,142 |
3,857 |
|
Value of units |
€690 |
€867 |
€992 |
€1,227 |
€1,438 |
|
New Payback Time |
17 |
14 |
12 |
10 |
8 |
Category: Wind Turbines 17 comments »
April 10th, 2009 at 5:04 am
Interesting reading, I checked out the average wind speeds for my area.
I used a very detailed weather almanac. I checked from today, 09/04/09 back 10 years, the average windspeeds were, for Shannon airport, 15Km/h. Which is 4.1666m/s, this pushes the breakeven point beyond 20years.
hardly worth the investment.
April 13th, 2009 at 4:39 pm
Hi Sean,
Thanks for your web enquiry. I’d be a bit surprised if the mean wind speed close to Shannon is less than 5m/sec. I get a reading of about 7 to 7.5m/sec at 100m high. You would need to re-calculate that based on an 11m hub height using the information attached to estimate the roughness class of the land etc.
You might like to have a go using the system outlined in the enclosed document and see if that changes matters.
I know I have a different take on this (and you may well say that since I sell wind turbines I would….) but the payback time on many investments is well over 20 years. Houses for example are (or at least WERE) purchased at a price that well exceeded twenty or thirty years rental. The justification being that the rent would go up with inflation over that 20 or 30 years. Arguably energy inflation will be a lot higher than other sources of inflation, so a well made turbine is a long term investment, certainly not a short term one though…
All the best, Quentin.
April 14th, 2009 at 4:30 am
Hi,
Thanks for the mail,
By the way, as clearly stated, I used the data from Shannon airport itself, Not anything that your remark…………….
“I’d be a bit surprised if the mean wind speed close to Shannon is less than 5m/sec. ” Might suggest otherwise.
As for your point on the investments, if you don’t wish people to comment on, and to Save you making justifications to back them up then maybe you should remove them from your table on the site.
All the best,
Sean
April 21st, 2009 at 5:45 pm
Hello,
I’d like to know where the 3000 kWh @ 19c figure comes from. I haven’t seen anything indicating that the feed-in-tariff is limited to only 3000 kWh. It would seem strange to limit the export to 3000 kWh if the turbine size is limited to 6kW, i.e. a 6 kW turbine operating at its rated ouptut for 30% of the time ( capacity factor ) should generate 15700 kWh per annum. Can you provide a link to where the 3000 kWh figure comes from ?
On another matter, your turbine is rated at 2.5kW. At what windspeed is this measured ? It looks to be just over 6m/s.
Best regards / Colm
April 21st, 2009 at 5:58 pm
Hi Colm,
That link is at http://www.esb.ie/esbnetworks/generator_connections/micro_gen_connections.jsp#q3
Here they say;
As an initiative to support micro-generation, ESB will provide an extra support payment of 10 cents per kWh for the first 3,000kWh exported annually. This payment will be made to the first 4,000 micro-generators connected in the next 3 years and will be paid over a 5 year period.
Yes – it is a bit odd in some ways, but the intention is to encourage householders to produce their own energy and sell a modest surplus. As such, it supports more modest turbines only.
We are still finalising our power curves, but expect that the 2.5kw rating will be at 12 m/sec or less. Current tests have shown this to be below 11m/sec, but we don’t want to publish that until we are more certain. Many turbines are rated at between 12.5 and 15 m/sec…
April 21st, 2009 at 10:48 pm
Thanks for the quick reply Quentin. That definitely takes out the incentive to put in larger turbines ! Having read the esb page you mention it seems to make the calculation of payback a very dark science indeed. With the import-export meter each kWh you produce can have one of 3 different values matching the following scenarios:
1. At a given time your wind-turbine is producing MORE than your house/farm is using. In this case, the electricity produced which covers your usage is worth 19.8c ( ESB Rural 24hr rate incl VAT ) and anything above that will get the export meter turning. For the first 3000 kWh the units on the export meter are worth 19c and after that only 9c.
2. At a given time your wind-turbine is producing LESS than your house/farm is using. Now the import meter is turning. The electricity from the turbine is now worth 19.8c ( as it is displacing electricity from the grid ).
What I find difficult to predict is how often your turbine production will be matching or exceeding your usage. Is the 40% figure you use above a figure for illustration purposes only or are there statistics that bear it out ?
Best regards / Colm
April 21st, 2009 at 11:01 pm
Hi Colm
I think there is a further possible rate at night if you have nighsaver electricity. I haven’t yet got my head around that one, but if you do have it, you would be saving even less. Arguably that would incentivise you to not use electricity at night..
I think all of this will change when smart metering is properly introduced, at which stage there is likely to be more than two tariff rates and the buzzword will be demand side management. The 40% is a wild guess to be honest. On the one hand, even when you are out or asleep, the fridge and freezer are working away, and yet, while you are at home at the weekend, you might be using very little power during the day. It also depends on the extent of the peaks and troughs. But someone with a high level of baseload such as freezers, heat exchange ventilation etc. will have round the clock use. Geothermal may be misleading because it is often a fairly high load that cuts in and out.
But the point remains that if you have a small turbine, there is a better chance that you will be either displacing ESB from your bill, or getting paid 19c. If you use a larger turbine, most of the additional cost of the turbine will have to be borne by a 9c rate. Q
May 1st, 2009 at 3:21 am
—-Thanks for your web enquiry. I’d be a bit surprised if the mean wind speed close to Shannon is less than 5m/sec. I get a reading of about 7 to 7.5m/sec at 100m high—-
100 m high ? above sea level or ground level ?
Are there real performance data available for your windturbine ?
Lars
May 1st, 2009 at 6:01 am
Hi Lars,
The wind maps give estimated mean wind speeds based on a turbine with a hub height 100m above the ground. There is a separate calculator used to plot how this wind speed might vary at higher or (in our case) lower levels. This wind shear plot depends on the roughness of the land – the nature of the vegetation etc.
We are still working out power curves for our turbine. We have been busy resolving some technical issues, but expect to be able to produce power curves shortly. The readings we have so far are along the lines that we expected, but there aren’t nearly enough of them to justify publication. Q
May 6th, 2009 at 4:47 am
I am very interested in your product, but completely confused on how to find the wind speeds at my home site in Kinlough, Co Leitrim…Can you help?
regards,
Nancy
May 6th, 2009 at 4:55 am
Hi Nancy, We can do a quick assessment of your site. If you can pinpoint it for us on either Google Maps, or give us your satnav co-ordinates and send us photos of the area so we can estimate the effect of local topography, we can make a good guess.
Photos from the proposed turbine site facing N, S, E and W and labelled would help us to do this a bit better.
Otherwise, I can email you info on how to do all this yourself.
Q
May 6th, 2009 at 10:52 pm
Hi Quentin,
the info you provide is excellent. I am on the west coast and so would feel that the site lends itself to a wind-turbine. However, I am running a air-to-water heat pump : you mention that this type of heat generation tends to draw large occasional loads as opposed to a more linear demand.
Is this possibly because, to make it economical, it is being run on night-saver ?
What is the impact of night-saver on the calculations ?
I’d really appreciate it if you could help on these details. Also, you mention a set of instructions on how to determine average wind speeds. If you could mail them to me or send me your email address I will mail you photo’s etc.
R&T,
Mac.
July 31st, 2009 at 2:09 am
Hi Quentin,
I see from the ESB requirements, that I must have my micro-turbine installed and maintained by someone qualified to their standard. I assume your people are so qualified. Any idea of the annual cost to fulfill this requirement?
Best wishes,
July 31st, 2009 at 2:21 am
Yes, we are qualified installers. In fact ESB only want RECI or similar approval but I have the City & Guilds wind and solar PV qualifications gathering dust somewhere in case it becomes a condition in the future!
In terms of maintenance, the inverter is pretty maintenance free. The turbine should be inspected yearly in a simple inspection procedure that can be done by the householder. Every five years we would want to take it down, check bearings and blades and replace if necessary – replacement at five years isn’t expected unless there is a lot of abrasive material in the air, downwind from a quarry or similar.
The charge for that would depend on distance, but would be a half-day for two people. Don’t know what that hourly charge will be in five years time, but it won’t be excessive. We don’t live on lobsters the size of Jack Russels, sadly….
August 16th, 2009 at 5:08 am
To whom it may concern,
We are currently looking into purchasing a geothermal with underfloor heating and a 2.5Kw Wind Turbine. Can you please let me know what the annual Kw usage of electricity one has with a 15Kw Geothermal and the contribution that a 2.5Kw Wind Turbine can make to this. We are in a very windy spot! Are there Kw left over that the turbine produces that will allow us to use in our house e.g. cooker, washing machine etc.
Many thanks,
Elaine
August 16th, 2009 at 5:33 am
Hi Elaine, Quentin here. Alas, both of these questions can’t be answered without more questions.
The consumption of the geothermal system will depend entirely on the heat losses of the house – i.e. its size, insulation value and the temperature you plan to run it at. If you have a BER cert, this info might be available.
THe output of the turbine will of course depend on the wind speed on your site. This can be assessed either by yourself or by us. If you email us on the site, I can send you details on this.
You will be constantly buying or selling power depending on whether your production from the turbine is more or less than your consumption at any one time. As your heating cuts in and out your load will vary, and during the summer, despite the lower winds, you may well end up exporting more. Quentin
May 19th, 2010 at 10:35 pm
I am very interested in your product, but completely confused on how to find the wind speeds at my home site in Kinlough, Co Leitrim…Can you help?
regards,
Nancy