Wednesday, December 30, 2009

Spirit of Ireland Energy Proposal


A Small Scale Sea Water pumped hydro storage in Okinawa Japan

"Spirit of Ireland" Energy Proposal
Where is it at?

As the year draws to a close, I have been pondering the prospects for future energy generally, and specifically for two Irish projects. One is Steorn’s “Orbo”, which I must say I cannot put much, if any, faith in at all, and the second is the “Spirit of Ireland” wind-hydro-storage proposal.

While initially greatly enthused by the Spirit of Ireland proposal, I have, over the year, expressed some reservations regarding both the structure of the proposed SOI organisation, and also regarding the proposed procedural strategy.

I have not been in a position to make any judgements on a technical level, as I lack the specialised knowledge, maths and science to do so.

There have been various loosely stated suggestions and plans forthcoming in dribs and drabs on the SOI discussion forum. These plans and strategies have worringly changed quite a bit over the year.

I recently became aware of a technical critique published by Andy Wilson, Director of Sustainability Institute. I wrote to Andy and requested permission to quote from an article he published pertaining to the Spirit of Ireland proposal. Andy has kindly allowed my to quote from his article. I have interjected with some remarks, these are in italics. The full article can be read at:

First though, here is Andy’s reply to my request for permission to quote. His contact details and that of Sustainability Ireland are at the foot of the letter:

Hi Tony,
Thanks very much for the email. It’s good of you to ask permission to quote.

There is absolutely no problem in that regard, and if you want to give
links to the source that would be appreciated.

People have often asked me why I don't debate the issue on the Spirit of
Ireland forum. I usually reply that to do so would be give weight to
something that has absolutely no credibility - unless one counts short
term storage to smooth out daily peaks and troughs in electricity supply
and demand. Even then, there would be massive environmental concerns about the consequences of the sea water leaking out from the reservoirs.

Please feel free to get back to me if you have further questions.

Best wishes,

Andy Wilson
Sustainability Institute
Co. Mayo

Extracts from Andy Wilsons Comment of the “Spirit of Ireland” Proposal

The (Spirit of Ireland) proposal apparently is to erect enough giant wind turbines to fully meet Ireland's electricity requirements.

(And additionally it was part of the original proposal to export surplus power to other countries, thus helping to pay back the investment –ed.)

Ireland currently uses some 25-30TWh (Terawatt hours, equivalent to one billion kilowatt hours) of electricity per annum.

(That’s approximately 3,400,000 one bar electric fires going 24/7 for the full 365 days - ed.)

The present wind capacity is about 1100MW (Megawatts), delivering some 2.9TWh of electricity per annum or about one tenth of the total demand. The Spirit of Ireland proposal is to massively ramp up wind capacity.

To produce an equivalent amount of electricity from wind as is currently used by Ireland would require an installed capacity of around 10,000MW (10,000MW x 8760 hours per year x 30 percent capacity factor).

14 Billion Euro worth of Turbines needed?

(Assuming an average turbine size of 1.5 megawatts – that would mean a total of some 6,666 – six thousand six hundred and sixty six turbines - (sounds a bit of an evil number doesn’t it!!) - would need to be erected, and that is one hell of a lot of turbines. With an average installed cost of $2m per megawatt – the bill would come out at approximately $20 Billion Dollars or about 14 Billion Euro. Please correct me if I am way off in my calculation. –ed.)

It must be pointed out that the Spirit of Ireland plan does not envisage an installed wind capacity of 10,000 MW, but only a fraction of this. In other words, even if all the surplus energy could be stored until needed, with no conversion losses, it would be nowhere near enough.

Difficulties with storage

The only proven technique for storing electricity on a large scale is pumped storage. Surplus electricity is used to pump water to (relatively) high altitude storage dams. When extra electricity is needed, the water is let out of the dams through turbines. Ireland already has one such pumped storage facility, at Turlough Hill in the Wicklow Mountains. Built between 1968 and 1974 at a cost of around £20 Million, it comprises two reservoirs. The upper reservoir - the one used for electricity generation - contains 2.3 million cubic meters of water.

The total energy storage capacity of Turlough Hill is thus about 1.6GWh (Gigawatt hour: one million kilowatt hours), or roughly one two-hundredth of one percent of Ireland's annual electricity demand.

Ireland would need 500 to 1250 Turlough Hills

Ireland would need 500 to 1250 Turlough Hills in order to balance out seasonal variations in supply from wind farms.

For wind installations to provide Ireland with electricity all year round, a storage capacity of up to ten or fifteen percent of total annual demand would be necessary. For the sake of argument we will assume a storage requirement of 2.7TWh.

Storage Potential

The potential energy (pe) of water in pumped storage is expressed by the formula: pe = MgH
Where M = mass, g = acceleration due to gravity (9.81 m s-2), and H = height (head) Thus 1kg of water raised 1 meter has potential energy of 9.81 joules. 1m³ of water (1000kg) raised 1 meter has potential energy of 9810 joules. m³ raised 100 meters has potential energy of 981,000 joules

Converting to kWh: 1m³ raised 100 meters has potential energy of 0.27 kWh. 10,000,000,000m³ raised 100 meters has potential energy of 2.7 TWh. This is equivalent to a lake of 1000km² in area and 10 meters deep. To allow for evaporation losses, seepage and sedimentation, one might increase volume by a further 15 percent. Hence a lake of 1150km², or three times the area of Lough Neagh. The construction of an artificial lake of this size, at a raised elevation, would present some interesting challenges.

(If, on the other hand, as pointed out on the Spirit of Ireland Forum, the proposed glacial valley/s allowed an average depth of say 100 meters – the combined lake size would need to be 115 km2 a much more realisable size -ed.)

Finally, here is a link to some discussions on the Spirit of Ireland Forum which contains a partial rebuttal of some of the points raised.


1 comment:

pobrien said...

"500 to 1250 Turlough Hills" i think you misunderstand some key concepts behind pumped storage. This is a 300MW peeking plant, if we had 20 of them it would cover our peek winter demand(max demand) 5GW, all by themselves for a 3 hour period before needing to be refilled.

Now 2nd critical point,power demand fluctuates between 1GW and 5GW depending on time of day, example during the night, only 4 Turlough Hills needed.

3rd point, Turlough resiviour can can be drained i believe in around 3 hour at peek 300MW. After that it needs to pump water back up - which can occurs within a little over 3 hours.

Now these pumped storage units, typically fill during the night off-peek and release during the peek times of the day. If we had 10GW(~4GW output) of wind backing up 6GW of pumped storage, and some 2GW of backup peeking gas power(reserve), throw some hydro(400MW), wave(400MW), bio(400MW) into the mix, we can easily surpass the 80% mark of total renewable electric.

check out other techniques for energy storage, eg hydrogen production, air compression, flywheel, thermal.. I think this area has great potential for expansion in the coming years.