Suitable sites for hydro power stations in Ireland

Daegerty · 28-04-2011 12:30am #1

Are there any potential sites that could without too much trouble be fitted with a decent size dam?

I'm not really thinking of a spirit of ireland style pumped storage thing but ordinary dams used to generate electricity. Nothing like wiping a few ghost estates off the map to give the housing market a much needed boost and since property prices are way down now would be the time to do the compulsory purchase order.

Even smaller dams in the middle of nowhere without destruction of much property would be more use to us than wind farms since you can at least switch these dams on when demand is high

dowtcha · 28-04-2011 8:48am

Perhaps these sites exist, however I think you'll find that the number of new hydro projects coming on line are few and far between, as for daming lakes etc. to create dispatchible power, I know of one or two projects which were on the go but have got snared up in planning and wildlife issues - and of course the whole ESB Lee Hydro scheme noahs arc scenario didn't exactly assist the cause. As we all know flood management is a real concern in many parts of the country, without introducing stored hydro schemes

Darragh3206 · 28-04-2011 10:56am

To develop a commercial Hydro plant you really have to know what you are doing and have experience in hydro development. No two hydro projects in the world are the same and each component is sized site specific. Ecology is the biggest problem with dam situations and are almost impossible to build in these times. The flooding problem can be easily prevented with adequate sized spill ways and flushing gates coupled with good weather monitoring in the catchment area. Also with the advances in hydraulic computer modeling it is possible to simulate a flood situation such as a 1000 year flood. This helps with the sizing for the spillway. I know of projects in turkey where new arch dams 200M high or so have to be built to withstand a 5000 year flood.

Cookie_Monster · 28-04-2011 1:18pm

What about smaller scale... With smart meters etc on the way would it be feasible for small scale dams on local river to be built without too much disruption?
For arguments sake 500 of these site producing low levels of power would be decent input to the grid, comparable to a wind turbine or 2 each perhaps?

Darragh3206 · 28-04-2011 7:05pm

if you are talking about grid-tie domestic micro hydro it is a great idea. a good site is very productive compared to domestic wind power. The ideal system is one which has a high head with little volume like a mountain stream, then is is possible to have a pelton or turgo turbine directly coupled to the generator, no need for a speed increaser. this cuts down on efficiency losses. it would be possible to export allot of power via a smartmeter but personally if i had a site like that with a dwelling i would also heat my house with the power and then think about export. I also would have my future electric car in the back of my mind.

If you meant commercial hydropower on a small scale ie 500KW or less it is very unattractive financially. this is because of various costs that will remain the same no matter what size a hydro plant is ie, Electrical control equipment such as SCADA, PLCs and Transformers. Then you have Cost of grid connection, grid application, Insurance, maintainace costs and the list goes on. If you wanted to build a 500KW or a 2MW station these costs remain nearly the same.

Having saying that i think it would be a great idea but im not so sure about how one would deal with the Ecology side of it. Also many of the best small scale sites are already built.

dowtcha · 28-04-2011 8:25pm

Have a look at this link lads, its the final word on renewable energy, on this you can see all renewable electricity applications approved for REFIT payments and the application size. On a per MW basis you can see 95% is wind, one biomass CHP a scatter of landfill gas engines and lastly the minute amount of new hydro applications

http://www.dcenr.gov.ie/NR/rdonlyres/91663570-824C-40A3-BE82-41BEC2D0DACB/0/SI532of2010.pdf

The numbers don't lie

Cookie_Monster · 28-04-2011 8:39pm

Darragh3206 wrote: »

if you are talking about grid-tie domestic micro hydro it is a great idea. a good site is very productive compared to domestic wind power. The ideal system is one which has a high head with little volume like a mountain stream, then is is possible to have a pelton or turgo turbine directly coupled to the generator, no need for a speed increaser. this cuts down on efficiency losses. it would be possible to export allot of power via a smartmeter but personally if i had a site like that with a dwelling i would also heat my house with the power and then think about export. I also would have my future electric car in the back of my mind.

This is exactly what I meant. Small scale local sources that can feed surplus into the grid. It's never going to replace a powerstation but every little helps and they would have a very small impact of the location. Once the smart meter and connection costs are sorted. I had asked that in a previous thread, will the smart meters allow for grid feed in a "plug and play" fashion for domestic generation be it wind, hydro etc

Capt'n Midnight · 30-04-2011 1:39am

In the developed world you can assume that the low hanging fruit is long gone.
http://www.esb.ie/main/about-esb/hydro-development.jsp

ESB's hydro-electric projects have harnessed 75% of the country's water power potential.

You either need fast flows or decent heights to get a resonable amount of power.

The geography of Ireland means that the centre of the country is fairly flat and low Ardnacrusha was built in the 20's so that's the Shannon and it's watershed sewn up. Most of Africa has a mile high advantage over us btw.

So you are looking at the other main rivers near mountains, . IIRC the turbine at Shakeltons mills on the Liffey in lucan is still in use so some of ththe 25% the ESB aren't using is already in use. Add to this planning difficulties and NIMBY's and there isn't a lot for commercial development. Yes there is potential for small schemes.

Turbines are not 100% efficient say 80-90%

Lets assume you have a head of 10m then (from mgh) for every 1 cubic meter of water you get
10 * 9.81 * 0.8 * 1,000 = 78,480 = 78Kw

or look at Ardnacrusha
85MW from 28m and 400m3/sec works out to 74Kw if you divide by (2.8*400)

so if you have 10m3/second flow AND a 10 m head you could get 0.75MW
but if you have 1m head and 10m3/second flow you only get 75Kw

Maybe a weir is a meter or two - IIRC the largest one is down in Cork and is only about 3m high.

To give you an idea of the sort of river you need ...
10m3/second is Suir / Blackwater
the Barrown is 7
the slaney is 4.4
the Boyne is 3 m3/second - a 3m weir might give you 75Kw at Slane

More info on water flows
http://www.epa.ie/downloads/pubs/water/flows/
http://www.epa.ie/downloads/pubs/water/flows/name,30473,en.html - Jan 2011 data for the volumes used above

ignoring the efficiency and looking at mgh again
1KwHr = 1 unit of electricity = 3,600,000 Joules = 367 m3 water x 1m x9.81 x ( 1000Kg/m3)

so if you have a 3.67m head (12ft) you only need 100 tonnes of water to get one unit of elecricity - you can see why resevoirs need to be so large and why in some countries the water is more valuable for irrigation and hydro electric plants can be idle.

dowtcha · 30-04-2011 9:31am

Small typo there midways surely: if 1m3/sec with 10m head gives 75kW, then 10m3/sec with 10m head gives 750kW, and with 1m head 75kW.

When looking at run of the river hydro schemes, the kW capacities quoted are to cater for when the river is flood, the power varies depending on river flow. This is as opposed to lake/dammed hydro schemes, which are more dispatchable

Darragh3206 · 30-04-2011 4:34pm

'You either need fast flows or decent heights to get a reasonable amount of power'.

This statement is in-correct. 'Fast flows' is not a term we use in hydropower, the amount of power one can generate in a hydro scheme depends on the mixture of Head and Flow. we know it as 'Q' or 'discharge' and is measured in M3/sec. also generally speaking the faster flowing part of the river is the part of the catchment which is higher up in the watershed. fast flows do not mean greater volume, quite the opposite.

If you have 1 M3/s Q with a head of 1M you have the same potential energy as 10L/s Q with a head of 100M.

Capt'n Midnight · 30-04-2011 5:20pm

dowtcha wrote: »

When looking at run of the river hydro schemes, the kW capacities quoted are to cater for when the river is flood, the power varies depending on river flow. This is as opposed to lake/dammed hydro schemes, which are more dispatchable

Installed capacity needs to be sized for max flow, but the revenue would be related to the average flow. If you have a dam you can average out the flow, but if you just have a weir then you could go for a lower flow rate to optimise the investment in generators, and let the flood pass over the weir.

The point is that you need a lot of water and height and investment to match a windfarm.

Cookie_Monster · 30-04-2011 5:24pm

Probably a stupid question but what's the reason you can't put 2 or 3 hydro plants on a single river. So what the disadvantage of putting another plant down stream or Ardnacrusha for example?

Capt'n Midnight · 30-04-2011 7:43pm

Cookie_Monster wrote: »

Probably a stupid question but what's the reason you can't put 2 or 3 hydro plants on a single river. So what the disadvantage of putting another plant down stream or Ardnacrusha for example?

Ardnacrusha has a head of Hydraulic head 28.5 metres (94 ft)

That's one third of the total drop from it's source in Cavan
putting another dam on the shannon to gain a few meters more would flood most of the midlands

https://secure.wikimedia.org/wikipedia/en/wiki/River_Shannon

Source Shannon Pot
- location Dowra, Cuilcagh Mountain, County Cavan, Ireland
- elevation 100 m (328 ft)

Though the Shannon has always been important for navigation in Ireland, there is a fall of only 18 m (60 ft) in the first 140 miles.

You could put a tidal barrage on the shannon estury

greenpower · 29-02-2012 4:31pm

In need of some advice. I own land that, after some basic calculations, I think has the potential to generate small scale hydopower. To have a sufficent quantity of water and flow I will need to take water from two indiviudal tributaries. This will involve the need to construct two intakes that will have two individual pipelines that will then connect into one pipeline that will transport the water to the turbine. To visualise the proposed pipeline it'll look like a Y...with the two intakes at the top of the Y and the turbine at the bottom of the Y. I'm assuming there will be additional losses.I've looked around and can't see anywhere this has been done previously. Usually its just been one intake with two branching pipelines...

gman2k · 01-03-2012 1:30am

greenpower wrote: »

In need of some advice. I own land that, after some basic calculations, I think has the potential to generate small scale hydopower. To have a sufficent quantity of water and flow I will need to take water from two indiviudal tributaries. This will involve the need to construct two intakes that will have two individual pipelines that will then connect into one pipeline that will transport the water to the turbine. To visualise the proposed pipeline it'll look like a Y...with the two intakes at the top of the Y and the turbine at the bottom of the Y. I'm assuming there will be additional losses.I've looked around and can't see anywhere this has been done previously. Usually its just been one intake with two branching pipelines...

Micro hydro is all about head and flow.
Good info on penstock, generators etc on http://homepower.com

Penstock info here http://homepower.com/view/?file=HP125_pg56_Ostermeier

And another good forum for info http://www.microhydropower-forum.com/board.php?boardid=2&sid=46fad19f0adb4cdd665af61980c8d53d

Suitable sites for hydro power stations in Ireland

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