Do you really mean 300 thousand pounds????

Dick Strawbridge built himself a overslung water wheel for his home, shown on the It's Not Easy Being Green tv show. It's not complicated to do, more resistant to detritus and probably easier to install and maintain. A decent small engineering firm should be able to the job, and it wouldn't require 'specialist' parts - other than a dynamo sized correctly, which is likely to be easier to obtain than a screw turbine.

Sadly it is never economic to generate electricity in small hydro projects. The ony justification is wher elec is essential and no grid supply is available. Even then, diesel generators are likely to prove a better choice. Water-wheels are very low-head devices producing surprising small amounts of power like 2 or 3 kW.

The problem with hydro is that power = massflow x head, but size and capital cost of turbines etc is rather proportional to mass flow. Since capital cost accounts for the vast majority of hydro cost, it follows that only hydro with high heads (like 50ft and more) are likely to be worth considering.

Very few water-wheels are sited in situations where there is a potential for a high head, so no water-mill is likely to be a basis for hydropower. Generally they were corn mills in arable agricultural settings, hence not mountainous locations. Some sites from the early industrial revolution (eg around Sheffield) were sited on rivers with steep falls, but generally these were utilised to feed a succession of water wheels as the river flowed down the valley, and never utilised a high fall individually. Sheffield had around 150 water-powered works c1810, but ran out of water resources to expand water-powered industry...enter the steam engine.

They are talking about 200 I think but this is in winter it will drop if we get a dry summer. thanks for the calc Tuna.

fun -- great crush it is high volume low head 1.5m situation.

Google; Mann Power and archimedian screw installations efficiency levels seem better than solar PV. We have one a couple of miles from us at Howsham mill. Clients are very happy with it.

At 13p per kWh feed in tariff, assuming 300 days a year usage, a 1kW generator produces just under £1000.

So a 50kW generator (as per viking house's quote) would produce £50,000 a year - that's a pretty good return on £200,000 assuming a reasonable (ie > 5 year) lifespan. VH's generator also works out at £4,000 per kW capacity - which compares pretty favourably with wind or solar, given that the latter are intermittent sources.

A smaller (2-3kW) generator should be possible for less than 8K on a DIY basis, which would be a better return on investment, but not on such a grand scale.

I'm interested in where funcrusher gets the 'never economic' argument from, given the above?

This is the email and ballpark quote I recieved for the Archimedian Screw: I'm not sure if I should have left in his contact details or not! Viking House.

Question 1. CAN YOU FIND 1,25m HEAD ….. and cheaply ! …. So it is not expensive to bring 4 cubic metres per second water to your hydropower site. ?I have done some calculations for you : A system can be built generating 35 kW max. (Based on quotation for screw and various options to control the system and assuming an ‘installation cost’ for civil works (which is not wise to ‘guess’ – so anyway here’s a guesstimate until you tell me more about the lie of the land and how far you will have to bring the water and the cost of bringing it . I can provide sketch-drawings (only at this stage) showing concrete-steel work needed for you or a civil-works contractor to cost for its installation)

I have calculated the annual power the machine will generate (using the EPA data earlier) and depending on how you use or sell the power I have calculated the range of earnings. By comparing the site’s earning with the ‘guesstimate’ above I have shown a simple payback period which does not include interest or for that matter future energy-cost increases. I’m impressed with the potential given the ‘conservative’ approach I have taken ! So below is my very simple argument :There are two scenarios tested, each one the extreme opposite ;

1 if you can use all power: without selling back to ESB work 13.5cents /kWh (Industrial rate)

2 if you only sell all power: to ESB for 8 cents /kWh Note : In fact you will probably have some intermediate scenario. (Use most versus sell surplus) Each Scenario shows 2 options:

A. Using a basic control system which will not be able to take advantage of flows above and below the ‘design flow’ of the screw.

B. Using a sophisticated double-inverter control system which takes maximum advantage by increasing the efficiency of generating power especially during lower or greater flows compared to the ‘design flow’ of the screw. These incremental benefits occur 60+% of the time and add upto a greater earning potential and so a shorter payback.

Basically the income per annum was calculated at between €9,500 and €22,050 bepending on whether you sell the Electricity to a neighbour or to the Electricity company. This was for a 35kW screw that operating at a head of 1.2/1.3. If in fact you have the fall of 2m which you say then the output is closer 50kW which I have not calculated for.
The cost comes in at €95,000 or €115,000 depending on whether you would use the double inverter control system. The cost of the installation is guessed at €60,000. This would give a payback of between 8 and 16 years and the machines are expected to work for 60 years because of the slow speed they revolve at. With the 2m head and if you were selling all the electricity to your neighbours then the payback could be 5 years with a yearly earning of €30,000 when everything is paid off.

NOTE : Until a more accurate cost for installation including all civil works and planning including any environmental assessment (if applicable) the figure of 60,000€ is only a simple guess !!
An increase in cost per kWe bought from ESB will increase earnings over time. Interest is not included but maintenance and allowance for shutdown is included.

John (O’Mara)
T. # 353 (0)1 286 3673
M # 353 (0)86 3811 062
Archimedes' Screw Technology for Ireland
The Fish-Friendly Hydro Power Solution
www.ritz-atro.com