AUG 20

Also happening in the UK, albeit on a smaller scale ...

There are a lot of small dams and wiers left over from the industrial revolution, which originally drove waterwheels. Now there's a small, but growing interest in retrofitting them with hydroelectric units. Mostly pretty small ones (50-100kw each), but there's such a lot of them around that it's reckoned there's the potential to supply ~3% of the UK's electricity needs.

That is really amazing...it completely circumvents the NIMBY crowd. It should really be looked at on a national scale.

Retrofits of older installations is a great idea, so many of the older dams have the same generators and protective equipment in them, not just in the USA but almost everywhere.

Makes sense to reuse what's already in place.

While only three percent, it's an important three percent. Hydro is "dispatchable", it can be turned on as needed to fill in when, for example, wind power flags. And the UK is going to be getting a lot of its power from wind.

Any information about price per kWh projections? Seems like it wouldn't be all that high as the dams are already in place Land use issues are over, the concrete poured. What is left is installing turbines and grid connections.

Well there's a project installing a 50kW reverse archimedes screw into the old mill race Settle in North Yorkshire. Total estimated cost of £410000! Dunno if that's indicative of the costs in general though.

There's a slightly larger 70kW scheme running in Tor Mills in Derbyshire, haven't been able to find out how that project cost. They're been told to turn their 'screw' off at night because there's been noise complaints from local residents ...

The USBR report referenced above analyzes costs. They identify sites where the cost is less than wholesale power, generally about $.05/kWh. Cost is computed based on the production MWh/year (water might flow heavily only part of the year) and amortizing at 5.125% interest. The report includes an analysis of each site. Some sites could produce electricity at half the wholesale rate (less than 3 cents/kWh). 5 pages of sites are less than the current price, 6 pages at less than 10 cents/kWh, 7 pages to 20 cents/kWh, and few higher than 30 (one was 70 c/kWh).

Because we don't have a carbon tax (or cost), and income-tax funded incentives don't apply to hydro, the possible opportunities are hobbled by cheap polluting power. Most of the sites analyzed are cheaper than current solar PV.

Cap-and-trade could in theory offset some cost, but the unpredictability of CO2 prices mean high risk and would require high returns, so project that could produce economically at 8c/kWh are still off the table.

I'm not sure that cost based on MWh/yr is adequate.

Sites that have less than 24/365 production (and behind dam storage) won't be competing against the average price of electricity but against the peak price.

During the parts of the year when there isn't adequate stream flow to operate 24 hours a day they can shut down during low demand hours, accumulate water, and start back up when demand is high.

Timing can make a huge difference in what the market is willing to pay per kWh. Here in the US off peak power can be bought for small pennies, it's even been the case that utility companies have been paid to accept surplus off peak power. Peak wholesale prices can top $0.20 per kWh.

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Let me throw something else into the mix.

Please take a look at the graph in the bottom right of this page...

http://www.wired.com/wiredscience/2008/12/could-the-elect/

Yes, it is California and not England, but the economics hold. The timing might vary.

Look at the afternoon usage, how lots of natural gas might come into play. If the hydro operator were timing wisely they could hold back and reserve their water when other sources were adequate and then go head to head with natural gas.

Not saying this is a bad idea at all but there are many considerations.

I believe the small hydro might better be called 'interuptible baseline' power. As I am seeing what is happening these will not really use the advantage of 'head' from the dams elevation but the kinetic energy of flowing water. Without the reservoir to store water it is a either 'use it or lose it' proposition.

Runoff season will be better but summer less.

Another big question is protecting these from trash such as wood in the river. When the most flow is available that would be a major consideration.

In canals it will be necessary for major rebuilds. Canals were built for a particular flow and routed to manage to get the grade for that flow. This is not 'just run out and dump the thing in a ditch' type of installation.

You’re website has very good infos. I learned very a lot from reading these.

Rather than 'interuptible baseline' I think the term is "dispatchable". Generation methods that can be turned on/off quickly such as hydro and natural gas turbines are generally referred to as dispatchable and offer special value as they can be load following as opposed to "always on" sources such as coal and nuclear.

Looking at the list of untapped dams in the US (Appendix 2 in Hank's linked pdf) it seems that the great majority of them are in the West which would explain why turbines were probably not installed when the dams were built. (Many of them have quite a bit of head.)

Many of these dams were built for irrigation purposes, to trap winter rains and snow pack runoff, hold that water, and feed it out during the summer/fall growing season when rain for all practical purposes is nonexistent.

The pattern of water flow is terribly different than that of the Ohio dams discussed in the post. These western dams may not have the potential to produce a lot of power for the grid. But they might offer a different, and quite important function, storage.

continuing...

We can utilize a lot of solar and wind on the grid but somewhere down the line we will need storage to move some of the solar into evening peak hours and some of the wind from low demand night hours to day/evening peak hours. We can do that with pump-up storage.

Dams generally have an "overflow" basin and a 'no structures' safety zone below the dam. Perfect place to park some extra water.

Then when there is surplus power on the grid some of that water can be pumped back behind the dam until grid demand is high. Then the water can be used to power the dam's turbine.

Pump-up hydro is very efficient (little loss in the pump-up/flow back process). And we've been using it for a hundred years or so. There are probably a hundred or so pump-up storage facilities around the world with three dozen or so of them in the US.

This study needs to be taken with a few grains of salt, because the authors did not take into consideration the current use of the dams. For example, the reservoir behind the Mount Morris Dam in NY under normal circumstances does not hold back enough water to generate electricity (it only stores water during flood conditions). Any change would back up water into a scenic and ecologically sensitive state park, which in turn would negatively impact the local tourism based economy. An earlier proposal to add hydro power generation to this dam was soundly defeated.

When the only dam on the list that I am familiar with is not suitable for the proposed use, I have to wonder if many other dams on the list have similar issues. Overall, I have to question the credibility of this study.

The study specifically addresses the 'other issues'/current use issues.

The study was designed to identify dams that had enough head and multi-year stream flow. It eliminated those dams which are located in protected areas such as national parks, dams on wild and scenic rivers, etc.

And in the study the authors state that the next step would be to investigate any other factors...

This report offers only an assessment of additional hydroelectric generation
potential at federal facilities. The report does not advocate one site over another
or additional hydroelectric development in general. Rather, it provides an
inventory of federal sites and a relatively simple assessment of the included sites’
viability. As mentioned earlier, the report cannot be used as a substitute for
detailed feasibility analyses.

Attacking the study by questioning its creditibility based on an issue not addressed in the report is bogus.

It's like damning the Tesla because it doesn't have a wide screen TV.

You have to remember that many of already in place damns are for navigation and floor control. So the Army Cor Engineers likely will not allow a lot of tweaking to the flows they want going thru the damns. I guess with time, during some seasons they might be will to hold back water when power need is lower and flow more when higher, as long as the river level stay in the rang they want. Also since most of these damns have near by local populations you don't get into the long power transmittion issues. And the on/off power production isn't like PV or Wind, it is seasonal. So is a lot easier to do capacity planning around.

I didn't want to imply that the navigation damn along the Mississipi, and all those river feading it were not great location. Only that the flow rate will be controlled by other factors. All you have to do is visit on of this damns, if you have kids they will love seeing the locks work at least once, and the several I've visited alone the Ohio all have small parks next to them. The amount of water flowing of the damn is a lot, ever in the slower flow times of the river.

Two ways to make electricity from flowing water.

1) Lots of head with moderate flow. That's the typical way, use a lot of pressure to spin a turbine.

2) Not that much head but lots of flow. This is a technology that is still being developed, think tidal harvesting. Given adequate improvements in technology and we could be getting a lot of our power from large rivers such as the Mississippi by installing turbines in deeper sections where they wouldn't interfere with other uses.

I read recently about the Vortex Power Plant.
This is a simple and relatively cheaper way to generate hydro power.
It is tolerant to debris like floating wood of some size, it doesn't harm fishes and aerate water.
It is convenient for small hydro facility (5kw) but should scale up easily due to its simplicity.

more info on this wiki :

http://peswiki.com/index.php/Directory:Zotloterer_Gravitational_Vortex_Power_Plant

This might be a good idea for small plants with irregular flow ;-)

What are we waiting for? Run of the river technology exists - lets get on with it

While the thought of turning small containment and other hydro-dams into electricity producers, one needs to look at the whole picture.
Many of these small dams simply won't be able to produce power in any useful amount because they either aren't big enough orlack a sufficient year-round water supply.
Location is a problem, too; unless someone comes up with a "drop-in" hydro-power system that uses siphonic action to draw in water and spin the turbine, it means spending large amounts of money to modify dams and develop power transmission lines to get that power to any sort of grid system.
What might work would be the "Chaining together" of several small dams by means of plastic above-ground piping or small canals to produce enough drop and flow to make a "collection point" generation station economically viable. By collecting the output of a number of small dams delivered to a single point, there could be some serious power generation developed near a distribution grid. It's easier to dig ditches and cover them than string wires, oddly enough.
Additionally, why not use simple flow turbines that only need the energy of a river's motion as a generation method, the advantage there being that you could use several of these turbines in a sort of "mill pond" arrangement for power at a fraction of the cost of even one dam upgrade.
One must weigh the balance of cost, ease of making, and energy gain to achieve real freedom from coal.

Many of these small dams simply won't be able to produce power in any useful amount because they either aren't big enough orlack a sufficient year-round water supply.

Read the third paragraph of the post. This is exactly what this study determined.