Hydro power to store our sustainable electricity

[CaptainPanic]

I've been struggling to understand the whole problem with the storage of electricity. The topic of storage of energy has been treated before, although it was not the main topic in that thread.

 

The popular view is: No wind, no electricity. No sun, no electricity. And storage is a problem, and hydrogen will save the day (eventually).

 

I do not understand why hydro (water) power is no suitable candidate to solve this problem. Is it just not advertised in the right way (marketing problem) or is there a technological disadvantage so serious that we should abandon this idea and continue to wait for other technologies (which are not yet mature)?

 

The Plan

The task of storing electricity, and generating it on demand comes on top of the existing power generation of any hydro dam. Therefore, additional pumps and generators (turbines) need to be installed at existing hydro power facilities. No additional dams are needed. The water level in the lake will just fluctuate a little more.

 

Capacity

Hydro dams have a typical power capacity of Megawatts or even Gigawatts. And even if the river feeding the storage lake dries up, they can continue to generate power for weeks or months. Therefore, the storage capacity is enough. We can simply add some extra generators for when there is no wind, and build some extra pumps for when there is a lot.

 

No mountains nearby

Electricity can be transported over large distances. A thousand kilometers is quite normal in modern grids. So flat coastal regions (with lots of wind) can use storage lakes at inland mountainous regions.

 

Price

Hydro power is one of the cheapest forms of energy. Using hydro power for electricity storage would perhaps mean installing additional pumps and generators, but it would not necessarily mean building more dams. Therefore, it is also cheap.

 

Grid capacity

Grids to and from a facility are in fact the same cables: current can go in two ways. The grid only needs to be expanded for the additional pumps / generators.

 

Efficiency

Losses are found in two places:

-The grid (transportation of electricity from power source to the lake's pumps and back from the lake to the consumer). This is typically a small loss of less than 5% (more like 1%).

-The pumps and generators (turbines). These operate at 80-90% efficiency. Bigger is better here... and hydro power just happens to be the biggest and therefore the best.

 

Experience

Although I find it hard to find links, it's known that France stores its nuclear power in storage lakes in the Alps at night. This is exactly the same technology, on megawatt or gigawatt scale. Therefore, this technology can be called "mature" or "state-of-the-art" or any other term meaning it's not even new.

The only decent links in English I found are these:

-this one mentions it, but doesn't link to anything itself [ctrl-f storage lakes]

-this mentions the increased flexibility in France's electricity production [see: 4.3 critical review: hydropower]

 

Start up times

Pumps and generators can be started fast to react on sudden fluctuations on a power-grid. But wind and solar are at least a little predictable (weather forecast).

 

Other solutions - competition for hydro

I doubt that any form of storage is going to approach 100% efficiency, and still remain cheap enough. Hydrogen generation is possible at 85% efficiency (in a lab, not yet big scale). Turning that back into electricity will give additional losses, meaning losses are in the same order of magnitude as for hydro.

 

A standard battery can never store the same amount of energy per invested euro/dollar (no source, just a guess). In addition, the expected lifetime of a battery is shorter than that of a hydro dam.

 

Pressurizing gas will come with the same kind of losses as hydro power, possibly larger. In addition, there is no existing large scale facility to pressurize a gas for energy storage. Natural gas technology probably comes closest, but the flow rates are much smaller than needed for megawatt scale electricity storage.

 

The "smart electricity grid" can distribute the load over a larger area... which statistically means that there is always wind and sun. But it's not yet built.

 

So, why does the argument of "storage problems" survive??

This solution is so obvious, that there must be a really good reason why each and every person in the field of sustainable energy is shouting that we have to wait for the development of better batteries and hydrogen storage systems... or that we need a better electricity grid for large areas to distribute the load. But what is that reason???

 

Or is it just the Dutch in their flat country who don't seem to realize that they are already connected to the European grid (with access to storage lakes)??

 

My best guess: this solution doesn't need any development, so it's just a marketing problem. There are no scientists shouting that "this is the future!".

[Klaynos]

Hydro is bad because of the impact on down and up river eco systems.

 

There's also some evidence that hydro also has a a significant carbon footprint due to the plants that are flooded decomposing....

 

http://www.newscientist.com/article.ns?id=dn7046#

 

You'e also got to get the power from the dam to the useful source...

 

In the UK we have a very unique effect after some soaps finish there is a MASSIVE surge for electricity (the largest in the world according to something I watched the other day) due to people turning their kettles on, hydroelectric plants are used to cover a large chunk of this because they're very easy to turn off and on...

[CaptainPanic]

Hmm, yeah... I agree that construction of a new hydro dam has serious disadvantages. It destroys ecosystems. But I postulated that you don't need additional dams to increase storage capacity.

 

Electricity transport reduces efficiency, but depending on demand, it is already transported over large distances nowadays.

[Klaynos]

Hmm, yeah... I agree that construction of a new hydro dam has serious disadvantages. It destroys ecosystems. But I postulated that you don't need additional dams to increase storage capacity.

 

Electricity transport reduces efficiency, but depending on demand, it is already transported over large distances nowadays.

 

I do tend to agree with you, and I know that some hydro dams do pump water back up.

[John Cuthber]

Do you mean something like this?

http://en.wikipedia.org/wiki/Dinorwig_power_station

[SkepticLance]

I have read articles on this. The biggest problem is energy loss. Pumping water uphill loses 20 to 30% of the energy, and other factors increase this to an overall loss of approximately 50%. When you generate power, and lose half of it trying to store that power, it is not generally very economical. It can be done for special purposes, or when energy availability is substantial. But for most places, it makes little sense to waste so much power.

 

A better approach, which does not waste power, is simply to use a wide range of energy generation options, to cover all needs. As previously mentioned, hydro-electricity without pumping uphill allows for short term increase in generation when needed. Nuclear runs 24/365. Wind power gives good generation when the wind is right, and solar when the sun is bright, but they need to be backed up by generation methods that do not suffer the inherent variability of wind and solar.

[swansont]

I believe you have overestimated the grid capacity and underestimated the losses (efficiency of transfer). Excessive transport loss is one of the arguments I have seen against remote solar, so both claims can't be right. In the US, insufficient grid capability is a serious concern. Do you have any sources that support your claims?

 

Also, adding more turbines to a dam may not be possible or result in additional energy. Storage capacity is a function of stored water volume. Power is a function of number of turbines.

[CaptainPanic]

I have read articles on this. The biggest problem is energy loss. Pumping water uphill loses 20 to 30% of the energy, and other factors increase this to an overall loss of approximately 50%.

[...]

A better approach, which does not waste power, is simply to use a wide range of energy generation options, to cover all needs.

 

I agree... I think that pumping water uphill should be possible with smaller losses, but I accept your numbers because I lack data, and I am too lazy to search for it today.

 

If we use a wide range of energy generation options, covering all needs, we reduce the need to store energy. This in turn means that the 50% loss is more acceptable... because it will not be 50% of all generated electricity, but rather 50% for all stored electricity. But with a good grid (and the European grid is better than the American) you don't even need to store that much.

 

In the US, insufficient grid capability is a serious concern. Do you have any sources that support your claims?

[...]

 

The Netherlands imports 20-30% of its electricity from France. The total electricity consumption of the Netherlands is about 16 GW. France's nuclear power stations are at least 200 km away (Belgium is in the middle), but probably further away. France exports nuclear electricity to the Netherlands, but stores it in the Alps. This means that the grid capacity and flexibility between the Alps and the Netherlands is sufficient to play with several Gigawatts, which is exactly what is needed. In addition, there exist new power cables that are being built specially for grid flexibility - the European electricity market is opening up, so more cables are needed. One example is a new 700 MW undersea cable from the Netherlands to Norway (another country with good hydropower).

 

Also, adding more turbines to a dam may not be possible or result in additional energy. Storage capacity is a function of stored water volume. Power is a function of number of turbines.

The storage capacity of a hydro dam is more than sufficient. A river can dry up, and the station can produce at 100% capacity for weeks. For 1 GW production, for 1 week, at 50 m water level difference, you need 1.23E12 kg of water, or 1.23E9 m3. That means that a lake of 5x5 km and 50 m deep is sufficient. Many lakes are actually much larger than that.

 

The power needs to be increased, because if you want to use the hydroelectricity as storage, you need to be able to produce more electricity than the base output of the hydro station. The "stored" electricity generation is on top of the normal hydro station's output.

[big314mp]

A hydro plant has a limited storage capacity. So instead of pumping water up and down hill, why not just close the dam (well, reduce flow, so that people down river still have a river) and let the river fill up the reservoir. The reduced power generation from the hydro facility would be compensated for by the wind/solar. When additional capacity is needed, just run more water through the turbines.

[swansont]

The storage capacity of a hydro dam is more than sufficient. A river can dry up, and the station can produce at 100% capacity for weeks. For 1 GW production, for 1 week, at 50 m water level difference, you need 1.23E12 kg of water, or 1.23E9 m3. That means that a lake of 5x5 km and 50 m deep is sufficient. Many lakes are actually much larger than that.

 

I think you need to investigate this further. A 50m water level difference is not the same as a 50m deep lake. That depends on the configuration of the dam.

 

 

Here, the dam would be unable to generate electricity far earlier than it drains. There are ecological reasons why you might not want to drain a lake anyway.

 

 

The power needs to be increased, because if you want to use the hydroelectricity as storage, you need to be able to produce more electricity than the base output of the hydro station. The "stored" electricity generation is on top of the normal hydro station's output.

 

 

But then you have to also worry about where to put the extra water, because that's also on top (literally) of the normal water. This is going to be inconvenient for any people living near the lake.

[CaptainPanic]

swansont, I agree that there are some practical problems if you would allow water levels to drop by 50 meters.

 

I merely wanted to indicate what amount of water you would need for 1 week of continuous power. I should never have written this here... and the moment I posted it, I knew I was asking for a comment. Mental note: when talking about a bigger scheme, make sure that the small details are either well described and without mistakes, or left out altogether... But thanks for the lesson, I need this (I like to illustrate things with numbers, but sometimes I over-simplify it, and that's alright in a conversation with friends, but not alright on a forum full of scientists who do mind each and every detail).

So, same idea, different choice of words/numbers:

The lake is actually a little larger, and the water level will drop less. Ok? Still totally feasible. This time I propose: 50x25 km, and only a 1 meter water level drop. I hope this is acceptable. and if it is not, please play with the numbers a bit until it is. I would prefer to shift the discussion to the changes in electricity production rather than the size of a lake. (Are there ever periods of 1 week when a major part of a continent has very little wind, no sun? What's the longest such period likely to occur in 100 years? What's the effect of this whole scheme for the income of the wind turbine owners?)

 

And regarding people who live near the lake: In the English channel, people have no problems with a 12 meter water level between high and low tide. So, let's say that my newly proposed 1 meter drop is acceptable. Also, in nature, lake and river levels drop and rise all the time.

[waitforufo]

You should check out Grand Coulee Dam and Banks Lake at...

http://en.wikipedia.org/wiki/Grand_Coulee_Dam

 

Banks lake is discussed under the irrigation section of this post but it is also used as an ancillary reservoir for power generation.

 

Don't look for to much support for this idea however. Most environmentalists never met a reservoir they liked.

[CaptainPanic]

You should check out Grand Coulee Dam and Banks Lake at...

http://en.wikipedia.org/wiki/Grand_Coulee_Dam

 

Banks lake is discussed under the irrigation section of this post but it is also used as an ancillary reservoir for power generation.

 

Don't look for to much support for this idea however. Most environmentalists never met a reservoir they liked.

 

Thanks for giving another example that this way of storing electricity is already wide spread, large scale, and in fact totally normal.

 

I don't want to include environmentalists in this technical discussion. And anyway, I wasn't proposing to build new reservoirs, I was proposing to increase electricity-storage capacity by installing additional pumps at existing reservoirs.

[big314mp]

I was proposing to increase electricity-storage capacity by installing additional pumps at existing reservoirs.

 

The capacity increases when the lake gets bigger. So why pump water into the lake, when you can just decrease flow out of the lake?

[waitforufo]

This is off the hydro storage concept but why not just move to local DC power distribution and local battery storage. When electrification first began there was quite a battle between Edison and Westinghouse regarding DC or AC electrification. Westinghouse had Nikola Tesla on his side and won the day. Technology however since that day has improved significantly.

 

AC electrification has the primary advantage of simple voltage transformation and transformer coupling. Once you reach a fixed location like a home or most businesses no transformers are found in the distribution system. Now there are transformers in most electrical equipment or appliances but most of those are part of a rectification to DC circuit. The remaining transformers are generally found in AC motors. Motors that could be replaced with DC motors.

 

Today semiconductor based DC/DC voltage step up and down voltage converters are common and efficient. Efficiencies of 87% are easily obtained.

 

So hybrid systems could be developed that received AC power from the grid and rectify that power to DC at each location. Each location could then have battery storage. (Think of it as a private water cistern in your attic which is actually quite common in many locations in Europe.)

 

An advantage of such a system would be that DC power could be generated locally by various means and also stored in the battery for later use. Various means include local fuel cells, solar, and perhaps but less likely wind. (I just don't see small scale wind systems becoming economical or popular, but who knows.)

 

I know most people on Science Forums would like to get completely away from burning fuel, but local consumption of fuel reduces transportation losses thereby reducing fuel consumption. Also natural gas to the home is very efficient when generating heat for both home temperature control and for cooking. Waste heat from the fuel cell could also be used for home heating. People are used to constantly available and reliable power sources. Local solar and wind will never be capable of providing such performance.

 

The presentation below discusses some of the issues involved.

 

http://www.ieee.org/organizations/pes/meetings/gm2007/html/SLIDES/PESGM2007P-001299.PDF

 

This presentation gives efficiency gains for various distribution methods. It does not consider alternative means of power generation with the exception of local fuel cell generation.

 

The presentation does show that the modern DC and AC systems are very comparable in terms of efficiency. The primary problems are

 

1) Making the conversion from AC to DC.

a) What do you do with all your old devices and appliances?

b) Now you have to purchase all new devices and appliances, or purchase DC to AC converters.

2) Purchasing your selected back up supply system(s)

a) grid

b) natural gas fuel cell

3) Purchasing your alternative supply systems

a) solar

b) wind

4) Purchasing the battery.

5) Storage space (This equipment will fill a moderate sized closet.)

6) Maintaining all this privately owned supply system.

7) Safety (If you have ever been around a large storage battery that overcharged you know what I am talking about.)

 

Maybe Nikola Tesla wasn't so dumb after all.

[nui015590122]

Thanks for giving another example that this way of storing electricity is already wide spread, large scale, and in fact totally normal.

 

I don't want to include environmentalists in this technical discussion. And anyway, I wasn't proposing to build new reservoirs, I was proposing to increase electricity-storage capacity by installing additional pumps at existing reservoirs.

 

my site below has review many websites about hho ,car water for gas,electric clean energy etc....may be helpfull for this thread..

[Klaynos]

my site below has review many websites about hho ,car water for gas,electric clean energy etc....may be helpfull for this thread..

 

Not really. And HHO does not exist. This is not the place to discuss this at all. Have you read the thread at all?

[nui015590122]

Not really. And HHO does not exist. This is not the place to discuss this at all. Have you read the thread at all?

 

I'm sorry.....But I have question and try to make it interest here..I think this is genius website and has many smart people!!!!

 

trury!!! I don't know i sale what is on my site.I think may be someone here can help and told me

 

about that all websites are scam or not and I will improve my website==>http://deleted

 

 

Thank you very much..

Edited September 28, 2008 by YT2095
removed ad links

[CaptainPanic]

On the above 3 posts - Why aren't the entire posts deleted? It's pure hijacking and spam...

 

The capacity increases when the lake gets bigger. So why pump water into the lake, when you can just decrease flow out of the lake?

 

Of course, the pumps and generators of a dam should never be running at the same time. That would be a complete waste. I think that if you want to use a lake as storage, it means that it needs to be able to generate more power during peak hours or hours of low wind/solar energy generation (compared to a normal dam in normal operation), so you'll need more generators. And if you want to store more than currently possible you will need more pumps.

 

This is off the hydro storage concept but why not just move to local DC power distribution and local battery storage.

 

[... (not going to quote all of the above post here, but all is relevant - see above) ...]

 

I think that it should be fairly easy to introduce a direct current (DC) "culture" in our homes. After all, all battery powered appliances are already DC.

 

Also, in the field of electricity distribution (long distance power cables) there exist several examples of high voltage direct current (HVDC) cables that are hundreds of kilometers of DC cable.

 

I think that storage using batteries is going to be much more expensive than large scale hydro. I think that the raw materials for construction, as well as the life time expectancy are in favor of hydro when compared to batteries (no matter what scale of battery). As an example: most hydro stations are running for periods over 50 years, but my phone's battery is dead after 4 years. I'd have to do a back-of-the-envelope calculation to see the maximum price of a battery to become a good competitor to hydropower for storage.

 

Can anyone comment on the type of control systems needed if a society would introduce a distributed battery storage? And compare that perhaps to a control system for hydro power? (I have very little understanding of how my electricity company even knows when to provide more power - I guess it's measured somehow?)

[npts2020]

I cant tell you what the consequences of switching to DC would be but I can describe in as much detail as you like how a ship generates and maintains AC electricity at 60hz, I assume commercial plants have a similar mechanism. Attached to the turbine shaft (usually not directly but through gears) is a flywheel with weights that tend to fly apart when load decreases this causes a valve that controls oil flow to the governor (which controls the throttle) to open and drain faster, causing the throttles to close, thus maintaining speed of the turbine and generator. It is the opposite when load increases. The only difference between the one I am familiar with and one for hydro, would be controlling water instead of steam flow. I was once considered to be an expert on this sort of control system by the navy but it has been a long time. Hopefully, this helps.

 

I once had a fairly senior engineering petty officer try to tell me that he could actually hear the generator speeding up and slowing down even after I explained all of this to him and told him what he heard was the throttle opening and closing to maintain speed. Fortunately, I was training the new guys and not him.

[CaptainPanic]

Reading the last 6 posts, it's pretty hard to stay on topic, isn't it?

No hard feelings for all those who post, I'm sure you all do it with the best intentions.

 

Anyway... I'll just ask my last (on topic) question again, so that it's the last thing somebody reads:

Can anyone comment on the type of control systems needed if a society would introduce a distributed battery storage (of electricity)? And compare that perhaps to a control system for hydro power? (I have very little understanding of how my electricity company even knows when to provide more power - I guess it's measured somehow?)

[npts2020]

Well, the control system on shipboard electric generators I described is how the electric company "knows" whether or not to step up or reduce output, it is mostly automatic. The measurement part is after the electricity is produced. As stated a hydro plant would likely have a similar mechanism. I am not an expert on batteries and cant really comment with authority about them or their control systems. If that didnt at least partially answer your question I apologize and will defer to someone who understands what you are asking.