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The need to put store large amounts of energy over short-term period is likely to increase in the future. Having access to such storage could optimize the operation of several generation technologies. Technologies such as wind power, solar power conversion and the various forms of ocean power (currents, tides and waves) will often generate excess output during off-peak periods as would hydroelectric power dams during period of excess rain. Connecting to some form of short-term and high-capacity storage system can optimize the cost effectiveness of such technologies.
There is renewed interest in various forms of thermal power generation that uses steam and that includes clean coal technology, nuclear power and eventually the production of intense heat through fusing hydrogen. Having access to energy storage during off-peak periods could benefit the operation of several types of thermal power station. The thermal componentry would be able to operate at constant temperature and pressure with reduced variation in output over prolonged durations.
Boilers, piping systems and turbines would be subjected to fewer cyclic thermal stresses. Their useful life expectancy would be greatly extended and improve the reliability of thermal power stations. Such power stations and their bottom-cycle companions would operate at or near peak efficiency for prolonged periods to optimizing the return on investment as well as overall cost effectiveness of power generation. Access to high-capacity hydraulic storage of energy will depend on the case that can be made for such storage technology.
Environmentalists have scorned new mega-hydroelectric projects like China's Three Gorges project even as the need for mega storage capacity increases. There will be negligible environmental impact from install pumping equipment at existing hydroelectric installations where water may be pumped to a higher elevation during the off-peak periods. Such installations would be feasible at locations where 2-reservoirs of high capacity are within close proximity to each other and at different elevations. There are many such pairs of lakes across Northern Canada where water may be pumped uphill to store power during off-peak periods and flow downstream through kinetic turbines to generate power during peak periods.
There are numerous locations around the world where such a transfer of water may be undertaken on a mega-scale. North America's Great Lakes are within close proximity to each other and hold tremendous volumes of water at different elevations. Large volumes of water may be pumped to higher elevations during off-peak periods and with minimal ecological impact. Power may be generated during peak periods from kinetic turbines placed in the fast currents that flow downstream. Such operation is possible in the river between Lake Nipigon and Lake Superior (change of over 400-feet) and in the channel between Lake Huron and Lake Superior (change of 18-feet). A canal that includes kinetic turbines placed at each of a series of locks could be built between Lakes Michigan and Superior (change of 25-feet).
The following table summarizes the major locations for hydraulic storage across North America:
A similar approach may be possible between the Caspian Sea and the now depleted Aral Sea (change of 246-feet) where a long interconnecting canal could be built. Massive volumes of water could be pumped uphill over a series of locks to the Aral Sea during off-peak periods. During peak periods that water would flow back to the Caspian Sea and through kinetic turbines installed at every lock to generate the power. That same approach could be used to move massive volumes of seawater between the Gulf of Aqaba and the Dead Sea (total change of 1000-feet). Such storage will become feasible due to developments in long-distance transmission technology that allows power to be sent more efficiently over greater distances.
The following table summarizes some major international storage sites:
Experiments are underway in India, China and Brazil that involve transmitting 800,000-volts (DC) and 1,000,000-volts (AC) over long distances and with minimal energy loss. That transmission technology allows for more off-peak power from more power stations that are located over a much larger geographic area to feasibly and efficiently gain access to mega storage of energy at distant locations. Such access to such capacity could allow companies in Canada to develop the massive potential for tidal electric power that exists in the channels of Hudson Strait. That power could be transmitted over the long distance to the hydroelectric dams in Quebec or to the mega storage potential that lies between the Great Lakes. Pumping equipment could be installed at several neighboring pairs of power dams across Quebec.
The inland storage systems would work well during periods of sufficient rainfall. However, there would be times of little rainfall where the height of water at hydroelectric dams could drop to critical levels, as has occurred in Australia, in South Africa and even in Quebec. It would be during such times when the inland transfer of ocean water would need to be considered. Such transfer is being considered for the Dead Sea and for the Qattara Depression in Egypt as well as for two mountain areas in that region. These include a large basin in the Galala Plateau near the Red Sea and a valley in the Aqaba Escarpment near the Gulf of Aqaba.
The dry climate in the region has resulted in a virtual absence of vegetation and related animal wildlife at any of these locations. Environmental studies suggest negligible change for the local environment after ocean water is pumped to the higher elevation or allowed to flow into the land depressions for the purpose of the hydraulic storage of energy. Prolonged periods of drought together with changing weather patterns could change ecosystems in valleys and basins located in coastal mountains. A combination of a variety of plants with saline resistant roots and that compliment each other can actually be grown using ocean water that is pumped into storage reservoirs. There are also a variety such as certain species of mangrove and coconut plants that can grow on a combination of fresh water and seawater.
Mega-scale hydraulic storage of energy can involve the use of fresh water as well as ocean water. The technology could be developed so as to reduce any adverse impact on local ecolosystems. The use of the technology could provide greater value to a large human population in both developed and developing countries than detriment to wild life. The storage technology could allow more efficient and more productive use of available energy resources. Its cyclical movement of water between reservoirs can provide a heat sink for large cooling systems in some regions and be a heat source for giant heat pumping systems in other regions. It has future application.
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Interesting and useful tabulation of data on lake pairs that might be used for pumped hydro storage. The storage capacities available are impressively large, and do justify the "mega" in the article's title. However...
One crucial item not included in the tables is the length of the connecting tunnels that would be required. From Google maps and some eyball estimates against the map scales, I get the following estimates for the first half of the list:
Nipigon - Superior: 25 mi (16' / mi.)
Superior - Huron: 0 mi (18' at Soo Locks, Sault St. Marie)
Superior - Michigan: 33 mi (0.5' / mi)
Nipissing - Huron: 40 mi (1.5' / mi)
Simcoe - Huron: 20 mi (6.8' / mi)
Winnipegosis - Manitoba: 2 mi (9.5 ' / mi)
None of these really look very promising, other than the Lake Superior to Lake Huron connection at Sault St. Marie. I believe there's already a power station there, adjoining the locks. Revamping that station to enable reverse pumping when there's excess power might be feasible. However, that would mean reverse flow in the river channel connection between Lake Huron and the lower side of the Soo locks. I'm not sure whether the river channel is large and deep enough to support that.
Len Gould 9.14.07
I question why not the obvious, Lake Ontario to Lake Erie?
Roger Arnold 9.14.07
Obvious, indeed. How'd that one escape the list? The infrastructure is already in place, with two power reservoirs connected to Erie by buried canals, and hydroelectric power stations discharging to the broad lower portion of the Niagara river well below the falls. Adding pumped storage capability would be a major upgrade to the plants, but the flow reversals would hardly be noticed. On Google maps, the stretch of the Niagra river between the hydroelectric discharge points and Lake Ontario looks more like a finger of the lake than a river.
Ramon Mischkot 9.15.07
Thank you for your well written, interesting, and provocative article on mega hydro storage opportunities. I believe hydro is the most economic and environmentally sound way to meet our power needs but is too often overlooked due to numerous institutional barriers. See my 7.13.06 article (Should You Invest More in Your Hydro Assets?) for a discussion of these barriers and an approach to addressing them.
Ferdinand E. Banks 9.17.07
Institutional barriers, Ramon. Are we talking about environmentalists here?
Ramon Mischkot 9.17.07
Ferdinand. Yes, but its broader than that. Barriers include a wide range of environmental issues that that must be given equal consideration with power needs by FERC under a 1986 amendment to the Federal Power Act. Other issues assessed in determining the life of hydro plants as a basis for their depreciable life include safety related relicensing issues. Working with hydro clients I have identified over 50 issues to address using and issues/impact matrix to identify relevant issues, the cost of addressing such issues, and the impact on plant operating cost. To date, I have found that if an appropriate economic life is used, which is 40 years or more, the cost of addressing any of the issues does not make hydro uneconomic. Barriers are more perceived than real once systematically analyzed. I am sure there are exceptions; I just have not found them.
Xuguang Leng 9.18.07
I very much doubt the feasibility of the scheme.
First of all, to utilize the elevation difference between Lake Superior and Lake Michigan, you have to build a channel connecting the two lakes. The channel has to be essentially flat in grade for most of the length, with elevation drop only in very short distance. The cost of such channel will be enormous, if it is even feasible. Otherwise, why not build a channel from Lake Superior to Atlantic Ocean, surely there is more elevation between the two.
Secondly, the generation/pumping capacity is limited by, not the lake capacity, but the channel capacity. To fully utilize the lake capacity, you need the channel that is enormous wide and deep, whichwill also be enormously expensive.
Bohdan Buchjynsky 9.18.07
As a developer that has had a FERC licensed pumped storage facility complete the development cycle, environmental and regulatory issues are just part of the problem in getting built. Finding a "market" for your facility can be even more difficult. Today’s utilities and power marketers look at hour-head and day-ahead pricing with capacity contracts for one to five years being considered as "long term". No entity will commit the development and equity capital required to develop and build a pumped storage facility without "real" long term contracts or commitments, 25 to 30 years or more. This contracting scenario currently does not exist.
As additional cyclical renewable energy is added to the grid, pumped hydro or pumped storage will become a critical tool in efficiently using that energy and maintaining system stability. However, few if any entities are looking at this need since the contractual structures are not there to support it. Look at the difficulty the Lake Elsinore, LEAPS project has had and seems to be only able to go forward as a "unique transmission project" with possible revenues from the CAISO. High head, low flow systems not connected to any natural waterway could mitigate the environmental and regulatory issues, especially if covered or sealed reservoirs are used. There are many locations throughout the US where these types of facilities could be located close to renewable generation locations to minimize transmission losses and provide generation into the same locations as the renewable generation is located. First market and institutional changes need to be implemented that recognized and value the characteristics of pumped storage or pumped hydro.
Xuguang Leng 9.18.07
Thirdly, the pumping/generation has maximum efficiency of about 75%. The less the elevation difference, the longer the channel, the less efficient the process will be. 25 feet elevation difference over 33 miles is not very useful.
Fourthly, there are natural channels between the lakes in some of the cases. In order to force the water flow through the new man-made channel, you would have dam or restrict the natural channel. Another very expensive if not impossible task.
Pump storage can be built in small scale at selected locations for good reasons.
Paul Stevens 9.18.07
Mega pumped storage, between suitable adjacent lakes, is exactly the solution to help nuclear get away from the Base-Load constraints that it currently exists in. Running at full achievable capacity during the day, while pumping into resevoirs at night and/or during seasonal slower periods of consumption helps eliminate any constraints or fears about over building and un-used capacity.
Periods of low precipitation have already had a measurable negative impact on North American hydro-electric production in the last decade. Re-using the water helps overcome this.
Of course, the impact of less flow downstream of any selected resevoir site would have to be studied, but I suspect it would be environmentally less than having to make up any electrical supply shortfall with NG, coal or wind turbines.
Patrick Good 9.20.07
As someone who grew up in the Buffalo-Niagara region, I believe Lake Erie-Ontario was left off the chart due to the fact that Mega Pumped Storage is already in use there at the Robert Moses Facility.
See - http://www.nypa.gov/facilities/niagara.htm
Len Gould 9.21.07
Another relevant missed item, though not exactly "pumped", is the concept of exploiting existing hydro generation, with added turbines if necessary, as peaking systems exclusively. An example is Quebec Hydro's huge hydro capacity, currently used primarily as baseload and feeding aluminum smelters (and lately a bit short of water). If a large nuclear capacity were installed nearby to pich up it's baseload, and adequate transmission provided, this could become a sufficient peaking resource to backstop all intermittent renewables ever likely to be built on the eastern seaboard.
Len Gould 9.21.07
"pick", not "pich"
James Carson 9.21.07
Unfortunately, the institutional barriers are more than formidable. For example, you may have heard about the freeway bridge collapse in Minneapolis. That bridge lies just below the only waterfall on the Mississippi River and at the head of a deep gorge that drops considerably over several miles. There is about 90MW of generation already in that vicinity, and there is no doubt that twenty to fifty times that could be generated were real hydro facilities built there. No utility will even suggest such a project. No way. They are not going to walk into that wood chipper.
Todd McKissick 9.25.07
With all the problems I see for pumped hydro storage, there seems to be an obvious solution not being discussed. Those problems include finding sites with significant drop, building more channels or waterways, contracting, locating near the resource vs. locating near the population (which would save transmission costs) and the unmentioned environmental/security issues.
One possible solution I see to this is using the local water tower to perform the "storage" function on a smaller and more efficient scale. Most towns have some sort of reservoir or aquifer with a pumping system to move it to hundreds of feet above. These systems are already in place and have their maintenance budgeted for already. Simply placing a tower fed turbine to 'dump' water back into the reservoir would generate power at much higher efficiency with much less transmission cost. For the most part, these towers have excess capacity that's rarely used beyond 30% so draining it another 50% through a turbine during peak times and pumping it back up during off peak wouldn't require new tanks or towers unless the already treated water was headed back into an untreated reservior.
Also, most of today's water supply systems are already ran by full SCADA systems so little additional control would be needed. Anybody know how much unused water tower capacity there is in the US?
Malcolm Rawlingson 9.25.07
Intereswting idea Todd,
I think the volume flow rates you need to generate at any significant output would need towers alot bigger (higher and larger capacity) than currently used. Also this is drinking water so not the same as letting a river flow through a turbine.
But not problems that could not be overcome but not sure the scale is large enough. Most towns only have one tower. For this application I think they would need many many more.
Malcolm Rawlingson 9.26.07
Lake Erie to Lake Ontario. Ontario Power Generation is currently building a 10 km tunnel from the Niagara River above the Falls (Level of Lake Erie) to its reservoir above Sir Adam Beck Generating Station.
I suppose it could be converted to a pumped storage scheme (don't think it is right now) but like Xuguang Leng I think it would be very expensive. Also the volume of water flowing down the river would be reduced. There are concerns that if any more water is taken from the Niagara River there will not be much of a Falls to see.
Like many of these schemes - if they were feasible we'd already be doing it.
Many things can be done. The acid test is whether it is really worth doing them.
Todd McKissick 9.26.07
Malcolm, There you go again keeping up the 'scale' watch. Dilligence is always a good trait. :) Doesn't that also mean actually running the numbers to find out?
Given that the cost would only be a couple TEEs and valves, a positive displacement turbine generator and some controls, how can you pass on whatever scale it offers? That's not even counting the 'distributed' factor and the distributed ownership it offers.
My town has two towers for 12,000 people and I know the operator. He replied that he gets overtime to cycle the level in the towers twice a year because otherwise they never change more than a small percentage. Using rough-guess numbers, that's storing about 15,000 gallons to a height of 150 feet for each 6,000 rural people in the country each night. Anybody?
Len Gould 9.27.07
Well... 160,600 lb at 155 feet. 73,000 kg at 50 meters. 3,673,000 x 9.8 = 3,600,000 joules potential. 1 watt second = 1 joule second, 1 watt hour = 3,600 joule seconds, so 3.6 x 10^6 joules approx = 1000 watt hours. 1 kwh.
Seems low to me, have I an error in there?
Len Gould 9.27.07
Ah. yes. forgot to shift the decimal when converting to Newtons. 36,000,000 joules potential = 10,000 watt hr = 10 kwh.
Malcolm Rawlingson 9.27.07
Perhaps it is just a couple of valves and a few T's...and a generator...and the grid connection but in order to make a significant contribution my guess is you would need tens of thousands of these facilities.
A car is just an engine/gearbox 4 wheels and a few metal/plastic panels....you could probably make one in your garage. but to make 20,000 a week at a price people can afford you must have a mass production plant.
Why don't you see that exactly the same economic principles apply to generating electricity?
The capital cost of generating and collecting small numbers of megawatts (even if the energy is free) is much higher than generating large numbers of megawatts from one plant.
The idea of distributed generation is not new....it has been around for a hundred years....and in fact is the way generation was done before Tesla figured out how to move large amounts of electricicyt over long distances without substantial I-squared R losses The reason we do not do it is because it does not work and is too expensive.. It has nothing to do with the technology or fuel source but everything to do with economics.
We could operate a distributed system right now by putting a diesel generator in everyones house.....except not everyone has a house. Could the average 50 story condo dweller really produce all the electricity his or her household needs....or the electricicyt to run the essential elevator banks 24 hours a day 7 days a week without interruption, or the electricicyt needed to pump water several hundred feet up the building? Such buildings (of which there are many) would depend on a grid system It is grossly inefficient from both a capital use perspective and a maintenance perspective.
Malcolm Rawlingson 9.27.07
So using Lens numbers, 10kWh ...that is not much :(....you would need at least one tower for each household. So lets say 3 people on average per household 2000 towers...now that is a bit more than a few valves and a generator...now you're building 2000, 15000 gallon water towers. They are not cheap to build. Water is heavy. Ten pounds per gallon. 15000 gallons weighs 150,000 pounds or 75 tons approx. Holding it 150 feet or more in the air takes a very strong and stable structure. Not an economic proposition and of course why it is not done now.
I don't know how much a water tower costs but I'd guess for the type of engineered structure and foundation you need you are looking at capital costs of over a million dollars...I will be pleased to be corrected on that but this is not your average farm building.
So we would need 2000 of them for our rural community. That is 2 billion dollars of infrastructure to produce 2000 x 10kWh That is only 20 Megawatts hours
I could build you a 1000 MW nuclear plant for that. You would get 50 times more output for the same dollars in.
So by Lens numbers you would need thousands of these facilities and that assumes you have enough ditributed other energy to get the water up there in the first place.
Like many of these ideas they sure sound promising but economically very hard to justify.
There is a reason we buy power from the grid...it is cheap, it is convenient, we don't have to do the maintenance, and it is very reliable.
Believe it or not exactly the same reasons why we buy cars made in a mass production plant rather than kit cars we build in our garage.
They call it mass production :)
Same reason it is cheaper to buy your goods from big retail outlets that small stores...economies of scale. I like corner stores and I pay more for stuff because I use them rather than Wally Marts. As long as folks know that this is going to cost them much much more then these ides are good. Problem is people want cheap electricity judging by the noise that is made whenever electricity prices go up.
Len Gould 9.27.07
"There is a reason we buy power from the grid...it is cheap" - don't you mean "used to be cheap?"
Jim Beyer 9.27.07
This isn't so much a storage comment (well, sort of) but more on the issue of load-leveling.
If an ordinary car/truck has 200 HP, that is nearly 150 kW, quite a bit actually. Now generating electricity via liquid fuel is economically problematic, but what if it is only done a few key minutes per day? The infrastructure is already there, and the usage is low, so the only real cost would be the fuel and the hook up.
If a PHEV has .2 kW-hr of Ultra-Cap storage, that could supply a 20 kW need for 30 seconds or so, long enough to turn on certain pieces of equipment. The car's batteries could recharge the ultra Cap in about 1-5 minutes. Maybe this peak-clipping to lower capacity needs could have a name, NEGAPACITY ?
Malcolm Rawlingson 10.2.07
Electricity is still cheap. There is no doubt it could be even cheaper but I know of no other product that has such versatility usefulness and practicality than electricity.
For what it does for my household - it is dirt cheap.
I pay about $80 a month including a Government imposed tax of 6%. For that I can run.
Computers and internet - for pennies a day Television and enetertainment - for pennies a day Washing Machine and dryer (gas) - used 4 to 5 times a day 50c a day including cost of pumping water from a 40 foot deep well. Pumping my water - actually save money there as I have no water bill but without electricity I would be bucketting it up or hand pumping. Microwave and oven - 50 cents a day max for cooking and preparing all my food. Refrigeration and freezing - keep all my food fresh and stores about three months future supply - pennies a day. Vacuum clean my house - pennies a day Heat my house (gas furnace - electric fan) about 50c a day in winter - nothing in summer. Run all the electric power tools I want - pennies a day Hair dryers curling irons etc - make wife and daughter look stunning - pennies a day. Run all kinds of small appliances for - pennies a day.
All that for about the cost of two cups of coffee for my wife and I a day.
Dirt cheap Len - just dirt cheap. Nothing else I use even comes close.
**** **** 3.6.08
Harry == Good article on alternate approaches to generating power as we wait for the day all power is space generated and beamed down to the earth (20 years, 50 years, 100 years, who knows). Did you consider some alternate ways for generation? Ultilizing ocean wave activity to pump water up coastal mountains to storage basins that would supply turbines on the coast whenever wind generators could not supply demand. Alaska could become a energy powerhouse. On a smaller scale , the top floors of office buildings, apartements etc. could have tanks of water, pumped up overnight by wind or grid, wind and solar providing power during the day for pumpups, with the tanks feeding turbines run by individuals or ultilities at high demand periods ( would also be an excellent fire water backup). High pressure natural gas forced the oil to the surface , why not use the same rock formations to store pressurized CO2, air or n2 that could also be used through a turbine when required. Perhaps we will use high altitude wind generators, transferring electricity down to earth via wires or beams of light. You cannot find an answer unless you are willing to explore and experience potential failure. Keep showing us that there are alternates available, we merely need to open our minds. You may well trigger thoughts in the next Tesla , someone that will use the earths magnetic field or perhaps gravity in a new way , that once discovered and explained will seem obvious in retrospect. While all the above will assist in the battle against global warming, it will not surprise me to learn that variances in Sun's energy output is the true cause.