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.

Conclusions

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.

Roger Arnold
9.14.07 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, which will also be enormously expensive.

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