A New Hoover Dam

Energy Island, West of Los Angeles

Replacing Electricity Generation Capacity from a Drought-Stricken Hoover Dam by Tapping Ocean Energy for Southern California

by Thomas Manaugh


Hoover Dam

Hoover Dam has provided electricity to Southern California for almost 80 years.  Unfortunately, a continuing drought condition in the southwest of the United States threatens to put Hoover Dam out of commission as a source of electricity from hydroelectric generation.  It has been estimated that there is a 50-50 chance that generation will cease by 2021 because of falling water levels of Lake Mead, the source of water for Hoover Dam’s generators. (1)

Energy Island

Instead of bringing electricity from Hoover Dam, Los Angeles and other communities in southern California could tap electricity generated from renewable sources of energy in the ocean off the coast of California.  Energy Island is described in a recently awarded patent as a way to provide reliable, abundant electricity for populations that live near oceans. (2)  No known legal or environmental concerns would preclude placing an Energy Island in waters 5 to 30 miles west of Los Angeles.

Characteristics of Energy Island

Multiple means of tapping energy are co-located on a large floating platform. Known technologies are combined in a design that allows providing a highly scalable source of electricity.  Co-locating generation capacity offshore offers special advantages:

  • Increased reliability of supplying electricity. That is a crucial step if renewable energies are to replace fossil fuels.
  • Efficiencies that come when multiple means of tapping energy share infrastructure. For example, it becomes cost-effective when one transmission line carries electricity to the grid from multiple electricity-generating devices that are co-located on Energy Island.
  • Economies of scale. Energy Island is much larger than other floating platforms that have been built or proposed for the purpose of converting renewable energies to electricity.  It can, for example, benefit from a lower per unit cost when it mounts one hundred wind turbine devices on its top surface instead of just one.
  • Safety and ease of installing and maintaining equipment.  It is easier and less expensive to install and maintain equipment on the top of a large floating structure as opposed a harsh and corrosive underwater environment.
  • Being a good neighbor. Located some distance from shore, wind turbines on Energy Island will present little danger to birds and bats; and no nearby neighbors will complain about noise or visual pollution.
  • Short transmission lines reduce costs. An Energy Island can be located in an offshore area that is near to most major population centers. Close proximity allows reduced capital costs for transmission lines and minimizes energy losses that occur when electricity is transmitted from one location to another.

Under the top surface of Energy Island’s floating platform is a narrowing duct that is structured to channel and concentrate water currents.  The water flows through turbines that are located on the top surface of the platform and extend through the top surface to intercept tidal or other ocean currents with their blades. Turning of the turbines causes generators on the top surface to turn and generate electricity. In the patent describing Energy Island, the length is specified to be no shorter than the combined length of three aircraft carriers.  The large, stable platform thus provided serves as a shared support structure for devices to tap other sources of energy besides tidal:

  • Turbines for generating electricity from wind
  • Solar photovoltaic panels for generating electricity from solar radiation
  • A device that floats on water and converts kinetic energy of wave movements into electricity
  • A device that extends below water, where the platform is located, and generates electricity from differences in water temperature at various depths. (Using that kind of device is not actually proposed for the Los Angeles location, but it could be part of an Energy Island in various tropical locations.

Variability of Supply

Integration of a diverse renewable energy mix on Energy Island will reduce the variability problem for the grid that is associated with renewable energy. Because correlation of output of electricity among different renewable sources is weak, periods of low total output will tend to be reduced in frequency and duration.   That is, when multiple sources of energy contribute to the total output from Energy Island, total output to the grid will be much less likely to be very low than would be the case if only one source of energy were operating.

Storage of Energy on Energy Island

Because Energy Island is designed as a floating structure, it contains some structural elements that are water-tight.  Those elements can be designed to do double duty by also accommodating storage of compressed air. That makes compressed air energy storage (CAES) an obvious choice for a cost-effective means of storing energy and also one that is particularly environment-friendly. Recent advances in CAES have shown it to be a method that can rival hydropower pumping as an efficient method of storing energy.   Thus, Energy Island will have its own built-in robust storage system. Electricity generated from the energy of compressed air will be sufficient to boost supply of electricity to an acceptable level during slack-tide periods, regardless of the level of contributions toward electricity supply that come from sources of renewable energy other than tidal during those periods.

Innovation and Optimization

Existing, well-known green technologies are specified in the innovative design of Energy Island.  Though its platform will be a welcoming location to test and develop other innovative technologies, the system does not depend on such new technologies to be successful.   Optimizing the design of Energy Island will be important to identify types and configurations of installed equipment to generate the most amount of electricity per unit of surface area. That is the present focus of research on the design of Energy Island.

Energy Island System: A Clean and Highly Reliable System to Supply Electricity

The diagram in Figure 1 shows how the modules of the Energy Island system are integrated in a way to provide a highly reliable and clean supply of electricity to the grid the delivers electricity to Los Angeles and other communities.

Figure 1


How large is Energy Island?

A modular design of the Energy Island platform allows it to be as small in surface area as a single football field or to be as large as 100 football fields or more.  Figure 2 shows one module with a top-surface area of 50 meters by 100 meters.  Schematically shown on the module are wind turbines, generators for tidal currents, arrays of solar panels (“s”), and transmission and tether lines to wave generator devices.

Figure 2


Figure 3 shows how multiple modules could be joined to provide an Energy Island embodiment with a top-surface dimension of 5000 meters long by 100 meters wide.  Not shown are joined modules “5” to “99.”

Figure 3


It is estimated that the latter embodiment would be sufficiently large to accommodate the same generating capacity as that provided by Hoover Dam – approximately 2,000 megawatts.  Each of 100 modules would contribute approximately 20 total megawatts of generating capacity from the various sources of renewable energies specified above.   How much would Energy Island Cost? It is estimated that each module making up Energy Island would cost approximately $80 million.  The total cost of constructing a 100-module embodiment of Energy Island (large enough to replace Hoover Dam) would be approximately $8 billion.

Next Steps

Design work needs to be done on details and optimization for Energy Island.  A demonstration project will need to be completed. A consortium of six large companies worked together to construct Hoover Dam.  Six large companies should have no trouble today to fund construction of a single working module for an Energy Island as a demonstration project.  The funding contribution required from each would amount to less than a rounding error in the profits of companies like Bechtel (one of the contractors for Hoover Dam in the 1930s), General Electric, Siemens, Google, Microsoft, and Southern California Electric. The above named companies are only examples of corporate entities that have a stake in finding solutions to global warming. It is not at all inconceivable that one or more companies would want to fund development of a practical way to satisfy consumers’ need for electricity and to do it in a way that does not contribute to global warming. Forward-thinking executives will not want to be left behind in a coming era when trillions of dollars now spent on fossil fuels will inevitably need to be spent instead on non-fossil-fuel sources of energy.


1)    “Lake Mead Could Be Dry by 2021” from Scripps Institution of Oceanography / University of California, San Diego, Tuesday, February 12, 2008, retrieved from the Internet, May 24, 2013, at http://scrippsnews.ucsd.edu/Releases/?releaseID=876 .

2)  “System for Generating Electricity from Alternative Energy Sources Located on a Floating Platform” by Thomas Manaugh, retrieved from the Internet, July 22, 2012, at http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2&f=G&l=50&co1=AND&d=PTXT&s1=manaugh.INNM.&OS=IN/manaugh&RS=IN/manaugh .

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