Power Plant of the Future
by Saïd Majdi and Thomas Manaugh, updated 5/14/2014
We are at the start of a revolutionary change in how energy is captured and used. How this change proceeds will affect every creature on planet Earth – including every human being. A fossil fuel is a finite resource, so humans’ use of fossil fuels as their major source of energy will eventually come to an end. Because fossil fuels produce greenhouse gases that contribute to global warming, replacing fossil fuels with other sources of energy must happen sooner rather than later.
Energy Needed To Replace Energy from Fossil Fuels Can Come from Oceans
Most humans live within 100 miles of an ocean, so energy from oceans can reach most consumers in the form of electricity without using long transmission lines. There are widely and massively available sources of energy from ocean locations:
- Solar radiation falls predominantly on the 70% of the Earth covered by oceans. Enough energy in the form of solar radiation falls on the Earth in a few hours each day to power all human activity for an entire year.
- A huge amount of kinetic energy is contained in tidal currents that are caused by gravitational effects on oceans by the sun and the moon.
- Energy from wind and waves is found in oceans all around the planet.
In recent years a need to develop new energy sources has led to many promising developments in ocean settings. Of particular interest are efforts to mount equipment on floating platforms, thereby opening up the possibility of placing energy-tapping equipment in waters of any depth. Some highlights of those efforts are presented in Table 1 for projects proposed, now under construction, or recently completed.
A particular project that is proposed by the authors is a way to beneficially co-locate multiple means of tapping energy on a large floating platform. That project, listed and described in Table 1 (bottom), is called “Energy Island.” It promises to provide special advantages in an effort to collect significant amounts of energy from ocean locations:
- 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 modules 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 turbines 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 a large floating structure and not in 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.
Table 1. Projects for tapping energy from ocean locations using floating devices.
|Tidal Currents||Sanda Sound, Scotland||Evopod ®is a floating tidal energy device being developed for generating electricity from tidal streams and ocean currents. It intercepts currents at the top of a water column, which are faster than currents at the bottom of the column.||
|Solar Radiation||Kagoshima,Japan||A floating platform in Kagoshima Bay will have 290,000 solar panels and will supply electricity to 22,000 homes in nearby city of Kagoshima.||
|Wind||Waters near Norway||Hywind® is the world’s first full-scale floating wind turbine. Using floating turbines avoids high costs for building foundations on the seabed and opens up deep water locations for tapping wind energy.||
|Waves||Reedsport, Oregon||PowerBuoy® is a floating device that bobs up and down in ocean waves. Relative motion between two sections is converted via a “power take-off” device to drive an electrical generator.||
|Layers of Water Differing in Temperature||Waters in Tropical Locations||For ocean thermal energy conversion (OTEC) to be used to generate electricity, a circulating fluid that is liquid in water from lower, cooler layers of the ocean must expand to a gas in water from upper, sun-warmed layers to drive a turbine. The National Renewable Energy Laboratory (NREL) described a proposed use for OTEC on floating platforms.||
|Tidal Currents, Solar Radiation, Wind, Waves, Layers of Water Differing in Temperature||MultipleOceanLocationsnear LargePopulationCenters
|A patented “Energy Island” invention is comprised of (a) a large floating platform and (b) equipment that can generate electricity from multiple sources of renewable energy. The electricity is transmitted to the grid via an underwater cable.||
Energy Island Co-Locates Modules to Tap Energy from Renewable Sources
Under the top surface of Energy Island’s floating platform is a narrowing duct 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. Mounting turbines and generators on the top surface protects the equipment from harsh underwater conditions and vastly facilitates easy and safe installation and maintenance of the equipment.
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 modules to tap other sources of energy besides tidal. All modules contribute as an integrated system to the grid for distribution of electricity to consumers.
Modules, in addition to the one producing electricity from tidal currents, include wind 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, and a device that extends below water, where the platform is located, and generates electricity from differences in water temperature at various depths. Because large differences in water temperature at various depths are found only in limited locations, using ocean thermal energy conversion (OTEC) to generate electricity is not a means of generating electricity that could be used in most ocean locations.
Variability of Supply
Electricity is inherently variable in amount supplied when it is converted from energies of sun, wind, and waves. Though supply from converting energy of tides is predictable, it varies from high, when tides are flowing, to zero during slack tide periods. Variability in supply from wind, sun, waves and tides is seen by some to mean that electricity from those sources cannot be relied upon by the grid to meet customers’ demands for electricity that must always be available at the flip of a switch. However, the grid can maintain reliable service to consumers by these mechanisms:
- The grid is able to move electricity around from one locale to a second locale to match supply to the second locale’s demand. This is possible because of a built-in flexibility of power plants and a margin that is held in reserve to maintain system reliability. (However, the grid has limits in its ability to accommodate variability in supply, so the grid favors suppliers which are able to provide a guaranteed level of supply.)
- Utility-scale storage devices can be put in place as part of the grid. That allows energy stored during a low-demand period to be used during a high-demand period. Indeed, several storage technologies have been proposed, including batteries, compressed air, superconducting magnetic energy stores, flywheels, and hydrogen-based storage systems. However, so far no utility-scale storage solution for supply-side management has been proven to be cost-effective except for pumped hydropower, a solution that is practical only in a very limited number of locales.
The main function of renewables is to reduce reliance on the diminishing fossil fuel sources, and by so doing, reduce emissions of greenhouse gases and their negative impact on the environment. These attractive benefits will continue to support an increased penetration of renewables in the energy mix. As penetration increases, energy storage or plant margin, or both, will also need to increase to preserve a capability of delivering a constant level of system reliability.
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.
Renewable Energies Must Supply Electricity Reliably
Argonne National Laboratory recently released results of a computer-modeling study, using data from an Illinois electrical power system, where thermal power plants are available for backup. According to the abstract published by the laboratory (7), modeling showed:
First, by minimizing cost, the unit commitment model decides which thermal power plants will be utilized based on a wind power forecast, and then, the economic dispatch model dictates the level of production for each unit as a function of the realized wind power generation. Finally, knowing the power production from each power plant, the emissions are calculated. The emissions model incorporates the effects of both cycling and start-ups of thermal power plants in analyzing emissions from an electric power system with increasing levels of wind power. Our results for the power system in the state of Illinois show significant emissions effects from increased cycling and particularly start-ups of thermal power plants. However, we conclude that as the wind power penetration increases, pollutant emissions decrease overall due to the replacement of fossil fuels.
Clearly, renewable energy does reduce emissions from fossil fuel plants; but to reduce costs for backup and to minimize release of emissions, supply of electricity from renewables needs to be as reliable as possible.
Argonne National Laboratory is developing batteries that can serve to provide electricity to the grid when levels of supply from renewable energies are low. Though batteries could be used to back up Energy Island’s electricity supply, another approach seems more promising because of the structural design of Energy Island.
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 (8). Unlike for batteries, components for compressed storage will not be fabricated from materials in short supply; and their eventual decommissioning will not require disposal of highly toxic chemicals.
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. Often no use of energy from storage will be needed because sufficient energy from other sources will be available during slack-tide periods. Energy Island will never need to go offline as a source of electricity for the grid because of lack of resources.
Stored energy will also be available during periods of exceptional demand. Thus, extra electricity from Energy Island would be available during periods of inadequate supply from other contributors to the grid. Those periods would include periods of peak demand, e.g., during summer days when consumers use their AC units at high levels.
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.
Energy Island System: A Clean and Highly Reliable System to Supply Electricity
Innovation and Optimization
Existing, well-known green technologies are specified in the innovative design of Energy Island. Though its platform could be a welcoming location to test and develop other innovative technologies, the system does not depend on such new technologies to be successful.
That said, as new technologies are developed, they can be implemented on Energy Island in ways to make the system even better optimized in its use of renewable energy sources. The top surface area of Energy Island will be extensive in order to enjoy economies of scale. Even so, the area available for installation of solar panels, wind turbines, and other devices will be limited. Thus, for optimizing the design of Energy Island, it will be important to identify types and configurations of installed equipment to generate the most amount of electricity per unit of surface area.
A group of researchers at MIT recently published results of an attempt to improve capture of solar energy. By stacking solar cells in a unique way, Bernardi et al (9) found they could capture from two times to more than 20 times more energy in a given area as would be captured by conventionally deployed cells in the same area.
Research by Dabiri (10) at Caltech has shown a ten-fold advantage in per-surface-area generation of electricity when tightly grouped vertical-axis wind turbines are used instead of conventional horizontal-axis turbines, which cannot be tightly grouped.
Thus, opportunities for cost-effective generation of electricity for a given surface area are suggested by (a) Manaugh with respect to an innovative design for co-location, (b) Bernardi et al with respect to increasing yields from solar cells and (c) Dabiri with respect to increasing yields from wind turbines. The work of Dabiri and Bernardi et al are instances of new technologies and methods that could be used to increase the amount of energy tapped from within the space defined by the dimensions of an Energy Island.
As part of the Energy Island system design, the authors have developed algorithms to maximize electric supply output by determining how much each renewable energy source contributes to that supply output at a given location.
The above artist’s conceptualization illustrates Energy Island, an invention that integrates both well-known and new technologies to supply electricity from renewable energy sources that are safe, clean, and renewable. The module shown can be joined with other identical modules to construct one very large floating structure. One suggested embodiment is a 5000-meter-long structure off the coast of California that would have a generation capacity equal to that of Hoover Dam.
Development of the Energy Island concept of extracting renewable energy from ocean locations is in its infancy. The concept is a hopeful one because it promises to be a practical alternative to the course of continued and expanding extraction and burning of fossil fuels. The fossil fuel course is the one that is now being pursued in spite of evidence it will destroy hope for a decently livable environment in the future. The evidence is clear to a vast majority of scientists.
Energy Island is at the stage of development that Robert Fulton’s steam boat was more than 200 years ago. Many laughed at the concept, but Fulton’s invention was a revolutionary innovation in commercially successful water transport. Nowadays, water transport brings products to consumers from distant locations all over the world, and it does so safely and efficiently.
Following the model of innovation in water transport, Energy Island can be developed to deliver electricity to consumers in a way that is safe and efficient. There is nothing more technologically complicated about Energy Island — nor inherently more vulnerable to harsh ocean conditions — than there is about a large, modern, climate-controlled cargo ship.
If a cargo ship can deliver a 10-cent banana to a food distributor by safely navigating to a port 3000 miles away, Energy Island should be able to transmit a 10-cent kilowatt of electricity to a distributor of electricity only 30 miles away. That is especially true because no fuel would have been purchased to generate the kilowatt.
Summary and Conclusions
The Energy Island system uses multiple co-located sources of energy to produce clean reliable electricity to the grid. Its development is important for these reasons:
- Energy from the oceans is tapped in a way that recognizes the enormous potential that is available.
- The design of Energy Island involves building a large physical structure that will allow tidal currents to be intercepted in a way to produce meaningful amounts of electricity for the grid. That large structure can also be efficiently employed — because of co-location — to provide a support for other means of using renewable energies. This design promises economies of scale and efficiencies that come from sharing physical and electrical infrastructure.
- The design for Energy Island is built around a critical necessity to supply electricity reliably to consumers without compromising on need to protect the environment.
- Because multiple sources of renewable energy are co-located on Energy Island, the system can be better optimized for (a) reliability, first priority, and (b) productivity than would be possible if the system were optimized for use of just one energy source.
- Though the system will vary in its total output, it will be capable of guaranteeing to the grid a certain, specified minimal level of supply. That feature will help to remove one major obstacle to the acceptance of renewable energy sources as replacement for fossil fuels.
- The system not only provides a highly reliable supply of baseload electricity to the grid; it also is capable of providing an independent extra supply during periods of exceptional demand.
- Using compressed air for energy storage allows for highly reliable electricity supply while doing so in a way that promises to be cost-effective and has minimal environmental impact.
- Though not dependent on unproven technologies to be successful, the Energy Island platform can be used to develop promising new technologies.
Human civilization has blossomed with the support of readily available fossil fuels. Now fossil fuels, a finite resource, are becoming less readily available and their use must be restricted because of global warming. Those facts are not denied by the vast majority of scientists. However, there is a resistance to accepting those facts, partly because presently there is a lack of safe and proven ways to have adequate energy without using fossil fuels at present levels or higher.
One solution to the problem of replacing fossil fuels is to tap abundant energy that can be found in ocean locations. Energy Island can be part of that solution.
1 “Evopod” from Oceanflow Energy, Ltd., retrieved from the Internet, July 22, 2012, at http://www.oceanflowenergy.com/.
2 “Construction of Japan’s largest solar power plant to begin in July at a cost of ¥25 billion” by Dante D’Orazio, retrieved from the Internet, July 22, 2012, at http://www.theverge.com/2012/4/10/2939187/japan-largest-solar-power-field-kyocera-construction.
3 “US and UK to collaborate on ‘floating’ wind turbines” from The Guardian on April 23, 2012, retrieved from the Internet, July 22, 2012, at http://www.guardian.co.uk/environment/2012/apr/23/us-uk-floating-wind-turbines.
4 “Utility Scale Wave Power, Thanks to U.S. Navy” from CleanTechnica, retrieved from the Internet, July 29, 2012, at http://www.ethicalmarkets.com/2012/06/25/utility-scale-wave-power-thanks-to-u-s-navy/.
5 “Markets for OTEC” from National Renewable Energy Laboratory (NREL), retrieved from the Internet, August 1, 2012, at http://www.nrel.gov/otec/markets.html.
6 “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
7 “System-Wide Emissions Implications of Increased Wind Power Penetration” by Lauren Valentino, V. Valenzuela, A. Botterud, Z. Zho, and G. Conzelmann on March 5, 2012, retrieved from the Internet, July 26, 2012, at http://pubs.acs.org/doi/abs/10.1021/es2038432.
8 “LightSail Energy Could Make Compressed Air Grid-Scale Storage Work” by Herman K. Trabish in Greentechmedia:, February 23, 2012, retrieved from the Internet, August 23, 2012, at http://www.greentechmedia.com/articles/read/LightSail-Energy-Could-Make-Compressed-Air-Grid-Scale-Storage-Work/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+gridtec
9 “Potential Order-of-Magnitude Enhancement of Wind Farm Power Density via Counter-Rotating Vertical-Axis Wind Turbine Arrays” by John O, Dabiri, retrieved from the Internet, July 27, 2012, at http://arxiv.org/ftp/arxiv/papers/1010/1010.3656.pdf
10 “New Dimension for Solar Energy: Innovative 3-D Designs More Than Double the Solar Power Generated Per Area” by Marco Bernardi, Nicola Ferralis, Jin H. Wan, Rachelle Villalon, and Jeffrey C. Grossman, retrieved from the Internet, July 27, 2012, at http://www.sciencedaily.com/releases/2012/03/120327094615.htm.