At the University of California, Berkeley, a team of engineers is pioneering ocean-source energy technology by using “carpet” to capture the energy generated by ocean waves.
The team, which includes wave energy guru and Assistant Professor Reza Alam, and Ph.D. Marcus Lehmann, an engineering researcher, aims not only to capture the kinetic energy contained in the ocean, but eventually to use it to purify seawater – drinking water being an increasingly diminishing resource on planet Earth.
This is particularly true where ever-growing populations living in coastal cities like Los Angeles demand greater and greater quantities of non-saline water for drinking, bathing, washing dishes and clothing, and for irrigation. (Re that latter, it’s disturbing to know that more than half America’s produce begins life in the warm, fertile and currently drought-stricken Central Valley).
As the United Nations Environment Programme (UNEP) notes, half the Earth’s population (about 3 billion people) lives within about 35 miles (or 60 kilometers) of a seacoast, and 75 percent of the globe’s largest cities are located on ocean shorelines. By 2025, that figure is expected to double.
The reason? Man has, since ancient times, migrated to the edges of oceans to take advantage of the edible wealth of sea life, which is more easily captured by fishing than land-based animals are by hunting. Coastal cities also capitalize on one of the oldest transportation modes known to man, namely shipping (which is less energy intensive than freight trains, trucks or airplanes).
Moreover, the Berkeley team has conducted experiments showing just how energy-rich ocean waves are. For example, less than 11 square feet (or one square meter) of their ingenious “carpet” – which is able to capture more than 90 percent of wave energy – is enough to power two U.S. households, or about 1,800 kilowatts of energy. One thousand eighty square feet, or 100 square meters, would generate the same amount of energy as a soccer field covered in solar panels. And all that energy would be generated in or near the world’s coastal cities, where the energy demand is greatest.
The system itself consists of a network of hydraulic actuators overlaid with a rubber mat whose future composition, presumably a durable and salt-water-resistant elastic composite, remains a secret at this point, according to Lehmann.
The cost of this energy is calculable. The cost of desalination can’t be estimated, since the wave energy project is still in its infancy vis-à-vis wave power conversion and absorption, but in its tertiary stages should surpass current desalination costs (from $.40 to $.90 per barrel in Saudi Arabia). A barrel is 31.5 gallons or 119.5 liters.
In these initial stages, however, Lehmann and colleagues are banking on a report from Carbon Trust which indicates that wave energy could produce more than 2,000 terawatt hours (or a phenomenal 2 billion kilowatt hours, or kWh) per year. This is enough to power two million U.S. homes, each using 1,000 kWh, which is well above the average.
Lehmann and his colleagues have also thought ahead to the environmental and sustainability issues. Unlike offshore wind (notably Cape Wind, the recipient of a $600 million loan that will not make it less of an eyesore from the Kennedy Compound in Hyannis Port, or less of an irritant to gas and oil tycoon, and Nantucket shoreline owner, Bill Koch), wave energy production is invisible.
This is because the project(s) rests about 60 feet under the surface, and in otherwise useless sea floor areas, or dead zones, like the Gulf of Mexico. This, forming at the mouth of the Mississippi River, in Louisiana, is the largest in the world. In addition, such projects will, in no location, impinge upon the visual and physical world dominated by fishing or recreational boating, or sea life.
The Alam/Lehmann team seems to have come upon the perfect recipe for “clean” energy. Still, as a rational person, I know nothing is perfect. Lehmann agrees:
“The exact location is part of our research. The downsides are more material needed for the same absorption efficiency at deeper water locations, and (the fact that) the ideal location will not be directly on the ocean floor to minimize environmental impact, sand erosion and sediment residue.”
Within the next two years, Lehmann anticipates testing the system in the field, in either Hawaii or Newport, Oregon, both of which provide wave test centers. (I expect the team to vote for Hawaii, as who wouldn’t?)
In the interim, Lehmann and colleagues continue to use the wave-testing tanks at UC Berkeley, the results of which were presented at the 10th European Wave and Tidal Energy Conference, Aalborg University, Denmark, September 2013.
One of the biggest hurdles to wave energy, according to Lehmann, may be the fact that each wave energy siting will require different materials, tools, and techniques, from the “carpet” material to the height of the hydraulic actuators.
“The challenge of wave energy is to design specifically for every individual characteristic of the designated wave site. Our system allows a lot of parameters to easily adjust.”
An accommodation which wind and solar seem unable to grant. For example, the Mojave Desert solar project mandated the removal of native (and seriously endangered) desert tortoises. And it’s now common knowledge that wind energy companies have filed at least 14 separate applications that would allow them to kill eagles, albeit inadvertently through turbine blade rotation.