Renewable energy has certainly made tremendous progress in the past decade. Indeed, most people would acknowledge that it has grown from being little more than a mascot, to a full-fledged member of the energy generation team.
And yet, despite the fact that people as reputable as the DOE’s National Renewable Energy Laboratory (NREL) have come out and said that renewables could provide 80 percent of our electricity by 2050, there are still plenty of naysayers who remain convinced that renewables will continue to play little more than a minor role in our energy future.
It is a simple, but inconvenient fact of life that we don’t know what we don’t know. Our ability to predict the future is ultimately limited by our imaginations. Indeed, if we were to go back 37 years and ask who, if anyone, came close to predicting what our world looks like today, it would more likely be the science fiction writers than the scientific authorities, who, encumbered as they were with all the facts, had plenty of reasons why certain things couldn’t possibly be done, in the absence of technological breakthroughs that would come later.
Today’s story is about a potentially very large source of renewable energy that has received very little attention: hydrokinetics, which is the production of energy from the flow of moving water. The term applies to both ocean tidal power systems as well as river flow systems, both without the benefit of dams.
According to the Energy Information Administration (EIA), this source of clean energy could very possibly produce as much as 23 GW by 2025 and 100 GW by the year 2050, and this just barely scratches the surface of its technically achievable potential. This latter figure represents roughly 10 percent of our present generation capacity, a sizeable chunk, especially considering that, unlike solar or wind, this power can be far more predictable and reliable. For comparison purposes, the U.S. had 51.6 GW of installed wind power as of September 2012. According to Christopher Mahoney, Director of Communications for the Electric Power Research Institute (EPRI), “technically recoverable wave energy alone could provide about 25 percent of U.S. energy demand.” (Cited in Mechanical Engineering, “Waves, Currents & Electric Potential”, by Mark Crawford, Feb. 2013).
We have already written about various types of tidal systems, including the barrage, the tidal fence and the tidal turbine. Other types include the oscillating water column and the heave surge device. Some companies involved in this space include Ocean Power Technologies, which partnered with Lockheed Martin on a 19 MW project in Australia. Aquamarine Power, a Scottish Company with an offshore pump called an “oyster” which powers an onshore hydro plant, claims they have a 64 GW installed capacity potential.
Less well known are methods for capturing power from flowing rivers without a dam. Verdant Power’s 1.05 MW Tidal Energy Project at Roosevelt Island in NYC’s East River will use turbine generators mounted to the bottom of the river that can sway to follow the direction of the current.
Last summer, Ocean Renewable Power Co. installed the first of several planned turbine generators in Cobscook Bay, Maine, a 180 kW unit. It became the first grid-connected tidal energy project without a dam in America. Two more units are scheduled to be installed this coming fall (see video).
With each passing week, month, year, we can expect to see new innovations in these areas that will not only help us achieve NREL’s prediction, but quite possibly surpass it with years to spare.