Energy visionaries have long promoted the idea of Ocean Thermal Energy Conversion which uses the temperature difference of warm surface water to cold deeper ocean currents to boil a liquid (e.g. ammonia) to drive an electricity producing turbine. It is an elegant energy solution that is gaining more mainstream attention.
The thermal and kinetic energy potential of the world’s oceans remains largely untapped by energy producers. Earlier we featured a new Lockheed pilot project in Hawaii that evolves the once novel idea of capturing ocean thermal energy conversion into clean electricity. What other power generation schemes might emerge from our oceans?
University of Michigan engineer Michael Bernitsas has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power.
The machine, called VIVACE, is being developed by Vortex Hydro Energy as the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.
VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy. The array of devices doesn’t depend on waves, tides, turbines or dams. Instead it is a unique hydrokinetic energy system that relies on “vortex induced vibrations” that have damaged bridges for decades. Rather than try to avoid damage by these vibrations, VIVACE captures the motion power by mimicking the movement of fish.
The concept model of VIVACE looks nothing like a fish, but future versions should have the equivalent of a tail and surface roughness a kin to scales. The working prototype is one sleek cylinder attached to springs that hangs horizontally across the flow of water in a tractor-trailer-sized tank in his marine renewable energy laboratory. The water in the tank flows at 1.5 knots.
Bernitsas estimates that an array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a river bed or it could dangle, suspended in the water. But it would all be under the surface.
While solar power is often described as the world's great untapped clean source of energy, ocean power deserves as much attention. In fact, it deserves a lot of attention given the expectation that the world will double energy consumption in the decades ahead. And the reality that most of the world's population lives close to an ocean.
Futures oriented energy engineers dream of capturing the steady kinetic and thermal of energy. Unlike solar and wind, ocean energy provides near 24/7 potential utilization.
A Low Mainteance Linear Generator? Now a Swiss team from Upsalla University has developed and tested a novel system. For nearly three years, a wave power plant has stood on the bottom of the ocean a couple of kilometers off the west coast of Sweden, near Lysekil. Rafael Waters, from the Uppsala University Division of Electricity, designed and built the facility as part of his doctoral project.
The team's 'linear generator' generates electricity with the slow up and down movements of the waves. An ordinary generator transforms rotation energy to electricity, and it needs to turn at about 1500 rpm to be efficient. (Images)
“This means that a wave energy station with an ordinary generator needs energy transmission systems such as gearboxes or hydraulic systems and other complicated details that wear out and require much more maintenance than a linear generator,” says Rafael Waters. “Our generator has functioned without any trouble every time we started it up over the years, even though it has received no maintenance and has sometimes stood still for months.”
The Energy Scanner Daily Top 5 highlights some of the best energy category scans submitted to the Future Scanner community.
Portugal’s Agucadoura commercial wave project Scan by fantasywriter
-The long-term view on wave power potential is positive. But engineers are still trying to figure out the best way forward given the diversity of ocean/tidal currents across regions in the world. Scaling standards for kinetic wave energy could be a challenge.
GridPoint grabs more attention, money
Scan by Mielle Sullivan
-The big near future disruption to electricity grids is the potent combination of ‘storage’ and ‘software’. GridPoint is a highly regarded ‘smart grid’ company worth watching. The other thing worth watching will be the calculated reaction of utility companies to the changing landscape of power generation! Big battles ahead as business models will be challenged around distributed power management. Storage and software are big disruptors!
Congress moves forward on Investment Tax Credit (ITC) for alternative energy-
Scan by Mielle Sullivan
-Emerging industries always need public sector help during early stages of development. Clean coal is getting help, deep water drilling is getting help. Alternative energy is no exception. We’re watching as the Investment Tax Credit (ITC) legislation works its way through Congress. And the world solar industry is watching to see what happens to the US tax credit extension.
MIT researchers are working with a Portuguese group to design a pilot-scale device that will capture significantly more of the energy in ocean waves than existing systems. The pilot plant will generate 750 kilowatts, roughly enough to power 750 homes.
Professor Chiang Mei and his colleagues have developed model simulations that can predict wave forces and guide design decisions to convert the captured mechanical energy to electrical energy.
"Given the future of conventional energy sources, we need lots of research on all kinds of alternative energy," Mei says. "Right now, wind energy and solar energy are in the spotlight because they've been developed for a longer time. With wave energy, the potential is large, but the engineering science is relatively young. We need to do more research."