Wave and Tidal Power

New Database to Help Increase Environmental Responsibility of Ocean Power

Sarah Rich

In collaboration with the International Energy Agency, the United States Department of Energy (DOE) recently launched a new database that brings together environmental monitoring and worldwide ocean energy development efforts. Called Tethys, the database will show the interrelationship between processes in nature and ocean power technology, and will function as a resource to help keep environmental responsibility at the forefront of ocean-based energy production projects.

Named after the Greek titaness of the ocean, Tethys will help industry regulators and energy project developers alike identify possible environmental effects of the efforts to gain sustainable, clean energy from the world’s oceans. Tethys offers real-world data that accounts for the interconnectedness of oceanic ecosystems and technology, and offers insight on the interactions between energy-producing machines, marine wildlife, and the physical processes of the ocean. Having all of this data compiled together-- from tidal current turbines projects to published studies on offshore wind farms and marine mammals--will allow for a safer expansion of ocean power. According to the DOE’s announcement, the database also has an accompanying report that highlights research on ways to monitor ocean energy projects and possible environmental effects.

The world’s oceans offer immense potential for alternative energy development. As with any alternative energy resource, however, ocean power developers must taken into account any negative environmental impacts from the technology in order for ocean power to be a truly renewable source of energy. As a living document, Thethys will constantly increase our global understanding of the ocean as new projects and new research data arise. In order to expand Tethys’s usefulness for current and future ocean power projects, the DOE encourages researchers to submit their studies to the database.

You can view an interactive map of Tethys here, and check out the technological developments in and environmental research on oceans around the world.

image: CC by 2.0 by Phil Manker

via: US Department of Energy

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System for Predicting Wave Energy Could Double Wave Power Generation

Megan Treacy

As part of a new study on wave power, the University of Exeter and Tel Aviv University have come up with a system that predicts the power of waves in order to maximize wave energy devices' ability to generate energy from the sea. The researchers found that this system could potentially double the amount of wave energy generated by a device.

Phys.org reports, "The research focused on point absorbers, commonly-used floating devices with parts that move in response to waves, generating energy which they feed back to the grid. Point absorbers are already known to be much more efficient in the amount of energy they produce if their response closely matches the force of the waves and previous research has looked at trying to increase this efficiency. However, this is the first study that has focused on increasing the device's efficiency by predicting and controlling internal forces of the device caused by forthcoming waves."

Wave energy potential is huge. It's been estimated that it could power the world twice over and the UK, where this study was conducted, could be powered twice over just by utilizing wave energy generators along its coastlines. So far, wave energy technologies haven't gained traction the way that solar and wind technologies have because the ocean is a very inhospitable place. Wave energy generators have to be able to withstand the force of each wave.

This new system predicts the power of the incoming wave, allowing the device to respond in a way that extracts the most amount of energy. This controlled reaction not only increases the efficiency of the device, but protects it from damage from rough seas. Where most current wave technologies would be shut off during a storm, a prediction system could allow the wave generator to keep operating effectively.

The University of Exeter is now working with Ocean Power Technologies, one of the largest wave energy companies, to further test the results and develop better technologies based on this research.

Image via mikebaird

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Maine Constructing 4 MW Commercial Tidal Power Project

Megan Treacy

Tidal power is one of the renewable energy sources that you hear the least about even though its potential for generating electricity is incredibly vast. The problem is that deploying turbines out into the ocean or rivers can prove to be awfully tricky. But one major project is moving full steam ahead and will be delivering power by this fall.

The Maine Tidal Energy Project started construction of the bottom support frame for Ocean Renewable Power Company's TidGen turbine generator system in March. The project's first phase will see five of those generators deployed in the Gulf of Maine with a capacity of 900 kW. That phase should be online by October.

The complete project will reach a capacity of 4 MW and already has 20-year power purchase agreements with Bangor Hydro, CMP and Maine Public Service.

The TidGen system consists of slowly rotating foils that power a permanent magnet generator at its center. It is gearless and made from composite materials that won't corrode underwater.

via Forbes

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Wave-Powered Ocean Robots

Philip Proefrock

A group of four autonomous, wave-powered robots has completed a trip from San Francisco to Hawaii and are now continuing on in two pairs, one set to Australia, and the other set to Japan. They are seeking to carry out the PacX Challenge in which they are trying to set the record for the longest ocean voyage by an unmanned ocean vessel and to demonstrte the abilities of these robots.

The Wave Gliders are built with a two-part construction, with a floating part, which also contains solar panels to operate on-board data collecting equipment and communications equipment, and a glider part, which is connected to the float with a cable and which is used to provide propulsion for the vehicle. The float measures 208 x 60 cm (about 82 x 24 inches) and the glider is 40 x 191 cm (about 16 x 75 in). The two are connected with a 7 meter (about 23 feet) cable. The robot weighs 90 kg (about 200 pounds).

The robots can be used for station-keeping data collection, as well as for autonomous travel, as the current project demonstrates. The Wave Glider has a speed of 0.4 to 2.0 knots (about 0.45 to 2.3 mph or 0.75 to 3.7 kph), but they are able to operate autonomously for up to 1 year. By being able to be autonomously operated, it is possible to do data collection at a remote ocean location without needing to use fuel and human effort to take a buoy to the location to deploy it and to keep it resupplied.

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U.S. Could Get 15% of Energy from Wave and Tidal Sources by 2030

Megan Treacy

Two recent studies done by the Department of Energy found that wave, tidal and other water power sources could provide 15 percent of U.S. energy needs by 2030.

The reports called the "Mapping and Assessment of the United States Ocean Wave Energy Resource( PDF)" and "Assessment of Energy Production Potential from Tidal Streams in the United States (PDF)," calculated the maximum kinetic energy in waves and tides that could be used for energy production. Our country currently uses about 4,000 TWh of electricity per year and the studies show that waves and tidal currents could potentially generate up to 1,420 TWh of electricity per year, but not all of that energy could realistically be developed.

The DOE plans to release additional resource assessments for ocean current, ocean thermal gradients, and new hydropower resources later in the year so that we'll have a full picture of the water power potential in the U.S.

The findings have been incorporated into NREL's searchable U.S. Renewable Energy Atlas.

via DOE

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