Tidal Energy : The Power of Ebb and Flow

Tidal power is pretty much exactly what it sounds like. It's a form of hydroelectricity that exploits the movement of water (tidal currents) to power turbines and create energy. Currently, tidal power is used very little, but the potential is definitely there, and it's gaining momentum. While with certain systems there are still some kinks to be worked out in order to fully preserve the surrounding wildlife, tidal power is clean, very renewable and available in abundance in pretty much all coastal areas of the world, although availability does depend on the system you use. There are two main types of technologies that harness the power of the tides: tidal stream systems, and tidal barrages.

Tidal Power Technologies

Tidal stream generators use the kinetic energy from the moving tidal current to power their turbines. The way it works is very similar to a windmill, just underwater. These systems are cheaper and have a much smaller impact on the environment than barrage systems. They can be placed in areas where there's a concentration of high-velocity natural waterflows. These areas exist basically anywhere there's an entrance to a bay or river, or between land masses where currents are strong.

Tidal barrages are much like a dam in that they use the potential energy from the difference in head from low to high tides. Unfortunately, barrages have yet to be declared environmentally sound, cannot be built in most places, and come at a high price because of the infrastructure that's needed. Unfortunately, technology has yet to alleviate the damage caused to fish in the surrounding area around tidal barrage systems. Because the water needs to enter the turbine to power it, the fish can too, and there is only so much to be done to prevent them. There is currently research going into guiding the fish away from the barrage with sonar, however, so if this technology improves, this system will become much more eco-friendly.

Tidal Possibilities - the East Coast

Like most green technologies, the initial investment in the technologies is large, and may take awhile to pay off. Because of this, many governments and corporations are unwilling to invest because the wait for a return on the initial investment may be a tad long. The rising costs of conventional energy sources like natural gas is spurring new interest in the area however. Now that new technology is emerging that causes less harm to the environment than a traditional hydro dam, many more locations are being scouted as potential tidal energy hubs.

Norway, Scotland and Ireland are actually among the leaders in research and development in tidal energy: Both with projects in their own countries, and projects taken on by their companies abroad. A North American survey of tidal potential revealed that much of it rests on our East Coast, in the area around the Bay of Fundy - notorious for its tides. Minas Basin in Nova Scotia was heralded as among the most promising coastal areas surveyed for tidal power, and Ireland's OpenHydro tidal power company has proposed a project there for 2009 that has the potential to power 117,000 homes - or produce 152 megawatts of power. This is only capturing 15% of the tides energy, as well. The survey was conducted by the Electric Power Research Institute in Palo Alto, California and prompted further site evaluations by the Nova Scotia and nearby New Brunswick governments.

Tidal Possibilities - Alaska

"The Economist magazine has also recently reported that Alaska is the best candidate state in America for tidal power - with ninety percent of America's tidal potential coming from its iciest state. In fact, Cook Inlet is currently being explored by Chevron, not for oil, but to research its potential for providing tidal energy. Ironically, oil is currently the major resource that Alaska delivers the US."

There are definite issues with powering Alaska using tidal power, however. Because Alaska has such a small population, one which is fairly scattered throughout the state, there are difficulties that arise when choosing how that energy should be transmitted, and to where. Such a small population also doesn't require a whole lot of energy, despite having higher heating costs and the industrial costs of drilling for oil there. However, there are plans in the works to run the excess energy down into the United States. There is currently research being done on running a transmission line between Canada and Alaska down to the US, which would make Alaskan tidal power even more beneficial.

There are also issues with Alaska's climate that make tidal power more difficult to set up. Tidal turbines have to withstand glacial silt degrading them at a much faster rate than normal, and partially frozen surrounding water in the cold season. But considering the rising costs of oil, and that many Alaskan communities are off the grid and depend entirely on large supplies of diesel, a new reliance on renewables may be a necessary investment.

Although less promising in Alaska than on North America's east coast, it's hard to deny that people are much more willing to look at renewables as viable, and willing to invest in the infrastructure, especially given the rising costs of oil. In order to have a greener source of energy this kind of motivation is key, and growing interests in tidal energy is definitely a positive step.

Source(s): "Steam and Surf in the Far North". Economist; 10/13/2007, Vol. 385 Issue 8550, pg. 34

Woodard, Colin. "On US border, a surge in tidal-power projects." Christian Science Monitor; 8/15/2007, Vol. 99 Issue 182, pg. 6.