A look at tidal energy generation

There is another vital source of energy generation we need to look at. At first I had a lot of trouble finding out about it until KTUU Channel 2 News did a story about it last month. The video by Blake Essig was enlightening and very informative, and it gave me links for more information in this promising technology that could be a great boon to this state.

Alaska biggest export besides seafood is energy. Most of this is oil, coal extraction and, if everything goes OK in it’s development, natural gas for both in state and export needs. But we have in abundance a whole lot more in renewable sources such as wind power, geothermal, solar energy and tidal energy sources to power our needs well into the future.

It stands to reason that Alaska can be a showcase for energy and development to the world of the present and the near future. Tidal power generation is one those technologies that could be very well the ticket.

Ocean Renewable Power Co. has been around since 2004. It has working projects in Maine, Nova Scotia, Florida and Alaska. Alaska is one we will looking deeper into. So far, Maine has been leading the way, bringing in close to $8 million for that states economy while creating more than 100 jobs in 13 Maine counties. It could go even higher in seven to 10 years, like as in a billion or more. Sound promising?

I think so. But how do they do it? Let’s find out, shall we?

ORPC designs and builds tidal power generators. They are modular designs to fit the power needs and the water systems of the community that is investing in them. The key component is the turbine generator unit itself, also known as a TGU.

Remember those old-fashioned push lawn mowers? We had one when I was a boy. I hated it, heaving and pushing it to make those horizontal blades spin to cut the grass. Well, take two of those, remove the long T handle and both sets of wheels. Keep the support cage and marry them up on a horizontal axle with a generator assembly between them like a wheel. That is a TGU in a nutshell.

Now sink it to the bottom of an inlet or river mouth. Fix it to the bottom and let the water flow through the blades. As they turn, the unit generates electricity to a power distribution station on the shore and then to the village or town it is supporting. The basic TGU unit can generate about 25 kilowatts in a 7.5-feet-per second current. Alaska has some of the highest and most powerful tides in the world. Water being 800 times denser than air, the possibilities for this region are endless.

Made of composite materials, these units can be configured to a variety of packages. They go by names like RivGen, TidGen and the largest of them all, OCGen.

RivGen is a small, single TGU generator mounted on what looks like a pair of pontoons on float plane, except these are sunk down to the river bottom that is deep enough. It is designed to tie directly into the existing diesel electric grid with automatic switching to turn off the diesel power when the unit is in operation. It’s very good for a small, remote village.

TidGen is a bit larger. Designed for shallow tidal and deep river bottom sites of 50 to 100 feet in depth. It uses several TGU units on a erector set like mounting brackets. These TidGen TGU units at peak can generate close to 180kW tied into a shoreline substation with a single power cable.

The OCGen is the largest. Made for depths of more than 80 feet, this is a huge piece of machinery. According to the illustration on the company’s website, it consists of stacks of TGU modules, four TGU modules per section. The picture shows a rectangle of 20 of them suspended at the desired depth, anchored by a low-impact mooring cable system to the sea floor. But it can be configured for more or less, even in a series of groups to the connecting power cable system. One four-module TGU unit will have a peak generating capacity of 600kW of electricity in a six-knot water current. Imagine that, all that power generated by the sea, clean power by the tides.

Testing with some of the smaller systems is slated for this summer here in Alaska working with the town of Nikiski and the Homer Electric Association in a pilot project. It will also include work on the west side of Fire Island to tie in that area’s tidal generators with the wind power rigs already there. These all come under the name of the Cook Inlet Tidal Energy Project.

The hope is that if all goes well in the testing. ORPC can begin installing tidal power generation stations in Alaska beginning in 2014. If this technology can withstand all that Alaska can dish out, this could be a major shot in the arm in dealing with the state’s energy needs.

It also means jobs for Alaskans. That is a big plus. It’s far cheaper than a huge dam project that most likely will never be built, far cheaper than the millions dumped into a natural gas project that may be. Both of those are mired in endless negotiations, debates and millions of dollars that will put years onto any of them becoming a reality, maybe for decades to come, which is unacceptable in my book.

The state of Alaska is rapidly growing, and the Valley is growing the fastest. We cannot wait for years or decades for a large dam to be built or for a natural gas line. One may be built, but I doubt both. A gas line would be the better bet. The technologies I have written about are being used now at a greater savings than the dam or gas line written above. Instead of waiting ages to meet the growing demand for clean energy, we can fix our attention of the renewable types of energy generation such as wind or tidal power. One is already here, the other fast on its heels. Both provide great promise for our future.

If both can survive all that Alaska can dish out, we can put an Alaska seal of approval on both. If they can work up here, logically speaking they can work anywhere on the planet, time enough for talking. The time for action is now. Let us make Alaska the showcase of clean energy development to the nation and then the entire world.

Wasilla resident Daniel D. Grota retired from the U.S. Army after more than 21 years of service.