When you think about clean energy, your first thoughts are most likely solar and wind. Water, however, is a huge source of power in the United States, with rivers and dams accounting for half of all the domestic renewable power produced in 2013. Imagine what you could achieve if you found a way to produce power from the ocean. Lockheed Martin (NYSE:LMT), the giant defense contractor, is working to do just that.

How water makes power
A hydro-electric plant is pretty simple to understand. Water flows over what amounts to a giant pinwheel attached to a generator, causing it to turn. It's not rocket science. The air does the same thing with wind turbines, only they really look like giant pinwheels.

(Source: ReubenGBrewer, via Wikimedia Commons)

Now, the rocket scientists, literally, at Lockheed Martin are working on taking this same concept and applying it to the ocean. Generally speaking, rivers only go one way. So setting up a pinwheel device is pretty easy. The ocean, however, has tides that come in and go out -- a back and forth movement. But, like rivers, that movement is predictable and regular.

So, the design of a tidal turbine (what an ocean pinwheel is called) has to be more flexible, literally and figuratively, swiveling to generate power as the tide comes in and as it goes out. Such an energy system also needs to be submerged in the saltwater ocean, an often inhospitable location.

Working flexibly in hostile environments -- now that's something Lockheed Martin knows how to do.

The most exciting part of this work, however, is that it isn't theoretical. Lockheed Martin has partnered with Atlantis Resources to install the world's largest tidal power farm in the waters off Scotland. Once completed, this project, known as MeyGen, will produce nearly 400 megawatts of power, enough to supply 200,000 homes with electricity. And like river-based hydropower, it is predictable, reliable, and environmentally friendly.

Not the only venture
But this isn't the only ocean-based power project Lockheed has going on. It's also working on a system to take advantage of the differences in temperature between the warm ocean surface and colder waters deep below. And Lockheed really has brought in the rocket scientists on this one, tapping its Space Systems division to advance the technology.

Although there's no large scale-project to report here, Lockheed was the first company to make ocean thermal energy conversion a reality with a 1970s project off Hawaii. Oh, and such ocean-based systems could also be used to desalinate seawater. Note that the West Coast is suffering through a horrific drought right now.

War machine
This is all well and good, but what is a company that makes war machines doing working on cutting-edge power projects? For starters, the military is always pushing the envelope. So Lockheed Martin has advanced technological expertise to apply to any industry it would like. Second, getting power to troops is a vital supply chain issue. In other words, Lockheed has a lot of experience in the area of power. You just don't realize it because bombs and planes are bigger headline grabbers.

And last, but not least, so much of the technology we now take for granted started in the government's hands -- for example, the microwave oven, memory foam, GPS, and, in many regards, the Internet. So it really isn't that odd to think a military contractor would take what it's learned on one side and try to apply it to civilian life.

And since environmentally friendly power is currently such a hot button issue, it seems like this is an opportune time for Lockheed to be moving beyond its military roots. You may not like that Lockheed Martin is helping provide your environmentally friendly power, but that doesn't mean you shouldn't be excited by what it's created. Keep an eye on Lockheed Martin's progress with these technologies; once perfected, both could be vital sources of reliable clean power.

Reuben Brewer has no position in any stocks mentioned. The Motley Fool owns shares of Lockheed Martin. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.