Most of us are familiar with the term 'green energy'. It is an umbrella term for sustainable / renewable energy. That includes a huge range of tech, including but not limited to solar and wind energy, bio fuels and others.
There is also something called 'blue energy'.
As noted by the Mother Nature Network:
Saltwater powerAs we have seen from the attempts at locating the missing aircraft in the Indian Ocean, in some regards we know more about space than we do about the ocean on our own planet.
It has been called saltwater power, osmotic power or blue energy, and it is one of the most promising new sources of renewable power not yet fully tapped. Just as it takes huge amounts of energy to desalinate water, energy is generated when the reverse happens and saltwater is added to freshwater. Through a process called reverse electrodialysis, blue energy powerplants could capture this energy as it is released naturally in estuaries around the world.
If we can stop polluting the seas and oceans on earth long enough to explore our options to make use of it for clean energy, there are some other forms of aquatic, or 'blue' power that show potential.
Continuing from MNN:
Ocean Thermal Energy Conversion (OTEC)
Ocean thermal energy conversion, or OTEC for short, is a hydro energy conversion system that uses the tempurature difference between deep and shallow waters to power a heat engine. This energy could be tapped by building platforms or barges out at sea, taking advantage of thermal layers found between the ocean depths.
and one more possible form of 'blue power':
We live in the 'land of 10,000 lakes'; we border one of the enormously valuable sources of clean fresh water, lake Superior. So long as we live on the blue marble, we need to be mindful of the benefits of clean water, of not polluting it, and of safeguarding everything from preventing pollution, to the possibilities of our water as a source of clean, renewable energy.
Vortex-induced vibrations
This form of renewable energy, which draws power from slow water currents, was inspired by the movement of fish. The energy can be captured as water flows past a network of rods. Eddies, or swirls, form in an alternating pattern, pushing and pulling an object up or down or side to side to create mechanical energy. It works in the same way that fish curve their bodies to glide between the vortices shed by the bodies of the fish in front of them, essentially riding in each other's wake.
The next time you hear a conservative insist that we cannot have regulation to ensure clean water, that we can not end our dependence on fossil fuels without economic collapse, think of this: since the founding of the EPA, we have made a 70% improvement to our air quality, while doubling our GDP. It is not either /or; that is a false choice presented by conservatives. Repudiate it. Keep our blue marble shiny blue - and green. Preserve our land, our air and our water. We CAN do it; it is a choice.
It is a choice we make by doing things like funding effective regulation and innovation.
From the EPA web site:
...between 1980 and 2012, gross domestic product increased 133 percent, vehicle miles traveled increased 92 percent, energy consumption increased 27 percent, and U.S. population grew by 38 percent. During the same time period, total emissions of the six principal air pollutants dropped by 67 percent.