Tag Archives: energy conversion

Seawater to Fuel?

The United States Navy recently announced that they had invented a process to turn sea water into fuel. It’s not exactly the water, but rather the water and Carbon Dioxide dissolved in the water which is turned into fuel.

Is this a game changer? Is it time to quit drilling for oil or digging for coal? No more nuclear reactors and the dangerous wastes, or even wind turbines, which kill so many birds and bats? No more deserts covered with solar panels? Hallelujah.

synthfuel

synthfuel

Scientists at the Naval Research Laboratory have found a way to extract Carbon Dioxide from the seawater, at the same time generating Hydrogen. These gases are then combined in the presence of a catalyst to become the equivalent of jet fuel.

Logistically this could be big for the Navy. Fuel could be produced while at sea lessening the risks of refueling in hostile waters. Remember the USS Cole? It was a guided missile destroyer that docked in Aden, Yemen for refueling. While there she was attacked by al-Qaeda resulting in the death of 17 sailors.

USS Cole

USS Cole

In addition to the production of jet fuel, with only slight modification of the process and or the catalyst, fuel for everything from cars to power plants to home heating oil can easily be produced. Seaside plants could churn out all the fuel the world needs right? Not exactly.

What has been neglected or at least not emphasized is the fact that the current process takes twice the electrical energy to produce the fuel as you get back when the fuel is burned. Bummer. It has been suggested that the process can be made more efficient. But there are absolute limits.

The first law of thermodynamics says, and I’m paraphrasing here – there is no such thing as a free lunch – when it comes to energy. The energy content of fossil fuels derive their energy from the sun. To make the fuel from sea water takes energy. But it gets worse, the second law of thermodynamics says you can’t even break even. There is no such thing as a 100 per cent efficient energy conversion process. There are always losses. Because of these simple laws, laws which can’t be broken, it will always take more energy than you get out in any energy conversion process.

Back to the navy. The process as noted may have logistical advantages, but it is no magic bullet for energy production. A ship at sea would have to supply energy, more than you get out, to produce the fuel. For fossil fuel powered ships this is a non-starter. Nuclear powered ships could use some of the nuclear power to generate electricity for the fuel production, but it would mean shorter durations between nuclear refueling.

Remember, there is no such thing as a free lunch, and you can’t even break even. Unlike Jaywalking or bank robbery, these laws can’t be broken.