Ask HN: Could ships that convert CO2 + water to natural gas save the planet? | Hacker News Reader

Ask HN: Could ships that convert CO2 + water to natural gas save the planet?

3 pointsgerad11 comments

DISCLAIMER: I know basically nothing about this topic. It's just a (naive and likely stupid) idea that woke me up this morning. If anybody knows where to get more info, or how to answer some of these questions around feasability, I'd love to hear it.

# IDEA

Imagine a ship sitting in the middle of the ocean (where little life naturally occurs), with an eSolar [1] installation deployed.

A giant array of mirrors, individually small, but in total much larger than the hull of the ship, automatically adjusts to keep an intense beam of heat focused on a boiler, even as the ship rolls in the waves.

Convection carries water from the ocean to quickly cool the boiler and keep pistons that generate electricity firing.

Generated electricity is used, along with water and carbon dioxide, to create CH4 (natural gas) and oxygen, at 80% efficiency [2].

Once the ship is full of natural gas, it folds up its solar array and sails to the port where the bid for natural gas is highest.

I haven't done any math to figure out cost, but it seems interesting/compelling from a high level. What do you think?

Anybody who wants to take this idea and execute on it should feel free to do so without reserve. I claim no ownership to anything. Execution is everything.

  [1]: http://www.idealab.com/our_companies/show/all/esolar
  [2]: http://newenergyandfuel.com/http:/newenergyandfuel/com/2009/04/01/boosting-bugs-with-electricity-to-make-natural-gas-from-c02/

So right now, they're flaring off natural gas in North Dakota from the Bakken oil fields because it's not worth their time, money, or effort to take it to market. Figure out how to transport that to someplace they need it, or to build something that can take advantage of cheap gas there. (http://www.nytimes.com/2011/09/27/business/energy-environmen...)

If you're going to use a ship for this, it would also have to be able to liquefy the natural gas (you have can store about 1000 times more energy with natural gas as a liquid than as a gas)

Basically, the capital costs and operating costs for this probably don't make any economic sense.

That's the most compelling argument I've seen yet for the (lack of) feasibility. Thanks for the info.

Seriously, your idea requires an awful lot of "holy grail" technologies.

Generating natural gas with 80% efficiency would solve tonnes of problems (if the price was right). If you could do that, you could get rid of 50% [totally made-up statistic] our existing power infrastructure - a good deal of our existing stuff is only there to "smooth out" demand. It would also make wind power a lot more practical.

If a ship could simply power itself, that would be a massive boon. Shipping companies would pay a lot for a ship that doesn't need to use fuel. And shipping doesn't always need to be timely - so storage isn't an issue.

If any part of your idea was economic, it would already be widely deployed. The main issue will be cost.

The CO2 + 2H20 -> CH4 + 4O2 has seemingly been done (per the paper linked). I agree that the issue would likely be economic factors, but perhaps it's worth investigating those more fully. There are already tankers that transport liquified natural gas all over the world, so there's clearly enough economic incentive for that. The question, of course, is the solar bit.

Imagine a ship sitting in the middle of the ocean

Ships are expensive to operate, difficult to keep running, break a lot. Why not park this ashore and then pipe or ship the fuel where needed?

A giant array of mirrors, individually small, but in total much larger than the hull of the ship,

You're going to have problems with balance. Such a large array might unbalance your ship and capsize her. Sail area should not be discounted: the wind is going to push on the array and kick your ship around.

Once the ship is full of natural gas, it folds up its solar array

Where do they stow the array? If it's on deck the salt air is going to corrode everything, quick. If it's inside where do you store the fuel?

All good points! In terms of parking it ashore, ships have access to plenty of water, which isn't necessarily the case in other desert areas.

Maybe a desert near the ocean though, like in Somalia, but then you still need a ship to transport the liquified natural gas to market (or a pipeline). If the economics worked, I guess either would be fine.

The reality is that if the idea were viable with a ship, it'd almost certainly be (probably more) viable without one too. If land use were the issue, then you could also imagine a flotilla of permanent rafts instead of ship.

Though other commenters have noted that the ships could move to the Southern Hemisphere in the winter to get more solar exposure.

This reminds me quite a bit of Green Freedom, a program out of Los Alamos which created gasoline out of atmospheric CO2 and H2O with some catalysts and an external energy source (they used nuclear). If I recall correctly, the gas would have cost around $4 a gallon, making it not quite competitive with gas where I live in Denver assuming you don't count for the externalities. When I get to work, if I remember I'll see if I can find a link and post it.

Wow, thanks for the tip! I assume this is the link? http://www.lanl.gov/news/newsbulletin/pdf/Green_Freedom_Over...

Will have to take a closer look.

My first thought is that this is probably more expensive than building a solar array on land and connecting it to an electricity grid. Although potentially a ship could spend the northern summer in the northern hemisphere and then go south for the northern winter, gaining access to more sunlight.

Yeah, you're probably right about it being more expensive, and much more difficult logistically, to do on a ship.

The motivation for it was threefold: 1. Less environmental impact (no covering up a large swath of land). 2. No cost to buy the land. 3. Plenty of access to water.

I hadn't even considered the possibility of moving the ships depending on sunlight conditions. That's really brilliant.

I believe the problem like the weight and volume of such a facility that installed on a ship, and the realibility

Reply on news.ycombinator.com