

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

<i>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.</i><p># IDEA<p>Imagine a ship sitting in the middle of the ocean (where little life naturally
occurs), with an eSolar [1] installation deployed.<p>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.<p>Convection carries water from the ocean to quickly cool the boiler and keep
pistons that generate electricity firing.<p>Generated electricity is used, along with water and carbon dioxide, to create
CH4 (natural gas) and oxygen, at 80% efficiency [2].<p>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.<p>I haven't done any math to figure out cost, but it seems interesting/compelling
from a high level. What do you think?<p>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.<p><pre><code>  [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/</code></pre>
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jefflinwood
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...](http://www.nytimes.com/2011/09/27/business/energy-
environment/in-north-dakota-wasted-natural-gas-flickers-against-the-
sky.html?pagewanted=all))

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.

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

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wisty
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.

~~~
gerad
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.

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bdunbar
_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?

~~~
gerad
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.

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bartonfink
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.

~~~
gerad
Wow, thanks for the tip! I assume this is the link?
[http://www.lanl.gov/news/newsbulletin/pdf/Green_Freedom_Over...](http://www.lanl.gov/news/newsbulletin/pdf/Green_Freedom_Overview.pdf)

Will have to take a closer look.

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mooism2
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.

~~~
gerad
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.

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

