Gas Goes Solid

Roland Piquepaille writes "This innovation from Japanese researchers can potentially revolutionize the energy distribution sector. Instead of transporting liquid gas, they changed gas into a solid material which is easier, safer and cheaper to distribute. Technology Review has the story. "Rather than extracting methane from hydrates, they want to turn methane into hydrates -- essentially, transforming the colorless and odorless gas into small pellets that can be easily stored, transported, and eventually turned back into natural gas. A few months ago Mitsui, in partnership with Osaka University, opened a demonstration plant near Tokyo to promote the concept and show that it works." Check this column for an analysis."

Comments

What is gas?

[The Original Yama]

In Japan, gas is solid.

In the USA, gas is liquid (i.e. petrol).

In Soviet Russia, gas is ... ?

Re:What is gas?

[Rhinobird]

IN SOVIET RUSSIA, gas is... ...called vodka.

Been there. Done that.

[Boss, Pointy Haired]

Tried to produce gas, came out solid.

Shit happens.

Things to remember

[wowbagger]

1) Hydrates are not stable at room temperature and pressure - you still have to keep them cold (-10 C). Granted, -10C is better than -100C, but you will still have to have a refrigeration unit or a pressurized tank.

2) When you break the hydrate down, you have methane and water. You have to do something with the water - dump it on the ground, feed it into the engine to be vaporized, something.

3) While hydrates may store more methane than storing the methane as a gas, I don't think hydrates store more methane per unit volume than storing the methane as a liquid.

4) You are storing methane and water - you will have more mass per unit methane than storing just methane.

Those things said, this could be a good thing, in that anything that allows better storage and transport of methane makes it a more viable fuel source.

Re:Things to remember

[Portent]

Actually methane hydrate is much better for transportation than liquid methane for two reasons.

First, it actually contains more energy per unit volume than liquid methane.

And second, it is much more difficult to liquiefy methane than to form the hydrate phase. Liquid form requires very very low temperatures, and very high pressure, while the hydrate phase can be attained at around the freezing point at much lower pressures.

Transporting methane in the hydrate phase is very attractive for countries that don't have their own power sources (southeast Asia). 1 cubic metre of methane hydrate holds 160 cubic metres of gaseous methane.

However, the infrastructure to use it efficiently is still under heavy development so it'll be a while before we see methane hydrate being used on a large scale.

One problem from the world of ice cream

[Shoten]

Heat shock, it's called. When the temperature of your freezer goes up by even a fraction of a degree (and it need not go anywhere near as high as 0 degrees celsius), some of the ice melts. When the temperature drops again, it re-freezes, but in a slightly different location. That's why ice cream (especially the really expensive stuff, that doesn't have many or any stabilizers like guar gum in it) will develop that coating of ice crystals after it sits in the freezer a while. The ice is migrating from inside the ice cream to the surface.

Now, what I have GOT to wonder is this...what effect might this have on ice pellets that contain lots and lots of tiny bubbles of methane??

Re:One problem from the world of ice cream

[Duke]

When the temperature of your freezer goes up by even a fraction of a degree (and it need not go anywhere near as high as 0 degrees celsius), some of the ice melts. When the temperature drops again, it re-freezes, but in a slightly different location.

Bzzt. No. But thanks for playing.

Whether a liquid or a solid, water is has a vapor pressure. If a system of ice and air is at the same temperature, there will be water vapor in the the air. The system will be (once there is enought water vapor in the air) in equilibrium - there will be no net movment of water from its ice form to its vapor form. But this is dynamic equilibrium, ice will be moving to vapor at the same rate that vapor is moving to ice. (Both processes - solid to gas and gas to solid - are called sublimation.)

If there is a temperature difference in your freezer, the ice will move from the (even slightly) warmer spot to a colder one. However, the process, for instance, of having all your ice cubes smoothing their edges and attaching themselves to each other would occur even if the contents of the freezer were all at the same temperature. The ice is trying to get itself into its minimum energy configuration, where it would be one big sphere.

If the top of the ice cream container is cooler than the rest of it, water will migrate to the top. The migration just requires a spatial temperature gradient, not a temporal temperature change.

Methane hydrates

[panurge]

It's true that there are vast reservoirs on the continental shelf- and a big fear of global warming is that it will cause the hydrates to start dissociating, filling the atmosphere with methane (=powerful greenhouse gas) and accelerating the warming process. It's the speed of warming, not the actual temperature, that is considered to be the biggest problem.

Methane hydrates are not particularly high-energy-density fuels- wouldn't be suitable for automotives, for example-but the bigger a store the easier it is to keep cold (lower surface area to volume ratio) so I guess they could actually be useful as a way of storing large amounts of gas economically and safely, the role they are basically playing on the seabed right now.

Basically, I just don't get the Japanese argument. Is it really going to be cheaper to transport several ordinary refrigerated trucks of methane hydrate than one very cold truck of liquid methane? It looks as if the technology might be more of a way to stockpile large reserves of gas. As electricity generation in many parts of the world is increasingly gas-fired using turbine generators, perhaps this is a way to protect fuel reserves and generator capacity better from terrorists.

Re:Methane hydrates

[Alyeska]

First, safety: The safest method of shipping gas (liquified or not) is by pipeline. If turned to a solid, and overland transportation (train/truck) is necessary, risk goes up tremedously -- compare pipeline accidents to car accidents in the US to get an idea of what you're looking forward to... just because they "melt slowly" doesn't mean it's not an environmental catastrophe if they spill in a neighborhood or highway. With pipelines, you have control.

But there's also the issue of "White Crude," not mentioned here. In Alaska, we have enough gas to fuel the world for years, but can't get it to market because it's so much cheaper to do so elsewhere. We and others are working on a chemical process that creates "White Crude," a room-temperature liquid, from NG. White Crude can be shipped within existing oil pipelines, separated easily at the terminus, and loaded into existing oil tankers. Once at port, white crude can be turned back into NG and distributed through pipelines to consumers.

Researched these things

[777333ddd]

Hydrates are quite interesting.

Right out of College about 13 years ago I joined one of those huge Oil Companies and the main thing I did there for 2 years was study gas hydrates. The reason we studied them was in order to *prevent* their formation which is the opposite of what this article talks about. The problem with hydrates in the oil business is that under high pressure and low temperature they form ... and guess what conditions predominate in undersea pipelines?

When oil comes from the formation, it is almost always mixed with water and some varying amount of gas or other hydrate forming HCs. Everything is fine up the wellbore and near the wellhead, but not too far away from the wellhead the fluid starts getting cold and these solid particles form. They can clog a pipeline if you don't take countermeasures. One is to run a device called a "pig" through the pipeline to clean them out. Another is to install insulation, heated lines, or inject lots of chemicals like MeOH to suppress the hydrates. But all of these things start increasing the production cost and/or decreasing capacity.

So our research looked into creating chemicals that you could inject in very small volumes near the wellhead to inhibit the formation of hydrates.

Anyway, all this hydrate study did make people think about the application of hydrates in the transport of natural gas (NG). I think it's a very interesting idea. Currently to get NG from a remote place to market, you need lots of big expensive gas turbines driving massive refrigeration equipment to create Liquified NG (LNG). Then you need these huge, wild looking LNG tankers. Then you need special port facilities to handle the super-cold LNG. The up front capex is so massive (think 10 billion plus for many potential projects) that no one just pays that upfront hoping the customers will show up. No. You get agreements on paper stretching out 30 years with customers and only THEN do you give the green light to the project.

Hydrates certainly wouldn't need near the compressor/turbine expense of LNG development, and there might be a sweet spot in terms of pressurization and temperature you might strike. However the rest of the economics I'm not too sure about. If most of the cost of a project is the tankers and you need a lot more of them for Hydrate, then you might be better off with LNG. The other huge thing in LNG's favor is that we know it works and can calculate a cost.

One interesting idea I saw floated once was the creation of hydrate subs. Huge deepsea vessels that would be able to stay cold and high pressure just by virtue of being well below the sea surface where those conditions are natural. Now unlike a typical sub, these guys would never surface and so would not need thick walls to handle pressure differences inside and out.

Imagine one of these things scooping up hydrate from the ocean floor and carting it off to a disassociation plant on the seabed (preferably in a subsea canyon as closs to the coast as possible) that evaporated the hydrate gas into a regular gas pipeline.

dave