[forapurpose]

> LNG is definitely happening, and that alone will make a massive difference in emissions

An important, if often repeated point: Natural gas reduces emissions at the point of consumption; that may be balanced out by higher climate change impact when it's mined.

If someone has good, conclusive information on that issue, it would be appreciated.

[brandmeyer]

People mean different things whey they talk about emissions. Shipping is particularly dirty because of the low-grade fuel that they've been using. Its very high in sulphur content, and typically contains a higher fraction of heavier compounds that don't burn as well.

So the ships produce more unburned hydrocarbons (smog precursors) and sulphur oxides (acid rain precursors).

So even if the total CO2 emissions are similar, the other toxics are still greatly reduced.

[tajen]

So... can we produce LNG without producing Diesel? I thought crude oil mandated the proportion, and it was a “good thing” that we found some opportunities to consume the Diesel part? We can’t convert the whole world to LNG because we’ll have way too much Diesel left.

[D_Alex]

We can produce natural gas, thence LNG, from natural gas reservoirs, which contain very little liquids. Eg. coal seam gas can be 95%+ methane, and essentially zero diesel.

[D_Alex]

I have some information...

1. When methane is burned, the carbon dioxide emissions are about 30% lower per unit energy than when liquid fuels are burned (50 g/MJ for methane, vs abt 74 g/MJ for liquid fuels) 2. When LNG is produced, an additional ~10% CO2 is generated, via energy consumption in the gas liquefaction plant 3. Methane leakage from production plant and pipelines is estimated at about 3% of total. This adds a greenhouse gas effect of about 63% (since methane is ~21 times more potent than CO2, greenhouse-effect-wise). 4. Pollutants such as sulfur oxides and soot from natural gas combustion are essentially nil. Heavy fuel oil for ships can have a very high sulfur content.

Sooo... it is quite possible that natural gas use has a higher climate change impact, due to leakages. For other pollutants, natural gas produces less.

[forapurpose]

Thank you! There is no substitute for actual knowledge.

[whatshisface]

>that may be balanced out by higher climate change impact when it's mined.

What do you mean by that? Natural gas is taken from oil wells, the exact same kind of holes in the ground that produce bunker fuel. It's the highest level on the refinery column.

Edit: Here is a picture of the gas market right now:https://en.wikipedia.org/wiki/Gas_flare#/media/File:Niger_De...

If LNG pans out we would move those fires into the engines of ships. It would probably be carbon-neutral up to the trucks that the pipe welders drove.

[forapurpose]

> Natural gas is taken from oil wells

There's a large boom, not new at this point, in extracting natural gas via fracking. My understanding is that the process produces emissions with high impact on climate change.

[whatshisface]

Increased production (and the associated environmental risks) would happen no matter what we were burning. Switching between two fuels doesn't change the amount that has to be produced: if for some reason we couldn't burn natural gas, the same increase in energy consumption would cause the same boom in fracking other oilfields in order to satisfy the demand for the other hydrocarbon.

Edit: If the concern is that the economics of NG are driving higher consumption, then you've got to realize that you could still reclaim the net win by doing some legal thing to halt consumption. The important variables here are damage per consumption and consumption: you want to lower both, but if an improvement in damage per consumption raises consumption you don't want to go back and make the damage per consumption worse. The only reasonable course of action if the damage was too high would be to go in and say, keep using the least-damaging fuel but you're going to have to burn less of it.

[soperj]

Based on what? Lots of Natural gas was just released into the air at oil fields before they started capturing it for sale.