[nickik]

One of the price advantages that Blue has over SpaceX is that they will fly with LNG rather then pure methane.

Edit: Will New Glenn also not use a third gas for pressurisation? Like BFR?

[jofer]

Wait, I'm confused... LNG is pure methane. Are there rockets that use methane that aren't storing it as a liquid? I would have to guess that any rocket using methane would pressurize it enough to be in liquid form for storage, anyway. Surely they wouldn't use methane in a gas state... It would take up far too much space to be practical.

[philipkglass]

LNG is 85-95% methane, typically, with ethane making up most of the rest. It contains small amounts of propane and butane.

I hadn't known that SpaceX was using a special grade of ~100% liquefied CH4 as nickik says above.

EDIT: shale gas is richer in ethane and higher hydrocarbons than traditional sources of natural gas. Maybe SpaceX is sticking to 100% methane just so they don't have to ponder variability of composition depending on how gas is being extracted.

[shmerl]

Methane can be synthesized from CO2 and hydrogen. More complex hydrocarbons are way more difficult to produce. So pure methane based engine is a better method for using on other planets.

[greglindahl]

When you liquefy natural gas, ethane and methane liquefy at different times, so it's relatively easy to purify methane. I don't know the price difference, do you?

[vermontdevil]

That’s my understanding. They are to use LNG as it’s own pressurization. Reduces a lot of complexity. Details are still vague as far as I can read.