That 'environmental accounting' thing has a partner that we use in the Architecture/design industry called 'total cost' or 'lifecycle', where basically you look at the total amount of energy something will consume over it's entire life. For example, common bricks are an environmental nightmare when looked at in this way, for they take a lot of energy to make; a lot of energy to transport; are not very strong (takes a lot to do anything), and you can't reuse them (structurally) & they take a lot of energy to dispose of.

Or, on the other hand, steel has a smaller 'total cost' than brick and is therefore somewhat more environmentally sensitive; it takes a lot of energy to make; Holds up a lot while using a little; is cheap to transport (due to small amounts go a long way & it's easy to move around); can be reused over and over; and can be disposed of easly. Heck, Buckminster Fuller thought that steel should be the 'coin of the relm', rather than the gold standard, because steel was infinately useful.

So, if it's possible for these Oil plants to be built and operated in places that are far away from major refinerys, there is less transport cost; also if they can be used to process/recapture something that was prevously waste, then your reducing the 'total cost', for that was something that you had to use energy for to get rid of.

It's an interesting way to look at things in the world; for, 'total cost'-wise, my 1968 Coronet is more environmentally sensable than a new SUV. SUV: takes a TON of energy to make, gets poor gas milage, very complex to make, very complex replacement parts (big tires, complex alloys & plastics), hard to fix (just wait until all those electronics start to give up), short life span (5-10 years), very hard to get rid of (alloys and plastics hard to recycle). Coronet: Took a lot less energy to make, gets same to better gas milage as an SUV (I get 20 mpg on the hyway- and that will go up once I get the headers on!) very simple design, very simple replacement parts, very simple to fix, long life span (30+ years), very easy to get rid of (other than the seats & dash, everything left is easly recyclable- it's all steel or rubber!).

It's not the whole picture; but it's a fun way to think about thing's total impact, energy-wise, on the world. :)