Understanding Energy Return on Energy Investment (EROEI)

1) Tar sands are more energy efficient than oil shale.

2) As for oil shale, Their process involves drilling heater holes 1,000 to 2,000 feet down where they heat oil barring shale to very high temperatures. This causes the kerogen in the oil shale to form crude oil and natural gas. Producer wells are drilled into the formation to extract the oil and natural gas. The tar sands however, are heated with hot water or steam to extract bitumen, which is heavy thick oil. The energy to create the hot water or steam usually comes from natural gas. The bitumen then has to be upgraded so that it can be refined. 

3) The tar sands are more efficient due to their better EROI, which leads to lower overall carbon emissions.

4) offshore drilling is currently the process with the highest EROI, and a high EROI leads to less carbon being emitted in it's production. 

5) I take clothes off the top of their piles in my drawer. They are the easiest to get to, so I wear them first.