Sunday, November 16, 2008

Crude Payback

By the time a barrel of crude petroleum emerges from the ground at a wellhead, it has already incurred considerable expenses. The costs of exploration and survey, of the drilling equipment, and of the business structure and education and training of the executives and technicians must be paid back. Not only that, but like a rich uncle who makes it big in the stock market, a productive well must pay for all its failed cousins.

After capture at a well, the crude petroleum must be transported--by ship, train, truck, or pipeline--to a refinery. The value or energy content of the oil must pay for this transportation, not just of the trip itself, but of the infrastructure of machines and people, business structure and administration, of the transportation system.

At a refinery, the crude oil is heated (which costs energy) and distilled into gasoline and a variety of other products. Catalysts and additives are used--each of which has its environmental and other cost footprints. The costs of designing and constructing the refinery apparatus, and of the training, ongoing salaries, and other expenses (such as medical and retirement benefits) of the people involved must be borne by the energy value of the crude oil.

A barrel of crude oil, that is 42 gallons, produces 19.5 gallons of refined gasoline (plus some other products). These are then shipped to consumer outlets which have obligated further extensive and expensive infrastructure costs of distributors, manufacturers, stores, and gas stations.

When a gallon of gasoline is pumped into an automobile, about 25% of the energy it delivers goes into producing forward motion of the vehicle.* The rest is lost in heat (into the exhaust and through the cylinder walls and head), to overcome friction and air turbulence, and to run equipment and appliances such as the engine's oil and water pumps and the electricity generator.

The net result of all this is that after crude oil is removed from the ground, about 5% of its energy value is delivered to the wheels of the car. The other 95% goes to infrastructure, people, and machinery necessary for the transportation, refinement, delivery, and utilization of the oil and its products.


* This figure of 25% is an average for a normal automobile with an internal combustion engine. Obviously when the engine is idling but the car is sitting still, the efficiency is zero. On the other hand, moving straight and level at a moderate speed (say, 20 mph) in clear weather without using such amenities as radio, heater, or air conditioner, the efficiency may approach 75%.