Energy - Wind Energy: Renewable Energy and the Environment - page 18

As an example of efficiency, in 1975 the U.S. Congress passed laws for corporate average fuel
efficiency (CAFE), fleet fuel economy for vehicles weighing less than 3,886 kg. Pickup trucks
and large vans did not count in the CAFE. This law has saved the United States millions of dol-
lars for imported oil. The problem is that sports utility vehicles (SUVs) were counted as light
trucks, and their fuel consumption is around 5.5 km/L (12 miles/gallon [mpg]), so the overall
fuel efficiency declined as SUVs gained market share. Even with the continued objections by
the automobile industry, finally in 2007, the CAFE was increased to 15 km/L (34 mpg) by the
year 2020. The European Union and Japan have fuel economy standards about twice those of
the United States.
An interesting note: the big three U.S. automobile manufacturers have received over 2,000 million
dollars in R&D from the government for the Partnership for New Generation of Vehicles [2]. The
goal was a sedan for five people that would obtain 34 km/L (80 mpg). Later, the automotive manu-
facturers said there is no way to reach that goal. President G. W. Bush is promoting government
incentives for fuel cells and the use of ethanol.
Amory Lovins, who was emphatically right about the soft energy path in response to the first
energy crisis [3], is strongly advocating hybrid cars and light-weight cars. And guess what? Hybrid
cars entered the market in 2000. Just think what large numbers of hybrid cars could do to alleviate
the present energy dilemma of too much imported oil for the United States. Again, the question is:
Where should the federal government place its incentives? It might be cheaper to subsidize higher-
efficiency cars than to subsidize drilling for oil. What is the cost for oil if the costs for the Gulf War
(Oil War I) and the Iraq War (Oil War II) are included?
In the past the Organization of Petroleum Exporting Countries (OPEC) wanted to keep the
price of oil in the range where they made a lot of money, but not so high as to encourage conser-
vation and efficiency. However, at some point the demand for oil across the world will be higher
than can be supplied. At the point where world oil production starts to decline, we will have even
higher prices.

2.5 EXPONENTIAL GROWTH
Our energy dilemma can be analyzed in terms of fundamental principles. A corollary of the first
law of thermodynamics is: it is a physical impossibility to have continued exponential growth of any
product or exponential consumption of any resource in a finite system.
The present rate of consumption and the size of the system give a tendency for people to perceive
the resource as either infinite or finite. The total energy output of the sun and the amount of mass
in the solar system are infinite sources at our present rates of energy and material use, even though
the solar system is finite. Even just the amount of solar energy received by the earth is a very large
resource. The energy dilemma is defined within the context of the system, and our present energy
dilemma is due to the finite amount of fossil fuels on the earth.
An easy way to understand exponential growth ( Figure 2.1 ) is to use the example of money.
Suppose Sheri receives a beginning salary of $1/year with the stipulation that the salary is doubled
every year, a 100% growth rate. It is easy to calculate the salary by year ( Table 2.1 ) . After 30 years,
her salary is $1,000 million per year. Notice that for any year, the amount needed for the next year
is equal to the total sum for all the previous years plus 1.
Suppose a small growth rate is used, the doubling time ( T 2) can be estimated by

T 2 69/ R (2.7)

where R % growth per unit time, generally years. Doubling times for some different yearly rates
are given in Table 2.2 .