Environmental Engineering Reference
In-Depth Information
suppliers, but manufacturers have systematically opposed such taxes by adopting
the strategy of improving fuel economy rather than paying even a small “gas-guzz-
ler” tax.
Developing countries present some special problems in improving the effi-
ciency of their transportation systems. In many countries the leading world auto-
motive manufacturers, including General Motors, Chevrolet, Renault, Volkswagen,
Fiat, Mercedes Benz, and Scania, have established subsidiaries where cars and
trucks are either assembled or entirely locally built. The cars are basically the same
as the ones produced in the manufacturers' home countries. Despite this, these cars
and trucks generally have fuel efficiencies that are 20-50% lower than their coun-
terparts in industrialized countries, mainly because of bad maintenance practices,
low-quality fuels, and poor roads.
In the maritime sector, a combination of technical measures to apply state-of-
the-art knowledge to hull and propeller design and maintenance could reduce en-
ergy consumption by 4-20% in older ships and 5-30% in new ships. Reducing the
speed at which a ship operates leads to a significant benefit of reduced energy con-
sumption. For example, a reduction in a ship's speed from 26 knots to 23 knots can
yield a 30% fuel saving. The knot is equal to one nautical mile (1.852 km) per hour,
approximately 1.151 mile per hour.
In the short run, at the consumer level, energy conservation efforts are clearly fin-
ancially rewarding; similarly, industries producing energy-intensive products can
increase profits considerably by reducing energy consumption.
However, savings in energy consumption can lead to additional activity through
either greater use of the same product or movement toward another energy-using
action, that is, it can generate a “rebound” effect. For example, as a
direct rebound
effect
, a car owner might drive a more-efficient automobile further than a less-ef-
ficient one. An
indirect rebound effec
t might be that a consumer uses the money
saved on a more-efficient automobile to buy another car. Similar effects occur for
energy consumed in buildings. There are also
economy-wide effects
, whereby new
technologies create new production possibilities and increase economic growth.
There are many studies on the subject and and the magnitude of the rebound ef-
fect varies from 0 to 50%, depending on the sector. Typical numbers for space heat-
ing are 10-30%; for space cooling, 0-50%; for lighting, 5-20%; for water heating,
10-40%; and for residential lighting, 5-12%.
