Energy Efficiency

When the world speaks about energy, invariably it speaks about energy supplies. The World Energy Council, the most representative body of the energy industry, organizes the World Energy Congress every 3 years, representing the energy [Page 483]supply industry. Energy policy on national levels tends to circle around energy supply options under the assumption that there will be an ever-growing energy demand.

The energy efficiency agenda, by contrast, is relatively new. It began in the mid-1970s after the oil price shock of 1973 and is seeing a strong revival since about 2006, again after oil prices soared. Also, enhanced concerns about global warming emerged after the near simultaneous publications of the Stern Review, the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, and Al Gore's book and film An Inconvenient Truth. Efficiency increases can serve as an appropriate answer to both global warming concerns and oil prices. However, in the public as well as among energy experts, the favorite answer is still a fuel switch to nonfossil fuels, such as renewable energies and nuclear energy. Energy efficiency remains the undervalued agenda.

The main reason for this state of affairs is that people are accustomed to the historical experience that economic growth accompanies the growth of energy consumption. This tenet was empirically well founded during the industrial revolution. Only since the mid-1970s has humanity seen some kind of decoupling of economic growth from energy consumption. The most important pioneer of decoupling was Amory Lovins who as early as 1977 wrote Soft Energy Paths, making energy efficiency the core of his scenarios without nuclear energy and with much less coal. After years of high energy prices, projections even by the energy industry were corrected downward, coming ever closer to Lovins's bold low energy scenarios. Based on Lovins's groundbreaking work, evidence was accumulated proving that at least a factor of four should be available in the increase of energy efficiency worldwide.

A major factor in the increase of energy efficiency should be the perspective for humankind. Assuming an increase of world population to 9 billion and a doubling of average levels of economic prosperity by 2050 (both rather cautious assumptions), a tripling of energy consumption should be expected unless energy efficiency grows by a similar order of magnitude. In the absence of this increase of energy efficiency, ecological nightmares of global warming, nuclear chaos, or both can be expected.

However, technological advances in energy efficiency will not suffice. As prosperity grows, people have a tendency to consume ever more energy even if efficiency is growing. This holds in particular during phases of low energy prices, as was the case between 1983 and 2005. During this period, all efficiency gains were overcompensated by additional consumption. This phenomenon is often referred to as the rebound effect, the Jevons paradox, or the Khazzoom-Brookes postulate. Figure 1 shows the development in the United States from 1970 to 2007.

Striking efficiency gains have been achieved in several sectors. Lighting with light-emitting diodes (LEDs) is at least twice as efficient as compact fluorescent lamps and 10 times as efficient as incandescent bulbs. Low energy houses need up to 90% less heating energy, using super insulation and heat exchange ventilation. Hybrid cars, combining an electric motor with a combustion engine, more or less doubled the fuel efficiency to 50 miles per gallon from 25. But even such success stories are much too small and too weak to keep energy consumption from growing.

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