Much of the fuel we burn is used to generate electricity, typically at about 30 percent efficiency. However, combustion has environmental drawbacks beyond the emission of carbon dioxide. Depending on conditions, carcinogenic and polluting products of incomplete combustion, such as particulates, nitrogen oxides, and polycyclic aromatic hydrocarbons, can also be produced.
Biological systems generate their energy directly in mitochondria at efficiencies of near 90 percent. The energy chemistry in mitochondria is analogous to that in fuel cells, wherein hydrogen and oxygen in the presence of catalysts are converted to water while generating electricity.
Understanding the common-metal catalysts in mitochondria and their adaptation to fuel cells, especially for mobile applications, could simultaneously reduce energy use by improving efficiency and reduce their unwanted by-products of combustion. There are encouraging results in this field as well (Winther-Jensen et al., 2008).
The commercial development and production of materials mimicking biological systems has been the focus of much industrial research effort. However, many biological materials remain outside commercial reproduction capability. For instance, long spider silk proteins, as fabricated into strands, have the tensile strength of steel, yet the structure of spider silk. As desirable as these characteristics are, the commercial manufacture of spider silk as an advanced material continues to elude engineers. Composite materials—steel-reinforced concrete or glass-fiber-reinforced plastic—have been staples of construction and engineering for years; yet they do not achieve the strength and toughness of biocomposites such as bone or tooth enamel.
Progress is being made in understanding the structure, physical properties, and means by which these materials are fabricated. Synthetic biology has been used to increase production under controlled conditions (UCSF, 2008). Further efforts in replication, manufacture, or modification could lead to lighter, stronger, more resilient, and, moreover, biodegradable engineered materials. This intriguing area is the subject of a recent NRC report on biomimetic materials (NRC, 2008).
As modern science dawned hundreds of years ago, its practitioners hoped to understand the large questions of life, including its origin and the maintenance of youth and health. Over time, scientists found those questions too complex to