2 Definitions: energy, sustainability and the future
What do we mean by energy and sustainability, and what is meant by future?
The term energy has a long history but the standard scientific definition today is that energy is the capacity to do work. The term power is related to energy and its definition is power is the rate of doing work. The two are linked together by the simple formula
energy = power x time
The term sustainability is not so simple to define but there is perhaps no better definition than that given in the United Nations report 'Our Common Future' produced by the Brundtland Commission in 1987. The Commission defined sustainable development, as 'development that meets the needs of the present without compromising the ability of future generations to meet their own needs ' (United Nations, 1987). This means that sustainable resources are those not significantly depleted over time, those which do not result in substantial pollution or other environmerntal hazards, and those that do not involve the perpetuation of health hazards or social injustice.
The Brundtland Commission's view that developments should not compromise the needs of future generations, suggest that we should judge the sustainability of energy systems on an indefinite time scale – far into the very distant future. This might be thought to be unrealistic when applied to the distant future. Future generations will be justified in blaming us for creating problems that were foreseeable, but they can hardly hold us responsible for eventualities that none of us could have anticipated.