Biosphere 2 engineering design

The creation of large materially closed ecological systems for research and experimentation presents a series of engineering challenges to achieve an adequate degree of closure, to transfer energy to and from the system and to maintain an approximation to natural conditions within the system. Biosphere 2 incorporates two large expansion chambers ('lungs') as the key system that enabled the low leakage rate of about 10% year(-1) and facilitated leakage measurement and detection. This high degree of closure achieved in Biosphere 2 made it possible to observe and account for the exchange of gases between the ecosystems and atmosphere, notably oxygen and carbon dioxide. Energy is transferred from an external energy center as electric power and using hot and cold water as a transfer medium through sealed piping systems. The energy system successfully maintained temperature and humidity conditions while at the same time serving as the primary means of condensing tens of thousands of liters per day of water vapor from the atmosphere for potable, agricultural and ecological uses. The certainty of water availability is a direct result of the fact that the system is materially closed. Subsystems of the facility include recycling of human and animal wastes, a system for generating waves in the artificial ocean, separation of fresh water from sea water and computerized sensing and control. (C) 1999 Elsevier Science B.V. All rights reserved.