ABSTRACT
Photosynthesis converts solar energy into chemical energy and establishes the carbon cycle, which powers all life on Earth. This biogeochemical cycle is currently out of balance: the rapidly increasing carbon dioxide (CO2) concentration in the atmosphere is driving accelerated climate change. Urban agriculture has the potential to exert a positive influence on this crisis, however, through more sustainable energy use and a reduction of fossil fuel consumption, achieved through the elimination of synthetic fertilizer, reduced use of machinery, increased local food production, and alternative distribution systems. This chapter will investigate the factors that need to be considered in implementing a sustainable, energy-efficient urban agricultural operation. These factors include the solar needs of plants, the potential extension of growing seasons indoors, and associated passive solar gains for buildings. An overview of greenhouse typologies, cover materials, and lighting systems identifies methods to optimize energy use and production in a variety of environmental situations. Chapter 3 additionally examines the potential for photosynthesis and the carbon cycle to make use of the exhaust systems of buildings so that used, CO2-rich air and excess heat can support crop cultivation. Intersections among the nutrient, water, and energy cycles are further explored in a series of case studies that demonstrate the breadth and diversity of current urban agricultural practice.
