Examining the historical and present energy metabolism of a Rust Belt City: Syracuse, NY 1840--2005
Early cities depended on local, solar-based energy resources for their metabolism. Over time, cities have become increasingly dependent on fossil fuels, both directly and indirectly, as they facilitate exploitation of solar resources from much farther away. Alternatives to fossil fuels, typically generated locally, often provide lower surplus energy to society. As cities consider the transition back to solar-based energy resources, it becomes necessary to understand the capability of the solar-based economy to provide e.g. energy (including food) from nearby lands. To do so, we compared the energy metabolism (respiration) of a typical rust-belt city, Syracuse, NY, with the net primary production in the surrounding county (production) over its development (1840-2005). We calculated the ratio of respiration to production (R:P) and examined how this ratio changed during the periods of industrialization, shifts in major fuel types, and deindustrialization. We found that from 1840 to 1950 respiration became increasingly centralized in the urban core; since then it has become more diffused. Urban respiration exceeded production in the county by 9:1 in 1930, and it remains just under 2:1 today. Respiration reached an absolute (67 PJ) and a per capita (339 GJ) maximum in 1970, then fell by 40 % and 20 % respectively, due to deindustrialization and population losses. Conversely, production increased 480 % from its lows in 1930 because of reforestation and improved agricultural yields. What this means is that to achieve a higher P:R ratio requires either increased production of food and fuels in areas surrounding the city, or decreased per capita energy consumption.