accounts for the land used directly for constructing the project
AND
the amount of productive land it would take to balance the CO2 produced during the use of this project
Example - footprint for a driving a car
CO2 uptake by average productivity land = 1.92 m^2 (kg CO2/year)^-1
land needed to balance energy use
for each amount of energy used by the car directly there is an extra 15% for car maintenance and 30% for construction and maintenance of the road
11 km (liter of gas)^-1
2.36 kg CO2 (liter gas)^-1
calculates to 0,73 m^2 (car-km/year)^-1
land also taken out of productivity by the road network
based on cars and amount of roads
0.17 m^2 (car-km/year)^-1
total = 0.9 m^-2 (car-km/year)^-1
=.09 hectares per 1000 passenger km per year
The footprint analysis can put many different factors into one framework.
hard to avoid double counting when using multiple factors
amount of land taken to farm
amount of energy used to pump water