A comparison of transportation modes on energy usage. The use of fossil fuels directly correlates with the creation of carbon dioxide. In the attached chart, the units of energy are British Thermal Units (BTUs). The vehicular data was supplied by the US Deptartment of Transportation. The human powered data was assembled from various conversations with fitness experts on caloric outlay for bicycling, running, and walking at various speeds. The conversion rate between food calories and BTUs is 1 BTU = 252 Kilocalories.