World energy supplies are often measured in the unit of quadrillion British thermal units (1012 Btu), generally called a "quad." In 2015, world energy consumption is projected to be 5.81 × 1017 kJ.
(a) With reference to Exercise 5.17, how many quads of energy does this quantity represent?
(b) Current annual energy consumption in the United States is 99.5 quads. Assume that all this energy is to be generated by burning CH4(g) in the form of natural gas. If the combustion of the CH4(g) were complete and 100% efficient, how many moles of CH4(g) would need to be combusted in order to provide the U.S. energy demand?
(c) How many kilograms of CO2(g) would be generated in the combustion in part (b)?
(d) Compare your answer to part (c) with information given in Exercise 5.111. Do you think that photosynthesis is an adequate means to maintain a stable level of CO2 in the atmosphere?