Nuclear fuel cost projections typically consist of current reported costs that are escalated at the rate of inflation. These projections usually consist of a single estimate in each year. In the...
Fueling the Hydrogen Economy: Energy Independence Now
fuels and, especially, environment-friendly natural gas.
The Need to Limit CO 2 Emissions
The largest source of dissipative material flowing into the biosphere from human activities is carbon in the form of CO 2, largely from combustion and processing of fossil fuels (natural gas, petroleum liquids, and coal). This is a problem because CO 2 is the major anthropogenic greenhouse gas held responsible for much of the overall rise in average global surface temperatures of about 0.7°C since 1860 [3,9,10], although the widely fluctuating actual temperature record from 1860-2000 in no way indicates a direct cause-and-effect relationship between atmospheric CO 2 concentrations and surface temperatures.
Tables 1, 2, and 3 summarize the proved reserves and the upper bounds of technically recoverable resources of (now) conventional fossil fuels and their potential carbon emissions in the form of CO 2. It can be seen that even the upper bound of 20,000 Tcf technically recoverable natural gas resources (about three and a half times proved reserves) contains only 290 billion (109) metric tons (gigatonnes) of carbon. The upper bound of 3,600 Bbbl of technically recoverable petroleum liquids (crude oil and condensates, Canadian oil sands, and natural gas liquids), or about two and a half times proved reserves, contains 410 gigatonnes of carbon. Thus, the total carbon content of the potentially recoverable hydrocarbon fuels is only 700 gigatonnes. This compares with 4,450 gigatonnes of carbon in the upper bound of technically recoverable resources of coal and lignite (about six times the proved reserves). Thus, the total potential carbon emissions from conventional fossil fuels range from about 1,000 gigatonnes for the proved reserves to more than 5,000 gigatonnes for the technically recoverable resources.
This data has major implications for energy and environmental policy. This policy should strive to limit cumulative anthropogenic carbon emissions in the form of CO 2 from 1991 to 2100 (largely from fossil fuel combustion) to 1,000 gigatonnes and, preferably, only 650 gigatonnes to stabilize atmospheric CO 2 concentrations at 550 parts per million by volume (ppmv) and 450 ppmv, respectively [9,10]. Assuming median climate sensitivities to increases in CO 2 concentrations, cumulative anthropogenic carbon emissions of 1,000 gigatonnes from 1991 to 2100 would limit further average global surface temperature increases to 2 to 2.5°C (3.6 to 4.5°F), and to less than 2°C (3.6°F) if these emissions are capped at 650 gigatonnes [3,9,10].
It is fortunate that the still growing abundance of economically recoverable natural gas and petroleum liquids resources gives us at least 20 years of lead time to decide how to stay most cost-effectively within a cumulative anthropogenic carbon emission limit of 1,000 billion metric tons between 1991 and 2100. The obvious first priority of U.S. energy policy must be to bring natural gas prices down by increasing supply, so that this least carbon-intensive and least-polluting fossil fuel, which is the ideal energy source for highly efficient central, modular, and distributed power generation, is utilized to the fullest extent in reducing current reliance on inefficient and inherently high conventional pollutant and CO 2 emission coal-fired, steam-electric plants.
The basic problem