Fossil fuels and uranium for nuclear energy are exhaustible resources, existing in finite amounts. For example, oil is produced from plant and animal remains that have been buried beneath the surface of the earth for hundreds of millions of years. This decomposition process can't be accelerated by man-made artificial devices. Alternative energies may be limited in their flow or flux, such as solar radiation or kinetic energy from wind or water, but they are inexhaustible resources and, therefore, sustainable.
According to the U.S. Environmental Protection Agency, the burning of fossil fuels contributes significant amounts of carbon dioxide and other greenhouse gases into the atmosphere; such as methane, hydrofluorocarbons, sulfur hexafluoride, perfluorocarbons and nitrous oxide. Since the mid 1700s, the concentrations of methane, carbon dioxide and nitrous oxide have, respectively, risen by 148 percent, 36 percent and 18 percent. McKinsey reports that a composite of U.S. government forecasts suggests that emissions will escalate from 7.2 gigatons of CO2e in 2005 to 9.7 gigatons in 2030, if greenhouse gases go unchecked. Alternative sources of energy would have the opposite impact on greenhouse emissions, reducing the amount of carbon dioxide and other toxic substances released into the atmosphere.
The 2010 Deepwater Horizon oil spill, in the Gulf of Mexico, was the largest in the history of the U.S., discharging 90 to195 million liters of crude oil into the ocean. By comparison, Exxon Valdez's 1989 spill only amounted to 40 million liters. The spill's plumes have reached the Lophelia corals, will kill the larvae of endangered bluefin tuna and adversely impact the ecosystem of the marshes on the southeast coast. A single liter of oil can taint a million liters of drinking water. While oil spills can decimate ecosystems, coal mining devastates large swaths of land. In addition, 54 percent of the electricity in the U.S. comes from coal, which represents the largest source of air pollution. Burning coal is the primary cause of acid rain, smog, soot and toxic airborne substances.
While renewable energy technologies, such as utility-scale solar and wind farms, can employ large tracts of land, disrupt ocean life and generate some noise, these environmental impacts are small compared to the damage done by fossil fuels.
According to RenewableEnergyWorld.com, a GTM Research report on the U.S. utility photovoltaic market claims that utility-scale solar photovoltaic plants can generate electricity at a cost of $0.07 to $0.08 per kilowatt-hour. With proven technology, the solar power industry has reached maturity. Solar PV is flexible, modular and affordable. The cost of wind energy has plummeted from $0.40 to less than $0.05 per kilowatt-hour, reports Energy Quest. At the same time, the increasing cost and difficulty of drilling for oil boosts the cost of wholesale oil. Because oil and natural gas reserves will continue to deplete, the price of fossil fuels will only continue to escalate. It is estimated that natural gas reserves may be exhausted by 2085.