We present brief comparative economic and environmental appraisals of the alternatives that have received the most attention in recent years: conventional biofuels (agrofuels), cellulosic ethanol (CE), microalgae, electric vehicles (EVs), plug-in hybrids (PEHVs), compressed natural gas (CNG) vehicles, “semi-clean” (SCPC) coal, clean coal, wood co-firing, nuclear, photovoltaic solar (PV), concentrated solar power (CSP), geothermal, hydropower, wind, and a novel alternative energy solution known as “WindFuels”. Critical reviews of the projections of both Levelized Cost of Energy (LCOE) and life-cycle CO2 emissions of these primary alternatives for clean, sustainable energy are presented. We identify and review the major challenges faced by these alternatives — many of which have received incomplete treatment in previous studies. Then from the projected LCOE, carbon neutrality, resource availability, technological challenges, and recent market data; the probable growth rates for the various alternatives are projected, and the environmental benefit and economic burdens associated with these alternatives are assessed.
