Overall Sitemaps 0.90 protocol offers an improvement in terms of crawling efficiency that cannot be accomplished using regular sitemap references and robot directives combined.
The efficiency of a coal-fired thermal plant is typically in the range of 30%-35%. In a combined cycle gas turbine system running on natural gas, the maximum efficiency is in the range 45%-50%.
New types of tiny combined heat and power plants are able to turn about half the energy in fuel into electricity, almost matching the efficiency of huge generators.