BFs are reliable producers of large volumes of pig iron and are supported by elaborate supply systems of iron ore mines, limestone or dolomite quarries, pelletizing or sintering plants, coal mines, coking batteries, coal trains, ore and coal carriers, and harbors. Such proven, high-volume performers and such expensive infrastructures have considera

blades. In addition, these large (up to 18.2 kg) single-crystal alloy blades need a ceramic coating in order to prevent their melting and provide resistance to oxidation and corrosion.

an incomplete and imperfect story of amazing technical transformations that is told from a variety of perspectives in order to understand better the complexities of the fascinating process, its stunning accomplishments, and its unforeseen (and often unforeseeable) failures.

BFs are prodigious (Peacey and Davenport 1979; Sugawara et al. 1986). A furnace producing 10,000 t of metal a day will need more than 4.5 Mt of hot blast air a year, and it has to be supplied with about 1.6 t of pelletized ore, 400 kg of coke, 100 kg of injected coal (or 60 kg of fuel oil), and 200 kg of limestone for every tonne of iron. These cha

energy-intensive electrolysis of water that needs 4.8 kWh per cubic meter of hydrogen.

In contrast, electricity intensity continued to increase even after 1950: electricity

This high efficiency also translates into a much reduced specific generation of CO2: steam turbine generation fueled by coal produces more than 1 kg CO2/kg, and by fuel oil, at least 0.8 kg, while CCGT will emit less than 0.4 kg/kWh (Islas 1999). Other environmental advantages include the fact that GTs do not require any external cooling and that n

industrial processes.

There are only three major classes of fossil fuels (coals, crude oils, and natural gases) and five major renewable energy flows (direct solar, wind, water, tides, biomass), and only a handful of prime movers (steam, water, wind, and gas turbines and internal combustion engines) are used to convert these energies into electricity, heat, and motion.