Today’s nearly 8 billion people turn out products and services whose annual value surpasses US$100 trillion; this global economic system consumes primary commercial energy at the rate of about 18 TW (with 85% of the total coming from fossil fuels); its population consumes about 2.6 Gt of grain and about 300 Mt of meat, as well as some 60 Gt of building materials, metals, and synthetics. Given these scales, any alternatives to processes and industries that now provide these inputs would require considerable periods of time to be widely adopted even if such innovations were
