Smil 5 second half

the key technological transformation happened in the 19th century, but it became much more complete and efficient in the 20th century

• China has caught up and surpassed the US in energy use, India is hoping to
• shift to higher quality fuels that produce more energy for a give amount of carbon dioxide released
• we have switched over increasingly to electricity, but where does the electricity come from?

complexities of energy choices:

Powered machinery has revolutionized coal mining
but it has declined in importance as a fuel even for electricity

• coal is easy to transport, develop oil and gas pipelines, shipping
• larger scale and more efficient generators
• natural gas is cheaper and generates less carbon but needs pipelines and other infrastructure
  
• fossil fuel works particularly well to generate electricity when the amount needed varies
• fossil fuel is a limited resource, but what is the key limit?
• running out of reserves, but that depends on extraction technology
  
• how much carbon we put in the atmosphere
• history of nuclear power
  

renewable energy

• the needs of the grid
• small-scale systems

Transportation

• improved engines
• electric cars are surprisingly efficient