Energy efficiency exists along with renewable energy sources like wind, solar, and biomass. By themselves and in combination with fuel cells, energy storage, geothermal energy, and nuclear energy, these renewal energy sources provide alternatives to fossil fuels like oil, coal, and natural gas. They address concerns spurred by fossil fuel use, such as the buildup of climate-changing gases in the atmosphere, the depletion of fossil fuel supply, and the vulnerability of nations that use fossil fuels because of security issues.2
There have been many advances in energy efficiency. Better software and computing technologies have improved the monitoring and control of energy use. LED lighting, which requires less energy use and is longer lasting than conventional incandescent and fluorescent lighting, has been developed. Superconductors carry and transfer electricity more efficiently and with fewer losses. They make it possible to build magnetic levitation trains and faster computer circuits that run on less energy, as well as more energy efficient advanced magnetic resonance imaging (MRI) machines.
Wind and solar power have become far less expensive than they once were. In many parts of the world, their costs are equal to, or lower than, other forms of electricity generation. Solar energy cells have been long available in pocket calculators and remote power applications. Though solar made up less than one percent of the electricity market in 2015, the International Energy Agency has projected it will be the world’s most important source of energy by 2050.3
Lithium-ion batteries are current leaders in energy storage and are used across many applications from laptops to mobile phones to electric vehicles. With mass production, their price is likely to keep declining. Even with these advances, there have been struggles to commercialize alternative energy. In the next chapter, the effort to make energy-efficient, low-priced electric vehicles widely available is discussed, and Chapter 8 is devoted to the commercialization of renewable energy and energy efficiency technologies.