For most people energy efficiency means putting the lights out when leaving a room, using the car less, or enabling energy saving modes on devices. Generally energy efficiency means to do more with less energy instead of wasting it as useless heat. On a broader scale it is not only a question of how to use electricity but also of how to generate and distribute it. Efficient generation of electricity is crucial to reduce greenhouse gases and fight the negative consequences of climate change especially as the world’s energy needs are constantly growing.
Nowadays fossil fuels are still important to maintain a stable energy network. In the US 85 percent of the energy comes from fossil fuels. Therefore energy efficiency in fossil power generation should be fostered. Only about 35 percent of the energy generated by coal power stations results in electric power. Producing electricity at the highest possible efficiencies would reduce CO2 emissions dramatically. Gas turbines and combined cycle power plants contribute to use fossil energy in a more sustainable manner. Short startup times, low startup emissions and little use of water are important. Combined heat and power plants are among the most efficient methods to generate energy.
It is even more important to replace further fossil energy sources by renewable sources: by wind, solar and hydro power. Increased efforts are made to develop efficient wind turbines, photovoltaic and solar plants. Energy efficiency combined with renewable resources could really provide clean energy. Nowadays (2011) about 14.3 percent of the energy produced in the US comes from renewable resources.
Reliable and low-loss transmission of electricity is another aspect. High-voltage direct current (HVDC) is an environment-friendly transmission system. Another one is the so called smart grid.In connection with this intelligent electricity grid, electric cars play a major role. They have not only low emissions but can also be part of the energy system as they are able to store energy and return it to the grid.
Lowering the CO2 emissions of houses is another crucial point. 40 percent of the electricity is consumed by buildings. Buildings can nowadays become prosumers, which means that they produce and consume energy at the same time. It is even more important to reduce emissions and to improve energy efficiency in the industry. Electric drives and motors are responsible for 70 per cent of industrial energy consumption, so there are efforts to make them more energy efficient.