Energy and our world

4. _____ currently is the largest source of renewable energy in the electricity sector
5. _____ energy has been used for millennia
7. The carbon in fossil fuels has been sequestered, or stored, underground for _____ of years
9. Generating renewable energy creates far lower ______ than burning fossil fuels
10. Solar technologies convert sunlight into ____ energy either through photovoltaic panels or through mirrors that concentrate solar radiation
12. Bioenergy is produced from a variety of organic materials, called _____ , such as wood, charcoal, dung and other manures for heat and power production, and agricultural crops for liquid biofuels
13. The theoretical potential for _____ energy easily exceeds present human energy requirements
17. ____ energy is energy derived from natural sources that are replenished at a higher rate than they are consumed

1. _______ energy utilizes the accessible thermal energy from the Earth’s interior
2. _______ fuels - coal, oil and gas are non-renewable resources that take hundreds of millions of years to form
3. ______ is a liquid fossil fuel. It is also called oil or crude oil
6. According to the Central Intelligence Agency, the world generates more than 66% of its electricity from fossil fuels, and another 8% from ______ energy
8. Solar panels have a lifespan of roughly 30 ____
11. _____ is the main element in fossil fuels. For this reason, the time period that fossil fuels formed (about 360-300 million years ago) is called the Carboniferous Period
14. ____ gas is another fossil fuel that is trapped underground in reservoirs. It is mostly made up of methane
15. ____created by burning biomass creates greenhouse gas emissions, but at lower levels than burning fossil fuels like coal, oil or gas
16. The rate at which ____ energy is intercepted by the Earth is about 10,000 times greater than the rate at which humankind consumes energy