Pellets have been produced for over a century. By using heat and pressure small cylindrical pellets can be produced from a variety of materials for different purposes. In the 1970s some companies which used pellet mills to produce animal feed, and started to look into producing wood pellets as a fuel source. However because of the cheap fossil fuels that were available, the wood pellet market struggled to grow. In the 21st century wood pellets and fuel pellets in general are seeing rapid growth, even resulting in supply problems. Due to high oil and gas prices, and concerns over climate change, fuel pellets become a clean, cheap heating choice that can help to reduce global warming. Over the last decade there are two major factors, which have been driving the growth of the pellet fuel market. The first is consistent rise of cost and price instability of fossil fuels, while the second is the increased attention of the effects of using fossil fuels like oil and gas on the environment. Other factors, which support the development of pellets, are that they are a fuel that can be produced locally, from local wood and biomass materials; Pellet production and distribution can produce an affordable fuel; creating local jobs while keeping the fuels carbon footprint to a minimum, etc.