According to the Industrial Resources Council, over 300 million scrap tires are generated annually of which almost 40 million end-up in landfills each year. This is in addition to about 180 million tires in stockpiles. The three major markets for scrap tires are: fuel, civil engineering applications, and ground rubber. Of the three, tire derived fuel(TDF) is by far the largest market with users including cement kilns, pulp and paper mills, electric utilities, and industrial facilities. TDF is popular because the energy provided by tires is comparable to that of oil and greater than that of coal, plus tires are low in sulphur and NOx gas emissions.