Circular Economy is the pursued goal of sustainable development of mankind for the 21st century. In short, the fundamental spirit of circular economy is the concept of Zero Waste. The example used in our daily lives means 100% of waste treatment, leaving no trace. At this time, it would be an ideal goal that the waste could be fully recovered into available raw materials or energies. In particular, waste-to-energy is a key factor, because all the wastes are almost related to energy. Resource recycling of waste metal from the household garbage is the best example. When smelting metals, the refining industry needs to reduce the metal oxides (mineral materials) to metals, such as steel, aluminium, copper, etc. The reduction processes consume considerable portion of energy for the entire smelting process, for example, 70.6% for steel and 77.4% for aluminium. However, if the waste metallic products can be fully recovered, as long as by melting and reshaping, the original oxide metal reduction processes that consume a lot of energy can be avoided. On the other hand, when the general garbage cannot be recovered as a resource, they can be converted into fuel or electricity by biological or thermal treatment. Another more important human waste utilization is the waste paper recycling. The production of one tonne of raw pulp emits about 6 tonnes of carbon, consuming about 100 cubic meters of water, using about 200 kilograms of chemical raw materials, and draining 300 tonnes of toxic waste water. The entire papermaking process is how terrible environmental pollution! The recycled pulp of one tonne can save energy 10-13GJ.The proportion of paper waste in Taiwan 2015 is 34.69% and the estimated amount is 2.5 million tonnes. If the paper waste could be fully recycled, it could save energy about 0.725 million kloe (kilolitre oil equivalent). In other words, it virtually reduces Taiwan's oil imports of 4.56 million barrels and CO2 emissions of 2.5 million tonnes annually.