What is gasification? Is it a new process?
Simply explained, Gasification operates by feeding carbon-containing materials into a heated and pressurized chamber (the gasifier) along with a controlled and limited amount of oxygen and steam. Any inorganic matter in the feedstock melts and is removed as molten metal and a molten stone called slag, both of which are valuable commodities. Any organic matter in the feedstock vaporizes and is captured as a very clean and high quality synthesis gas (syngas) which consists primarily of carbon monoxide and hydrogen and which can be used to create energy or to produce a very clean diesel or ethanol.
Gasification is a technology that has been widely used in commercial applications for more than 50 years in the production of fuels and chemicals. Current trends indicate that the use of gasification will only continue to increase. This is because gasification can accommodate a very wide variety of gaseous, liquid, and solid feedstocks such as coal, oil, and low- or negative-value materials and wastes such as municipal solid waste and sewage sludge, petroleum coke, heavy refinery residuals, secondary oil-bearing refinery materials, hydrocarbon contaminated soils, and chlorinated hydrocarbon byproducts. Gasification of these materials offers many potential benefits, and is much more environmentally-friendly, than more conventional options such combustion or incineration.
Isn’t a gasifier a cleverly disguised incineratior?
No, they are quite different, with very different environmental impacts. While both gasification and incineration are thermal processes, the similarity ends there.
Incinerators operate at relatively low temperatures in an oxygen-rich environment that allows feedstocks to burn. This burning produces a great deal of CO2, SOx, NOx, and acid gases such as HCl and HF. This burning also produces hazardous ash, both as a solid that collects at the bottom of the incinerator and as particulates in the flue gas produced during the incineration process. This ash must be collected and disposed of in a hazardous waste landfill.
Gasifiers, on the other hand, operate at 3,000°F to 4,000°F, using a thermo-chemical conversion process that does not include enough O2 for the feedstock to burn. This thermo-chemical process causes the feedstock to break down on the molecular level, converting feedstocks into a liquid metal, a slag, and a very clean and high-quality syngas. All of these products are valuable commodities that can be sold: the liquid metal can be reused, avoiding the need for the mining and refining of new metal; the slag can be used to make stone building materials and cement, avoiding the need to quarry new materials; and the syngas can be used to produce electricty much more cleanly than other methods or can be converted into a very clean diesal or ethanol, reducing the need for the production and refining of foreign oil. Sierra Energy’s FastOx™ Process, for example, does not produce any emissions, does not produce any waste products needing to be landfilled, and allows our society to recycle 100% of its waste.
Why should we gasify waste?
Gasification is much more environmentally-friendly than landfills, not merely because of its lower net carbon footprint, but because of its lower energy consumption, better recycling efficiencies, increased groundwater safety, and better atmospheric emissions. Every ton of waste that is gasified saves the world from the equivalent of more than 22 tons of greenhouse gases that would be produced if that ton of waste is placed in a landfill.
Not only does gasification prevent the production of enormous amounts of greenhouse gases that are produced by landfills, it also avoids the need for ever-larger and more numerous landfills to hold our society’s increasing waste stream. Gasification also allows metals and other minerals to be recycled for further use, avoiding the need for the mining of virgin metal and stone. And gasification allows any organic materials in our waste to be reused to produce energy and fuels, avoiding the environmental and political consequences associated with the production and refining of new foreign oil and other fossil fuels.
Will waste gasification undermine recycling programs?
No. Gasification is not an alternative to recycling – it is an alternative to landfilling. We are committed to recycling and firmly believe in the R3 waste priorities: reduce, reuse, and recycle. For example, it is always better to recycle plastic into other plastic materials. Such recycling requires less energy than other forms of recycling and reduces the need for harvesting virgin materials.
We will never gasify any feedstocks that have not first proceeded through a recycling program. If we are asked to accept an unsorted waste stream, we will sort it ourselves to remove as many recyclable materials as possible prior to gasification. Unfortunately, no recycling program is 100% efficient. Every waste stream contains materials that either cannot be sorted, or that cannot be recycled in an environmentally-friendly manner, and which are thus sent to a landfill. These materials are our target feedstock. Rather than undermine recycling programs, our process actually improves recycling by allowing the reuse of 100% of the world’s waste stream, meaning an end to unused waste and an end to landfills.
Sierra Energy also supports zero waste programs. If our world can ever achieve such a laudable goal, we can run our gasifiers on agricultural byproducts and other feedstocks that will remain even if we can reduce our municipal solid waste to zero.