Environmental regulations can, of course, impact the development and implementation of green technologies. This can happen on an industry level, for example, when automobile fuel efficiency technology is improved in response to rising CAFE standards.
It can also happen on a smaller scale and affect one company at a time, such as MaxWest Environmental Systems (Maxwest), which has developed gasification technology to break down sewage sludge.
The U.S. Environmental Protection Agency (EPA) recently ruled that MaxWest’s patented gasifier is not an incinerator and therefore will not be regulated as such. According to the company, this means the technology can be developed and implemented at a lower cost to municipalities (see the press release here).
MaxWest owns at least one patent and one published patent application relating to its gasification technology. U.S. Application Publication No. 2013/0195727 (‘727 Application) is entitled “Fluidized bed biogasifier and method for gasifying biosolids” and directed to a gasifier and methods of gasifying biosolids obtained from sewage sludge.
A fluid bed gasifier (200) includes a bubbling reactor bed section (204) which receives sewage sludge through feed inlets (201) and flue gas through a flue gas inlet (203). The gasifier has a freeboard section (205) between the reactor bed section (204) and the outlet (210) of the gasifier.
A cyclone separator (207) separates material exhausted from the fluidized bed reactor into clean producer gas for recovery and ash for disposal. An oxygen monitor (209) may be used to help control oxygen levels in the gasification process together with a producer gas control (208), which monitors oxygen and carbon monoxide levels in the producer gas.
It appears that the control of oxygen levels was critical to the EPA ruling. According to the ‘727 Application, the biogasification process occurs in an “oxygen starved environment” which prevents combustion. Because there is no combustion, the gasifier is not classified as an incinerator.
An older gasifier technology is described and claimed in MaxWest’s U.S. Patent No. 7,793,601 (‘601 Patent), issued in 2010 from an application filed back in 2005. The ‘601 Patent is entitled “Side feed/centre ash dump system” and directed to an apparatus for gasifying solid fuel where the biomass feed material is introduced into the primary oxidation chamber (400) through in opening (408) in the side of a wall (402) or in the floor of the chamber (400).
The wall (402) has multiple layers, and the innermost layer (405) is made of a high-temperature refractory material capable of withstanding elevated temperatures. According to the ‘601 Patent, the wall (402) is therefore capable of allowing oxidation of biomass while maintaining a tolerable skin temperature on the outside of the wall.