This Small Business Innovation Research (SBIR) Phase I project will integrate activated carbon production and high efficiency power generation. High-temperature steam and nitrogen-containing exhaust gas from a hydrogen-fueled engine will be used to drive the conversion of biomass to syngas and activated carbon in a single reactor. Reactor conditions will be studied to optimize the yield and composition of both carbon and syngas. The business context for this proposal is deployment at a wood pellet mill where heat and power from the gasifier are utilized to reduce the cost of pellet production. The carbon will be studied as an additive to pellets to increase the energy density and improve stability, two qualities which will address barriers to industrial markets for pellets. The product carbon will also be assessed for the treatment of acid mine drainage by the adsorption of metals. The broader commercial and environmental impacts of this research are due to the potential to increase the use of biomass, such as forest thinnings, to displace fossil fuels by high efficiency conversion through combined heat and power. By reducing the cost of producing wood pellets and increasing their value and reliability, pellet fuels can displace coal. The efficient and wide spread production of bio-carbon has application in the protection of water and soils as well as enhanced carbon sequestration. The widely distributed plants that will result if this initiative is successful can have a significant economic impact by creating jobs in clean energy and water quality.
Intellectual Merit In this NSF-sponsored, Phase-1, SBIR project MicroChem Technologies Inc. successfully completed a proof of concept of a biomass gasification system, the Pyroxy Process, that is planned to be deployed at the commercial scale of 3 MWth with integrated biomass gasification and activated carbon production. A hydrogen-rich gaseous product (syngas) was produced that can be utilized to produce heat and power at high efficiency. The gasifier co-produced the syngas with activated carbon under optimized conditions of temperature and residence time so the gas was free of contaminants without external gas conditioning. The PyrOxy Process is based on a theory of biomass thermal conversion that takes advantage of the sequence of biomass reaction pathways that are controlled by temperature and oxidation. Focusing on the production of both a gas and a solid, reaction pathways are controlled to a much greater extent than in other conversion systems, which results in optimized yields and compositions of each phase. The system has to accommodate the heat and mass transfer challenges as well. In Phase 1 we have shown that softwood pellets can be processed in a moving bed reactor by control of heating rate, temperature, steam, and oxygen levels, and separately controlled gas and solid residence times. The interaction of the syngas with the carbon product improves each product. The major research activities have been to design, build, shakedown, and operate a 2 kg/hour PyrOxy system that validated the hypothesis. Chemical analysis systems for the gases and liquids were established to determine yields and level of contaminants. Computer control systems and process monitoring capabilities were developed and installed and used for controlling the reactor to run in a safe and efficient fashion. After the initial shakedown, the reactor was routinely operated 1-3 times per week per the program plan. The emphasis in this Phase 1 project was on gasifier operation and gas quality. The major conclusions are: We have validated our hypothesis that control of operating parameters produces clean syngas and activated carbon. Operation was performed under conditions that gave no detectable syngas contaminants. High quality gas compositions were obtained: the H2/CO ratio was 2-3 (a conventional biomass gasification system has a ratio of 1); acetylene was absent from the product gas. One notable achievement was the robust physical properties of the activated carbon product, which averaged 12% mass yield from the wood feedstock. Activated carbon surface area was 450 M2/g. Broader Project Impact MicroChem Technologies (MCT) focuses on the intersection of bioenergy and water quality. The target markets are municipal, commercial, and industrial installations that have combined heat and power needs in the 3 MWth (e.g., a residential community of 1000 homes). Small scale production of energy from wood resources is a challenge because of the loss of efficiency generally encountered by producing power or fuels at small scale and expensive because of the higher capital costs associated with small scale systems. MCT overcomes these barriers by close integration of the heat and power requirements of the site. The advantages of working at small scale include the greater opportunities for heat utilization and the opportunity to take advantage of cheaper feedstocks when they are available. The market includes (1) distributed systems that require combined heat and power (CHP) and integrated water treatment, such as the modern dairy farm, or (2) only CHP, in which case MCT will utilize the activated carbon in separate applications for cleaning air and water. The goal is not to compete on the global commodity market for activated carbon or the wholesale power market. Rather, the goal is to identify opportunities in localized vertically integrated niches that take advantage of the growing demand for power from renewable resources and the increasing demands for clean water. Deployment at wastewater treatment plants will lead to wide geographical distribution over the United States. This will have societal benefits through the creation of jobs, both skilled and unskilled, and lead to on-the-job work force development. These will be public-sector profit centers that can both reduce costs and generate revenue for city and county governments. This could become a model for how communities can provide important services as well as providing clean, reliable energy and water. Similar power park and modular deployment options could be used by agricultural enterprises where the activated carbon is integrated with agricultural water and soil protection.
