Gasification is used to convert a solid feedstock, such as coal, petcoke, or biomass, into a gaseous form, referred to as synthesis gas or syngas, which is primarily hydrogen and carbon monoxide. Pollutants can be captured and disposed of or converted to useful products more easily with gasification-based technologies compared to conventional combustion of solid feedstocks. Gasification can generate clean power, and by adding steam to the syngas and performing water-gas-shift to convert the carbon monoxide to carbon dioxide (CO2), additional hydrogen can be produced. The hydrogen and CO2 are separated–the hydrogen is used to make power and the CO2 is sent to storage, converted to useful products or used for enhanced oil recovery (see Gasification Systems Program Research and Development Areas figure). In addition to efficiently producing electric power, a wide range of transportation fuels and chemicals can be produced from the cleaned syngas, thereby providing the flexibility needed to capitalize on the changing economic market. As a result, gasification provides a flexible technology option for using domestically available resources while meeting future environmental emission standards. Furthermore, polygeneration plants that produce multiple products are uniquely possible with gasification technologies.
Gasification Systems Program Research and Development Areas are in color. Grey sections are part of other closely aligned DOE/NETL Research Technology Programs. (click to enlarge)
The Gasification Systems program is developing technologies in three key areas to reduce the cost and increase the efficiency of producing syngas: (1) Feed Systems, (2) Gasifier Optimization and Plant Supporting Systems, and (3) Syngas Processing Systems:
FEED SYSTEMS–Research is underway to reduce the cost and increase the efficiency, through design and advanced plant integration, of fuel and oxygen feed to commercial gasifiers. High-pressure solid feed systems will expand the use of our Nation's Western low-cost, low-rank coals for high-pressure gasifiers (currently limited to more expensive fuel), enable co-feeding of coal with other advantageous fuels (such as biomass), and encourage higher pressure (and therefore more efficient) operation of dry feed gasifiers. Advanced air separation technologies, such as ion transport membrane (ITM) technology, will lower the cost of oxygen production through reduced capital costs, and result in more efficient integrated gasification combined cycle (IGCC) power plants through turbine integration, as compared to today's commercially available, energy intensive technology for oxygen production–cryogenic air separation.
GASIFIER OPTIMIZATION AND PLANT SUPPORTING SYSTEMS–Gasifier Optimization and Plant Supporting System technologies under development are targeted at increasing gasifier availability and efficiency, improving performance, and reducing the capital and operating costs of advanced gasification plants. Ongoing research and development projects are developing more durable refractory materials, creating models to better understand the kinetics and particulate behavior of fuel inside a gasifier, and developing practical solutions to mitigate the plugging and fouling of syngas coolers. Future work will focus on the development of a cutting-edge gasifier, which will start with multiple competing concepts to support the most aggressive and successful technologies being developed, both in the Gasification Systems program, and other Department of Energy programs. Possibilities include advanced concepts to efficiently gasify low-rank coals, hybrid coal-natural gas gasifiers, and catalytic gasification for use with fuel cells for power production. Future work will also aim to reduce the amount of water used in gasification plants and integrate technologies throughout the plant and beyond in a holistic approach to increase efficiency and reduce costs.
SYNGAS PROCESSING SYSTEMS–A major cost element in gasification plants is converting raw syngas into a clean and specific gas used to create the plant's target product suite. High-hydrogen, low-methane, ultraclean syngas is versatile and can be used for power production with CO2 capture, fuels or chemicals production, and for many polygeneration applications. The work underway emphasizes technologies (e.g., advanced hydrogen membranes) that can be efficiently integrated into the plant, optimized with the temperature and pressure requirements of other systems, and meet product delivery specifications. The technologies being developed are focused on high-efficiency processes that operate at moderate to high temperatures and clean syngas of all contaminants to the extremely low levels needed for chemical production–often significantly lower than the U.S. Environmental Protection Agency required levels for power plants.