By Gale Morrison, Associate Editor

The U.S. Department of Energy is sending out a call to thinkers in business and academia to help redesign the technology of the energy industry. The DOE says it is time to engineer the reality of a sweeping energy plan called Vision 21.

A digital rendering of a Vision 21 coproduction plant, created of modules to produce a wide variety of products.

The first draft plan has already been published, and at a workshop this summer, a range of experts, including technical developers, utility executives, researchers, professors, users, and interested engineers, will get to comment on it.

In preparation now and expected to go out by the end of the summer is a solicitation to the energy intelligentsia to begin research and development into the practicality and feasibility of the DOE's next-generation energy plants.

Officials believe they have worked out a broad and realistic strategy for producing energy from available fossil fuels in a manner that jibes with economic and environmental needs.

Key players in the project include Lawrence Ruth, who heads the Vision 21 coordinating committee, and Victor Der, director of coal and power systems at the DOE in Washington. They and others at the Department of Energy call Vision 21 a broad concept to drive research and development of cleaner, more flexible, and more efficient energy generation. Under the plan, multiproduct energy facilities will be built in the second and third decades of the approaching century.

With support from its field office, the Federal Energy Technology Center, where Ruth works in Pittsburgh, the agency is providing an answer for the energy generation industry to the lingering question of what to do in the face of mounting evidence of global climate change. The DOE has decided to take a cooperative approach to generating energy from fossil fuels with almost no emissions.

A Vision 21 plant will be flexible in the fuel it can burn and will emit almost no pollutants. The realistic expectation is not zero emissions, noted Darren J. Mollot, Washington headquarters representative to the Vision 21 coordinating committee. As he pointed out, "We like to say 'negligible.'"

At present, the energy sector is responsible for about three-quarters of humankind's carbon dioxide emissions, one-fifth of its methane, and plenty of nitrogen oxide, all of which share blame as greenhouse gases. To reach its ambitious goals for high efficiency with negligible emissions, Vision 21 will draw on energy technologies such as coal gasifiers, oxygen separation membranes, and advanced fluidized bed combustors, which are already being developed under other programs. The program also will sponsor the development of energy-generating tools and systems of its own.

The plan aims to integrate concepts for high-efficiency energy generation involving new techniques and designs, like those in integrated gasification combined cycle, or IGCC, plants and advanced pressurized fluidized bed plants. The R&D blueprint specifically excludes conventional petroleum refineries and coal slurry preparation plants, and on the opposite end of the scale it also excludes biomass-only plants.

The DOE believes that the world can have a new class of fuel-flexible facilities that can produce electric power, process heat, and high-value fuels and chemicals, and at the same time put out virtually no noxious, sulfuric, or otherwise objectionable emissions. These coproduction plants will be capable of a variety of configurations to meet differing market needs.

The Energy Department's plan will garner special attention in certain quarters because it allows for maintaining the energy mix, which leaders in the energy generation industry have been championing.

In February, James J. Markowsky, executive vice president for power generation at American Electric Power of Columbus, Ohio, addressed some of the technological challenges of the Kyoto Protocol—the world environmental treaty still up for ratification—to a gathering of Congressional and White House representatives.

The Kyoto Protocol calls for CO₂ emissions in 2010 to be 7 percent less than they were in 1990. Markowsky, in a presentation on behalf of ASME, pointed out that to meet that goal the United States would have to retire most of its coal-burning plants, which right now generate about 56 percent of the country's electric power. He said natural gas, given today's technology, is the only available way to generate the power the United States needs and still meet the emissions standard. Citizens in the United States, Japan, and other leading industrial countries are turning away from nuclear power and the ecological risks of hydroelectricity. He pointed out that so-called "renewables," solar and wind energy and the like, will not fill the gap.

Currently the nation burns about 3.5 trillion cubic feet of natural gas to generate about 11 percent of the country's electric power. Markowsky predicted that, if the country came to rely principally on natural gas for its electricity, consumption for power generation could grow to more than 13 trillion cubic feet in 2010 and almost double 20 years later, to 25 trillion cubic feet in 2030. That forecast assumes that the country will be able to buy 250 million metric tons worth of CO₂ credits on the world market each year. Natural gas consumption would be much higher if credits were not available.

Markowsky said that, if power generation consumes 13 trillion cubic feet, he doubts that the country can gather and distribute enough natural gas for all its needs—a total of 30 trillion cubic feet—by 2010. What's more, a country reliant almost exclusively on a single fuel would run serious political, economic, and possibly military risks. According to Markowsky's predictions, the country would have to rely on natural gas to produce 76 percent to 87 percent of its electric power in 2030, depending on the availability of pollution credits. He suggested that, instead, the country develop an energy industry using a range of fuels and, to give it a chance to be worked out, set a later deadline of 2030 for meeting the Kyoto Protocol's requirements.

Ruth and his colleagues at the DOE are preparing the formal solicitation that will go out by the end of the summer and will invite industry and academic researchers to pick up chunks of the R&D work that Vision 21 will entail.

The integrated gasification combined cycle plant in Tampa, Fla., is one of three demonstration sites under the DOE's current clean coal technology program.

"The specific details of the solicitation are still being worked out so I can't pass them along yet," Mollot said. "However, it won't be prescriptive. The goals will be stated, such as 60 percent efficiency for coal/solid fuels, and 75 percent efficiency for natural gas systems, and the industry teams who respond to the solicitation are free to propose innovative approaches to achieve those goals."

Vision 21 lays out several ambitious goals. As Mollot pointed out, energy-generating efficiencies should be 60 percent using coal and 75 percent using natural gas. The current fleet average efficiency for coal plants in the United States is 33 percent, according to DOE estimates, and efficiency for state-of-the-art coal plants runs between 35 and 42 percent. Simple cycle natural gas turbine technology is 35 to 40 percent efficient, and natural gas combined cycle, 45 to perhaps 58 percent.

Boiler operators. which tend to use coal, base their efficency calculations on the high heat value of their fuel. The calculations tend to be more conservative than the measures used by turbine operators, whose fuel is more likely to be natural gas and whose calculations are based on the fuel's low heat value. As a result, the efficiency ratings for the different types of plants and the fuels are not directly comparable. High heat value, which yields a lower efficiency rating, includes heat released by condensation of water vapor after combustion.

Vision 21 plants, when they are built, will not have identical configurations, Mollot said. Instead, each will be a series of interconnected modules. Future designers will integrate these modules to meet specific market needs. A Vision 21 plant might serve as the hub of an industrial complex, providing steam or heat in addition to electric power. Another configuration might coproduce high-value chemicals or fuel gases for neighboring manufacturing facilities. Or it might be a power plant-coal refinery combination, producing electricity and transportation-grade liquid fuels.

At the same time, the goal is for very low emissions of traditional pollutants, including such smog- and acid rain-linked compounds as NOx and SOx. At the same time, carbon dioxide emissions—which loom so large in the greenhouse theory—would be reduced 40 to 50 percent by efficiency improvements and possibly could be reduced to zero, if those efforts are coupled with carbon sequestration.

The energy plant also could produce clean, affordable transportation-quality fuels at costs equivalent to $20 per barrel or less (in 1998 dollars), high-value chemicals, and industrial-grade heat and steam with potential for gas production.

The DOE is reviewing proposals now for what it calls an early entry coproduction facility. The program dovetails with Vision 21, but is not directly a part of it.

According to Gary Stiegel, the Federal Energy Technology Center's product manager for IGCC in Pittsburgh, the goal is to stimulate design and testing to lay the groundwork for advanced coproduction plants. Industry has been challenged to develop technology for plants that will yield low emissions and high efficiencies, will require low capital expenditures, and will turn out at least two products, one each in at least two of three categories: power, chemicals, or fuel.

Stiegel said that the program has been in development for the past few years. It shares with Vision 21 the theme of coproduction and higher efficiency, although the focus on efficiencies in the early entry program is not as strict.

The program will proceed in three stages. First will come concept definitions, a feasibility study, and the identification of goals and risks. Second will be R&D in areas of technical uncertainty to mitigate risk. The third stage will update the original phase one design and develop a strategy for designing, building, and operating real plants.

The DOE's purpose is to encourage industry to develop and deploy coproduction technology sooner than might happen without the additional incentive of the government's program, Stiegel said.

At least some of the knowledge that the program is expected to harvest will likely be adopted by Vision 21. The department's clean coal technology program also will feed ideas to Vision 21. The clean coal program has two integrated gasification combined cycle energy plants running, and a third is starting up. Tampa Electric Co. has one in Polk County, Florida, and PSI Energy runs the Wabash River station near Terre Haute, Ind. The third facility, which has yet to begin producing electricity, is Sierra Pacific Power Co.'s Pi-on Pine plant at Reno, Nev.

In an IGCC plant, the CC, or combined cycle, starts conventionally enough by using gas turbines to generate power, but it adds a wrinkle by directing exhaust heat into a boiler to produce steam, usually to drive a steam turbine for additional power, thus getting a double hit from the same fuel. The IG, or integrated gasification, comes in as an emission-reducing technology added to the mix. By converting coal to gas before burning, the process reduces many of the objectionable emissions—including particulates, SO_x, and NO_x—of conventional coal combustion. CO₂ emissions come down, too, because of higher efficiency. With a yield that has already hit 45 percent and may go past 50, gasification and the combined cycle make for more efficient power generation than the traditional way of burning coal directly, which tops out at 42 percent.

The Wabash River plant, for example, partners PSI Energy with Dynegy Inc. in the upgrade of a conventional plant. The project is funded about 50 percent by the Department of Energy. The IGCC system at the Wabash River station generates a net 262 MW. Dynegy, which is based in Houston, runs the gasifier, an oxygen-blown, two-stage entrained-flow system that produces a medium-Btu synthetic gas from high-sulfur bituminous coal. PSI's parent, Cinergy Corp. of Cincinnati, has a deal to buy out Dynegy's contract and run the gasifier itself.

The city of Lakeland, Fla., has an agreement with the DOE to set up a clean coal demonstration plant of another sort. This is an advanced pressurized circulating fluidized bed plant, which could be in full operation by 2005, said the DOE's project manager, Don Geiling. The project will combine the benefits of fluidized bed combustion with partial gasification of coal.

In this plant design, a carbonizer receives a mixture of dried coal and limestone. The coal is partially gasified to produce a syngas and a char/limestone residue. The limestone absorbs sulfur compounds generated during the mild gasification.

The char and limestone mixture goes to a pressurized circulating fluidized bed, where it joins a stream of crushed fresh coal and is burned. The exhaust gases from the fluidized bed combustion are hot, about 1,600°F, and rich in oxygen. They are cleaned and sent to a gas turbine topping combuster, which is also the destination of the syngas created in the carbonizer. The new mixture burns very hot, pushing the efficiency of the plant's gas turbines. The gas turbine's primary job is to drive a generator, but hot exhaust passes through a waste heat recovery boiler to generate more steam, which is added to the output of the fluidized bed boiler to drive a steam turbine. The gas turbine produces the compressed air that feeds the fluidized bed combustor.

According to the DOE, the net impact of the addition of the topping cycle is an increase in both power output and efficiency. The first-of-a-kind 240-MW plant is expected to have a heat rate of 8,406 Btu/kWh or an efficiency of 40.6 percent, based on high heat value.

The DOE's plans also will consider integrating R&D biomass gasification and combustion with next-generation fuel cells and high-performance turbine technology.

In the past, many energy R&D efforts were carried out independently, each progressing toward a stand-alone facility. While some technologies likely will be introduced into the market as individual facilities, Energy representatives have said, "The ultimate high-efficiency, most economical, and cleanest energy complex in the future will likely be a combination of these advanced technologies integrated into a variety of configurations."

The Vision 21 plant will be capable of using a variety of fuel feedstocks, including coal and natural gas, perhaps mixed with biomass or municipal wastes.

According to the DOE, a Vision 21 plant could produce a slate of products—electricity, liquid or gaseous fuels, and industrial-grade heat and steam—from a diverse slate of feedstocks. This "new fleet of energy facilities could be deployed in the 2010 to 2030 time frame," the agency has said. The draft plan lays out five program elements: systems analysis, enabling technologies, supporting technologies, systems integration, and plant designs. The analysis phase will consider markets and economics, will define and evaluate process, and will set requirements.

Among the enabling technologies that Ruth and his colleagues rank as most important are gas separation, fuel-flexible gasification—that is, the creation of synthetic gas from biomass or other energy sources besides coal—and advanced combustion systems.

Supporting technologies include materials. For instance, program planners say that higher-strength, corrosion-resistant, and more durable materials will be needed for future energy production. Improved ceramics will be necessary for the high-temperature membranes needed for gas separation.

Specifically, one of the needs is a less costly means of producing oxygen for the gasification process. To replace the costly cryogenic air separation used today, R&D will be conducted on innovative membranes. Similarly, advanced membranes, some adapted from declassified uranium enrichment processes developed for national defense, could offer a better way to separate a pure stream of hydrogen from the coal-derived gases for use by a fuel cell or in a coal-to-liquids process.

Materials research is needed to develop the groups of catalysts and sorbents for coal conversion and pollutant removal. In particular, sorbents will be needed to work in the hot gas streams exiting a coal gasifier or combustor.

Once the systems integration phase has put new and refined techniques together in reliable, serviceable subsystems, the program will move into designing plants that ultimately will operate on a commercial basis.

Gasification and gas reforming—that is, the separation of natural gas into carbon monoxide and hydrogen as building blocks for chemicals—are core technologies for Vision 21 because they produce a gas stream that can be burned for electric power, or used as a source of hydrogen for a fuel cell or chemical process, or processed as a fuel gas for industrial plants. To enhance the fuel flexibility of Vision 21, R&D will be conducted to determine how best to gasify fuel mixtures, such as coal and biomass or fuel-rich wastes.

Markowsky of American Electric Power sees an opportunity for U.S. industry to reap great rewards by developing clean coal technology and then transferring that know-how abroad.

There is a rapidly developing world that can't afford to import oil or natural gas to curb pollutants, but those countries need power just the same and will use what's at hand: coal. Markowsky outlines one possible scenario that lets everybody come away a winner. U.S. industry ships its clean-coal technology to China, India, the Philippines, and other developing countries, which would get the power they need for their growing economies without the increase in pollution they would suffer by burning coal.

They pay for the technology not in cash, but with a swap of pollution credits based on the emissions they have avoided—maybe those 250 million metric tons of credits that Markowsky figures into other predictions.

The DOE believes that Vision 21 operators will have to fine-tune plant operations to accommodate changes in fuel feedstocks and other variable conditions. The use of artificial intelligence and new sensor technology to control plant operations will be a key R&D effort, officials said.

Before an investment is made in construction, researchers plan to demonstrate a virtual energy plant. Mollot makes it sound like an advanced and very practical version of "Myst." A computer would hold the design of the plant and the theory of its technology. As Mollot described it, "You could go in and turn the knobs to see how things actually respond."

Tom O'Brien, a research scientist at the Federal Energy Technology Center's office in Morgantown, W.Va., sees the task as a merger of state-of-the-art engineering and visualization software to create a vastly more adaptable program than is currently available.

"We want to put everything computer-related under one umbrella," O'Brien said. The goal is to create a program that can shift from plant schematics to a 3-D physical visualization and then let a user click on a vessel to launch a fluid analysis of the chemical reaction taking place inside it.

The virtual energy plant program will combine finite-element analysis, computer-assisted design, virtual reality, computer fluid dynamics, event simulation, and a variety of other database, analysis, and visualization software, most of which is available right off the shelf as separate applications. The challenge is to put it all together in a single bundle.

Another area of consideration at the Department of Energy is carbon sequestration.

According to Energy officials, if a Vision 21 plant, with its reduced emissions, can be coupled with a practical method of carbon sequestration, the result could be a facility with little environmental impact except its footprint. This spring, the DOE issued a 223-page report dubbed "Carbon Sequestration: State of the Science." In releasing it, Secretary of Energy Bill Richardson said the technology "could provide new options for the world to respond to climate change concerns."

Carbon sequestration, the capturing and permanent storage of carbon-containing gas, is not the brainchild of Vision 21 and is being developed separately. According to Mollot, the DOE's current plans are to give energy plants the option of being "sequestration-ready." Readiness would consist of designing the plant to turn out, as one of its products, a concentrated stream of CO₂. That stream could feed a carbon sequestration system that could be added later. One possible method of making a plant sequestration-ready would be to separate incoming air, perhaps with a membrane, and send oxygen and carbon dioxide to the combustor. Burning fuel in a mixture of oxygen and carbon dioxide would produce an exhaust stream that contains CO₂ and water vapor.

According to the Energy Department's timetable, the first spin-off technologies developed under Vision 21, possibly new oxygen and hydrogen separating membranes or advanced turbine systems, may be introduced before 2010. The goal of the program is to have workable systems ready to be designed into commercial energy plants by 2015.


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