How UAF is Building What May Be the Last New U.S. Coal Plant
By John Solan, P.E., Mike Ruckhaus, P.E., and Chilkoot Ward, P.E.
On a quiet Friday at 5 p.m. in December, 1998, the outdoor thermometer at the University of Alaska Fairbanks showed minus 20 degrees Fahrenheit. Inside the UAF Atkinson power plant, an aging tube in the Unit 1 power stoker burst under 625 pounds per square inch of pressure, filling the facility with steam.
Steam condensation tripped off the plant uninterruptable power supply, which in turn shut off power to the control system, shutting down the plant and pitching the entire campus into darkness. Frigid air began attacking the buildings and dorms that were heated by the steam system from the Atkinson combined heat and power plant. Meanwhile, computer networks and communications systems at the sister campuses in Juneau and Anchorage failed due to their reliance on facilities and equipment located on the Fairbanks campus.
|Cold weather tenting for the Atkinson Heat and Power Plant retrofit project at the University of Alaska Fairbanks campus. The plant is being overhauled at a cost of $245 million. Photo courtesy: Stanley Consultants.|
If the plant staff didn’t move quickly enough, untold millions of dollars’ worth of damages would occur, from frozen plumbing and HVAC systems to the water treatment plant to damaged research equipment and lose priceless in-progress research specimens and samples.
The top priority was to dry out the campus switchgear and restore the power supply to the campus. Once the switchgear was functional, the staff restarted the three undamaged boilers. Working through the night, they restored light and heat to the campus in 12 hours. They would repair the ruptured tube and restart the remaining boiler later that week.
Thankfully, no one was hurt in the Dec. 11, 1998 incident. Although a crisis was averted, the event served as notice to UAF that its two end-of-life boilers, installed in 1964, were a catastrophe away from significant damage to the university’s infrastructure.
A Campaign Begins
UAF is a university looking to the future. Founded in 1917, the university has 10,000 students and 2,000 faculty and staff at the Fairbanks campus, which includes 3.4 million square feet of academic, research, administrative and housing space. Research funding, which grew from $56 million in 1997 to $108 million in 2010, was one of the key drivers in its expansion.
UAF needs energy generation to grow. A $108 million life sciences teaching and research building, a $5.3 million arctic health greenhouse, $4.7 million energy technology facility and a $110 million engineering building have been built or are in the construction stage. In addition, partly because it has its own source of heat and power, UAF is considered a place of sanctuary for the surrounding community in case of emergency, including floods and earthquakes, therefore a reliable source of energy was important.
UAF was witnessing campus growth that exceeded its aging utility service capacity, which operated on technology developed in the 1890s. No significant utilities investment had been made since 1999. As a result, it developed a campus utilities development plan in 2006, which was followed by a series of reports and discussions with local and state political bodies. It culminated in the state funding $3 million for a preliminary engineering study to evaluate technology and fuel options, and the effort was awarded to and performed by GLHN Engineers in 2010.Cost Comparison
The Coal Decision
Engineers started their analysis with the big picture: Fuel supply and emissions. The mission was to produce energy and more of it; yet because Fairbanks is in a valley clouded with wood smoke from homes and businesses, the area was classified as a non-attainment area for Pm2.5 under EPA standards. UAF needed a larger plant that produced more energy for future campus expansion but couldn’t exceed its current emissions level. It would need a solution with emissions characteristics that were far lower than the existing equipment could accommodate.
Temperatures in Fairbanks range from 90 degrees Fahrenheit in the summer, to 60 below in the winter. In 2011, the university generated 57,000 MW-hrs annually and purchased another nearly 9,000 MW-hrs from the local utility. Chilled water production for air conditioning amounted to 3.9 million ton hours.
While UAF would have loved to use alternative energy sources to generate power, it wasn’t realistic. In January, it would require 4,900 acres of photovoltaic panels in the paltry available light, even if energy storage was available. Biomass – wood or other organic fuel — requires 54,000 acres per year, or 50 acres per day. Installing wind turbines would require hundreds of miles of transmission lines due to the low average of wind speed in the area. Hydro power on the nearby Chena and Tanana rivers would take decades to develop and there is no viable source of geothermal.
Fuel cost was another major factor. The nearest natural gas pipeline is 400 miles away, so it wasn’t an option in the near or even long term. Liquefied natural gas ($17/MMBTU) must be trucked into Fairbanks, re-vaporized and then distributed via city gas lines, but the supply can become limited as the temperature falls. Fuel oil ($18.85/MMBTU) and buying power ($50/MMBTU) were also high cost alternatives. Coal, supplied by rail from 130 miles away, costs $3.67/MMBTU.
Fuel costs were only part of the formula, of course, along with capital and operational costs. In all, Stanley Consultants evaluated several options for UAF:
- Do nothing different and rehab existing boilers. The two older coal-fired boilers would produce 100,000 pounds of steam per hour and the remaining diesel boilers would generate 200,000 pounds of steam per hour. Cost, $25 million through 2024, including capital and operating costs. No allowance for campus growth. Reliability issues.
- Coal-fired gasifier, reciprocating engine and heat recovery system. Complicated arrangement with an estimated cost of $26 million, through 2024, including capital and operating costs. It produces power first rather than heat.
- Gasifier, gas boiler and steam turbine. Generates heat first, which is attractive in a cold climate, but is also complicated and costs $31 million through 2024. Would not net out emissions.
- Gas turbine generator, heat recovery steam generator. Would need liquefied natural gas storage and vaporization facility. Produces power first, rather than heat. Fuel costs high and no reliable source. Cost projected at $38 million through 2024.
- Gas boilers and steam turbines. Cost and issues same as gas turbine generator.
- Municipal solid waste gasifier and gas boiler with steam turbine was looked at but there were too many unknowns to develop a cost model.
- Buying electricity from the local utility to generate steam was cost prohibitive.
- Circulating fluidized bed boiler and steam turbine. Two 140 Kpph CFB boilers would provide 100 percent of future needs. Creates heat first with high efficiency. Cleaner technology that would net out emissions in the present and future. Cost, $24 million through 2024.
Given the economic and reliability factors, the decision for the last option surfaced as the best option. This also had the benefit that would allow UAF to retain its efficient combined heat and power generation that averages up to 70 percent efficiency. A circulating fluidized bed boiler creates heat first, ideal for a cold climate generation system. The two new boilers would be clean enough so that the steam capacity could be increased to meet future energy needs while staying under the existing emissions cap.
Building a new coal plant in today’s generation environment is unusual to say the least. The Department of Energy’s inventory of planned generators as of November 2016, lists only five planned conventional steam coal plants, including UAF. Three of those have indefinite construction dates, and the fourth, Two Elk Generating Station in Wyoming, has completed minimal construction. The UAF plant is 60 percent complete and scheduled for commissioning in early 2018 with commercial operation in November 2018. The new boilers could be the last conventional coal-fired units built in America, at least for many years.
|Steam drum lift. Photo courtesy: Stanley Consultants|
The Funding Campaign
UAF filed an initial capital request in Juneau for the plant’s funding and gained the support of Alaska Senator Pete Kelly, who served on the Senate finance committee. The state approved $245 million for the new plant in 2014, after failing to approve funding in 2013. It was just in time. Plunging oil prices caused a ripple of state budget slashing. One year’s delay would have killed the project.
With funding in hand, the project commenced. An issue arose immediately. It became apparent that two new boilers and new facilities would cost $50 million more than was funded, due to the realities of building a power plant in Alaska. The project team went to work on new plans: UAF would install one large boiler in place of two smaller ones. It would produce 240,000 pounds of steam per hour instead of 280,000 and forfeit some flexibility, but its redesign, along with eliminating administrative, maintenance and storage facilities, would allow the project to meet the budget.
Detailed Design Underway
In September 2014 UAF procured a Babcock & Wilcox CFB boiler. The company states that fluidized-bed technology reduces NOx and SO2 emissions by allowing the control of bed temperature and using reagents such as limestone as bed material. It can also burn biomass or waste fuels, which are difficult to burn in conventional boiler systems. The manufacturer’s experience and design shows that the CFB boiler brings high combustion efficiency, an economical design, higher reliability and availability, lower maintenance costs, reduced erosion, fuel flexibility and low emissions.
The key for UAF was to obtain a guaranteed Pm2.5 emissions rate from Babcock & Wilcox, and therefore not derail the emissions permitting process. While there was some debate, the manufacturer ultimately made the guarantee, despite its high-performance level. It would be one of the lowest Pm2.5 emissions guarantee for a coal boiler in the U.S.
As the detailed design process began, UAF had selected the construction manager at risk (CMAR) contractor; this early involvement would allow the project team to capitalize on the contractor’s construction expertise and implement it in the design effort. The CMAR contractor, Haskell Davis Joint Venture (Haskell Corp. and Davis Constructors), provided independent cost estimating and design review as each segment of the project developed. Stanley Consultants partnered with a local firm, Design Alaska, which performed civil, architectural, HVAC, plumbing and fire protection planning. Design Alaska also provided insight into artic engineering practices.
Engineering challenges for seismic, extreme weather conditions, and a space constrained site were increased when the design was also to account for UAF’s role as an essential facility in the community, a place of refuge. Buildings had to be able to functionally withstand seismic events. The soils underneath the facility were porous and sandy, therefore were subject to liquification in an earthquake. They had to be consolidated down to 50 feet deep before construction began.
The final design produced some novel features. Combustion air can be pulled from out outside or inside the building, depending on the time of year. In warm weather, an intake duct takes air from higher in the building, which takes advantage of heat collected in the upper building. It reduces the amount of pre-heating required before air enters the boiler.
Steam turbines exhaust low-grade heat that normally goes to waste. During winter, UAF’s heat recovery system captures exhaust heat from the turbine and transfers it via the chilled water distribution system for preheating the air into the buildings throughout campus. In the summer, the surface condenser is removed from service and the chilled water system functions normally.
The air-cooled condenser controls are designed for sub-arctic conditions. The system varies air flow over the ACC cells to ensure that no cells stagnate and potentially form ice. In addition to these features, some renewable energy generation will be installed. Solar panels that will be installed on the entire south side wall of the ash handling building will generate up to 45 kilowatts during summer.
|Installation of the steam turbine on its pedastal at the UAF Atkinson Power Plant. Photo courtesy: Stanley Consultants|
The permitting process was unremarkable. The emissions netting approach allowed the project to avoid non-attainment new source review for Pm2.5 as well as standard new source review for the remaining pollutants. Ambient dispersion modeling was also avoided.
The Alaska Department of Environmental Conservation granted a minor source permit for the redesigned boiler on Aug. 26, 2015 and a revised permit on Oct. 21, 2016. There was little public comment, because most residents understood there was no viable alternative to coal, and that the plant’s efficiency and pollution control capability would be an improvement of the continued operation of the existing coal boilers
Construction started during the summer of 2015 with compacting soils six months before the building’s foundation was laid in spring 2016. The soil was heated to prevent freezing. Construction was fully underway by the spring of 2016. The power island foundations were completed by fall of 2016 and structural steel erection had commenced and was proceeding.
Sub-arctic conditions continue to affect construction, with a plan to continue construction through the winter until temperatures hit minus 30. To date, only a few days have been cold enough to halt construction. To minimize productivity and schedule impacts, the temporary and permanent siding was installed on the turbine and baghouse buildings early so that workers would be able to work in climate-controlled conditions.
The new plant is designed to achieve a miniscule .012 pounds of Pm2.5 per MMBTU; to triple the plant’s heat and power output while improving efficiency by 20 percent. The new plant will emit only 20 percent of the nitrogen oxide 2 and 3 produced by the previous plant. Sulphur emissions are lower as well, while it allows reduced oil consumption and renewable energy can be purchased using the CFB boilers as a reliable base load. It will have one of the lowest emission rates for Pm2.5 of any coal plant in the U.S. For the near- and mid-term future, coal, using the latest available technology, was the right choice to power UAF’s growth.
John Solan is a senior mechanical engineer at Stanley Consultants in Denver. Mike Ruckhaus is senior project manager at the University of Alaska Fairbanks. Chilkoot Ward is UAF’s Director of Utilities.