PowerPoint Presentation

Brita MjosMay 19-August 15, 2014Alaska Center for Energy and Power

District Heating in Alaska

My name is Brita Mjos and my internship at ACEP this summer focused on district heating applications in Alaska. 1District Heating

HEATING MULTIPLE BUILDINGS ON THE SAME PIPE LOOPFROM ONE HEAT SOURCE

More efficient than each building having its own boiler

Adaptable to many heat sources

Provides space heating, domestic hot water, cooling, and industrial heat applications (greenhouse heat, milk and veg dehydration)

Can be part of a CHP system

Denali Education CenterDistrict heating describes a system where multiple buildings are connected to the same central heat source by a pipe that distributes hot water or steam. This design is more efficient than individual boilers in each building, and can utilize heat sources that would not be feasible on a smaller scale. The distributed heat can provide not only space heating, but also domestic hot water, and even industrial purposes like hotel drying rooms and food dehydrating. 2District heating can use diverse heat sources:

Coal (UAF campus, Downtown Fairbanks, Fort Wainwright)Biomass Wood (Tok, Mentasta, Fort Yukon, Gulkana)Municipal waste (ARCO man camp, Scandinavia)Human solid waste (Scandinavia)Geothermal (Chena HS, Juneau GSHP, Iceland)Heat recovery from generators (Cordova, Tok Green Machine, Fort Yukon)

Oil, natural gas, seawater HP, landfill methane capture

Coal unloading at Downtown Fairbanks power plantKaishan screw expander at Chena Hot Springs

District heating systems can tap diverse heat sources. In the case of Fairbanks, where coal is plentiful, less expensive than other fuels, and used for power generation, the hot steam that emerges from the steam turbines still contains enough heat to distribute it to fifteen miles of the downtown Fairbanks area. The UAF campus is also heated with residual steam from its coal-fired power plant. This is known as combined heat and power, or CHP. Other district heat systems in Alaska utilize waste heat from diesel generators, as well as geothermal hot springs, ground source heat pumps, and heat-specific boilers that use woody biomass. In villages with sewage and trash disposal problems, using the solid waste as a fuel for heat generation could be a solution. Scandinavia and Germany already heat cities with municipal and human waste incinerators. 3

http://www.chenapower.com/geothermal-power/

Chena Hot Springs geothermal power plant Toks chipper and biomass generator for CHPhttp://www.agsd.us/biomass/index.htmlhttp://www.agsd.us/biomass/index.html

Chena Hot Springs near Fairbanks is the only site in Alaska currently generating power and distributing heat from a hot spring, but exploration of several other sites is ongoing. These include Pilgrim Hot Springs near Nome, and the villages of Akutan, Atka, and Adak on the Aleutian chain. Tok successfully powers and heats its school and greenhouse with a woodchip-fired boiler, using wood harvested as part of a State fire mitigation plan. Existing systems are important for understanding where improvements can be made on future projects. For instance, the Tok CHP boiler generates sufficient power for the school, but much more heat than is needed. 4

Mentasta, installing a 5-building biomass DH loop summer 2014 Nome, a candidate for geothermal district heat

Gulkana, heating 9 buildings on cordwood district heat

Woody biomass is an abundant resource in Alaska. Several villages are in the process of constructing biomass-fueled district heating loops, which will offset expensive heating oil. Cordwood systems require a lot of work to ensure an adequate wood supply, which is a main reason some villages opt for pellet boilers instead. 5ConsiderationsEnergy Efficiency = #1 PriorityMinimize Heating Loop LengthSystem ExpansionPermafrostWater QualityExpenseAvailable Labor and Community Interest

I learned a lot about the elements of a district heating system a community should consider before proceeding. The most important factor is energy efficiency. Regardless of the fuel type, it will go much further if buildings are constructed with the northern climate in mind. Extra insulation, triple pane windows, and sealing all air leaks are some of the features Alaska construction should include. 6Field Trips

Coal boiler in downtown FairbanksInsulated pipe at ChenaUAF utilidorI visited several locations around Fairbanks with district heating systems in place. They varied from a sports store heating the retail shop and a small cabin with a cordwood boiler, to the downtown Fairbanks Aurora power plant which heats 15 miles of the city with waste heat from coal power generation. UAF Facilities gave me a tour of the utilidor which holds 5 miles of distributed steam pipes, as well as other utility lines. I also visited Chena Hot Springs and the distributed geothermal heat system there. 7DoE, Idaho universities collaboration KodiakRecommended Upgrades: Lighting, belts, insulate freezers, water conservationKodiak Fishmeal Company accepts waste from all processors and locals for high-value fishmeal, bone meal, and fish oilIs there an application for a seawater heat pump, like the Seward Sealife Center?Chillers? Dryers? Water heating? What will Kodiak sites choose to implement?UAF as future IACIndustrial Assessment Center Kodiak Seafood Processors

I traveled to Kodiak with a team conducting energy efficiency evaluations of three seafood processing plants. We found numerous opportunities for efficiency improvements, particularly in the lighting, water use, and refrigeration systems. Having commercial fished in the past, I found the processing side of the fishing industry an insightful comparison, especially when considering the sustainability of the industry beyond the fish stock management. Kodiak is a noteworthy community on the energy front, as the city is already able to turn off its diesel generators completely and rely on the power from 6 wind turbines above town and a hydroelectric dam. 8Handbook

Annotated bibliography

The tangible products of my internship include a handbook on district heating, specific to Alaskas conditions, so an agency or community considering a district heating project can learn the basic components and considerations of a system. I also compiled an annotated bibliography of the sources I referenced, which provide helpful information about the many aspects of district heating. Thank you, ACEP!

George RoeGwen HoldmannMarcia CassinoChris PikeAll staff and interns who answered my questionsU.S. Dept. of Energy Mike Ruckhaus, UAF facilitiesBuki Wright and Matt Burdick, Aurora Joel Buth, Goldstream SportsThomas Lund, Chena HS internRex Goolsby, Dave Frederick, Ray Spears, Dave P-MJohn Gardner, IACCCHRC staff

Thank you to ACEP for the opportunity to work here this summer. I learned a lot! Thank you also to the many community members who shared insights with me and answered many questions.