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HomeMy WebLinkAboutSewardCityNews July 2015Seward City News - Business, City of Seward, Council, Technology Drilling Seward waterfront for ocean heat July 27, 2015 11:51 am·Views: 820 City Project Manager supervises as Denali Drilling starts a vertical bore test hole near the bike path, in the lawn adjacent to the Branson Pavilion, as they seek ocean warmth to heat City of Seward Buildings. Heidi Zemach photo. By Heidi Zemach for Seward City News – Denali Drilling, a firm contracted by the City of Seward, is drilling a 300’ deep vertical bore hole at the Seward Waterfront about 120-feet along the bike path near Branson Pavilion. Beginning Monday, July 27, they will drill a 6” steel casing to the depth believed to contain saltwater, in a project expected to last over the course of a few days. The city’s consultant, engineer Andy Baker, of Your Clean Energy, LLC, anticipates that the test well will show salt water temperatures laying deep beneath the surface of similar warmth to those currently found in nearby Resurrection Bay. If so, the warmer water can be tapped into to provide ocean-source geothermal heat for four city buildings—the Seward Library Museum, City Hall, City Annex building (old library) and the Seward Fire Station, through a connected closed-loop heat district. The Library museum and city annex are about a block away along Adams Street. “Some people drill for oil. Some people drill for natural gas. We’re drilling for heat,” said Baker, whose enthusiasm for this innovative pilot project is infectious. The warmer water currents found in Resurrection Bay are transported to coastal communities like Seward and Juneau from the equator in large ocean gyres. Baker believes they also lie in the Alluvial gravel, 300 feet below the developed waterfront area. The top layer of water probably consists of freshwater from the surrounding glacial mountains, and the lower layer consists of warmer seawater temperatures, he said. Baker was contracted earlier this year by the City of Seward to explore the financial feasibility of the heat-district concept, and has completed a preliminary report on his findings. The test well will provide access to the ocean resource and help assure its feasibility. If the test well temperatures prove out, then the City can make application to the Alaska Energy Authority renewable Energy Fund and compete for grant monies to design and construct a starter heating district to serve the four City buildings. In 2012, Baker led the design team for an ocean source heat pump system at the Alaska SeaLife Center, a large, significant Seward-owned waterfront aquarium building. They system was built in 2011 and has remained on line successfully for four years since start up. This innovative and cutting edge project has attracted interest across Alaska and in renewable energy circles both in the U.S. and overseas. The design proved that the bay’s temperatures are ideal for heating large buildings with ocean source heat pumps. Saltwater flows directly into the center basement from a water intake pipe in the bay, and then into a titanium plate heat exchanger where ocean heat is transferred to heat pumps connecting it to the building’s floor heating and water-heat system. The heat pump system has greatly reduced the center’s energy bill and carbon footprint, and has almost completely replaced its old diesel boiler heating system. Maintaining and operating a seawater intake pump system takes special skills and constant attention, however, as sea water is corrosive, and filter feeder marine life from the ocean will get into the pipe system and eventually biofoul them. A closed-loop geothermal system, where there is no seawater circulating, just an environmentally-safe antifreeze liquid, pre-heated by the underground seawater, is more reliable, and would be easier for the City to operate, Baker said. The system would circulate from the vertical ground loops by the bike path to the city buildings through closed a loop of piping that runs directly beneath the road or sidewalk. “We have one efficient building —the library, that is set up really well for this system by having the floor heat, and then we have the older buildings that are of course not as efficient,” said Seward Building Inspector Stefan Nilson, who was born and raised in Sweden, where use of geothermal energy is commonplace. He sees potential for the geothermal ocean-heat concept in Seward, not only for city buildings, but for private buildings located all along, or near the waterfront. Advertisement “With this system in place we can monitor and see how other similar, efficient, privately-owned buildings would fare with this system,” Nilson said. He’s been an enthusiastic proponent of efficient buildings, greater energy conservation, and hopes the City’s test well yields good results, and that the financial pieces come together to make the project affordable. “It will be nice to have a small Alaska town on the map, showing the pursuance of alternative energy and energy efficiency. That’s something that everyone involved is excited about.” “Yes, it’s an amazing untapped resource right in our yard, and I guess the surprise for me has been to learn that it’s proven and common in other cold climate parts of the world and so “new” to us Alaskans,” said Ron Long, Seward’s assistant city manager and community development director. He favors a deliberate, though cautious approach by the city to moving the project forward. “Seward’s become a focal point for a lot of interest around the state, mostly due to the success of the SeaLife Center’s system. There’s a shelf life for that interest though, and it’s important to seize the moment, so to speak. That was one of the reasons we put it forward, and in hopes of putting it to work in a local demonstration project that has good potential to lower heating costs.” Drillers piece the slurry pipe together. The large hole at the base of the drill stack will contain slurry extracted from the ground. Heidi Zemach photo. How The Drill Test Works Beginning Monday afternoon, Denali drillers plan to slowly drive 6” steel casing into the ground to 300 feet, drilling and advancing the casing along. On the third day, they’ll insert a 4” PVC screened well-pipe inside the casing. Then they’ll slowly pull the casing up and out, 20 feet at a time, leaving just the PVC screened well inside the ground. The pipe’s screened sections will create an open water column that matches the natural formation allow the surrounding water to flow into the pipe, but will keep out any silt or gravel, Baker said. Only its top 18-inches will be left protruding from the ground. The future vertical ground loops that would be used in the system would be buried six feet below the surface, allowing all waterfront park activities, biking, hiking, camping, to continue to take place, unfettered. The drilling will make some noise, and create mild ground vibrations during the daytime hours. Denali Drilling will use a large air compressor to break up rocks and gravel as the casing probes ever deeper, Baker said. Slurry will be excavated in the process, consisting of things like sand, silt and rock cuttings, which will be re-buried in a series of pits. Once the test well is completed, a marine data logger, about the size of a cell phone will be lowered into the hole several times per week to take measurements of temperature, salinity, and depth. The monitor should immediately reveal how deep the layer of fresh water is on the upper portion of the column, and how warm the sea water is below. Readings also will be taken at extreme high and low tides, and after major rain events to create a picture of how the temperatures in the deep water column are affected by those events. The data will allow Baker to estimate the heat capacity of the boreholes for heat pump use requirements, and determine whether the upper level of vertical loops require insulation in order to deliver the warmer temperatures from depth to city buildings. Baker will present his report and test-well findings to the City Council at a future meeting next month.