Transmitting development strategies18 August 2009
Brian Yanity presents a review of regional hydro power development strategies involving proposed international transmission lines connecting the US state of Alaska and Canada
Southeast Alaska is blessed with abundant water and steep terrain, resulting in a huge hydro power resource. The total theoretical hydro potential of SE Alaska is probably in excess of 10,000MW of capacity, with only about 200MW of this potential already tapped. Much of this potential will not be developed due to environmental concerns, or is located in protected wilderness areas or national parks. However, hundreds of remaining hydro power sites (mostly small-scale) could be developed with minimal environmental impact. Most of the region’s existing and proposed hydroelectric sites are lake-tap developments, on relatively small drainage basins with heavy runoffs. These lakes, typically formed by glaciers which receded after the last ice age, are perched at higher elevations, with tunnels or penstocks leading to powerhouses at lower elevations. Lake-tap projects often do not require a dam, and thus tend to have relatively low environmental impacts.
Regional hydro power resource assessment studies in SE Alaska date back to the 1920s, with the first report being “Water Powers of Southeastern Alaska” (US Forest Service, 1924). In the 1940s, the comprehensive study Water Powers Southeast Alaska (Federal Power Commission and US Forest Service, 1947) evaluated over 200 potential hydro power sites in SE Alaska, and also discussed a regional transmission system to interconnect hydroelectric plants and communities. The last regional study specific to small-scale hydro resources was commissioned by the US Army Corps of Engineers (CH2M Hill, 1979). This 1979 study was a reconnaissance-level analysis of mostly small (less than 10MW) run-of-river sites near twenty small communities in SE Alaska. A more up-to-date region-wide small hydro resource assessment is needed.
SE Alaska’s largest hydroelectric plant is the 78MW lake-tap Snettisham facility near Juneau. In addition, the region has sixteen existing hydroelectric plants in the small (1MW-50MW) category, six mini hydro plants (100kW-1MW), and at least ten micro hydro (less than 100kW) installations, as listed in Table 1. There are probably more micro hydro installations located on private property than listed in Table 1, but public information on such facilities is hard to find. Table 2 lists plants proposed or under construction.
Regional transmission line proposals
Utilities, local governments, and industry in SE Alaska have long proposed a variety of electrical interconnections between communities and hydro plants as part of a comprehensive regional electric power system. The benefits of new electric transmission lines include reducing the need for nonrenewable diesel generation, stabilization/equalization of power rates, increased regional electric system reliability, and the creation of revenue from the export of power. Potential environmental benefits of interties include the reduction of greenhouse gas (GHG) emissions though the reduced use of diesel generation and oil-fired heating. Energy security, and improving the reliability of the region’s electric grid, is of great interest after the city of Juneau was cut off from the Snettisham hydroelectric plant twice in the past year. In April 2008 and January 2009, avalanches damaged the Snettisham-Juneau transmission line, forcing the city to temporarily rely on expensive diesel power. The two main challenges facing both transmission line and hydroelectric development are high construction costs and long permitting/construction periods. Other important considerations, which are beyond the scope of this paper, include operation and maintenance costs of remote transmission lines and minimizing intertie energy losses.
A preliminary regional intertie study in 1980 for the Alaska Power Administration (Harstad Associates, 1980) concluded that a transmission system connecting Juneau-Snettisham with Petersburg, Wrangell and Ketchikan was technically feasible. The Southeast Alaska Transmission Intertie Study (Harza Engineering, 1987) for the Alaska Power Authority [now the Alaska Energy Authority], was the first comprehensive regional study on new transmission links in SE Alaska. Power system studies in the 1987 report recommended that a transmission grid for the region should be a predominantly 138kV AC system with high-voltage DC (HVDC) transmission for submarine cable segments exceeding 40km in length. The proposed regional system would also utilize the existing Snettisham-Juneau, Tyee Lake-Wrangell-Petersburg and Swan Lake-Ketchikan transmission lines at their present design voltage levels of 138kV.
The Southeast Conference, a regional economic development organization for SE Alaska, has commissioned several studies on new regional transmission lines since the 1990s. The Southeast Conference’s Southeast Alaska Electrical Intertie System Plan (Acres International, 1998) proposed an integrated electrical intertie system and 20-year power grid plan for the region. The study commissioned by the Southeast Conference was the two-part Southeast Alaska Intertie System Plan (D. Hittle & Associates, 2003), which proposed a regional intertie system to be built in eight phases.
The recent AK-BC Intertie Feasibility Study (Hatch Acres et al., 2007) for the Alaska Energy Authority further examined Southeast Alaska regional transmission intertie development scenarios with the possibility of power exports. The study area was constrained to the southern half of SE Alaska and bordering areas of BC. The 2007 study discussed many specific hydroelectric projects which, when combined with new interties, could be made economic if an interconnection with Canada was built. Figure 1 is a map showing the various existing/proposed intertie and power plant projects in SE Alaska and neighbouring parts of BC. All power plants shown on the map, existing and proposed, are hydroelectric except for the proposed Mount Hays wind farm, Bell Island geothermal and Wrangell Narrows tidal projects. Existing diesel generation facilities are not shown. Table 3 lists the various SE Alaska regional electric intertie proposals discussed in the 2007 report and previous studies.
The Swan-Tyee Intertie is a 92km, 138kV transmission line between the existing Tyee Lake and Swan Lake hydroelectric plants. The line will connect Ketchikan to Wrangell and Petersburg. The stated purpose of the Swan-Tyee Intertie was to transmit excess energy from the Tyee Lake plant to Ketchikan, with a primary benefit of displacing diesel generation in Ketchikan. Increased electric heating loads in Petersburg and Wrangell are reducing Tyee’s amount of surplus, but new generation projects in the area (such as the Thomas Bay complex) would also result in capacity-sharing benefits for Ketchikan. The transmission line is presently under construction by the Southeast Alaska Power Agency (formerly the Four Dam Pool Power Agency) and is scheduled for completion at the end of 2009. The total construction cost is estimated to be $100M.
Kake-Petersburg and Kake-Sitka Interties
First described in a 1981 reconnaissance report for the Alaska Power Authority (Robert W. Retherford Associates, 1981), the proposed intertie would connect the town of Kake to the interconnected Petersburg/Wrangell/Tyee Lake system. The primary benefit of a transmission line between Kake and Petersburg would be utilization of surplus generation at the existing Tyee Lake hydro plant to offset diesel generation in Kake. During the 1980s, both a Kake-Petersburg intertie feasibility study (Ebasco Services Inc., 1984) and the regional intertie reconnaissance study (Harza Engineering, 1987) for the Alaska Power Authority concluded that the transmission line was economically feasible. However, a 1996 feasibility study for the Alaska Department of Community and Regional Affairs, Division of Energy (R.W. Beck, 1996), concluded that the Kake-Petersburg Intertie was not economic compared to the base-case of diesel generation in Kake. However, the more recent AK-BC intertie report estimated that a $31M, 69kV Kake-Petersburg Intertie would be economic starting in 2011 (Hatch Acres et al., 2007). Supporters of the intertie project are presently seeking funding for final design and permitting activities.
A 72km submarine, 138kV DC extension of the Kake-Petersburg line to the Takatz site on Baranof Island was estimated to cost $160M in 2007 dollars. Takatz is the site of a proposed 28MW hydroelectric plant about 32km east of Sitka. Also, the Takatz site is near Baranof Warm Springs, a potential source of geothermal power. An interconnected Sitka-Takatz-Kake transmission system, in combination with a Kake-Petersburg intertie, would thus enable Sitka to be connected to the Petersburg-Wrangell-Ketchikan system. Another more futuristic possibility would be a submarine cable connecting Kake to the Snettisham-Juneau system.
The Thomas Bay Energy Development near Petersburg is a proposal consisting of three separate hydroelectric projects: Cascade Creek (80MW of potential), Scenery Creek (40MW), and Ruth Lake (20MW). Several different developers have put forward proposals for the Thomas Bay area’s three potential hydroelectric sites. The 2007 AK-BC intertie report estimated the construction cost of a Thomas Bay-Petersburg transmission line to be $66M in 2007 dollars, with a total length of 32km, with about half the length consisting of submarine cable (Hatch Acres et al., 2007). Potential project developers have more recently estimated the cost at a lower amount of about $30M. Another possibility is combining the Thomas Bay-Petersburg and Kake-Petersburg intertie routings, with Kake directly connected to Thomas Bay.
Recommended by the 1987 regional intertie study, the 27km Metlakatla-Ketchikan Intertie was evaluated in a 2000 reconnaissance report by R.W. Beck. The AK-BC intertie report estimated the construction cost of a 34.5kV Metlakatla-Ketchikan transmission line to be $14.9M in 2007 dollars, and that the line would be economic starting in 2013 or before (Hatch Acres et al., 2007). Metlakatla is located on Annette Island south of Ketchikan, and a new intertie to Ketchikan could encourage the development of the proposed 4MW Triangle Lake hydroelectric project on the north part of the island.
Prince of Wales Island
On Prince of Wales Island, the 34.5kV interties of the Alaska Power & Telephone (AP&T) Company connect the 4.5MW Black Bear Lake and the 2MW South Fork hydroelectric plants to the communities of Klawock, Craig, Thorne Bay, Kasaan, Hollis and Hydaburg. Together, these two hydroelectric plants provide the majority of power for Prince of Wales Island. While the island’s transmission lines currently operate at 34.5kV, they are designed and insulated for a capacity of 69kV. Expansion of the Prince of Wales Island power grid is planned to include the communities of Naukati Bay and Coffman Cove, both of which are now entirely dependent on diesel power. This AP&T grid extension project is funded and ready for construction. From Coffman Cove, an 80km DC submarine cable to Wrangell was estimated by the 2007 AK-BC intertie report to cost $170M in 2007 dollars (Hatch Acres et al., 2007).
On the southern part of Prince of Wales Island, a transmission line is planned to connect the AP&T grid to the proposed 5MW Reynolds Creek hydroelectric plant located about 16km east of Hydaburg. A joint venture between the Haida Corporation and AP&T, the Reynolds Creek project is construction ready, and is partially funded. The 1987 and 1998 regional intertie reconnaissance studies recommended a Prince of Wales-Ketchikan intertie as one of the last phases of the regional intertie system. The regional intertie report for the Southeast Conference (D. Hittle & Associates, 2003) estimated the cost of the Prince of Wales-Ketchikan Intertie to be $31.7M in 2003 dollars.
Juneau-Greens Creek Mine-Hoonah Intertie
The 1998 and 1987 regional intertie reconnaissance studies recommended the Juneau-Hoonah intertie as part of a longer connection including Tenakee Springs, Angoon, and Sitka. A 15km, 69kV submarine cable line connecting Juneau to the Greens Creek Mine, on Hawk Inlet, was completed in 2006. The Kennecott Greens Creek Mining Company purchases power from Alaska Electric Light and Power, the Juneau utility, which is in the process of building the first (15MW) phase of Lake Dorothy hydroelectric plant to meet most of the mine’s electric power demand. An extension of this line to Hoonah was estimated to cost $30M in a study for the Alaska Energy Authority (Emerman Consulting, 2006), although more recently the cost estimate has escalated to over $40M. Due to the cost of the proposed transmission line, Hoonah has re-focused on studying energy resources closer to the community, including three hydroelectric projects with an estimated potential of 600kW each: Gartina Creek, Water Supply Creek, and Elephant Falls. At present, Hoonah is entirely dependent on diesel generation.
A 1984 study for the Alaska Power Administration and the Northern Canada Power Commission (R.W. Beck and Associates, 1984) estimated that a Skagway-Juneau HVDC intertie, mostly submarine cable, would cost $35.8M in 1983 dollars. The 2003 regional intertie report for the Southeast Conference (D. Hittle & Associates, 2003) estimated that a Juneau-Haines 69kV, mostly overhead AC line cost $70M in 2003 dollars. A Juneau-Haines transmission line consisting of a HVDC submarine cable in Lynn Canal would have less environmental impact than an overhead transmission line onshore, and also much less risk of avalanche damage. Today, the estimated cost of a Juneau-Haines submarine cable HVDC intertie is roughly $150M.
Alaska-Canada transmission proposals
Alaska-British Columbia interconnection proposals
With the exception of BC Hydro serving the very small community of Hyder on the BC border, no electrical connection exists between Alaska and Canada. The most studied Alaska-BC (AK-BC) transmission intertie proposal is the Bradfield Intertie, which would
connect the existing Tyee Lake hydroelectric plant in Alaska to BC. The 138kV line would follow the North Fork of the Bradfield River, and then follow the Craig River over the US/Canada border into BC’s Iskut River Valley. A preliminary investigation for the Alaska Power Authority (Harza Engineering Company, 1988) proposed a transmission line between Tyee Lake and gold mining operations at Johnny Mountain Mine, BC, which is located about 20km from the US border. This report recommended a 67km, Tyee-Johnny Mountain 138kV line, which was estimated to cost $16.7M in 1988 dollars. The Johnny Mountain Mine only operated briefly between 1988 and 1990, although mining operations in this area may be restarted in the future. A 2006 report for Southeast Conference (D. Hittle & Associates, 2006) evaluated the Bradfield Intertie, and the Alaska Energy Authority’s recent AK-BC intertie study (Hatch Acres et al., 2007) provided further analysis. The 43km section of the Bradfield Intertie within the US (Tyee Lake to US/Canada border) was estimated to cost $32M in 2006 dollars, while the 50km Canadian section (US/Canada border to Forest Kerr) was estimated to cost $36M (in US dollars).
In BC, the backbone Northwest Transmission Line (NTL) has been proposed by British Columbia Transmission Corporation (BCTC), the BC provincial government, and other stakeholders in the northwestern part of the province. At this time, no decision has been made to proceed with constructing the NTL, and the project is undergoing environmental assessment studies. The Province of BC is seeking a partnership with the private sector to help fund the project, which is estimated to cost $400M (Canadian). This 335km, 287kV line would connect the existing BCTC grid at Skeena Substation (near Terrace) to the proposed Bob Quinn Substation in the Iskut River Valley, following the route of Highway 37. An existing 138kV BCTC line runs between Skeena and Stewart along much of the NTL route.
Calgary-based AltaGas Ltd is proposing the 195MW Forest Kerr hydroelectric project on the Iskut River, which could possibly be connected by a new transmission line to the NTL and several large-scale mines proposed for this region of BC. Plans for the Forest Kerr project include a 138kV line to be connected to the existing backbone lines operated by BCTC, which in turn is part of the greater North American grid system, connected to Alberta and the US state of Washington. Also proposed on the Iskut River are the McLymount Creek (60MW) and the More Creek (55MW) hydroelectric projects. In addition, the proposed Anyox (30MW) and Kitsault-and-Homestake (26MW) hydroelectric projects south of Stewart, BC could also be connected to the NTL.
If the Bradfield Intertie were to be connected to the NTL, via the Forest Kerr project, it would in turn enable the export of hydroelectric power from SE Alaska into Canada. The Alaska Energy Authority’s recent AK-BC intertie study concluded that the export of energy after the year 2015 to British Columbia via the Bradfield Intertie appears to be economic at discount rates of 6% (Hatch Acres et al., 2007). The 2007 report also estimated that for SE Alaska power exports to BC to be competitive, generation costs would need to be at most $60/MWh (6 cents/kWh), although this price could be higher pending GHG restrictions or other incentives to encourage renewable energy. BC’s domestic consumption of electricity has begun to outstrip its supply. Although for many years the province had a surplus of power, it is now a net importer of electricity. Demand for electricity in BC is expected to increase as much as 45% by 2025, and BC presently imports about 10% of its electricity from outside the province (Hatch Acres et al., 2007).
A 1983 study (BC Hydro, 1983) analyzed a proposed electric transmission line between Whitehorse, Yukon and British Columbia, and briefly discusses possible Alaska-Canada interties. The 1987 regional intertie study for the Alaska Energy Authority proposed an intertie from the proposed molybdenum mine at Quartz Hill in Alaska to Kitsault, British Columbia, to import power from Canada. However, the mine site at Quartz Hill, about 80km east of Ketchikan, was not developed, largely due to global molybdenum prices. Another possible Alaska/BC intertie is under investigation by Alaska Power and Telephone, which has received a preliminary FERC permit for the 85MW Soule River project near Hyder, Alaska. The community is located on the US/Canada border near Stewart, BC. The Soule River project would include a proposed 16km, 138kV submarine cable to connect to the BCTC grid at the Stewart Substation.
Alaska-Yukon interconnection proposals
The Yukon Territory presently has 129MW of installed electric generation capacity, consisting of 76MW hydro, 52MW diesel, and 0.8MW of wind. The vast majority of this capacity is owned by the Yukon Energy Corporation, and the remainder by the Yukon Electrical Company Ltd. Historically, the mining industry is the largest single factor influencing electric power development in the Yukon. The Yukon Energy Corporation’s 20-year resource plan (Yukon Energy Corporation, 2006) states that the two industrial sectors of mining and gas pipeline development will drive future electricity demand. In the mid-1990s, the report Yukon Energy Resources: Hydro (Yukon Economic Development, 1997) listed eleven undeveloped small hydroelectric sites (each under 20MW of potential) that were considered feasible.
A transmission intertie roughly following the Klondike Highway from the Skagway, Alaska to Whitehorse, Yukon was examined in the early 1980s by the Alaska Power Administration and the Northern Canada Power Commission. A report to the Northern Canada Power Commission (FWS Engineers, 1983) estimated that the 148km Canadian section of the intertie, from Whitehorse
to White Pass, would cost between $10.5M to $11.5M in 1983 Canadian dollars. This was followed by a study for the Alaska Power Administration and the Northern Canada Power Commission (R.W. Beck and Associates, 1984), which concluded that the proposed intertie would only be economic if excess hydroelectric power generated in the Yukon would be exported to Alaska. However, in the future a likely scenario could be Alaska exporting power to the Yukon for gas pipeline or mining development.
Hydro and regional economic development
Economic development opportunities associated with a regional transmission system include the utilization of Alaska-generated hydroelectric power for mining operations in both SE Alaska and NW BC. Also, a surplus of hydroelectric power in SE Alaska would enable a further transition from fuel oil to electric heating for homes and buildings, as well as future applications of electric vehicles and hydrogen production. Electric heating is already widely used in SE Alaska, and some public buildings in the region are presently being converted to electric heat. New interties will make many more potential hydroelectric sites economic to build, along with possible wind, tidal and geothermal sites located along transmission line corridors.
A surplus of renewable electricity in the SE Alaska/NW BC/Yukon region would make widespread electric heating and charging the batteries of electric vehicles economic, preferably integrated with demand-side management and ‘smart-grid strategies’. Surplus electricity delivered over future transmission lines could reduce the cost of electricity in small diesel-dependent Native communities such as Angoon, Hoonah, and Kake. These rural communities are shrinking economically, and would benefit from community-scale cold storage facilities for the fishing industry. With a lower cost of power, community cold storage will become more economic, thus permitting the restoration of fishing fleets closer to fishing grounds. Another future possibility is large-scale hydrogen production from water using electrolysis.
Surplus electricity for energy-intensive industries is another possibility, including metals processing such as aluminum smelters. An example in the region, built in the early 1950s, is Alcan’s aluminum smelter in Kitimat, BC, which is powered by the nearby 896MW Kemano hydroelectric plant. However, aluminum smelters require economy of scale in power generation, and a single smelting complex typically consumes at least 500MW of power. It is unlikely that new aluminum smelters would be built in SE Alaska, not only because of the scale of power required, but also due to concerns of the possible environmental impacts of smelting. A smaller-scale electricity-intensive application for the region could be the IT industry. About half of the energy consumed at an average internet “server farm” data center is devoted to cooling the servers. Given adequate telecommunications infrastructure, server farms are most economic where electricity is cheap, and the weather conditions are cool enough to mitigate the need for air conditioning and energy-intensive chillers.
TransCanada’s proposed natural gas pipeline route from the Alaska’s North Slope to Alberta parallels the Alaska Highway through the Yukon and part of northern BC. If built, the gas pipeline would need compressor stations at key locations in order to operate. These compressor stations would easily require the power equivalent of up to 30MW each. The standard energy source for a gas line compressor is gas directly diverted from the pipeline. However, if electrically-powered gas compressors are used, hydro power and other renewables could be used to power the gas line’s compressor stations, greatly reducing the carbon footprint of the pipeline’s operating energy requirements. Even if gas-powered compressors are used along the pipeline, each compressor station has electric power needs which could be met by connecting to a regional power grid. Another possibility enabled by a gas pipeline route along the Alaska Highway would be to electrically connect Interior Alaska (and perhaps the Anchorage-Fairbanks grid) to the main BC grid system via the Yukon. A related futuristic proposal is the construction of an all-electric railroad line paralleling the entire length of the Alaska Highway.
Policy and regulatory framework
The environmental impacts of hydroelectric plants and electric power lines are site-specific, and are beyond the scope of this paper. The vast majority of SE Alaska’s potential hydro power sites and transmission line corridors are located within the Tongass National Forest, which is administered by the US Forest Service. Hydroelectric plants sited on land owned by the US government, such as the Tongass National Forest, must receive licenses from the Federal Energy Regulatory Commission (FERC). Any generation and transmission projects on lands owned by the US government must also require an Environmental Assessment (EA) and/or an Environmental Impact Statement (EIS). Power sales agreements in the region may also have to be approved by FERC, the Regulatory Commission of Alaska, the BC Utilities Commission, and/or the Yukon Utilities Board.
In 2000, the US Congress authorized $384M in federal funds to assist in the construction of a SE Alaska regional intertie system (Public Law 106-511). To date, most of these 106-511 federal funds have not been used. More recently, the US Congress passed the Energy Policy Act of 2005 (Public Law 109-58), which includes a provision to enable the US Department of Energy to designate National Interest Electric Transmission Corridors. These special corridor designations streamline the regulatory approval process for transmission line right-of-ways, and could be applied to SE Alaska intertie projects. The development of transmission projects in SE Alaska involving Canada could also be assisted by the Canadian electric power entities of BC Hydro, BC Transmission Corporation and Yukon Energy Corp.
The economies of scale involved with bi-national hydroelectric and transmission line projects could result in significant electricity cost savings for both SE Alaska and NW BC. Higher overall capacity factors for SE Alaska hydroelectric plants, due to export opportunities, would improve project economics. Export revenue from Alaska utilities selling excess power to Canada could in turn subsidize the capital and operation costs of both new and existing US facilities in SE Alaska. Power sales agreements for exports of surplus Alaska-generated power to Canada would need to be negotiated. The 2007 BC intertie study for the Alaska Energy Authority proposed four possible ownership models for an AK-BC intertie: transmission cooperative, unified system operator/regional transmission organization, power marketing oversight unit, or the state of the Alaska acting as the owner/operator (Hatch Acres et al., 2007).
The 2007 BC Energy Plan issued by BC Ministry of Energy, Mines and Petroleum Reserves has a stated goal of reducing GHG emissions, and encourages renewable energy development. BC Hydro has a Standing Offer Program for small (less than 10MW) and clean electricity producers. BC Hydro also contracts with Independent Power Producers (IPPs) with a competitive procurement process. Powerex, the wholesale power marketing subsidiary of BC Hydro, specializes in power sales outside of the province. It is plausible that Powerex could purchase Alaska-generated power for resale to the Pacific Northwest states of the US (Washington, Oregon), and even as far south as California.
There is a need for cooperation between the Canadian, US, state, provincial and tribal governments on energy policy, environmental permitting and other regulations. A recent technical/policy review for the state/federal Denali Commission (NANA Pacific et al., 2008) recommended that planning discussions be initiated between important regional electric power stakeholders such as the Alaska Energy Authority, BC Transmission Corporation, BC Hydro, the Yukon Energy Corporation, electric utilities in Southeast Alaska, IPPs and the Southeast Conference. Also vital will be the inclusion of tribal organizations such as the Central Council Tlingit Haida Indian Tribes of Alaska (CCTHITA), a federally recognized Indian Tribe for all of SE Alaska. CCTHITA has created an energy department, is partnering with the US Department of Energy and has a significant relationship with Canadian First Nations. Perhaps a bi-national US/Canada energy commission could be created for the southeast Alaska/northern BC/Yukon region, to coordinate policies not only for electric power infrastructure, but also for the Alaska Highway gas pipeline.
Brian Yanity is an electrical engineer with WHPacific, Inc. in Anchorage, Alaska. His work focuses on village-scale renewable energy projects for rural Alaska. Email: [email protected]
Special thanks to the following reviewers for their comments and feedback during the preparation of this paper: Robert Venables of the Southeast Conference; James Strandberg of the Alaska Energy Authority; Eric Marchegiani of the US Department of Agriculture – Rural Utilities Service; Duff Mitchell of Cascade Creek, LLC; Bob Grimm and Glen Martin of the Alaska Power & Telephone Company; Terry Otness of the Central Council of the Tlingit and Haida Indian Tribes of Alaska; and Lesley Wood of the BC Transmission Corporation.
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