Geothermal energy in remote Alaska
Geothermal energy isn't the first thing that springs to mind when I hear of Nome, Alaska. I think of the event the annual Iditarod Trail Sled Dog Race commemorates: a 1925 relay of sled dog drivers and their teams who delivered diptheria serum to the stricken gold-rush town, braving blizzards. I think of the extremely harsh winter of 2012, when the U.S. Coast Guard icebreaker Healy escorted the Russian fuel tanker Renda through winter sea ice to deliver 1.3 million gallons of fuel to Nome after a fall fuel delivery failure.
It's not easy living in a remote city in Alaska. For power and heating needs, Nome relies primarily on diesel-driven generators. That makes the cost of living very high and planning ahead a struggle.
Antony Scott discusses the problem. He's a senior economist and policy analyst at the University of Alaska Fairbanks, the Alaska Center for Energy & Power (ACEP).
"The change in electricity prices associated with diesel price increases in the last 10 years is very substantial. Nome has seen the diesel part of their power costs go from, oh, maybe 6 cents or less to 19 or 20 cents a kilowatt hour in less than the last 10 years."
"It’s an extremely volatile commodity, and for Nome, the utility receives between 1 and 3 diesel deliveries per year, during the ice free summer season. The diesel fuel is priced off when the product is lifted from the refinery [...] the time that it is loaded on the tanker substantially determines what price Nome will pay." "They grab a price that happens during a limited time window and then they have to [...] bear that price for an entire year." ~Antony Scott
Nome pays one price for per gallon of fuel a year, and it can be upwards of $6. It's not surprising that developing alternative energy sources is looked on favorably. Already a wind farm helps provide supplement power. And now, a diverse group is working toward developing geothermal energy to serve the city of Nome.
Pilgrim Hot Springs
60 miles from Nome lies Pilgrim Hot Springs, a valley cupped between mountains. Over past glacial and interglacial periods, erosion from the mountains filled the valley, leaving roughly 1030 feet of sediment ('unconsolidated material') sitting atop deep bedrock. Somewhere, the bedrock is cracked; heat and hot water rise from the fractured bedrock and trickle through the unconsolidated material toward the surface, swerving around less permeable patches of clay then flowing swift through unconsolidated areas with little resistance.
Hot water rises because it is lighter than the other water surrounding it, in the same way that hot air in a two-story house will rise toward the ceiling and the second story while cool air sinks.
When it reaches the surface, the hot water feeds the many hot springs scattered across Pilgrim Hot Springs valley.
"We have deep cracks in the earth: big faults or fractures that are allowing water to circulate deep in the earth." "The hot water that is circulating really deep in the earth is picking up heat and we are seeing it here at the surface in the form of hot springs, and hopefully in energy production when it is completed." ~Gwen Holdman
A challenge met by new technologies
Gwen Holdman, director, Alaska Center for Energy & Power, references another project she worked on before tackling efforts at Pilgrim Hot Springs.
"The first geothermal power plant operating in Alaska is at Chena Hot Springs in interior Alaska and I was fortunate enough to be the project engineer and project manager on developing that particular project. It’s the lowest temperature geothermal plant operating anywhere in the world." ~Gwen Holdman
She once met the the national energy authority director of Iceland, Gudney Johansen, who was surprised that anyone would develop a geothermal energy power plant at Chena Hot Springs, Alaska. Water temperatures there are about 40 degrees lower than any other geothermal project in the world at 160 degrees Fahrenheit.
"Alaska’s situation is very different from Iceland. In Iceland they have a national electric grid and everything is connected to the grid, so of course you wouldn’t develop a project like the Pilgrim Hot Springs or the Cheena project if you had a big grid and had access to much lower cost energy sources like hydro power or maybe natural gas generation. But because this is an islanded grid it is a completely different situation; you don’t have anything but on- site diesel generation to serve this community. It is a completely different economic challenge than what they see in a place like Iceland. However, Mr. Johansen’s remarks gave me pause; I realized it [the Pilgrim Hot Springs Project] was allowing us to gain expertise and knowledge in a part of geothermal energy development that the international community wasn’t paying attention to at all." ~Gwen Holdman
Whereas past scientific explorations at Pilgrim Hot Springs determined developing geothermal energy at Pilgrim Hot Springs would be too difficult, new technologies have opened up new possibilities.
"At that time [30 years ago] the resource was deemed not developable based on the current technology and the current understanding of the resource. However when we looked at the data two years ago we realized there was some potential with improved technology and utilizing the new research findings in developing low temperature sites, such as the power plant at Chena Hot Springs." ~Gwen Holdman
Exploring the resource
Geologist Dick Benoit was brought in as a geothermal consultant at the Pilgrim Hot Springs site. He speaks about drilling a new well during the summer of 2013. He's not the first – in 1979 the Department of Energy funded exploration performed by the University of Alaska Fairbanks. ACEP's spearheading of site tests began in 2008.
"The highest and best use of this site would be generating electrical power." "There is a plume of hot water rising, close to vertical from great depths, many thousands of feet. It gets to about 100 feet of the surface, hits an impermeable clay layer, and then spreads out laterally in all directions from the church, like a thin layer. Maybe about 10 feet thick, at other places it may be 30 or 40 feet thick. It’s 90 degrees Celcius right near the Pilgrim church."
"What we’ve seen so far comparing 2012 and 2013 data against 1979 and 1982 data is that there has been some changes in the very shallow parts of the field, but the deeper parts have largely remained unchanged in the last 31 years."
"The purpose of the new well is to hopefully verify that there is enough water stored in the top 1000 feet of the earth here that we can consider using it for installation of a geothermal electrical power plant." "For power generation you want to see the temperature and the pressure of the resource remain constant. In that way the source would last forever." ~Dick Benoit
Combined, water pressure and temperature determine how effective a geothermal power plant can be. Stressing the system by testing wells is a way to find out how much yield the site could provide.
"We know that there is a natural flow rate from the bedrock of 200 – 400 gallons a minute. But what we really want is to increase that 10 fold. So what really happens when we do that? There’s a lot of different things that could happen. And one is we could actually draw up hotter fluid we know exists deeper in the system. If we increase the velocity of water going through that we might bring up hotter fluid, and that would be a really positive development in terms of increasing the potential efficiency of a power generation plant." ~Gwen Holdman
Chris Pike is a research engineer, one of the project managers with the Pilgrim Hot Springs project, Alaska Center for Energy & Power. He describes the underground layout of the valley.
"The basement is at about 1030 feet give or take. And when I’m talking about basement, I’m talking about bedrock at about 1030, 1050 somewhere in there. We hit it at 1036 feet this year." "Above that you’ve got different layers of clay and gravel and sandstone. The sandstone is what we call an indurated sand stone. It’s actually a bi-product of some of the geothermal fluids. As some of the geothermal fluids come up and cool down. Some of the chemicals in there actually precipitate out and then form this sandstone." ~Chris Pike
The team hypothesizes that there's one main passageway through the basement, a sweet spot in the bedrock where most of the hot water is transported above into the valley – an optimal location for a power plant.
"The general thought is that somewhere, it’s a fractured bedrock, so there are cracks and that kind of stuff. And somewhere in that bedrock, you have that hot thermal fluid coming out of that bedrock and the theory is that it comes straight up until it hits a layer of clay." "If we can get to that spot, it’s kind of like putting a straw down into the ground, putting that straw right into the upflow zone. So we’re going to have the highest flows and the hottest water. And flow and water are the energy we are trying to get from the system. So if we can find that zone, it is the key to finding what this system is capable of producing." ~Chris Pike
In it together
Scientific efforts like the testing at Pilgrim Hot Springs that are publicly funded gain vital information which lowers risk for private investors, who can then move in and fulfill the community's wish for an alternative energy source. The successful communication and cooperation between private (Nome Joint Utilities, Mary’s Igloo Native Corporation, Unaatuq, LLC and the US Geological Survey) and public entities (US Department of Energy and the Alaska Energy Authority) that happened at Pilgrim Hot Springs – which has now attracted a private developer – can be seen as an inspiration.
Ethan Berkowitz, who has served as a member of the Alaska House of Representatives, believes the public/private partnership efforts at Pilgrim Hot Springs paint a positive example for solving problems across Alaska.
"Alaska has a lot of energy resources and a lot of energy needs. This is the opportunity to marry the two of them together. We have a great geothermal resource at Pilgrim, and we’ve engaged in the research that’s necessary, we’ve found a public partner, a private partner and we were able to develop a project in such a way that solves the needs of the community."
"Largely spearheaded by the efforts of ACEP, the Alaska Center for Energy & Power, we were able to create a map of understanding about the resource which attracted private investment and that kind of public/private partnership really sets a model for solving Alaska’s energy problems." ~Ethan Berkowitz
Diesel off = saving money
"The real benefit can be realized if you can figure out a way to turn off that diesel engine, at least for a period of time. And when we talk about diesel off and the potential to operate in a diesel off mode, what we mean is: for some period of time you have the diesels turned off and you are generating power to serve your consumers through a combination of renewable energy and storage." ~Gwen Holdman
Even though geothermal energy is unlikely to provide for 100% of Nome's power needs, any time the city is able to turn off their diesel power generators they save money, save on shipping costs, and cut down on pollution entering the atmosphere.
There's more to come in our project about geothermal energy at Pilgrim Hot Springs. Moving forward, we'll explore how sensors underground, on aircraft, and even aboard satellites help scientists search for the bedrock crack. Then we'll look even deeper beneath the earth to see where geothermal heat begins, and bring it back to the surface and the workings of a geothermal power plant.
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