• Modeling and analysis of geothermal organic rankine cycle turbines coupled with asynchronous generators as a primary power source in islanded microgrids

      Green, Nathan; Wies, Richard; Huang, Daisy; Shirazi, Mariko (2019-05)
      Local renewable resources, such as geothermal hot springs, are being explored as prime electric power and heat sources in remote permanently islanded microgrids, and in some cases these renewable resources have already been implemented. In these types of remote areas, diesel electric generation is typically the prime source of power, even in areas where alternative resources are readily available, despite the high fuel cost due to transportation. This thesis shows that geothermal hot springs, when locally available, can provide primary power for these remote microgrids with temperatures as low as 20°C below the boiling point of water. The geothermal heat can be converted to electrical energy using an organic Rankine cycle turbine in combination with a self-excited induction generator. A steady-state energy balance model has been developed using MATLAB® and Simulink® for simulating greenfield and brownfield geothermal microgrids at Pilgrim Hot Springs, Alaska and Bergstagir, Iceland, respectively, to demonstrate viability of this microgrid design. The results of the simulations have shown that modest loads can be primarily powered off of these low temperature geothermal organic Rankine cycles over long time scales. As expected, more power is available during colder months when sink temperatures are lower, thus increasing the temperature differential. More research is needed to examine system response over shorter time scale transients, which are beyond the scope of this work.
    • Renewable energy development in Alaska: policy implications for the development of renewable energy for remote areas of the circumpolar Arctic

      Holdmann, Gwen Pamela; Johnson, Ronald; Peterson, Rorik; Greenberg, Joshua; Sfraga, Mike (2019-12)
      The territories that comprise the Arctic region are part of some of wealthiest and most advanced countries on the planet; yet, rural Alaska, northern Canada, the Russian Far East and Greenland--characterized by off-grid communities, regional grids, and higher degrees of energy insecurity--have more in common with the developing world than the southern regions of their own country. This thesis explains this paradox of energy development in the Circumpolar North and tackles the issue of developing renewable energy in remote areas where technical and socioeconomic barriers are significant. The primary research questions are two-fold: 1) Why did the Alaska electrical system develop as a non-integrated patchwork of regional and isolated grids? and 2) What are the major factors in Alaska that have resulted in a greater uptake of renewable energy systems for remote communities, compared to other similar places in the Arctic? This thesis demonstrates that state-building theory provides a cogent framework to understand the context of electrical build-out in the Circumpolar North. A major finding of this thesis is that the buildout of electric infrastructure in the non-Nordic countries, including Alaska, exemplifies a process of incomplete nation-building. Interconnected regional grids, where they exist, are largely due to the twin national priorities in infrastructure development in the north: extracting natural resources and enhancing national security. This thesis also draws on sociotechnical transition theory to explain why Alaska exhibits such high levels of energy innovation when compared to other similar regions across the Arctic. This research concludes that drivers such as extremely high energy costs, a highly deregulated utility market with dozens of certificated utilities, state investment in infrastructure, and modest subsidies that create a technological niche where renewable energy projects are cost-competitive at current market prices have spurred energy innovation throughout Alaska's communities, remote or otherwise. Many of the evolving technical strategies and lessons learned from renewable integration projects in Alaska's remote islanded microgrids are directly applicable to project development in other markets. Despite differences in climate and geography, lessons learned in Alaska could prove invaluable in increasing resiliency and driving down energy costs in remote communities world-wide.