Different Energy Reliance Scenarios
Although the eUtah study is unique because it evaluates a 100% renewable energy supply for Utah, there are certainly other approaches to meeting Utah’s energy needs over the next century. Consequently, the eUtah study examines five different scenarios for meeting Utah’s growing electricity needs through the middle of the 21st century; they are:
The eUtah 100% renewable scenario: This scenario relies almost totally on renewable energy sources by 2050, comprised of geothermal, solar, and wind energy, complemented with energy storage in the form of compressed air. Minimal natural gas is used to support generation from compressed air energy storage, resulting in carbon dioxide reductions of 95 percent relative to 2010. High efficiency improvements are assumed here, with demand rising to about 37 million MWh by the year 2050.
Renewables + natural gas: In this scenario, CO2 reductions of around 70% are achieved relative to 2010 using solar, wind, and geothermal generation, supplemented by a significant amount of combined cycle power plants fueled by natural gas. The high efficiency demand scenario is used here. Demand rises to about 37 million MWh by the year 2050 in this scenario. Interestingly, annual natural gas consumption for electricity would only rise by about 13% relative to today.
Renewables + natural gas and carbon capture: This is the same as the Renewables/Natural Gas scenario, except that carbon capture and storage has been added to natural gas combined cycle power plants in order to achieved CO2 emission reductions relative to 2010 of 93 percent by the years 2050. The high efficiency demand scenario is used here. Demand rises to about 37 million MWh by the year 2050 in this scenario.
Nuclear plus coal with carbon capture: This scenario provides an example of a conventional approach to CO2 reduction and assumes that the structure of the present electricity sector, which is dominated by thermal plants, will continue, but with carbon reductions as an added goal. Natural gas plays a supporting role to coal with CCS and nuclear power, both in the form of combined cycle plants and single-stage gas turbines. The scenario results in approximately 70 percent CO2 emission reductions relative to emissions in 2010 and 80 percent relative to the emissions in 2050 in the BAU scenario. A medium level of efficiency improvements, extending present utility planning for demand side management, is used with this scenario. Demand rises to about 42 million MWh by the year 2050 in this scenario. A "nuclear only" variant is also included to show the unique financial risk of adopting nuclear as the sole solution for Utah's growing energy needs through mid-century.
Business-as-Usual (BAU): This is a reference scenario that assumes the continued dominance of coal in the supply system. Existing plants are assumed to retire at 60 years, and are assumed to be replaced by new coal-fired power plants. A coal-to-coal scenario is useful because it allows us to compare the cost of the other scenarios as low-carbon alternatives. It also allows a calculation of the cost of limiting carbon emissions using different approaches. Finally it allows an estimation of the financial risk of sticking with coal and assuming no carbon constraints, in the event that such constraints are applied at various levels of carbon price or tax. No new efficiency or DSM measures are assumed. In this case, electricity generation grows to about 52 million MWh by 2050.
These scenarios are evaluated against each other for a variety of criteria, including cost, investment risk, and water consumption, through the middle of this century.
