Novel Approaches in Geothermal Energy Recovery

Our geothermal plant can function independently as the power produced from the cycle will be used to power any on-site equipment. No energy storage is required as power produced is designed to meet the town’s energy requirement. Since CO₂ reduces pumping requirement and can be used directly in turbomachinery, the energy requirement for the plant is only 565 kW. Utilizing CO₂ as the process working fluid also provides Core Energy with two possible sources of revenue. These two options are electricity production and carbon sequestration which can be easily scaled up.  

Geothermal energy is a reliable source of energy that can be used all year round regardless of the weather or time of year. The reliability of geothermal power solves some of the main problems that occur with other forms of renewable energy such as wind and solar energy. 

This design solution was first performed through hand calculations and the usage of the ODE solver function in MATLAB. To verify these calculations, each value was compared to literature sources along with the process simulation created in Aspen HYSYS.  

The pressure change across the injection and production well was determined using Bernoulli’s Equation: 

Darcy’s law was then used to account for the pressure drop across the reservoir. The permeability was found through literature to be 5.92E-16 m².

To simulate how the stream temperature would vary across the wells and reservoir, the ODE below was used. For each temperature profile, the overall heat transfer was calculated and then solved in MATLAB.

The total capital investment required for this plant design was $45,000,000. The cost is broken down between drilling & completions, equipment costs, land purchase, raw material procurement as well as the working capital.

The feasibility of our design was determined through four major economic indicators; net present value (NPV), internal rate of return (IRR), return on investment (ROI), and payback period. In the economic analysis, the cost of transporting CO₂ to Rocky Mountain House, equipment cost, drilling and completions cost were all taken into consideration. Once fully optimized, our design resulted in a NPV of $12,880,000, IRR of 1.33 %, ROI of 29 % and a payback period of 213 years.

CO₂ sequestration is an environmentally friendly measure this plant will be contributing to. As the CO₂ flows through the reservoir, a fraction of it will continuously leave the loop and dissolve into the reservoir. This provides a potential long-term solution for removing this greenhouse gas.

With the potential of CO₂ leaking underground, there is the risk of the fluid mixing with the reservoir brine. This can result in two main problems i.e., mutual dissolution between CO₂/water and salt precipitation. To counteract the dissolution, dehydrators may be installed at the surface of the plant to separate the CO₂ out from the solution.  To monitor the salt precipitation, pressure transducers will be installed at the bottom of the wells and if the pressure decreases this indicates the working fluid is leaking out. Another method to mitigate the salt precipitation issue is to inject fresh water with low salinity into the reservoir.

Since this is a development project, it will result in more jobs for locals and help stimulate the economy. Jobs in various fields such as construction, engineering, operations, and transport will result from this project. The geothermal site can also be easily incorporated into communities without causing any visual disturbance or discomfort. They require a small amount of land area and do not require transportation or combustion of fuel.