Nuclear process heat can be used to recover and refine oil while reducing carbon emissions.
Fuel Refining
There are two incentives for nuclear heat in the refinery: lower energy costs and reductions in carbon dioxide emissions. There are three potential applications of the high temperature gas-cooled reactor in the refining segments of the petroleum industry.
- Tertiary recovery in existing oil fields
- When oil is pumped from a well, much of the oil — up to 50 to 70 percent — is left behind. The oil left behind is held in place by capillary forces. That's when the fluid and internal well pressures are equalized. The oil held in place can be flushed out using methods like water flood, fire flood, carbon dioxide injection, steam injection and surface injection. Each method uses a fluid injection to push the trapped oil out of the well so that it can be refined. These methods have a common weakness. The fluids pumped in will flow on the path of least resistance to the production well. In this process, the fluid will bypass most of the oil held in place by rock.
- In-situ recovery of petroleum from tar sands
- Tar sands are heavy and sticky mixtures of viscous oil, sand, water, and clay. The mixture is heated in large tanks until the sand and clay settle and the oil floats on the hot water to the top of the tank. There are also in-situ, underground oil recovery methods that inject steam into underground deposits where the steam heats the tar sands, allowing the oil mixed with clay and sand to flow into production wells. The mixture is a solid at room temperature unless hydrogen is added to convert it to a syncrude, a heavier form of crude oil. Syncrude can be sent by pipeline to refineries to be converted into gasoline, diesel, and jet fuel, although the process is extremely energy intensive.
- Eventual in-situ exploitation of oil shale deposits
- An alternative to tap oil shale deposits uses a high temperature gas-cooled reactor to provide heat to replace the electricity. This will avoid the high energy loss in the conversion to electricity. The use of thermal energy rather than electricity has the potential to significantly reduce cost. An efficient heat transport system is required to heat the oil shale through a series of pipes.
In the Western United States, natural gas is currently used as the primary heat source for all three processes. With the proper heat transfer and transport systems, a nuclear reactor can provide the required heat without burning natural gas and producing significant amounts of carbon dioxide. The high temperature gas-cooled reactor can also support future refinery operations by providing process heat and the hydrogen required for the various oil refining processes.