Molten Carbonate Fuel Cells
Exploring the use of Molten Carbonate Fuel Cells to capture carbon dioxide from natural gas-fired processing units while generating electricity
Reducing the greenhouse gas intensity of in situ steam generation and providing clean energy to the Alberta power grid
There are two methods to extract bitumen from the oil sands. The 20 per cent of deposits located less than 70 metres below the surface are mined using large shovels and trucks. The remaining 80 per cent of deposits are too deep to be mined, and so the bitumen is extracted in place, or in situ, by drilling wells.
The most common method of in situ production is called steam assisted gravity drainage (SAGD). Using this method, two parallel wells are drilled into the oil sands reservoir. Steam is injected into the reservoir through the top well to heat the bitumen. The softened bitumen then falls to near the bottom of the reservoir, where it is pumped to the surface through the second well.
In situ production has a smaller land footprint and uses less water than mining. However, the energy needed to produce steam results in greenhouse gas (GHG) emissions and higher GHG intensity compared to conventional oil production. The members of COSIA’s GHG Environmental Priority Area (EPA) are looking at ways to reduce the GHG intensity of in situ oil production by exploring a number of different technologies including improved energy efficiency, alternative sources of less carbon-intensive energy, and carbon capture and storage (CCS).
Cenovus Energy Inc. and its partners are exploring a Molten Carbonate Fuel Cell (MCFC) technology that would combine capturing carbon dioxide (CO2) with generating low GHG-intensive electricity.
Technology and Innovation
A fuel cell converts chemical energy from a fuel into heat and electricity through an electrochemical process. MCFCs are one type of fuel cell that operates at high temperatures to produce electricity, heat and water. They contain an anode, a cathode and a molten electrolyte salt layer. The flow of electrons from anode to cathode through an external circuit produces electricity (see picture below).
MCFCs have been used in commercial power generation since the 1990s. In 2014, POSCO Energy started up a 59-megawatt MCFC power plant in Hwasung City, South Korea.
“The fact that MCFCs are already being used for commercial power generation represents a significant step forward for the technology,” says Craig Stenhouse, Manager, COSIA at Cenovus. “It can also be adapted to capture carbon dioxide.”
Cenovus led a joint industry project (JIP) to estimate the cost of a pilot to capture CO2 from a natural gas-fired combined heat and power generation plant and to produce electricity by using MCFC technology.
The JIP was based on a feasibility study funded by the JIP participants and Alberta Innovates-Energy Environment Solutions. That study concluded that using MCFCs would be far less energy-intensive and more cost effective than conventional post-combustion carbon capture methods.
Learn more about incorporating carbon capture into MCFCs
To capture CO2, part of the internal CO2 circulation in a traditional MCFC could be replaced by CO2 from a natural gas-fired unit’s flue gas without affecting the fuel cell’s operation (see picture below).
For SAGD application, the MCFC can be directly connected to the flue gas of a once through steam generator (OSTG). The CO2 can be separated from the flue gas, and power is simultaneously produced. The separated CO2 can be further purified, compressed and shipped to storage sites or used for enhanced oil recovery. With this technology, the normally costly process of separating CO2 from the exhaust stream is offset by the sale of the electricity generated by the fuel cell.
Learn more about incorporating carbon capture into MCFCs
Cenovus and the other JIP partners carried out a preliminary front end engineering design (pre-FEED) associated with installing and operating a 200-kilowatt pilot project. The pre-FEED also included a cost estimate for equipment installation and operation.
The University of Calgary has provided Cenovus with a letter of expression of interest to host the pilot at its 14-megawatt cogeneration plant on the school’s main campus. If the pilot goes ahead, it would remove about eight per cent of the CO2 from the plant’s emissions, or 10 tonnes of CO2 per day.
“The University of Calgary is a world leader in high-temperature fuel cell research, so it is a natural fit for us to be working with industry on this project,” says the University of Calgary’s Viola Birss, Professor of Chemistry, Canada Research Tier I (Fuel Cells and Related Clean Energy Systems), and Director of Calgary Advanced Energy Storage and Conversion Research Technologies. “We see a lot of collaboration potential on this project, as well as opportunities for students to get hands-on experience with the technology.”
Combining MCFCs and OTSGs to cogenerate steam and electricity at in situ facilities will produce significantly lower GHG intensive steam and electricity at the same time as CO2 is captured. The excess electricity will be sold into the Alberta power grid. The electricity export will provide clean energy to Albertans and a revenue stream to offset the costs associated with carbon capture.
Having a close to zero GHG-intensive electricity output will also earn carbon credits, further offsetting the carbon capture costs.
“One of the main issues with technologies like carbon capture is their cost,” says Wayne Hillier, Director of COSIA’s GHG EPA. “Combining MCFC technology with carbon capture is transformative because it could bring the cost of carbon capture down, making it a more viable solution – economically and environmentally.”
Cenovus led the Molten Carbonate Fuel Cell JIP with Devon and Shell. Associate Members – AIEES and the University of Calgary – were also involved.
“We were fortunate to have an ideal number of participants with a wide range of management and technical skills. It was a model JIP, in my opinion.” says Stenhouse. “By sharing the costs associated with the project, the risk was also significantly reduced.”
Decision will be made at the end of each phase whether to proceed to the next phase.