NRG Energy, Inc. and JX Nippon Oil & Gas Exploration Corp. completed construction of Petra Nova, which they say is one of the world’s largest post-combustion carbon capture systems. The companies say the project was completed on time and on budget.

Petra Nova first captured carbon dioxide (CO₂) on Sept. 19, 2016 and has delivered more than 100,000 tons of captured CO₂ to the West Ranch field through an 80-mile pipeline. Final performance acceptance testing on the facility was completed on Dec. 29, 2016 and the facility turned over for operations.

The U.S. Department of Energy provided up to $190 million in grants as part of the Clean Coal Power Initiative Program, a cost-shared collaboration between the federal government and private industry.

Kemper County

Meanwhile, in late January Mississippi Power said it was extending the expected in-service date of the Kemper County energy facility until late February 2017.

The company continues final start-up activities at the project, achieving integrated operation of both gasifiers, including the production of electricity from syngas in both combustion turbines, on Jan. 29.

Construction photo of the Kemper County project. Credit: WikimediaThe utility, a unit of Southern Co., says the updated schedule reflects an approximate one-week outage necessary to repair and make modifications to further improve the plant’s ability to achieve sustained operations sufficient to support placing the plant in service for customers.

Mississippi Power also revised its cost estimate subject to the cost cap for the Kemper project by $51 million. These increased costs will be paid by Southern Company and Mississippi Power, not by Mississippi Power customers. Customers would pay as much as $4.2 billion of the expected $7.1 billion project cost, including the power plant, pipeline, and lignite mine.

Petra Nova Performance

During performance testing, the Petra Nova system reportedly met all performance criteria including capturing more than 90% of CO₂ from a 240 MW equivalent slipstream of flue gas off an existing coal-fueled electrical generating unit at the WA Parish power plant in Fort Bend County, southwest of Houston. At this level of operation, the companies say that Petra Nova can capture more than 5,000 tons of CO₂ per day.

Construction began in 2014 with a goal to be operational by the end of 2016. Hilcorp Energy Co., the operator of West Ranch oilfield, will use the captured CO₂ to boost production at West Ranch oilfield, jointly owned by NRG, JX Nippon and Hilcorp.

The project will demonstrate the ability of an advanced amine-based CO₂ capture system to capture 90% of the CO₂ emitted from a flue gas stream equivalent to 240 MWe in size. The Energy Department's National Energy Technology Laboratory (NETL) says the host power generation unit will not be derated because the power and thermal energy required to operate the CO₂ capture and compression system will be provided by a cogeneration plant comprised of a combustion turbine with a heat recovery boiler.

The scale of the project was increased from early plans because the original 60 MWe project was determined to be too small to immediately induce significant oil production.

How It Works

Petra Nova uses the KM-CDR Process, jointly developed by Mitsubishi Heavy Industries, Ltd. (MHI) and the Kansai Electric Power Co., Inc., and uses a proprietary KS-1 high-performance solvent for the CO₂ absorption and desorption. The carbon capture facility was constructed under a fixed-price contract by a consortium of Mitsubishi Heavy Industries Americas, Inc. (MHIA) and TIC (The Industrial Company).

According to NETL, When entering the CO₂ capture system, the flue gas is first routed to the flue gas cooler for conditioning (cooling) dehydration, and additional sulfur dioxide (SO₂) removal. NETL says that the flue gas is cooled because the absorption of CO₂ is favored at lower temperatures.

(Click to enlarge.) Diagram of process flow for amine absorption. Credit: NETLThe cooled flue gas will contact a circulating sodium hydroxide (NaOH) solution for polishing SO₂ removal, where 98% of the remaining SO2 is removed from the stream because it interferes with the amine’s ability to react with CO_2.

The conditioned flue gas then is routed to the absorber, where CO₂ is captured by the amine-based solvent through a chemical reaction. The CO₂ rich solvent stream is sent to the regenerator, or stripper, where the CO₂ is released from the solvent using low-pressure steam.

Heat from the steam breaks the weak bond between the CO₂ and the solvent, liberating the CO₂ and leaving the solvent behind for additional CO₂ capture use. NETL says the captured CO₂ will be compressed, dried, and then transported via pipeline to the West Ranch oil field, near Vanderbilt, Texas.

NETL says the West Ranch oil field has produced oil continuously since 1938 under a series of different owners. In recent years, production rates at West Ranch have declined through conventional production techniques. In order to increase production, CO₂ captured from Parish Unit 8 will be injected into the field for EOR.

(Read "Insight: Carbon Capture and Sequestration Face an Uphill Battle.")

Carbon dioxide injection helps lower the oil viscosity and reduce forces that trap the oil in the reservoir. The CO₂ provides a driving force to sweep oil fromthe reservoir that could not be recovered during primary and secondary phases of production. Once the oil reaches the surface, it will enter a recycle facility where it is separated from the CO₂, which will be re-injected for additional use.

Both Hilcorp and the University Of Texas Bureau of Economic Geology will monitor the movement of CO₂ in the oil reservoir. Over the next few years, oil production at the field is currently estimated to increase from approximately 300 barrels per day before beginning enhanced oil recovery (EOR) operations to production of up to 15,000 barrels per day using captured CO₂.

To date, Hilcorp has drilled nearly 100 new wells in the West Ranch field, says Jeffery D. Hildebrand, chairman and CEO of Hilcorp.

Petra Nova is 50-50 joint venture by NRG and JX Nippon. Additionally, the Department of Energy is providing up to $190 million in grants as part of the Clean Coal Power Initiative Program (CCPI), a cost-shared collaboration between the federal government and private industry.

A portion of the project was financed with project loans from the Japan Bank for International Cooperation (JBIC) and Mizuho Bank, backed by Nippon Export and Investment Insurance (NEXI).

NRG, JX Nippon and Hilcorp expect to host a ribbon cutting at the site in the first half of 2017.