Powerspan’s ECO and ECO2 head towards commercial scale

In August BP Alternative Energy and Powerspan Corp announced a collaborative agreement to develop and commercialise Powerspan's carbon dioxide capture technology, ECO2, for power plants. The scope of the agreement includes financial and technical support for pilot demonstration and commercial scale-up activities, which may include joint development of large-scale demonstration projects that would capture CO2 from power station flue gas, with the captured CO2 sent for secure, long-term storage deep underground. The ECO2 process, which uses scrubbing with ammonia bicarbonate solution (rather than amine), is a post-combustion CO2 capture process suitable for retrofit to the existing coal-fired fleet, as well as for new coal-fired plants. The process can be readily integrated with Powerspan's Electro-Catalytic Oxidation, ECO, multi-pollutant process for control of sulphur dioxide, nitrogen oxides, mercury, and fine particulates emissions from power plants. ECO, being also ammonia based, lends itself to integration with the ECO2 carbon dioxide capture technology.

BP says it sees ECO2 as one of the most promising solutions for post-combustion capture of CO2 and says the collaboration is an opportunity for BP to broaden the scope of its low carbon power offerings by having a CO2capture technology that is compatible with new and existing coal fired power stations.

"BP's technical capability, experience with large projects, and commitment to advancing low carbon power solutions uniquely qualifies them to assist Powerspan in scaling up the ECO2 technology for commercial application," said Powerspan CEO Frank Alix.

Pilot scale testing of ECO2 technology is expected to begin at FirstEnergy's Burger plant (pictured above) in Shadyside, Ohio, in early 2008.

The plan is to sequester the captured carbon dioxide on-site in an 8000 ft deep test well drilled at Burger earlier this year, on which FirstEnergy is collaborating with the Midwest Regional Carbon Sequestration Partnership (one of seven regional partnerships established by the DoE to research carbon sequestration at various locations in the USA).

The Burger pilot programme could therefore well be the world's first demonstration of both CO2 capture and sequestration at a conventional coal-fired power plant.

Initial estimates developed by the US Department of Energy (DOE) indicate that the ammonia-based ECO2 capture process could provide significant savings compared with commercially available amine-based CO2 capture technologies.

Ammonia has several advantages over amine (MEA) processes, including higher CO2 loading capability, lower energy consumption for regeneration, and lower cost reagent. MEA processes suffer from higher equipment corrosion rates, while amine degradation by flue gas requires higher make-up levels.

The ECO2 technology has been developed under a May 2004 co-operative R&D agreement between Powerspan and the DOE's National Energy Technology Laboratory storage.

The CO2 capture takes place after NOx, SO2, mercury and fine particulate removal. Once the CO2 is captured, the ammonium bicarbonate solution is regenerated to release CO2 and ammonia.

The ammonia is recovered and sent back to the scrubbing process, while the CO2 is in a form that is ready for geological storage. Ammonia is not consumed in the scrubbing process, and no separate byproduct is created.

Both Powerspan and DoE have conducted laboratory scale tests on ECO2. The Powerspan tests (130°F, gas residence time 4-5 secs, and flue gas composition O2 and N2 as well as CO2) have demonstrated 90% carbon dioxide removal under conditions comparable to a commercial scale absorber, confirming test results previously obtained by the DoE under similar conditions.

The Burger ECO2 pilot unit will process a 1 MW slipstream (20 tons of CO2/day) from the existing 50 MW Burger ECO demo unit, which has been in operation since early 2004, with support from the Ohio Coal Development Office, which has contributed over $5.5 million. The pilot ECO2 facility will be designed to capture 90% of incoming CO2 and is also intended to demonstrate the ability of ECO2 to integrate with ECO.

Assuming successful pilot scale testing, Powerspan plans to move to commercial demonstration of the ECO2 process, envisaging a 100 MW system, also capturing 90% CO2 (2000 tons/day, or 500 000 tons/year at 70% capacity factor), which would make it one of the largest CO2 capture systems in the world.

Design of the commercial demonstration unit would begin in 2009 with operations starting in 2011, Powerspan has said.

The commercial demonstration would preferably be installed where an ECO unit is located and also within close proximity to an enhanced oil recovery (EOR) site, says Powerspan.

With success of the pilot and commercial demonstration phases, "it is reasonable to project availability of full-scale ECO2 systems beginning in 2015 (assuming a design start in 2012)," the company says.

As of June 2007, Powerspan was targeting ECO2 capital costs in the $300-$500/kW range for a 100 MW plant, or $150-$250 million for a 500 MW plant (assuming ECO is already installed).

DoE studies, as reported by Powerspan, suggest the following comparative costs for four capture options:

For ECO (installed on a supercritical PC plant) the plant capital costs are $295/kW, energy use is about 10% of power plant capacity, total energy costs to release CO2 from solution and compress are about $3.50/ton, and additional power costs are less than $0.01/kWh.

On the basis of such figures, Chris McLarnon, Powerspan's VP R&D, concluded in his presentation at last May's Electric Power conference in Chicago that "ECO2 could be installed on current or new coal plants and be economically preferable over IGCC for coal-based plants with CO2 capture."

Also, amine systems need the inlet SO2 level to be 10 ppm or less, while conventional wet scrubbers have 40-60 ppm SO2 at their outlet. Thus amine capture may require additional FGD, with associated costs, estimated at $3-5/ton CO2 (ie per MWh), and an extra waste stream. The ECO-ECO2 combination avoids this added cost/waste, according to Powerspan.

Commercial scale ECO plants

Meanwhile, FirstEnergy has also announced that it plans to install a commercial scale ECO system on units 4 and 5 of the Burger plant, which have a combined installed capacity of 312 MWe, instead of unit 4 (215 MWe) of its Bay Shore plant in Oregon, Ohio, as previously planned. As well as increasing the "scrubbed megawatts" the switch is also said to better fit "the coal-purchasing strategy for both plants." FirstEnergy says the ECO installation will "enhance the visibility of Burger" and give the company "more flexibility in [its] use of eastern coal." In addition it "provides a cost-effective method for meeting environmental regulations, including the Clean Air Interstate Rule and the Clean Air mercury Rule."

According to Powerspan the ECO process (described in MPS, May 2002, pp 39-43) will produce "a highly marketable ammonium sulphate fertiliser" byproduct (instead of the synthetic gypsum produced from traditional limestone scrubbing technologies). It also produces no liquid discharge or landfill waste.

Design engineering for the new Burger ECO system will begin in 2007, with start-up anticipated during the first quarter of 2011. The estimated cost of the facility is around $168 million.

Because FirstEnergy is planning to install selective non-catalytic reduction technology at Burger to remove NOx, the new ECO unit will not have NOx controls. But it is a feature of the ECO process that such NOx controls could be backfitted later.

According to a June announcement, American Municipal Power-Ohio, Inc (AMP-Ohio) has also committed to the use of Powerspan ECO sulphur dioxide emissions control technology, on its proposed American Municipal Power Generating Station (AMPGS) project and has executed a memorandum of understanding with The Andersons, Inc to process and market the ammonium sulphate fertiliser byproduct. The project is under development near the Ohio River in southern Meigs County, Ohio.

In October 2005, AMP-Ohio (Columbus-based non-profit wholesale power supplier and services provider for 121 member municipal electric systems in Ohio, Pennsylvania, Virginia, West Virginia and Michigan) and its partners, the Blue Ridge Power Agency and Michigan South Central Power Agency, announced plans for the new electric power plant. The proposed 1000 MWe facility will use pulverised coal and aims to incorporate the best of the latest generation of available and proven emissions control technologies to ensure that it meets or exceeds all environmental regulations and emissions limitation requirements, aspiring to be one of the cleanest pulverised coal units in the USA.

As well as controlling sulphur dioxide emissions, the AMPGS ECO installation will also provide co-benefits in the form of mercury and particulates control. The use of ECO technology will greatly reduce the annual volume of material from the power plant that needs to be placed in a landfill.

In addition, the AMPGS ECO system will be designed with features that allow for future expansion to make the plant carbon dioxide “capture ready," preparing the facility for the possibility of future statutory CO2 emission limits.

"AMP-Ohio originally announced [its] intent to pursue Powerspan technology at AMPGS last November," said AMP-Ohio President/CEO Marc Gerken. "At that time, we made the final decision contingent upon a technology study and contractual discussions. Since then, we have conducted due diligence, completing the study that determined that the Powerspan technology is a good fit for the AMPGS project."

The Andersons – a diversified company whose interests include the grain, ethanol and plant nutrient sectors of US agriculture – will handle processing and sale of the fertiliser byproduct. Denny Addis, President of the company's Plant Nutrient Group said "Powerspan's state of the art multipollution control technology promises to produce high quality ammonium sulphate plant nutrient for our Midwest customer base. Serving AMP-Ohio's plant nutrient operational and distribution needs is a natural extension to our core production and distribution business."

AMP-Ohio filed the air permit-to-install application with the Ohio EPA in May 2006. Additional major path permit applications were filed in May 2007, including Ohio Power Siting Board generation application, Army Corps of Engineers Section 10/404 permit, OEPA 401 certification, solid waste permit-to-install, and NPDES permit.