User:Scribbles08/sandbox

CBE 195 Final Project

Objectives: Expand Wikipedia content relating to the topics discussed in this course on Carbon Capture and Sequestration.

Integrated Gasification Combined Cycle (IGCC)

Project Description

My group members and I will expand article content on IGCC, specifically relating to its relevance in carbon capture.

Summary

Integrated gasification is the process of gasifying coal to produce electricity. The coal is gasified by burning crushed coal in an environment with less than half the amount of oxygen needed to fully burn the coal to produce syngas. Syngas is then combusted in a combined cycle generator to produce electricity. This process reduces emissions of sulfur dioxide, particulates, and carbon dioxide.

Ideal Contributions

We would like to add Technical content, more recent references, and discuss the Kemper project. We can also add the reactions that take place because the page only has a process flow diagram. We can also add information on development areas that can improve IGCC such as the gasifier as well as large projects that incorporate IGCC like the Kemper County Energy Facility.

Possible Contributions to IGCC Article

Summary:

An integrated gasification combined cycle (IGCC) is a technology that uses a high pressure gasifier to turn coal and other carbon based fuels into pressurized gas—synthesis gas (syngas). It can then remove impurities from the syngas prior to the power generation cycle. Some of these pollutants, such as sulfur, can be turned into re-usable byproducts through the Claus process. This results in lower emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. With additional process equipment, a water-gas shift reaction can increase gasification efficiency and reduce carbon monoxide emissions by converting it to carbon dioxide. The resulting carbon dioxide from the shift reaction can be separated, compressed, and stored through sequestration. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, similar to a combined cycle gas turbine. This process results in improved thermodynamic efficiency compared to conventional pulverized coal.

Significance:

Coal can be found in abundance in the USA and many other countries and its price has remained relatively constant in recent years. Out of traditional fossil fuels like oil, coal, and natural gas, coal is used as a feedstock for 40% of global electricity generation. Fossil fuel consumption and its contribution to large-scale, detrimental environmental changes is becoming a pressing issue, especially in light of the Paris Agreement. Thus, the lower emissions that IGCC technology allows through gasification and pre-combustion carbon capture is crucial to addressing aforementioned concerns.

Operations:

IGCC plants are advantageous in comparison to conventional coal power plants due to their high thermal efficiency, low non-carbon greenhouse gas emissions and capability to process low grade coal. The key disadvantage is the amount of CO2 released without pre-combustion capture.

Installations:

The DOE Clean Coal Demonstration Project helped construct 3 IGCC plants: Wabash River Power Station in West Terre Haute, Indiana, Polk Power Station in Tampa, Florida (online 1996), and Pinon Pine in Reno, Nevada. In the Reno demonstration project, researchers found that then-current IGCC technology would not work more than 300 feet (100m) above sea level.[2] The DOE report in reference 3 however makes no mention of any altitude effect, and most of the problems were associated with the solid waste extraction system. The Wabash River and Polk Power stations are currently operating, following resolution of demonstration start-up problems, but the Piñon Pine project encountered significant problems and was abandoned.

The US DOE's Clean Coal Power Initiative (CCPI Phase 2) selected the Kemper Project as one of two projects to demonstrate the feasibility of low emission coal-fired power plants. Mississippi Power began construction on the Kemper Project in Kemper County, Missippi, in 2010 and is poised to begin operation in 2016, though there have been many delays. The electrical plant is a flagship Carbon Capture and Storage (CCS) project that burns lignite coal and utilizes pre-combustion IGCC technology with a projected 65% emission capture rate.

The first generation of IGCC plants polluted less than contemporary coal-based technology, but also polluted water; for example, the Wabash River Plant was out of compliance with its water permit during 1998–2001[3] because it emitted arsenic, selenium and cyanide. The Wabash River Generating Station is now wholly owned and operated by the Wabash River Power Association.

IGCC is now touted as capture ready and could potentially capture and store carbon dioxide.[4][5] (See FutureGen)Poland's Kędzierzyn will soon host a Zero-Emission Power & Chemical Plant that combines coal gasification technology with Carbon Capture & Storage (CCS). This installation had been planned, but there has been no information about it since 2009. Other operating IGCC plants in existence around the world are the Alexander (formerly Buggenum) in the Netherlands, Puertollano in Spain, and JGC in Japan.

The Texas Clean Energy project plans to build a 400 MW IGCC facility that will incorporate carbon capture, utilization and storage (CCUS) technology. The project will be the first coal power plant in the United States to combine IGCC and 90% carbon capture and storage. Commercial operation is due to start in 2018.[6]

There are several advantages and disadvantages when compared to conventional post combustion carbon capture and various variations and these are fully discussed at reference 6.[7]

IGCC Process Overview

• The solid coal is gasified to produce syngas, or synthetic gas. Syngas is synthesized by gasifying coal in a closed pressurized reactor with a shortage of oxygen. The shortage of oxygen ensures that coal is broken down by the heat and pressure as opposed to burning completely. The chemical reaction between coal and oxygen produces a product that is a mixture of carbon and hydrogen, or syngas. C_xH_y + (x/2)O₂ → (x)CO₂ + (y/2)H₂
• The heat from the production of syngas is used to produce steam from cooling water which is then used for steam turbine electricity production.
• The syngas must go through a pre-combustion separation process to remove CO₂ and other impurities to produce a more purified fuel. Three steps are necessary for the separation of impurities:

1. Water-gas-shift reaction. The reaction that occurs in a water-gas-shift reactor is CO + H₂O $\rightleftharpoons$ CO₂ + H₂. This produces a syngas with a higher composition of hydrogen fuel which is more efficient for burning later in combustion.
2. Physical separation process which can be done through various mechanisms such as absorption, adsorption or membrane separation.
3. Dried, compressed and stored/shipped.

• The resulting syngas fuels a combustion turbine that produces electricity. At this stage the syngas is fairly pure H₂.

CO₂ Capture in IGCC

Pre-combustion CO₂ removal is much easier than CO₂ removal from flue gas in post-combustion capture due to the very high concentration of CO₂ after the water-gas-shift reaction. During pre-combustion in IGCC, the partial pressure of CO₂ is nearly 1000 times higher than in post-combustion flue gas. Due to the high concentration of CO₂ pre-combustion, physical solvents, such as Selexol and Rectisol, are preferred for the removal of CO₂ vs that of chemical solvents. Physical solvents work by absorbing the acid gases without the need of a chemical reaction as in traditional amine based solvents. The solvent can then be regenerated, and the CO₂ desorbed, by reducing the pressure. The biggest obstacle with physical solvents is the need for the syngas to be cooled before separation and reheated afterwards for combustion. This requires energy and decreases overall plant efficiency.

Other absorption, adsorption and membrane technologies can be used, but these technologies are typically developed for purity, while compromising recovering. Whereas, for the purpose of IGCC, recovery is most important while purity can more so be compromised. In other power plants, CO₂ is captured in the flue gas after combustion has occurred. This can be more difficult due to the lower concentration of CO₂ in the flue gas.

Plant Specifications

90% capture: Syngas has very high H₂ composition and uses special H₂ combustion turbines.

50-60% capture: Doesn’t need special turbine and outputs about the same CO₂ levels as a natural gas plant.

18-30% Capture: A shift reaction is not used to increase purity and production of CO to CO₂. Only the CO₂ formed during the gasification step is removed.

IGCC Economics with and without CCS

An economic analysis by the Department of Energy concluded that the total plant cost (TPC) increases by 30-40% by the inclusion of a CCS system in IGCC plants. It was also determined that IGCC plants without CCS have HHV efficiency of 41.1% while plants with CCS have 32% HHV.

Costs and Reliability The main problem for IGCC is its high capital cost that prevents it from competing with other power plants. Currently, PC plants are the lowest cost power plant option. The advantage of IGCC comes from the ease of retrofitting existing power plants that could offset the high capital cost. In a 2007 model, IGCC with CCS is the lowest-cost system in all cases. This model estimated IGCC with CCS to cost 71.9 $US2005/MWh compared to pulverized coal with CCS that cost 88 $US2005/MWh and natural gas combined cycle with CCS that cost 80.6 $US2005/MWh. The cost of electricity value estimated was noticeable sensitive to the price of natural gas and the inclusion of carbon storage and transport costs.

The potential benefit of retrofitting has so far, not offset the cost of IGCC with carbon capture technology. A 2013 report by the U.S. Energy Information Administration demonstrates that the overnight cost of IGCC with CCS has increased 19% since 2010. Amongst the three power plant types, pulverized coal with CCS has an overnight capital cost of $5,227 (2012 dollars)/kW, IGCC with CCS has an overnight capital cost of $6,599 (2012 dollars)/kW, and natural gas combined cycle with CCS has an overnight capital cost of $2,095 (2012 dollars)/kW. Pulverized coal and NGCC costs did not change significantly since 2010. The report further relates that the 19% increase in IGCC cost is due to recent information from IGCC projects that have gone over budget and cost more than expected.

Recent testimony in regulatory proceedings show the cost of IGCC to be twice that predicted by Goddell, from $96 to 104/MWhr.[14][15] That's before addition of carbon capture and sequestration (sequestration has been a mature technology at both Weyburn in Canada (for enhanced oil recovery) and Sleipner in the North Sea at a commercial scale for the past ten years)—capture at a 90% rate is expected to have a $30/MWh additional cost.[16]

The high cost of IGCC is the biggest obstacle to its integration in the power market; however, most energy executives recognize that carbon regulation is coming soon. Bills requiring carbon reduction are being proposed again both the House and the Senate, and with the Democratic majority it seems likely that with the next President there will be a greater push for carbon regulation. The Supreme Court decision requiring the EPA to regulate carbon (Commonwealth of Massachusetts et al. v. Environmental Protection Agency et al.)[20] also speaks to the likelihood of future carbon regulations coming sooner, rather than later. With carbon capture, the cost of electricity from an IGCC plant would increase approximately 33%. For a natural gas CC, the increase is approximately 46%. For a pulverized coal plant, the increase is approximately 57%. This potential for less expensive carbon capture makes IGCC an attractive choice for keeping low cost coal an available fuel source in a carbon constrained world. However, the industry needs a lot more experience to reduce the risk premium. IGCC with CCS requires some sort of mandate, higher carbon market price, or regulatory framework to properly incentivize the industry.

References

1. Mao, Yisha. "Considerations For IGCC Power Plant Designs." Considerations For IGCC Power Plant Designs. Stanford University, 12 Dec. 2012. Web. 19 Apr. 2016. <http://large.stanford.edu/courses/2012/ph240/mao2/>.
2. Padurean, Anamaria, Calin-Cristian Cormos, and Paul-Serban Agachi. "Pre-combustion Carbon Dioxide Capture by Gas–liquid Absorption for Integrated Gasification Combined Cycle Power Plants." International Journal of Greenhouse Gas Control 7 (2012): 1-11. Web. 18 Apr. 2016. <https://www.researchgate.net/profile/Calin-Cristian_Cormos/publication/271560078_Pre-combustion_carbon_dioxide_capture_by_gasliquid_absorption_for_Integrated_Gasification_Combined_Cycle_power_plants/links/55c8621d08aebc967df89b04.pdf>.
3. Schlissel, David. The Kemper IGCC Project: Cost and Schedule Risks. Rep. The Institute for Energy Economics and Financial Analysis, n.d. Web. 18 Apr. 2016. <http://www.ieefa.org/wp-content/uploads/2012/12/Kemper-IGCC-Project-Cost-and-Schedule-Risk-Report.pdf>.
4. Maurstad, Ola. "An Overview of Coal Based Integrated Gasification Combined Cycle (IGCC) Technology." Laboratory for Energy and the Environment (2005). MIT LFEE 2005-002 WP. Web. 18 Apr. 2016. <http://sequestration.mit.edu/pdf/LFEE_2005-002_WP.pdf>.
5. Holt, Neville, George Booras, and Douglas Todd. A Summary of Recent IGCC Studies of CO2 Capture for Sequestration. Proc. of The Gasification Technologies Conference San Francisco. Gasification & Syngas Technologies Council, 14 Oct. 2003. Web. 18 Apr. 2016. <http://www.gasification-syngas.org/uploads/eventLibrary/31HOLT_paper.pdf>.
6. "IGCC Efficiency / Performance." National Energy Technology Laboratory. U.S. Department of Energy. Web. 18 Apr. 2016. <http://www.netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/igcc-efficiency>.

Monitoring Geological Carbon Sequestration Sites

Project Description

I will expand article content on carbon sequestration, specifically relating to the monitoring geological carbon sequestration sites.

Project Summary

In order to detect carbon dioxide leaks and the effectiveness of the geological sequestration sites, different monitoring techniques can be employed. Monitoring can be done at surface or subsurface levels through several different technologies. At surface level there is Interferometric Synthetic Aperture Radar (InSAR) and eddy-covariance and chamber accumulation methods (measuring increases in concentration and flux of carbon dioxide). At subsurface levels there are seismic, electrical and temperature perturbation monitoring.

Ideal Contributions

I would like to add information about the different monitoring techniques at both surface and subsurface levels. I would also like to provide some examples of current monitoring projects in play for geological sequestration sites.

Possible Article Additions

Monitoring Summary:

In order to detect carbon dioxide leaks and the effectiveness of geological sequestration sites, different monitoring techniques can be employed to verify that the sequestered carbon stays trapped below the surface in the intended reservoir. Leakage due to injection at improper locations or conditions could result in carbon dioxide being released back into the atmosphere. It is important to be able to detect leaks with enough warning to put a stop to it, and to be able to quantify the amount of carbon that has leaked for purposes such as cap and trade policies, evaluation of environmental impact of leaked carbon, as well as accounting for the total loss and cost of the process. To quantify the amount of carbon dioxide released, should a leak occur, or to closely watch stored CO₂, there are several monitoring methods that can be done at both the surface and subsurface levels.

Subsurface Summary:

In subsurface monitoring, there are direct and indirect methods to determine the amount of CO₂ in the reservoir. A direct method would be drilling deep enough to collect a fluid sample. This drilling can be difficult and expensive due to the physical properties of the rock. It also only provides data at a specific location. Indirect methods would be to send sound or electromagnetic waves down to the reservoir where it is then reflected back up to be interpreted. This approach is also expensive but it provides data over a much larger region; it does however lack precision. Both direct and indirect monitoring can be done intermittently or continuously.

Seismic summary:

Seismic monitoring is a type of indirect subsurface monitoring. It is done by creating vibrational waves either at the surface using a vibroseis truck, or inside a well using spinning eccentric mass. These vibrational waves then propagate through the geological layers and reflect back creating patterns that are read and interpreted by seismometers. It can identify migration pathways of the CO₂ plume. Two examples of monitoring geological sequestration sites using seismic monitoring are the Sleipner sequestration project and the Frio CO₂ Injection test. Although this method can confirm the presence of CO₂ in a given region, it cannot determine the specifics of the environment or concentration of CO₂.

Surface Monitoring:

Eddy covariance is a surface monitoring technique that measures the flux of CO₂ from the ground’s surface. It involves measuring CO₂ concentrations as well as vertical wind velocities using an anemometer. This provides a measure of the total vertical flux of CO2. Eddy covariance towers could potentially detect leaks, however, the natural carbon cycle, such as photosynthesis and the respiration of plants, would have to be accounted for and a baseline CO₂ cycle would have to be developed for the location of monitoring. An example of Eddy covariance techniques used to monitor carbon sequestration sites is the Shallow Release test. Another similar approach is utilizing accumulation chambers. These chambers are sealed to the ground with an inlet and outlet flow stream connected to a gas analyzer. This also measures the vertical flux of CO₂. The disadvantage of accumulation chambers is its inability to monitor a large region which is necessary in detecting CO₂ leaks over the entire sequestration site.

inSAR Summary: Interferometric Synthetic Aperture Radar

InSAR monitoring is another type of surface monitoring. It involves a satellite sending signals down to the Earth’s surface where it is reflected back to the satellite’s receiver. From this, the satellite is able to measure the distance to that point. In CCS, the injection of CO₂ in deep sublayers of geological sites creates high pressures. These high pressured, fluid filled layers affect those above and below it resulting in a change of the surface landscape. In areas of stored CO₂, the ground’s surface often rises due to the high pressures originating in the deep subsurface layers. These changes in elevation of the Earth’s surface corresponds to a change in the distance from the inSAR satellite which is then detectable and measurable.