scholarly journals Turning CO2 Capture On and Off in Response to Electric Grid Demand: A Baseline Analysis of Emissions and Economics

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Stuart M. Cohen ◽  
Gary T. Rochelle ◽  
Michael E. Webber
Keyword(s):  
Co2 Emissions ◽  
Co2 Capture ◽  
Electricity Demand ◽  
System Level ◽  
Energy Requirements ◽  
Electric Grid ◽  
Peak Demand ◽  
Capital Costs ◽  
Generation Capacity ◽  
Co2 Capture Systems

Coal consumption accounted for 36% of America’s CO2 emissions in 2005, yet because coal is a relatively inexpensive, widely available, and politically secure fuel, its use is projected to grow in the coming decades (USEIA, 2007, “World Carbon Dioxide Emissions From the Use of Fossil Fuels,” International Energy Annual 2005, http://www.eia.doe.gov/emeu/iea/carbon.html). In order for coal to contribute to the U.S. energy mix without detriment to an environmentally acceptable future, implementation of carbon capture and sequestration (CCS) technology is critical. Techno-economic studies establish the large expense of CCS due to substantial energy requirements and capital costs. However, such analyses typically ignore operating dynamics in response to diurnal and seasonal variations in electricity demand and pricing, and they assume that CO2 capture systems operate continuously at high CO2 removal and permanently consume a large portion of gross plant generation capacity. In contrast, this study uses an electric grid-level dynamic framework to consider the possibility of turning CO2 capture systems off during peak electricity demands to regain generation capacity lost to CO2 capture energy requirements. This practice eliminates the need to build additional generation capacity to make up for CO2 capture energy requirements, and it might allow plant operators to benefit from selling more electricity during high price time periods. Post-combustion CO2 absorption and stripping is a leading capture technology that, unlike many other capture methods, is particularly suited for flexible or on/off operation. This study presents a case study on the Electric Reliability Council of Texas (ERCOT) electric grid that estimates CO2 capture utilization, system-level costs, and CO2 emissions associated with different strategies of using on/off CO2 capture on all coal-fired plants in the ERCOT grid in order to satisfy peak electricity demand. It compares base cases of no CO2 capture and “always on” capture with scenarios where capture is turned off during: (1) peak demand hours every day of the year, (2) the entire season of peak system demand, and (3) system peak demand hours only on seasonal peak demand days. By eliminating the need for new capacity to replace output lost to CO2 capture energy requirements, flexible CO2 capture could save billions of dollars in capital costs. Since capture systems remain on for most of the year, flexible capture still achieves substantial CO2 emissions reductions.

scholarly journals Turning CO2 Capture On and Off in Response to Electric Grid Demand: A Baseline Analysis of Emissions and Economics

2008 ◽  
Author(s):  
Stuart M. Cohen ◽  
Gary T. Rochelle ◽  
Michael E. Webber
Keyword(s):  
Co2 Emissions ◽  
Co2 Capture ◽  
Peak Load ◽  
Energy Requirements ◽  
High Price ◽  
Co2 Absorption ◽  
Electric Grid ◽  
Dynamic Framework ◽  
Generation Capacity ◽  
Co2 Capture Systems

Coal consumption accounted for 36% of America’s CO2 emissions in 2005, yet because coal is a relatively inexpensive, widely available, and politically secure fuel, its use is projected to grow in the coming decades [1]. In order for coal to contribute to the U.S. energy mix without detriment to an environmentally acceptable future, implementation of carbon capture and sequestration (CCS) technology is critical. Techno-economic studies of CCS have demonstrated its large expense due to substantial energy requirements and capital costs. However, such analyses typically calculate cost indicators using static plant performance parameters that are assumed to be constant over plant lifetime. That is, CO2 capture systems are generally assumed to capture a constant percentage of CO2 from power plant flue gas and consume a particular amount of plant gross generation capacity. Such studies do not consider dynamic plant operation that may result from diurnal and seasonal variations in electricity supply and demand, nor do they capture the economic desire to minimize CO2 emissions costs while maximizing profits by selling electricity at high price times. In this study, CO2 capture systems are analyzed in a grid level dynamic framework by considering the possibility of turning capture systems off during peak system load to regain generation capacity lost to the energy requirement of CO2 capture. This practice eliminates the costs of building additional generation capacity to make up for CO2 capture energy requirements, and it allows plant operators to benefit from selling more electricity during high price time periods. Dynamic CO2 capture operation is particularly suited to post-combustion (PC) CO2 absorption, a leading capture technology that, unlike other capture methods, offers the ability for flexible or on/off operation. This paper presents a case study on the Electric Reliability Council of Texas (ERCOT) electric grid of baseline cost and CO2 emissions estimates associated with different strategies of using on/off CO2 capture operation to satisfy peak electricity demand. It compares base cases of no CO2 capture and “always on” capture with scenarios where capture is turned off during: 1) peak load hours every day of the year, 2) days of the year of system peak load, and 3) system peak load hours only on seasonal peak load days. The study considers the implications of installing PC CO2 capture on all coal-fired plants in the ERCOT grid to better understand if on/off operation is desirable and which operational strategy may be the most economically viable under a policy of constrained CO2 emissions.

Analysis of Flexible CO2 Capture Over an Investment Life Using a Dynamic Electric Grid Model

2010 ◽  
Author(s):  
John R. Fyffe ◽  
Stuart M. Cohen ◽  
Michael E. Webber ◽  
Gary T. Rochelle
Keyword(s):  
Carbon Dioxide ◽  
Co2 Emissions ◽  
Co2 Capture ◽  
Energy Requirement ◽  
System Level ◽  
Co2 Removal ◽  
Electric Grid ◽  
Modeling Framework ◽  
Capital Costs ◽  
Co2 Capture Systems

Global focus on greenhouse gas emissions has led the United State’s legislature to discuss various strategies to reduce carbon dioxide (CO2) emissions. With coal-fired plants responsible for roughly half of United States (U.S.) electricity generation and approximately 30% of the nation’s CO2 emissions, coal-fired plants will be largely affected by any future CO2 emission regulations. However, coal-based generation could continue to meet our electricity demands while complying with future CO2 emissions restrictions with the addition of carbon dioxide capture and sequestration (CCS) technology. Most studies of CCS systems have demonstrated a permanent energy requirement of 11–40% of a plant’s output when operating continuously at a 90% CO2 removal rate. This study, however, used a dynamic model of the Electric Reliability Council of Texas (ERCOT) electric grid to consider post-combustion CO2 capture systems that can operate flexibly. Post-combustion CO2 capture systems using chemical absorption and stripping are particularly suited for retrofitting existing plants and operating in a flexible manner. Flexible carbon capture allows plant operators to vary the energy used for CO2 capture and compression in order to regain this generation capacity when desirable. Thus, flexibility can be used to choose the CO2 capture rate that allows the most economical combination of operating costs, electricity price, and output levels. Furthermore, operating at lower CO2 capture energy requirement levels and increasing output capacity during peak demand periods could dramatically reduce the amount of replacement capacity needed to replace potential output lost when CO2 capture systems are in operation. This research uses an existing modeling framework of a dynamic hourly dispatch system to study the economic, environmental, and performance implications of flexible CO2 capture over an investment lifetime. The effects of CO2 prices, natural gas fuel prices, and replacement capacity costs were analyzed along with various operating strategies. The fuel mixture behavior and emissions effects are presented, showing that large emissions reductions can be achieved using the current ERCOT plant fleet with the addition of flexible CO2 capture. An annual system-level cash-flow analysis is used to determine a net present value (NPV) for a group of CO2 capture plants under a range of possible replacement capacity costs. If replacement capacity costs are accounted for, flexibility can improve the NPV of a CO2 capture investment by substantially lowering the associated capital costs to replace output lost to CO2 capture energy requirements.

Comparing Flexible CO2 Capture in Gas- and Coal-Dominated Electricity Markets

2011 ◽  
Author(s):  
John R. Fyffe ◽  
Stuart M. Cohen ◽  
Michael E. Webber
Keyword(s):  
Natural Gas ◽  
Co2 Emissions ◽  
Co2 Capture ◽  
Electricity Markets ◽  
Power Plants ◽  
Electricity Price ◽  
Economic Viability ◽  
Electricity Prices ◽  
Modeling Framework ◽  
Co2 Capture Systems

Coal-fired power plants are a source of inexpensive, reliable electricity for many countries. Unfortunately, their high carbon dioxide (CO2) emissions rates contribute significantly to global climate change. With the likelihood of future policies limiting CO2 emissions, CO2 capture and sequestration (CCS) could allow for the continued use of coal while low- and zero-emission generation sources are developed and implemented. This work compares the potential impact of flexibly operating CO2 capture systems on the economic viability of using CCS in gas- and coal-dominated electricity markets. The comparison is made using a previously developed modeling framework to analyze two different markets: 1) a natural-gas dominated market (the Electric Reliability Council of Texas, or ERCOT) and 2) a coal-dominated market (the National Electricity Market, or NEM in Australia). The model uses performance and economic parameters for each power plant to determine the annual generation, CO2 emissions, and operating profits for each plant for specified input fuel prices and CO2 emissions costs. Previous studies of ERCOT found that flexible CO2 capture operation could improve the economic viability of coal-fired power plants with CO2 capture when there are opportunities to reduce CO2 capture load and increase electrical output when electricity prices are high. The model was used to compare the implications of using CO2 capture systems in the two electricity systems under CO2 emissions penalties from 0–100 US dollars per metric ton of CO2. Half the coal-fired power plants in each grid were selected to be considered for a CO2 capture retrofit based on plant efficiency, whether or not SO2 scrubbers are already installed on the plant, and the plant’s proximity to viable sequestration sites. Plants considered for CO2 capture systems are compared with and without inflexible CO2 capture as well as with two different flexible operation strategies. With more coal-fired power plants being dispatched as the marginal generator and setting the electricity price in the NEM, electricity prices increase faster due to CO2 prices than in ERCOT where natural gas-plants typically set the electricity price. The model showed moderate CO2 emissions reductions in ERCOT with CO2 capture and no CO2 price because increased costs at coal-fired power plants led to reduced generation. Without CO2 prices, installing CO2 capture on coal-fired power plants resulted in moderately reduced CO2 emissions in ERCOT as the coal-fired power plants became more expensive and were replaced with less expensive natural gas-fired generators. Without changing the makeup of the plant fleet in NEM, a CO2 price would not currently promote significant replacement of coal-fired power plants because there is minimal excess capacity with low CO2 emissions rates that can displace existing coal-fired power plants. Additionally, retrofitting CO2 capture onto half of the coal-based fleet in NEM did not reduce CO2 emissions significantly without CO2 costs being implemented because the plants with capture become more expensive and were replaced by the coal-fired power plants without CO2 capture. Operating profits at NEM capture plants increased as CO2 price increased much faster than capture plants in ERCOT. The higher rate of increasing profits for plants in NEM is due to the marginal generators in NEM being coal-based facilities with higher CO2 emissions penalties than the natural gas-fired facilities that set electricity prices in ERCOT. Overall, coal-fired power plants were more profitable with CO2 capture systems than without in both ERCOT and NEM when CO2 prices were higher than USD25/ton.

Use of Biomass in Partial Co2 Capture Systems in the Process Industry

2019 ◽  
Author(s):  
Hans Aksel Haugen ◽  
Tonje Warholm Thomassen ◽  
Jon Hovland ◽  
Ragnhild Skagestad
Keyword(s):  
Co2 Capture ◽  
Process Industry ◽  
Co2 Capture Systems

scholarly journals Recent advances in integrated CO2 capture and utilization: A review

2021 ◽  
Author(s):  
Shuzhuang Sun ◽  
Hongman Sun ◽  
Paul T Williams ◽  
Chunfei Wu
Keyword(s):  
Greenhouse Gases ◽  
Co2 Emissions ◽  
Co2 Capture ◽  
Fossil Fuels ◽  
Environmental Issues ◽  
Research Attention ◽  
Recent Advances

CO2 is one of the most important greenhouse gases leading to severe environmental issues. The increase of CO2 emissions from the consumption of fossil fuels has received much research attention....

Optimization of intercooling compression in CO2 capture systems

2009 ◽  
Vol 29 (8-9) ◽  
pp. 1744-1751 ◽  
Author(s):  
Luis M. Romeo ◽  
Irene Bolea ◽  
Yolanda Lara ◽  
Jesús M. Escosa
Keyword(s):  
Co2 Capture ◽  
Co2 Capture Systems

scholarly journals Decarbonisation of calcium carbonate at atmospheric temperatures and pressures, with simultaneous CO2 capture, through production of sodium carbonate

2021 ◽  
Author(s):  
Theodore Hanein ◽  
Marco Simoni ◽  
Chun Long Woo ◽  
John L Provis ◽  
Hajime Kinoshita
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Co2 Emissions ◽  
High Temperatures ◽  
Sodium Carbonate ◽  
Co2 Capture ◽  
Major Contributor ◽  
Calcination Process ◽  
Carbon Dioxide Co2

The calcination of calcium carbonate (CaCO3) is a major contributor to carbon dioxide (CO2) emissions that are changing our climate. Moreover, the calcination process requires high temperatures (~900°C). A novel...

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