Cottam Power Stations --- Before Apply CCS Technology

Before we start to talk about CCS at power stations, let’s look at some news about CCS from Research Councils UK.

“In April 2012, The Engineering and Physical Sciences Research Council (EPSRC) and the Department of Energy and Climate Change (DECC) announced a £13 million investment to establish a UK Carbon Capture and Storage (CCS) Research Centre.”

“EPSRC plans to invest approximately £10 million over a five-year period while DECC has started its CCS commercialisation programme and roadmap which will set out the Government’s vision for achieving commercial deployment of CCS in the UK in the 2020s, including investing £125 million in CCS research and development from the year 2011 to 2015.”

Now let’s look at the application of carbon capture and storage in power stations. There are many proposals of CCS in power stations in the UK, today I will focus on Cottam power stations.

A view of the coal-fuelled Cottam power station in Retford, U.K.

Cottam power stations has a pair of power stations (Cottam power station and Cottam development centre), located at Cottam near Retford in Nottinghamshire. Cottam power station is owned by EDF energy , whereas Cottam development centre is owned by E.ON UK.

Cottam power station is a coal- filled power station which has a generating capacity of 2 million kilowatts (kW) per year. It generates about 4% of total electricity supply of the UK market. In 2007, WWF ranked Cottam power station as the second of UK’s worst climate polluting power station, and the 20th in the EU (WWF, 2007). In the year 2006, it has around 10,029,024 Tonnes of carbon dioxide emission with near 940g carbon dioxide released per kWh electricity generated.

Next post I will talk about how CCS works at Cottam power station, how much carbon emission can be reduced and what is the cost.

Reference:

• Research Councils UK. http://www.rcuk.ac.uk/Pages/Home.aspx
• EDF Energy's coal-fired power stations.

  http://www.edfenergy.com/energyfuture/edf-energys-approach-why-edf-energy/coal-and-edf-energy
• Europe’s Dirty 30, WWF (2007). http://awsassets.panda.org/downloads/european_dirty_thirty_may_2007.pdf
• Photo from Talea Miller (2009).  Experts Sound Off on U.S. Role, Expectations for Copenhagen. http://www.pbs.org/newshour/updates/north_america/july-dec09/climate_11-25.html

A New Number, A New Peak

On 5th December, 2012, the Mauna Loa Observatory: Scripps Institutionof Oceanography gave the average value of concentration of atmospheric carbon dioxide in November. Two months ago, before I wrote the first post, the mean atmospheric CO₂ concentration in September was 391.07ppm.The concentration of carbon dioxide in the atmosphere in November 2012 hit a new peak - 392.92ppm. 

A paper by James Hansen from the NASA Goddard Institute for Space Studies stated that “350 parts per million” is the safe upper limit for the atmospheric carbon dioxide concentration, otherwise there may have a risk of seeding irreversible catastrophic effects. Another research from Ken Caldeira suggested that anthropogenic carbon dioxide released in the future may need to be eliminated in order to stabilise the global-mean temperatures.

Reference:

• Mauna Loa dataset. Mauna Loa Observatory: Scripps Institution of Oceanography。 
• Caldeira, K., Matthews, H. (2008), Stabilizing climate requires near-zero emissions,Geophys. Res. Lett., 35, L04705
• Hansen, J. et al (2008). If emissions of greenhouse gases are reduced, how quickly do their concentrations in the atmosphere decrease. 

CCS in the UK

The CCSA published a paper on 5th December 2012 discussed about “gas will support decarbonisation of the electricity mix.”

The UK government confirmed a number of steps that would be taken to stimulate investment in gas generation in its Gas Generation Strategy on 5th December 2012. New gas-fired power stations which emits at least have less carbon are going to be built over the following twenty years to replace retiring coal, older gas and nuclear power stations. Also those power stations need to provide the flexibility to balance out increasing amounts of wind and nuclear energy.

Secretary of State Edward Davey said that “The Gas Generation Strategy also confirms the Government’s commitment to supporting the development and commercialisation of Carbon Capture and Storage (CCS) technology, which will help to decarbonise gas, as well as coal, in future.”

On 03 April 2012 the UK government launched a new CCS Commercialisation Programme Competition in order to support practical experience in the design, construction and operation of CCS.

There are many CCS project proposals are planned in the UK. Here are two examples given by CCSA.

Don Valley Power Project, Yorkshire.

On February 10 2011, it was announced that bids had been submitted to the EU NER300 process to fund CCS projects for two projects in Hatfield. The first is a 900 MW IGCC plant in a consortium with National Grid, which was awarded 180 million euros funds from the EU's EEPR competition. The second project, a joint venture with Calix, was announced in November 2010 and is a 450MW gas fired Endex NGCC plant.

Caledonia Clean Energy Project, Scotland

Summit Power Group, National Grid, Petrofac - coal feedstock CCS plant;

On 20 March 2012 Summit Power Group announced entering into agreement with National Grid  to seek funding to develop a full-chain commercial-scale CCS plant in the Port of Grangemouth, west of Edinburgh on the Firth of Forth. The plant will use coal feedstock and produce hydrogen gas for commercial use. Carbon dioxide will be captured and transported via pipeline to St Fergus by National Grid Carbon and stored under the North Sea by CO2DeepStore, a Petrofac subsidiary.

Reference:

•     CCSA weekly newsletters, 06 December 2012. http://www.ccsassociation.org/news-and-events/ccsa-weekly-newsletter/
•     Government confirms role of gas in decarbonisation strategy. Theengineer. http://www.theengineer.co.uk/sectors/energy-and-environment/news/government-confirms-role-of-gas-in-decarbonisation-strategy/1014861.article#ixzz2EOH1WGgP
•     Don Valley Power Project . 2CoEnergy. http://www.2coenergy.com/don_valley_power_project.html
•     Summit Power, National Grid and Petrofac Team Up on Decc Carbon Capture Programme in UK. http://co2deepstore.com/co2-storage-for-caledonia-clean-energy-project 

Carbon Capture at Power Plants

The process of capture of atmospheric carbon dioxide and store it in geology for a long term is called carbon sequestration. Reduce the emission of carbon dioxide produced in power plant is a major geo-engineering method to mitigate the increase of atmospheric carbon dioxide concentration.

Carbon dioxide can be stored in deep sedimentary formations. Here is a map of sedimentary basins showing suitability as sequestration sites (Benson, 2008).

  

Combustion-based systems provide most electricity today. There are three capture techniques that can be used at fossil fuel power plans. They are pre-combustion, post- combustion and oxyfuel.

This is an amine-based postcombustion CO₂ capture system from a coal-fired power plant in Oklahoma, USA.

Post-combustion capture technology is the use after the burning of fossil fuels in the air. Carbon dioxide is separated by scrubbing from flue gas. Typically about 85%-90% carbon dioxide is captured by this “scrubbing process”. Post-combustion capture technology can be retrofitted to existing fossil fuel power stations. It can also be used at natural gas combined cycle (NGCC) power stations (Rubin, 2008).

Pre- combustion capture technology is used before the combustion of fossil fuels. Fossil fuels can be converted to a form amenable to capture. Fossil fuels are to a gas mixture of carbon dioxide and hydrogen firstly, and the carbon dioxide converted can be separated by scrubbing and then be stored. IGCC (Integrated Gasification Combined Cycle) is a process that electricity is through gas turbines and steam-powered stations. It costs less energy to remove CO₂, therefore, this process improves overall efficiency of power stations.

This is a precombustion CO₂ capture system used to produce synthetic natural gas from coal at the Dakota Gasification Plant in North Dakota.

Oxyfuel technology is “oxycombustion capture technology”. This technique uses pure oxygen during the fossil fuel combustion. Hence the flue gas produced contains only carbon dioxide and steam. Carbon dioxide and water can be separated by a cooling process, after that the flue contains almost only carbon dioxide left. Oxycombustion is the most efficient carbon capture method but cost more than other two methods.

Carbon dioxide under super critical state will be in to the target formation and stored after it is in power plants. There is growing agreement that exceptionally high retention rates are for carbon dioxide sequestration. Hepple and Benson (2005) considered that the goal of retention should be between 90 per cent and 99 per cent over a thousand years if sequestration is on a large scale.

There are four types of trapping modes: structural and stratigraphy trapping, residual CO₂ trapping, solubility trapping and mineral trapping. This graph shows the evolution of trapping mechanisms over time (IPCC 2005).

Reference:

• Benson, SM. Cole, DR. (2008) CO₂ Sequestration in deep sedimentary formation. Elements 4: 325-331
• Benson SM, Hoversten M, Gasperikova E, Haines M (2005) Monitoring protocols and life-cycle costs for geologic storage of carbon dioxide.
• Hepple RP, Benson SM (2005) Geologic storage of carbon dioxide as a climate change mitigation strategy: Performance requirements and the implications of surface seepage. Environmental Geology 47: 576-585   
• IPCC (2005) Underground geological storage. In: Metz B, Davidson O, de Coninck HC, Loos M, Meyer LA (eds) IPCC Special Report on Carbon Dioxide Capture and Storage, prepared by Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press.
• Edward S. Rubin. (2008) CO₂ Capture and Transport

Carbon Capture and Storage - CCS

The website of the Department of Energy & Climate Change of the UK givesn a description of “What is CCS?” and “How does it work?” Also, it mentioned that the British Geological Survey had estimated that the minimum UK carbon dioxide storage is 7. 8GT and the capacity may range from 24GT to 240GT for a hundred years storage.

Here is a video from BGS about CCS in the UK.

The Low Carbon Future: Carbon Capture and Storage: a brief intro.

Here is the link to an introduction about carbon capture and storage from Chin-Mei. From next blog, I will talk about carbon sequestration.  

The Low Carbon Future: Carbon Capture and Storage: a brief intro.: Source: awards.earthjournalism.org From the International Energy Agency (IEA) to the Intergovernmental Panel on Climate Change (IPCC)...

Here are some brief explanations about carbon sequestration.

What is Carbon Sequestration?

      Carbon Sequestration is the capture and storage of anthropogenic carbon dioxide through geo-engineering projects. Carbon dioxide can be stored with existing geology such as depleted oil reservoirs.

How much Carbon dioxide can be stored?

        It is estimated that the potential maximum global storage of carbon dioxide may up to 900 G tons.

What are the storage options?

Depleted oil and gas reservoirs

Use of carbon dioxide in enhanced oil and gas recovery (EOGR)

Deep saline formations

Use of carbon dioxide in enhanced coal bed methane recovery

Conditions needed to store carbon dioxide?

      In most case, geological sequestration will take place at temperatures and pressures above the critical point (Critical temperature: 31 °C; Critical pressure: 73.8bar). For most geological settings, Carbon dioxide would be sequestered at densities of 600-800 kg/m3.

From the next blog I will talk about methods used for carbon sequestration.

 Reference:

•      Brown, H. (2012) Carbon sequestration - out of sight, out of mind. 
•      Burgess, W. (2012) Introduction to carbon geosequestration. 

Ocean Iron Fertilisation. Does This Work?

Last post I talked about the impact of Ocean acidulation on marine animals and food net. How do we mitigate this?

Most potential methods used to mitigate ocean acidification are controversial. There is no known effective way to prevent the pH value of ocean continue decreasing as the carbon dioxide concentration of the atmosphere is increasing constantly.

On the one hand, long term scale of the value of ocean pH is mainly controlled by the input of eroded (or dissolved) rocks which give negative and positive ions. On the other hand, on short term scale, the ocean pH value if affected by the dissolved weak acid or alkali, for example, carbonate acid and borate. As I mentioned before, the increase of atmospheric carbonate acid accelerated the production of carbonate acid in the ocean.

Recently, there are several geo-engineer projects are proposed. One of them is “Iron fertilization”. It is the introduction of iron into the upper ocean in order to stimulate phytoplankton blooms. Schiermeier (2012) stated that “Each atom of added iron pulled at least 13,000 atoms of carbon out of the atmosphere by encouraging algal growth which, through photosynthesis, captures carbon.” Moreover, diatom contributes to about 40 per cent of all oceanic Carbon sequestration (Jones, 2012).

The most recent open ocean trial of ocean iron fertilization was conducted from January to March 2009 in the South Atlantic. Another one, in July 2012, iron fertilization was carried out in the ocean off western Canada by the Haida Salmon Restoration Corporation (Tollefson, 2012).

Ocean iron fertilisation seems to be an effective method to mitigate ocean acidification. However, some scientists suggested that massive ocean iron fertilization might cause toxic algal blooms or deplete oxygen levels in the middle of the water column.

 Reference:

• Aumont, O.; Bopp, L. (2006) Globalizing results from the ­­­­­­ocean in situ iron fertilization studies. Global Biogeochem Cycles
• Tollefson, J. (2012). Ocean-fertilization project off Canada sparks furore. Nature 490 (7421)
• Schiermeier, Q.(2012). Dumping iron at sea does sink carbon
• Jones, V. (2012). Global Biogeochemical Cycles. Global environmental change lecture powerpoint.
• ­Cao, L.; Caldeira, K.(2010) Can ocean iron fertilization mitigate

  ocean acidification?

A Short Video Explains How Ocean Acidification Affects Marine Species

Here is a short video talking about ocean acidification and its impacts on sea lives and different depth of sea water.

The ocean absorbs almost a third of the carbon dioxide which released into the atmosphere every year, then carbon dioxide reacts with sea water to form carbonic acid. As a result, the acidity of sea water increases. Even a small change of seawater pH value may cause significant impacts on marine species. Consequently the food web is affected indirectly. Moreover, ocean acidification is impacting shallower area much more than deep area. 

Next post, I will talk about potential methods used by geo-engineers to slow down ocean acidification.

What Happened To the Oceans?

From this post I will talk about how the increases of concentration of atmospheric carbon dioxide affects the ocean and carbon reduction methods used related to the ocean.

Ocean acidification is one of the major results as the increases of concentration of atmospheric carbon dioxide. Frank (2004) stated that up to 30 per cent of anthropogenic CO₂ are dissolved into the oceans, lakes and rivers. Carbon dioxide reacts with water to produce carbonic acid H₂CO₃. Carbonic acid is soluble acid which gives hydronium ions (H⁺).

The chemical reaction is

CO₂ + H₂O = H₂CO₃ = 2H⁺ +CO₃^2-

As the concentration of H+ ions in the ocean increases, the acidity of the ocean rises (pH value reduces). The Copenhagen Diagnosis (2009) described that the acidity of surface ocean waters has increased by approximately 30 per cent, and the amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by near 2 billion tons per year. Currently, the average pH value of surface ocean was around 8.07, however, the value was 8.179 before industrial revolutions (Orr. 2005), meanwhile it is predicted that the average pH value of surface ocean will continue to grow , and the number may reach about 7.95 by the year 2050.

The increase of ocean acidity may cause numerous results. Firstly the change in pH value of the ocean has serious impacts on marine lives, especially oceanic calcifying organisms (e.g. corals, foraminifera and coccoliths). The rate of dissolution of calcareous material increases when the acidity rises, as a result, calcification rate of those oceanic calcifying organisms is reduced significantly.

A research by Albright (2010) specified that, by the end of this century, coral reefs will be erode quicker than they can be built. This may have massive impacts on the long-term viability of these ecosystems and perhaps affect more than one million species that depend on coral reef habitat.

The photos from National Geographic below show what happens to a pteropod’s shell when placed in sea water with pH and carbonate levels projected for the year 2100. The shell slowly dissolves after 45 days.

Reference:

• Frank, J.; et al. (July 2004). Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans. Science 305(5682).
• The Copenhagen Diagnosis: Climate Science Report:http://www.copenhagendiagnosis.org/
• Orr, James C.; et al. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437 (7059): 681–686.
• Albrighta, R.; et al. (2010) Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmate.
• What is Ocean Acidification. http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F

What Else Besides the Warming?

Last time I posted some videos about the global warming caused by the increase of atmospheric carbon dioxide concentration. The leading global surface temperature reconstructions illustrated that Earth has warmed since 1880.  The 20 warmest years have happened from the year of 1981 and with all 10 of the warmest years occurring in the past 12 years. 

Besides global warming, there are many other effects directly or indirectly caused by the atmospheric carbon dioxide increases.

Sea level rises

Global sea level has been rising around 17 centimeters for the last hundred years. The sea level rising rate in the past ten years was almost double that of the last century. Moreover, the sea level is still continue to grow at this moment.

Glacial retreat and shrinking ice sheets

Data from NASA's Gravity Recovery and Climate Experiment show that Greenland lost 150 to 250 cubic kilometers of ice every year from 2002 to 2006 while Antarctica lost around 152 cubic kilometers of ice from the year of 2002 to 2005. Meanwhile, The national snow and ice data center of the USA stated that glaciers are declining universally in the world, including in the Himalayas, Alps, Rockies, Alaska and Andes. The Greenland and Antarctic ice sheets have reduced massively.

Both the size and thickness of Arctic sea ice has declined rapidly over the last several decades

Here are comparison photo form NSIDC

 Ocean acidification

The increase of atmospheric carbon dioxide has increased the acidity of the oceans.  

The Copenhagen Diagnosis indicated that, ever since the start of the Industrial revolutions, the acidity of

surface ocean waters has increased by approximately 30 per cent. This increase is the consequence of individuals releasing more carbon dioxide into the atmosphere and thus, more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by near 2 billion tons per year.

Extreme events

The increase of carbon dioxide in the atmosphere is one fundamental source of the increase number of extreme events. The high temperature events records of the USA has increased since last 50 years while the records of low temperature events reduced.

After reading week, I am going to discuss potential methods we could use to reduce the concentration of atmospheric carbon dioxide.

Reference:

• U.S. Energy Information Administration:  http://www.eia.gov/energyexplained/index.cfm?page=environment_how_ghg_affect_climate
• The Copenhagen Diagnosis: Climate Science Report:  http://www.copenhagendiagnosis.org/
• NSIDC:  http://nsidc.org/cryosphere/sotc/glacier_balance.html
• NASA GISS Surface Temperature Analysis (GISTEMP):  http://data.giss.nasa.gov/gistemp/
• NOAA, Global Surface Temperature Anomalies http://www.ncdc.noaa.gov/cmb-faq/anomalies.php 

Videos About Global Warming

  One of the most well-known results of increase of atmospheric carbon dixoide is the "Global Warming". Here are several videos from Youtube talk about how the carbon dioxide and other greenhouse gases changed the climate.

The Earth’s climate has warmed over the last hundred years, and human activity changing the atmospheric composition is likely a significant driving factor. National Energy Information Center (NEIC) in May 2001 specified that "Greenhouse gases are accumulating in Earth’s atmosphere as a result of human activities, causing surface air temperatures and sub-surface ocean temperatures to rise. Temperatures are, in fact, rising. The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability."


Reference:

• National Energy Information Center (NEIC), http://www.eia.gov/oiaf/1605/ggccebro/chapter1.html

The Carbon Cycle and Atmospheric Carbon Dioxide Sources

The principal source of carbon dioxide is degassing of the Earth from volcanic activities, mid-ocean ridges, hotspots or subduction-related volcanism. Carbon is converted into different forms through the atmosphere, hydrosphere, and lithosphere. Part of the outgassed carbon dioxide remains in the atmosphere, some of them is dissolved in the oceans, some carbon is preserved as biomass in living or dead organisms, and some is deposited as carbonate rocks such as limestone. 
 

Here, is a table shows Carbon pools in the major reservoirs on earth from Wikipedia:

Pool	Quantity (gigatons)
Atmosphere	720
Oceans (total)	38,400
Total inorganic	37,400
Total organic	1,000
Surface layer	670
Deep layer	36,730
Lithosphere
Sedimentary carbonates	> 60,000,000
Kerogens	15,000,000
Terrestrial biosphere (total)	2,000
Living biomass	600 - 1,000
Dead biomass	1,200
Aquatic biosphere	1 - 2
Fossil fuels (total)	4,130
Coal	3,510
Oil	230
Gas	140
Other (peat)	250

Approximately eighty per cent of atmospheric carbon dioxide is from the Earth’s outgassing(Hibbard. 2000). Meanwhile, respiration and fuel combustion are other two major source of atmospheric carbon dioxide.

Respiration consumes oxygen from the atmosphere and produces carbon dioxide.

Oxygen + carbohydrate > energy + water + carbohydrate

O₂ + CH₂O > energy + H₂O + CO₂

On the other hand, photosynthesis takes carbon dioxide from the atmosphere and produce oxygen.

6CO₂ + 6H₂O (+ light energy) > C₆H₁₂O₆ + 6O₂

The combustion of organic matters will release carbon dioxide to the atmosphere.

C + O₂  > CO₂

Moreover, some of carbon dioxide is produced and released into the atmosphere via metamorphism of limestone （CaCO₃ + SiO₂ > CO₂ + CaSiO₃） and the precipitation of Calcium carbonate from calcium and bicarbonate in the ocean by maritime organisms such as corals.（Ca²⁺ + 2HCO₃^- > CaCO₃ + CO₂ + H₂O）  

Here is a short vedio from NASA briefly describes the carbon cycle of the Earth and the change of atmospheric carbon dioxide. 

From next post, I am going to talk about the impacts of change in atmospheric carbon dioxide, then I will    discuss about the potential methodologies of carbon reduction.

Reference: 

• Carbon pools in the major reservoirs on earth. http://en.wikipedia.org/wiki/Carbon_cycle#cite_note-GlobalCarbonCycle-1
• Falkowski, P.; Scholes, R. J.; Boyle, E.; Canadell, J.; Canfield, D.; Elser, J.; Gruber, N.; Hibbard, K. et al. (2000). "The Global Carbon Cycle: A Test of Our Knowledge of Earth as a System". Science 290 (5490): 291–296.
• The Carbon Cycle and Earth's Climate. http://www.columbia.edu/~vjd1/carbon.htm 
• Chemical precipitation: terrestrial carbon cycle. Encyclopædia Britannica, Inc.