Carbon Capture and Storage Footprint
The developed world has been making considerable progress toward providing sustainable energy sources. New York State, for instance, has committed to a project producing 2.4 gigawatts of energy from offshore wind farms by 20301. While this is an admirable goal, new clean energy sources are not solving the problem of harmful emissions from some traditional industrial sources. The exhaust from burning coal, for instance, is about 15 percent carbon dioxide. Fortunately, a new approach is beginning to take root around the world.
Carbon capture and storage, is also known as carbon capture and sequestration, or CCS, refers to various processes for capturing excess carbon dioxide from sources such as energy production and manufacturing sites and transporting it to locations where it can be safely stored. This prevents the fundamental greenhouse gas from entering the atmosphere and adding to the phenomenon of global warming or secondary effects like raising the acidity of ocean waters.
The captured CO2 is generally pumped into underground mineral formations where it's less likely to impact the environment. This has been done in the past in certain industries, such as oil drilling where the technique is used to increase the flow of oil from deep below ground. However, long-term capture and storage of carbon dioxide is a modern concept that must consider the possibility of leaks, as well as chemical interactions with ground water and certain minerals.
CO2 may be captured directly out of the air at fossil fuel plants using membrane filters or adsorption, or carbon scrubbing. This is most often done with amines, which are nitrogen-rich organic compounds that readily bind to the carbon dioxide when it's passed through a liquid solution.
However, pumping and compacting the CO2 such that it can be effectively stored also requires heavy power use. Quite often the energy consumption is increased by at least 20 percent, and that cost is passed on to consumers. That's a major obstacle to CCS systems being used in many industries. Acidic compounds formed in connection with other industrial byproducts, such as sulfur dioxide, could also have a corrosive effect on piping and exhaust systems.
Storage of the CO2 involves injecting it under pressure into deep formations where there are empty spaces to be found, or into porous mineral carbonates that can absorb additional carbon dioxide. Submarine storage is considered risky because of the possibility of acidification and resultant damage to sea life. It's estimated that there is enough storage space in geological formations to contain our current rates of waste CO2 for centuries to come. However, seismic activity and potential collapse from increased pressure and instability are concerns that have to be taken into account.
CCS initiatives are now well under way at numerous locations throughout the world. The first commercial deployment of CCS took place in 2000. This was the Weyburn-Midale project (http://ptrc.ca/projects/weyburn-midale) in the oilfields of Saskatchewan, Canada, where over 8,500 metric tons of carbon dioxide were being captured every day by 2011.
There are currently 22 large-scale CCS operations underway or in the planning stages. It's estimated that the combined CO2 capacity for these projects would be as high as 40 million metric tons per year.
Some of the CCS projects already in use include:
- Petra Nova: This project at a Texas power production plant went into operation in January of this year and is expected to capture about 1.6 million metric tons of carbon dioxide yearly with an efficiency of 90 percent.
- Abu Dhabi: Located in the capital of the United Arab Emirates (UAE), this project was launched in November of 2016 by the Emirates Steel Industries association to capture waste carbon dioxide during the production of steel and iron. It is expected to collect about 0.8 million tons annually, to be used in oil recovery.
- Tomakomai: This city in Hokkaido, Japan, began operation in April of 2016. It is currently capturing about 100,000 tons yearly from a hydrogen production plant. The collected CO2 is being injected into a nearby off-shore geologic formation.
Three additional CCS projects are expected to be in operation within months:
- Kemper County Energy Facility: This Mississippi project will be the first to use a TRIG process developed in partnership with the US Dept. of Energy and is expected to capture around 3 million metric tons annually. It will be part of an electric plant managed by Mississippi Power, a subsidiary of Southern Company based in Atlanta, GA.
- Illinois Industrial CCS: This will be the world's first CCS system in operation at a biofuel facility in Decatur, IL. It will capture approximately 1 million metric tons annually to be injected into deep underground saline deposits.
- Gorgon CCS: This Australian project is being estimated to capture as much a 4 million metric tons annually from natural gas production in the coastal fields of western Australia. This carbon dioxide will also be injected into deep saline formations.
- Yangchang CCS: Currently under construction, this system is projected to capture about 400,000 metric tons per annum from chemical plants in Shaanxi Province, China. Though China has several other CCS operations in the planning phase, this will be the first and possibly largest to date.
CCS is a promising leap forward in reducing greenhouse gas emissions. Industry and power plants are traditionally the major sources of CO2. While conventional and renewable energy comparison and its emission footprint, clearly points to the superiority of the later, some renewables might still produce CO2 making further developments of CSS technologies a necessity.
However, as more government and industry authorities commit to CCS and renewable energy, it's estimated that we could mitigate the effects of carbon dioxide by as much as 55 percent over the next century. If CCS technologies can become more efficient and affordable to keep pace with solar and wind solution, there may be a much lower threat from climate change.
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