Environmental Analysis

The main reason behind CCS technology is to reduce the negative environmental impacts related to greenhouse gas (GHG) emissions, which is dominated by carbon (alongside methane and nitrous oxide). CO2 is the second most abundant greenhouse gas in the atmosphere, after water vapor, and is considered the most emitted gas (About 65%, shown in chart below). Currently, the global mean concentration of CO2 in the atmosphere is about 400ppm, where the safe level is below 350 ppm [27].

(Global greenhouse gas emissions from 2010) [31]

The figure below: in a 20-year period, the global carbon emissions from fossil fuels only has been increasing dramatically, reaching almost 10 times its value from 1900 to 2010 (10,000 Million Metric Tons of Carbon). The total global CO2 emission was about 370.4 Billion Metric Tons during the period between 1990 to 2005. [35]

(Global carbon emissions from fossil fuels, 1900-2014) [31]

Since fossil fuels contain carbon, which is a major component of fossil fuels, carbon emissions will continue to be around until we as a society go completely renewable. For that, the main resource of harmful CO2 emissions in the atmosphere is created by burning fossil fuels (other reasons include deforestation, cement production, and land clearing for agriculture) such as oil, natural gas, diesel and especially coal which contributes for almost 43% of carbon dioxide emitted from fossil fuel use (1 ton of coal burned = 2.5 tons of CO2 emitted). [29] The amount of CO2 that is produced from burning coal by itself in power plants is more than that from cars, trucks, planes and other transportation types combined. [12]

Risks and problems caused by CO2:

The main and biggest issue is global warming and climate change:

How is it contributing in global warming? What are the results?

Greenhouse gases, especially carbon dioxide, trap energy from the sun in our atmosphere. This is known as the greenhouse gas effect. Solar energy is usually 70% absorbed and 30% reflected back to space. Without these greenhouses, the Earth would be, on average, about 90°F (33°C) colder [12]. With excess GHGs in the atmosphere, some of the reflected energy is trapped, leading to an increase in the temperature.

If this carbon emission continues following the current trend, we might be facing dramatically increased temperature values (It is predicted that, if the current rate of carbon emission continues, the average global temperature would increase 0.2°C per decade). Even if the emissions are constant (at the year 2000 rate), the temperature would still be increasing by 0.1°C in the next century, as well as the thermal expansion.

Such emissions will also lead to other problems including air pollution, rising water levels, damaging the ecosystem, accumulating in low-lying areas, affecting agricultural production, species extinction, and ranges of diseases. [29]

2. Another impact of CO2 is the contamination of ground water by CO2 leakage water aquifers for reasons such as uncontrollable natural disasters. Being an effective solvent in some conditions makes it capable of extracting toxic contaminants affecting the water quality [32].

What are the solutions?

If we want to prevent the global warming and climate changes issues, the ideal solution is to stop producing CO2, this is by switching to renewable energy such as solar or wind energy as a substitute to fossil fuels. Studies show this will not happen for a long time until we become independent of oil, coal and gas. Also, these alternative energy resources are of course more expensive that fossil fuels. Today, plants and trees are not enough to consume the huge amount of carbon especially with the current industrial development [27]. Then if we cannot stop producing carbon, then the best solution we have it to use a technology such as CCS where CO2 will be captured and stored underground.

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Environmental Risks of CCS technology:

In general, this technology has few disadvantages to the environment, health and safety. These damages are by maximum similar (or even less than) risks that are encountered in the oil industry especially in Enhanced Oil Recovery (EOR) processes.

However, one of the greatest risks of CCS is the leakage of CO2 from its storage sites which might affect human health (either in a direct or indirect way) as well as the surrounding environment. This is a slow process that can occur over decades. It is worth noting that storing carbon for long terms (hundreds or thousands of years) has not been proven yet. Leakage of carbon dioxide in the oil field can be classified as either abrupt leakage (through injection well failure or up an abandoned well) or gradual leakage (through undetected faults or wells) [3].

Another issue is the migration of CO2 into the surrounding geological formations. This is mainly dependent on the formation lithology (for example: dissolving in saline water), and pressure conditions.

Usually the power plants used for CCS purposes use about 15-25% more energy than the conventional plants, depending on the method used. This leads to increasing both direct (from the facilities where CCS is installed) and indirect (from transportation and extraction of fuel) emissions.

Environmental Benefits of CCS technology:

Main advantage behind applying this technology: Reducing the amount of carbon in the atmosphere while at the same time maintaining usage of fossil fuels as a primary source of energy for the future. This will lead to reducing the Global Warming Potential, measured in CO2 eq./MWh, as shown in the figure below where it drops from 800 to less than 200 CO2 eq./MWh.

(Global warming potential with and without CCS for different types of plants: pulverised coal, combined cycle gas turbine, and integrated coal gasification combined cycle) [6]

2. Proved that CO2 emissions are reduced significantly in the medium- and long-runs.Whereas it might increase temporarily in the short-run due to few reasons such as leakage and crop yield effects [27].

3. GHG emissions would be reduced 18% globally by 2050 with applying energy efficiency and low technologies (without CCS), compared to 25.8% with CCS (7.8% difference) [3]

4. If applied to coal and gas fired electricity, CCS will contribute in a global reduction in GHG electricity emissions as well.

5. MIT predicted that by 2050, global GHG will be reduced by 3-4 Giga Tons annually with CCS technology. [3]