As humans, it’s tough to acknowledge how the Earth sustains life. Instead we prefer, to act like selfless children on Christmas day, desiring for more presents to keep us going and on the rare occasion truly appreciate and give back. Our wonderful planet has showered us with gifts of water, oil, phosphorous, coal and precious Earth elements yet an enormous toll is taken on the Earth by us as our demand for such resources surpasses what the Earth can provide. The time to be greedy is not now as the world population is growing at an unprecedented rate. In the next 40 years, the global population is expected to increase from 7 billion to 9 billion and by 2030 the energy demand will increase by 50% [1]. As 80% of the world’s energy needs are provided by coal, fuel and gas, it is inevitable that carbon dioxide (CO2) emissions will be extraordinary. However, experts believe that implementing Carbon Capture and Storage in fossil fuel power stations may be a solution in tackling excessive CO2 emissions which will be explained in this article.
As a planet, we cannot allow excessive CO2 emissions to continually be released into the atmosphere as it has exacerbated global warming. It has affected our coral reefs, water pollution, marine organisms, ocean sea levels, the global temperatures and has caused a domino effect in many other areas. As a result, scientists have invested research into Carbon Capture and Storage, a process which allows fossil fuel usage while ensuring that the polluting product is stored in the ground rather than contributing to the greenhouse effect.
The aim of Carbon Capture and Storage (CCS) is therefore to mitigate climate change while supporting high energy demands. CCS has been a recent project but the engineering problem is that has not yet become large scale due to fading support following current political and economic difficulties. Seeing President Trump withdraw from the Paris Agreement[2] is a depiction of poor views towards climate change as well his first budget proposal to Congress of a 77% cut down to $31 million in 2018 for CCS research funding[3]. In addition, it is easier for companies to buy emission allowances for €3 per tonne of CO2 under the EU Emission Trading Scheme, whereas CCS is €30-100 per tonne of CO2[4] – which causes countries to choose more cost-efficient processes despite being a deadly CO2 emitter. The EU has also not got the infrastructure nor storage space under the sea.
There are alternative approaches to reduce emissions. In 2015, 99% of Costa Rica’s electricity came from renewables[5] in the form of solar, wind, geothermal and hydroelectric energy. Other approaches to mitigate climate change include carbon capping. Here companies are given a limit on the amount of greenhouse gases it can release into the atmosphere. If exceeded, they will be charged, which in turn forces them to slowly reduce their emissions. However, the issue is the extent to which emissions are reduced. Based on our current consumption rate, fossil fuels are expected to be depleted by 2060 [6]– in under 40 years time. Furthermore, if the world’s current fossil fuel reserves were burned without mitigating, nearly 750 billion tonnes of carbon would be emitted. Thus, we need a faster and more effective approach in preventing greenhouse gas emissions, which is why we need technology like CCS. For without CCS, news headlines even worse than the once feared “The world has now permanently reached 400pm CO2” will arise.
A report has shown that CCS could cut annual costs of meeting our carbon targets by up to 1% of GDP or £42 billion per year by 2050[7] and it works in a set of processes.
The first step is capture and there are many different methods, two being pre-combustion and post-combustion. In pre-combustion, coal reacts with oxygen to produce a synthetic gas made from carbon monoxide (CO) and hydrogen gas (H2). The CO2 then reacts resulting in carbon dioxide and hydrogen. The CO2 is captured and the H2 is either sent to a turbine to produce electricity or used in hydrogen fuel cells for cars. The disadvantage of this is that it cannot be fitted or used for older coal power plants.[8]
During post-combustion, CO2 is separated from flue gas by bubbling gas through an absorber column packed with amine solvents. Once the chemicals in the absorber become saturated, a stream of heated steam at 120 degrees is passed through to release the trapped CO2 which is transported for storage.[9]
After capture, 90% of the CO2 emissions produced from fossil fuels is captured[10]. It is compressed at a high pressure into liquid where it goes to a site by truck or pipelines. The reservoir for where the CO2 is then stored into 5,000km underground[11] is chosen carefully in either a deep saline aquifer or depleted oil and gas fields so that the site has a vast number of porous rocks for the CO2 to be trapped. An impermeable layer rests above the porous rocks as a cap to prevent the CO2 from escaping.
Figure 1 – Image of an underground depleted oil and gas field. The arrows show the CO2 leaving the power plant from where it was produced and it being injected into the porous rock. (Source: https://www.youtube.com/watch?v=GglSLuWP5cM)
A sophisticated system that spans three different levels to monitor the CO2 is put in place which sends information back to the plant regarding the changes in pressure and CO2 concentration levels so any dramatic change can be acted upon immediately.
Unlike renewable energy or carbon capping, CCS takes immediate action in dealing with the CO2 while still allowing the use of fossil fuels. CCS may not completely prevent all the CO2 from escaping into the atmosphere but it certainly slows the procedure of a two-degree temperature rise which is detrimental to our planet. This means that we are currently helping to shape our future and people can then be informed of how much CO2 we have prevented – which hopefully should encourage companies to invest in building infrastructure for CCS in the EU.
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