So CCS isn't perfect either?!

Like many things in life, a world of safe CCS may be too good to be true.

Carbon capture specialist Udayan Singh highlights the key problem areas for CCS: the safe transportation of CO₂ and precise and secure injections of CO₂ into geological formations. If this method is to be introduced there will be great pressure on the quality and constant maintenance of carbon pipelines and injection, as leaks could cause vast environmental damage and would prove very costly.

The devastation of the Lake Nyos disaster
http://www.emigennis.com/2014/04/06/lake-nyos-disaster-reference-photos/

Forgarty & McCally state that if CO₂ concentrations were to reach 7%, enough carbon would be present in the blood of humans to cause narcosis and eventually asphyxiation. To support their points, they offer the Lake Nyos, Cameroon 1986 case study. 100,000 tonnes of CO₂ was released as an overturn of a volcanic lake (near Lake Nyo, as described by Damel et al) as the bottom part became over saturated with CO­₂, Holloway importantly claimed that this was due to a slow leak of CO₂ from magmatic sources into the lake. The leak resulted in  carbon concentrations of up to 10% in surrounding areas and consequentially over 1700 people died whilst hundreds contracted skin conditions or suffered from memory loss. This volume of CO₂ equates to seven days of CO₂ emissions from a single coal-fired power plant, and shows just how catastrophically dangerous this technique may have the potential to be. Pro-CCS scientists argue that this singular event cannot form the basis for summarising the risks associated with CO₂ leakage from a geological formation, however, as CO₂ is heavier than surrounding air it accumulates readily in depressions such as lakes. Therefore I believe that this case study does provide strong and accountable evidence for the dangers faced by carbon capture, and it insists that serious considerations need to be introduced before CCS is implemented worldwide.

Additionally, another potentially severe environmental risk caused by CCS is the potential for ocean acidification caused by leaked CO­₂. Ocean acidification is caused by carbon dioxide reacting with the ocean to create carbonic acid (CO₂ + H₂O à H₂CO₃). The ocean represents the planets largest carbon sink, an increase in carbonic acid severely threatens carbonate secreting organisms in the ocean and in doing so reduces the oceans capacity for carbon storage and so more CO₂ is released into the atmosphere and in doing so worsening the greenhouse effect. 

Moreover, Forgarty & McCally point out that ocean acidification can cause an increase of contaminant (e.g. Arsenic and lead) leaching which would endanger the lives of countless species. Furthermore, Holloway (1996) argues that as well as oceans, groundwater located (100-200m below the surface) may be contaminated from CO_2­ leakage. CO₂ groundwater contamination may cause increases in water hardness as well as transforming the concentrations of trace elements present in the water and therefore has seriously negative effects on our drinking water aquifers.

Finally, there is much discussion within the scientific regarding induced seismicity caused by the injection of CO₂ into the ground. Environmental scientists Verdon & Stork state that large volumes of CO₂ injected into a geological reservoir increases the pore pressure of the reservoir rock, which increases the chance of rock failure. Holloway importantly argues that this could result in micro-seismicity or activating previous faults which may trigger earth tremors. Seismic events within reservoirs could damage cap rocks, natural springs or open up faults allowing for CO₂ leakage further damages to other parts of the environment, environmental effects described above can impact the plant. 

Through my research into the risks associated with CCS, it is absolutely clear that this climate mitigation method is not perfect, and requires serious evaluation as to whether these risks can be limited or if the method is even viable at all in sight of these concerns. Luckily for you, I’ll be doing this in my next blog post!

The great potential of Carbon Capture & Storage

Carbon emissions reductions

This year, British home secretary Amber Rudd committed the UK to the ‘fifth carbon budget’, which binds the nation to a maximum CO₂ output between the years 2028-2032 of 1,725 MtCO₂e. Currently, it is thought by many that the UK will not meet this target without substantial changes to energy policy. CCS has a potential to account for 17% of necessary the nations carbon emissions reductions, and so would offer great support for the British energy industry as it may mean that there wouldn’t be a need for such a rapid switch to renewable energies which would inevitably be very costly.

Storage potential

There appears to be a vast storage potential for CO₂ within the Earth, but due to the numerous types of geological formations, the planet’s potential is difficult to estimate. Scientist Udayan Singh reports on IPCC suggestions that there may be the opportunity to store 2000Gt of CO₂ within the planets formations. Further investigations into this reveal that between 675-900 Gt of CO₂ could be stored into oil and gas fields, 1000-10,000 Gt of CO_2­ may be contained in saline formations and between 3-200 Gt of CO­₂ within coal beds. Udayan Singh importantly points out that in 2010, annual global CO₂ emissions were less than 34 Gt of CO₂, thus clearly demonstrating that the world can take confidence in this environmental policy. In addition it is also important to note that as our fossil fuel consumption increases, more space in geological formations for CO₂ storage will become readily available.

Key carbon storage examples:  UK & India case studies

In terms of the UK’s personal environmental policy, Jon Gibbins and Hannah Chalmers predict the UK offshore CO₂ storage potential to be at least 20 Gt of CO₂. This type of formation alone could store the UK’s CO₂ emissions for 40 years!

Fig. 1 - A geological map of India, showing the presence of basaltic rocks
as well as highlighting regions of good, limited or fair storage potential
https://hub.globalccsinstitute.com/publications/regional-assessment-potential-co2-storage-indian-subcontinent/22-potential-geological

Researchers Udayan Singh also reveals information regarding the storage potential of India (the world’s third largest CO₂ producer) and combined their research with McGrail et al’s laboratory experiments to conclude that India alone has an incredible potential for CO₂ storage within onshore and offshore saline aquifers (360 Gt) and within Basaltic rock settings (200 Gt). McGrail et al’s tests revealed that the basalts within the region showed fast chemical reactions with CO₂-saturated water, enabling it to produce stable carbonate minerals. When analysing fig 1, one can realise that due to the vast quantities of basaltic rock within India (formed as a result of the Deccan Traps eruptions which produced material that covers 500,000km² of India’s Western provinces), India’s storage potential within this type of geological formation, and future potential after further scientific research into this field is immense.

Another advantage which would result from storing CO₂ within depleted oil and gas fields is that it will allow for the  recovery of further oil and gas that was not initially recovered for a variety of reasons, for example because it was not initially economically viable. CO₂ also has many industrial purposes, and is used in pharmaceutical, fertilizer and beverage carbonation industries (Udayan Singh).

These methods provide further advantages, as pumping CO₂ into oil fields can also help to retrieve more fuels that were not recovered during initial oil exploration. This is due to the fact that CO₂  injection reduces the viscosity of oil, thus improving the ability of oil  to flow up boreholes to the surface.Whilst in basalt formations, CO₂ reacts with the basalt to form carbonate minerals, further adding to the stability of the formation.

Economic incentives

An interesting economic incentive to carbon capturing is the emission trading mechanism, which limits a country to a maximum volume of CO₂ that can be emitted. However if a country to reduce its emissions below the maximum amount, they would be able to use the CO₂ as a commodity which they could then use in trading and thus generate profits from. This offers yet another advantage for Less Economically Developed Countries, who may not otherwise prioritise emission reductions due to their respective financial situations.

Furthermore, the UK government reports that should CCS be fully implemented into power plants that produce electricity for domestic use, energy prices for citizens would decrease by up to £0.02 per Kilowatt hour (Kwh) by 2030 (fig.2). Correlating this to the whole UK population would show significant energy savings nationally. 

Fig. 2 - A chart expressing future energy savings (in pence per Kwh) per year
with CCS implementation.
https://www.tuc.org.uk/sites/default/files/carboncapturebenefits.pdf

Therefore one can conclude by realising that there is a great potential for CCS, with positive practical and economic aspects, what now needs to be decided is whether these positives outweigh negative issues, which will be talked about in the next blog post.

Another option: Carbon Capture & Storage

What does it entail?

Carbon Capture & Storage (CCS) is defined by the Intergovernmental Panel on Climate Change's (IPCC) Special Report on Carbon Dioxide Capture and Storage as a “process consisting of the separation of CO₂ from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere”. Energy policy experts John Gibbins & Hannah Chalmers offer insights into the three types of carbon separation: post-combustion, pre-combustion and oxyfuel combustion.

Post-combustion capture aims to remove CO₂ just before emission into the atmosphere. An aqueous amine solvent is used to remove the CO₂ from the waste gas at a temperature of approximately 50ᵒC. This solvent can then be re-created for later use by heating it to approximately 120ᵒC before further cooling and recycling. The captured CO₂ is dehydrated and compressed before being transferred to a safe geological storage facility.

Pre-combustion capture involves reforming fossil-fuels with sub-stoichiometric volumes of oxygen at high pressures of approximately 30-70 atmospheres creating a synthesis gas which consists of CO and H₂. Steam is then added before the temperature is reduced to allow for the conversion of CO to CO₂. The CO₂ can then be captured, leaving a Hydrogen-rich gas, as through the use of a physical solvent the CO₂ can be dissolved at higher pressure before being released as the pressure in the system is reduced. Following this, the gas dehydrated and compressed for transporting to a storage site. This method does not require heat to separate and capture the CO₂, and therefore has an advantage over the post-combustion method as it requires less energy for the process to function.

Yukun Hu offers important information on the final process, oxyfuel separation. This method begins by adapting the combustion chamber so that it is filled with almost-pure oxygen using an air separation unit. The fossil fuel is then burnt within the oxygen and a mixture of recycled flue gases which are used as a replacement for Nitrogen (which the carbon would usually burn with in the atmosphere). This produces CO₂ and water vapour which is cleaned and separated during the dehydration and compression processes. Key advantages to this process compared with the other carbon capture methods include the lowest level of CO₂ emissions for all three processes, lower fuel consumptions as well as having the highest combustion efficiency.

Diagram illustrating the processes that take place during the different types of carbon captures.

Transportation:

Unlike the capture methods, there is a fairly unanimous opinion on the best ways to transport captured CO₂. As explained in the IPCC's report, if the gas is only being transported relatively short distances, ships or large vehicles are preferred. However if there is a large transporting distance to the storage site, e.g. thousands of kilometres, then pipelines would be the favoured option. This method of carbon transport is currently in use in nations such as the USA, who have pipelines transporting 40Mt CO₂ over 2,500km every year.

Storage:

Cross-section of a carbon capture storage site, including a
 water-filled reservoir (e.g. Sandstone), cap-rock (e.g. Basalt)
and Oil and Gas fields.
http://www.glossary.oilfield.slb.com/Terms/c/cap_rock.aspx

Favourable geological sites for carbon storage include both onshore and offshore oil and gas fields, Basalt formations, unamenable coal seams and deep saline aquifers. A key requirement for a storage site is depth. To create an optimum density (500kg/m³) for storage, a depth of 1km is needed. Furthermore, a cap-rock (an impenetrable, hard rock which prevents the escape of materials such as oil and gases from escaping to the surface)  would also be required to ensure that the CO₂ can actually be stored underground. 

Although the scientific methods and reasoning behind CCS appear to be reasonable on a practicality level, there remains many further advantageous and problematic aspects to this option will be discussed in the coming blog posts. 

Analysing SPICE

No…not that kind of SPICE…

SPICE refers to the Stratospheric Particle Injection for Climate Engineering project. This was a motion created by a collaboration of minds from the University of Cambridge, Oxford, Bristol and Edinburgh, set up to investigate the benefits, risks, costs and practicality of injecting sulfur aerosols into the atmosphere as a geoengineering method to control the effects of global warming.

This project is of specific interest because it is unique in not only investigating the effectiveness of sulphur in the environment but also researching into public opinion surrounding this form of Solar Radiation Management. If public opinion were not to be on side, this form of geoengineering is unlikely to ever become part of world’s environmental policy. SPICE carried out three workshops, in Cardiff, Norwich and Nottingham with a wide demographic of personnel in an attempt to understand genuine public perception of geoengineering. Several controls were made, such as attempting not to overload participants with too much information as to prevent deterring the development of their natural thoughts. At the workshops, researchers offered background information on climate change and the current challenges being faced before describing the specific method of SRM so that the participants could develop a reasonable understanding from which they could develop their own conclusions on the matter.  Researches then explained that sulfur aerosols would be injected into the stratosphere via a 20km pipeline, as this may be the most cost-effective and environmentally-effective way of releasing the aerosol. Participants were then told that a 1km ‘test-bed including scaled-down versions of the tether, balloon and pumping system will be designed and constructed’ to give geoengineering researchers greater knowledge of the functionality of a tethered balloon within various weather systems as well as to allow for an improved understanding of the scattering of pumped particles.

The response:

“The only thing is when you put in the money it would take to set up those schemes to get that short-term gain, that could be money going into actually solving the problem, I think that’s where the issue is. That’s why it feels like it’s cheating as I said” (Laurel, Norwich).

The public workshop groups discovered a consistent and coherent  response from each group, a view that SRM is not actually solving the original problem, and is instead just treating the symptoms of the issue and that financial resources should be spent tackling emission issues head on. Furthermore, although the participants welcomed the test-bed for sulfur injection, there still remained many concerns over the practicality of aerosol injection. Primary issues were based upon where the injection would take place, with participants stating that they would not want this process occurring near their local areas, and the need for transparency amongst the research process, testing and the executing the policy.

This data poses yet another stumbling block for aerosol injection as it is clear through this research that currently, public opinion is not in favour of this method. This is majorly significant as with such doubts about this method across the nation, governments are less likely to support this environmental policy in fear of political backlashes, and thus poses severe doubts over the realistic chances of this method ever becoming practically developed. 

Hang on, there are downsides to Solar Radiation Management? Like an environmentalist once said, ain't that a kick in the head...

Dean Martin captured on a rumoured SRM flight mission 

In total, 240W of sunlight per square metre is absorbed by earth and is the principle method of how the Earth natural maintains or increases its temperature. Since the beginning of the industrial revolution, atmospheric CO₂ has almost doubled to 401.1ppm and at current trajectories is predicted to surpass the 450ppm ‘tipping point’ in which issues including ocean acidification and temperature increases may become so critical that they pass the point where by which they are salvageable. 

Caldeira writes that the doubling atmospheric CO₂ results in a radiative forcing of approximately 4Wm^-2. He then states that as a percentage of sunlight absorbed by the Earth per square metre, 1.7% of incoming solar radiation would need to be prevented from reaching the Earth’s surface to minimalise temperature rises. Thus, one would think that limiting this sunlight could help limit global warming. Enter, solar radiation management (SRM) – specifically Sulfur aerosols. For a detailed insight into the specifics behind this technique, see last weeks blog post.

So there you have it, a miraculous cure to save the planet from the impending doom of climate change. Well, not quite. Just like most quick-fixes, there are numerous severe stumbling blocks of this scenario, such as: resultant effects on regional climate; continued ocean acidification; the effects on clouds and the consideration about what happens if we change our mind and wish to stop this approach.

Oh, the weather outside is frightful…

A map of East Asia showing which areas are effected  by
reductions in precipitation, and by how much  (measured in mm).
http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0889.2009.00427.x/pdf

Alan Robock identifies a link between large volcanic eruptions and weakening African and Asian monsoons. In addition, Robock also points out the link between the eruption at Lake Fissure (Iceland) between 1783-84 and the following reduction of precipitation in Africa, Asia and Japan which resulted in the a famine responsible for the deaths of 25% of the Egyptian population.

S. Tilmes et al takes Robock's link further by discuss climate model experiments which have been used to simulate the consequences of Sulfur aerosol injections. They also write that when testing effects on regional weather systems with atmospheric CO₂ at pre-industrial levels that would result from SRM, there are significant impacts on precipitation and evaporation predominantly in the tropics and mid-latitude regions. They discovered a decrease in a mean precipitation of 3.6% over land. Specifically, the region hit with the greatest reductions in monsoon precipitation are East Asia (by 6%). This impact is extremely worrying as it would result in reduced yields for important crops in this region, leading to food shortages and a worsened quality of life for up to 1.5 billion people that live in this region. Thus, in light of this potential hydrological impact one could argue that it may be immoral to injection sulfate aerosol . 

When the world starts to shine like its had too much wine...it may be because Sulfer Aerosols offer no help with regards to the problem of ocean acidification

Up to 33% of Carbon Dioxide emissions from the human combustion of fossil fuels is absorbed by the ocean consequentially resulting in ocean acidification. As CO₂ is absorbed by the ocean it reacts with water to form Carbonic acid (H₂CO₃). This Carbonic acid dissociates within the water to produce bicarbonates releasing Hydrogen ions, hence causing an increase in acidification. The knock-on effect of this is that it would reduce the amount of carbon that could be stored in the oceans, which are the world's largest carbon sinks. doing so cause further global warming. Aerosol interjection offers no relief for this issue and would only allow this issue to worsen.

Everybody loves somebody...unless Sulfur aerosols divide international communities and starts a world war

Robock shines light on the political complexities tied to this stream of geoengineering. If an event were to happen, for example a world war, the aerosol injection programme would become seriously hindered. If there were to be a sudden halt to sulfur injections then we would see rapid global warming due to fact that greenhouse gas levels would have continued rising at exponential rates. Environmentalists such as Caldiera argue a rapid global warming process would cause exceedingly more damage to the worlds ecosystems than a more gradual global warming that we see happening today.

Furthermore, Robock suggests that if we were to proceed with this process, how do nations decide on whether a specific region such as East Asia should have to absorb the potential harsh impacts of this whilst other regions are relatively unscathed? This is an extremely valid point raised, and leads one to hypothetically argue that this could one day present the grounds for conflict itself if a nation being unfairly subjected to man-induced environmental alterations was rise up and fight against the environmental predicament that they had found themselves in. Therefore we must ask ourselves whether we would be truly comfortable with a global warming quick-fix that has the potential to one day be a proxy for future global conflicts.

In conclusion, although the analysis in last weeks blog post does suggest that injecting sulfate aerosols into the atmosphere would cool the Earth and restrict global warming. I feel that upon evaluating the side-effects and political uncertainties of this method, global governments should not seek to implement this form of geoengineering. Instead, we should investigate further other forms of geoengineering, such as solar mirrors or perhaps Carbon Capture and Storage. Both of which will be discussed in the continuation of this blog.