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Carbon is the villain. It is the reason for the trapped heat that is causing Climate Change. The two main gases that cause the greenhouse effect are carbon dioxide and methane, CO2 and CH4, and C is for carbon. We burn oil and gas and coal and turf, all laden with carbon. So, carbon is the villain, right?

Wouldn’t it be poetic if it was also the hero?

Carbon can save us by being used in more sustainable and cheaper batteries, solar panels, supercapacitors (read: fast batteries) and fuel cells.

To be fair, this isn’t all carbon does. It makes most of you, you. If you are mostly protein (and you are), proteins are mostly carbon. This this is what makes it both a problem and a solution. It’s everywhere.

Carbon, just by itself, can be wildly different. The number to keep in mind: four. Carbon wants to have four bonds.

What you want in a material is: 1) strong bonds and 2) lots of bonds.

For strong bonds you need to be small. This is because the larger the atom, the less the bonds to it care. They are so far away, they don’t feel as impacted by the nucleus, like a voter in Kerry not caring about the problems in Dublin.

For lots of bonds, you need a Goldilocks of not too many electrons and not too few. The reason 4 is the magic number is because its as far from 0 and 8 as you can get. Carbon has these 4 electrons, and it either wants to get 4 more or get rid of them, and to do this it needs bonds. More electrons or fewer electrons, it could achieve this with fewer bonds.

So to explain why carbon is just so good, really just look at it on the periodic table: it’s at the intersection of Strong Bond Street and Many Bond Avenue.

 

How can we use this? There are two ways this can go: diamond or graphene. Diamond puts these four strong bonds to good use by being bonded to four other carbons at equal distances, in a pattern that looks like this:

Periodic Table of the Elements and location of carbon

Graphene, on the other hand, breaks our rule: four bonds is better. It does this by making a hexagonal pattern, bonding to three others. The last electron is allowed to float freely between the others, strengthening the bonds. This free electron also gives the great electrical properties of graphene, as loose electrons are necessary for the movement of electricity in a material.

The fact that the carbon is only bonded to three others is what makes it a “2 dimensional” material as there are sheets one atom thick.

Structure of graphene from hexagonal benzene

Like rolling paper into a straw, the graphene sheets can be rolled up into a tube, called a carbon nanotube. Scientists find these extremely exciting materials because they act like wires, with a similar level of conductivity as graphene but in a more useful form.

Carbon nanotubes rolled from sheets of graphene.

Now that the properties are explained, we can move on to why this is important: carbon is the hero.

First step is producing energy. Solar panels now are made with silicon. These are fairly efficient, about 20%. But for almost any application, efficiency can be replaced with savings in cost and weight, and the limit for silicon is getting thin enough sheets to use as little material and to be asl light as possible. Graphene has the advantage of being already thin, as well as atomically lighter.

The graphene can be incorporated into the solar panel in multiple ways, as there needs to be materials creating and receiving the electron to make the electricity and a way to transport it after. Graphene can be incorporated into almost all parts of this process, to make the cells more efficient or to completely redesign them, like making them flexible. Expect to see graphene in your solar panels in the future.

A flexible graphene based solar panel

Next is storing that energy. The most traditional way to do this is batteries. The big players here are lithium ion batteries. These are currently limited in speed of charging and lifespan by the electrodes, rather than the actual battery material. These are currently graphite, which is many disorganised stacks of graphene. These are being improved by replacing them with carbon nanotubes, which can have a higher contact area with the battery, speeding up the process and last longer.

If this isn’t a radical enough change, lithium ion batteries could be superseded by graphene ones completely. These operate by letting charged atoms drift from one sheet to another, releasing electrical energy. Lithium is actually quite rare, so a more abundant replacement is of great benefit. It also needs to be light, because even if you have and amazing but heavy material, it still won’t be good per kilo. Graphene can solve both these problems, and is a candidate for the batteries of the future.

Current use of graphite in lithium-ion batteries

A more experimental option are the much-hyped supercapacitors. Capacitors operate by physically separating positive and negative charges on parallel sheets. They are better if they have larger surface area or a smaller gap between them. You can probably see where this is going. Graphene sheets have an enormous surface area and are thin enough so that the capacitors made from them would have enormous energy density.

There must be a separation of the graphene sheets, done by “intercalation” or insertion of charged atoms between layers. With current technology, these supercapacitors are at the level of other battery technologies such as nickel hydride.

Graphene sheets in a supercapacitor

The final energy storage method that these materials open up is hydrogen fuel. Hydrogen can be made by using electricity to break apart water, H2O, into oxygen, O2, and hydrogen, H2. The same fuel cell can be used in reverse to recombine oxygen and hydrogen into water and an electric current is generated. This means it is in a sense a battery, but with a fuel that can be extracted and stored like a traditional fuel, and the energy per kilo is higher than petroleum.

Graphene has potential as both the anode and cathode (positive and negative electrodes), which has advantage over the competition as it is lighter and less expensive than the rare metals that it would replace. It also is a candidate for the storage of hydrogen. This is useful as hydrogen is so small it tends to leak out of any container you put it in. The graphene is “buckled” like crumpling a sheet of paper, and the high points attract and bind hydrogen, meaning it won’t leak out of the container.

Hydrogen fuel cell

So, carbon has been both the problem and the solution. While creating the problem in the form of carbon dioxide and methane, it has the potential to be the solution. Graphene can be made into solar panels, batteries, supercapacitors and hydrogen fuel cells and storage while carbon nanotubes can improve the batteries we already have.

Maybe carbon isn’t the hero we deserve, but it’s the one we need.

The topic I will be discussing is how the southern ocean influences climate change and how the SO-CHIC (southern ocean carbon and heat impact on climate change) project aims to understand and quantify the variability of heat and carbon dioxide in the southern ocean.

The oceans of the world play a crucial role in regulating the earth’s climate. Oceans absorb the majority of radiation from the sun and distribute this heat around the globe. When ocean water is heated it evaporates and it affects the humidity of the surrounding air to form rain and cause storms and so the ocean affects climate and weather. The southern ocean is disproportionately responsible for absorbing 75% the excess heat and 60% carbon dioxide associated with anthropogenic climate change. However due to the low human population and hostile environment of the southern ocean the way in which heat and carbon dioxide is exchanged between the atmosphere ocean and ice has not been as much as the other oceans.

SO-CHIC is a 5 year long (2019-2024) EU funded project which will investigate this atmosphere-ocean-ice exchange by looking at the key processes controlling this exchange using a combination of observational and modelling approaches. One of these approaches is using a technological instrument called the Air-Sea Interaction Profiler (ASIP) developed in Ireland by Professor Brian Ward of NUI Galway. ASIP is used to observe what is happening in the upper 100 m of the ocean in very fine and temporal detail which fills in the crucial gaps that the longer term instruments provide. It is an autonomous instrument and it runs pre-programmed without any human intervention. ASIP has three thrusters which allow it to submerge into the ocean and then ascend with its own buoyancy. There are sensors mounted on the top of it which provide data on turbulence, temperature and conductivity. When it reaches the surface it connects to a GPS satellite to determine its position and to transmit a message using the Iridium global satellite constellation. After sitting on the ocean surface for 20 minutes it repeated the profile. ASIP is limited by its lithium-ion batteries which provide 7000 m of profiling and need to be replaced once they are used up.

 

Authors: Pratheek Kishore, Octavian Stoicescu, Nicollas S.M. Borges, Abhijith Jyothis P.

Nuclear energy has been suggested as a possible solution for climate change for a while, but how effective is this solution? What are the benefits of nuclear energy that would help with the current climate predicament? The purpose of this blog is to explore nuclear energy as a viable alternative energy source for cleaner emission and how this aids in alleviating climate change. We will consider the current state of the climate, the theory behind nuclear energy, comparison of different energy sources and their risks, and finally the future of nuclear energy (nuclear fusion?). 

We often hear about global warming being a current issue,  what we don’t hear is that this is something that’s been having an impact on our world for quite some time. The total average land and ocean surface temperature increase from 1850 to 2012 is 0.78  ͦ C. Total Glacier mass lost around the world except glaciers present on the periphery of ice sheets from 1971-2009 is 226 Gt per year. The Global Mean Sea Level (GSML) has risen by 0.19 m, as is estimated from a linear trend, from 1901-2010 and permafrost temperatures have increased in most regions worldwide from observations of trends since the early 1980s.Humans have been clearly impacting the climate of the planet for a very long time, but what does this all mean? It’s easy to look at statistics and forget these numbers have real world implications. For example, in some terrestrial systems, “Spring Advancement” can clearly be observed, which is the premature occurrence of spring-related events such as hibernation, breeding, flowering, and migration. Ocean acidification due to climate change decreases calcification which favours the dissolution of calcium carbonate and bioerosion, ultimately yielding coral reefs that are poorly cemented. Rocky shore animal and algae distribution, as well as abundance, has been observed to be altered due to climate change along with a significant decline in mussel bed biodiversity in the Californian coast. The body sizes of several marine species such as the Atlantic cod have been clearly negatively linked to changes in the temperature. The effects of climate change can be observed all around us, from the forests to the oceans, from the desert to the tundra, but perhaps the most relatable and personal effect would be the impact of climate change on humans. Climate change can have varying effects on several ecosystems, which can lead to food security issues globally. Climate extremes might increase the spread and ultimately the likelihood of attaining some diseases and infections. We can observe from studies on heat waves the effect increased heat will have on health, which leads to  increases in cardiovascular and respiratory disease, and generally increased mortality. During 2004-2018, in the United states alone, an average of 702 deaths annually were heat related (287 deaths had heat as a contributing cause, and 415 had heat as an underlying cause). So as you can see, climate change is an issue that has clear and direct effects on our ecosystems, on our environment, and on ourselves. If this matter is not addressed with the utmost of care and research, it may lead to dire consequences for us and our future on this planet. This is why there must be a global effort to utilise trialed and tested solutions to counter this problem. Currently our energy is supplied primarily by fossil fuels, which are not only limited in supply and depleting quickly, but major contributors to climate change through the emission of greenhouse gasses. Following this trajectory is not a viable solution for our future. But what could such a solution be? It turns out we had one answer from the mid-20th century: Nuclear Energy.

The atom with masses as small as 1.6735575 × 10-27 and length scales of around 10-10 m is our current best bet at tackling climate change? As small as atoms are one must realise the immense magnitudes of energy they hold in the form of binding energy of its nucleus i.e. the energy required to hold the atom together. Einstein’s famous formula E = mc2 is what is in-fact used to calculate the energy that gets released. The difference in masses of the reactants and products of a nuclear reaction, called the mass defect, is multiplied by c2 which as we know is a massive number. Hence this explains the enormous amount of energies released during such reactions. One can extract this energy methodically via nuclear reactors using a fuel source-fissile material.  The energy released by an average sized nuclear reactor in a day is of the order of 1013 J! A measure of the efficiency of  such power/energy generating plants is the so-called capacity factor which is defined as the ratio of the actual energy output during a specific period of time to the maximum energy that can theoretically be produced during the same period. Nuclear energy has a capacity factor of 93% twice that of coal. Currently this amount of energy at these rates of efficiency can be produced by no other source . Moreover, the carbon footprint associated with actual energy production or running of the nuclear power plant is almost nil. This, coupled with the high energy densities of the fuels, makes it a leading contender in providing a potential solution to the current climate change crisis. Current estimates of nuclear fuel reserves suggest that there is enough to power all the nuclear reactors in the world for 200 more years! To get a sense of this note that a volume of ideally enriched uranium fuel of the size of a golf ball is sufficient to provide an average human being more than sufficient to meet the energy needs for their lifetime. Despite not being a popular source due to its high initial setup cost’s nuclear energy currently responsible for up to 10% of global electricity generation, in spite of only being dominantly used in around 30 countries or less.

There are multiple fuel source categories such as oxide fuel, metal fuel, non-oxide ceramic fuels, liquid fuels etc. But the dominant fuel used in most nuclear reactors is oxide fuel of Uranium-235. Although to achieve the efficiency and numbers we have just stated above one needs to enrich mined uranium by percentages of around 3-5 % To ensure a sustainable chain reaction of the neutrons, the exact percentages may vary based on type of reactor and other factors/requirements. As a result, less than 1% of mined uranium can actually be used as fuel. Some of the principal methods that are widely used to enrich fuel are gaseous diffusion, gas centrifuge and laser separation.

As it is with everything there is no light without the dark and so it is with uranium fuel. extracting/ mining uranium is a high energy consuming process with a large carbon footprint! And there are safety risks also associated with its transportation, treatment and back-end activity associated with spent nuclear fuel management. However there exist certain strategies such as Twice-through fuel cycles and advanced fuel cycles which are aimed at reducing the mitigating and avoiding such issues. 

A further possibility to handle the issue is via using alternative fuels such as Thorium which provide a better alternative! Almost all the thorium that is mined may be used as fuel unlike uranium. Other advantages are that it produces far lesser nuclear waste and is much safer! But almost every reactor currently works only on uranium. There’s always a catch isn’t there ? The problem is that while thorium is extremely fertile i.e. All of it as is mined in theory can be transmuted into fissile material which is the actual fuel that can work in a nuclear reactor it is not fissile itself i.e. it  cannot be directly used as nuclear fuel. However there is currently a lot of research going around in order to develop efficient thorium fuel cycles that may be used by the nuclear reactors! Which sure seems like a step forward in the right direction. 

One of the other disadvantages with nuclear energy are high investment energy sources. However, one can say for certain that we are more capable today in handling nuclear energy than we have ever been in the past. And it is certainly a worthwhile investment. Surely its advantages can be weighed over its disadvantages. As a result, Further research in nuclear reactor methods, Alternative fuel cycles and safety protocols can immensely boost the impact nuclear energy may have in pulling back the adverse effects of climate change. To quote an Indian physicist, the late Dr Homi Bhabha: “No energy is more expensive than no energy“. 

One way of measuring how “effective” a process (in this case, a type of energy production) is, is by doing a life-cycle assessment (LCA). LCA takes into account the extraction of the fuel, processing, distribution, and disposal of the waste.  A life-cycle assessment can measure the impact that the production of nuclear energy could have. An LCA from a 2017 study predicts that the life-cycle emissions from fossil fuels with carbon capture and sequestration plants to be between 78 and 110 gCO2eqkWh⁻¹ by 2050. The same study gives the life-cycle assessment for a combination of nuclear, wind and solar to be between 3.5 and 11.5 gCO2eqkWh⁻¹. Another study on nuclear power says that so far, nuclear power has prevented 64 gigatonnes of CO2 greenhouse gas emissions and 1.84 million air pollution-related deaths (as of 2013) and could prevent another 80-240 gigatonnes of CO2 and 420000 – 7.04 million deaths by 2050.

Fusion energy has been in development for decades and it’s a common joke that fusion energy is always thirty years away. The strife towards fusion is because there is minimal environmental impact, unlike fission reactors fusion produces no radioactive waste, and even if there would be a nuclear meltdown the radioactive material (tritium) is only a transition element which is present only in small amounts in fusion reactors. The half life of tritium is around 12.3 years and hence it would not render the facility radioactive for centuries. Also if there would be a breach in the reactor, the plasma would be extinguished meaning the reactor will be intrinsically safe. The only byproduct of the reactor is helium which is not a greenhouse gas, and being the second lightest element, it would ascend in the atmosphere and drift off into space. Fusion is when you take two atomically light nuclei and smash them together to create a heavier nuclei, however the heavier nuclei is not an exact sum of the mass of the two original ones hence the extra mass is converted to energy accompanied by the release of a couple of bosons. There are several different types of fusion reactors currently being researched and developed, some examples being magnetic confinement fusion (MCF), inertial confinement fusion (ICF), Stellartor and magnetized target fusion (MTF). MCF, as it might sound, is when you confine a plasma within a volume and heat It enough so that fusion is possible. However the temperatures required to initiate fusion such that on average a particle has enough energy to break the Coulomb barrier is around 170 million degrees kelvin, which is roughly 11 times the temperature of the core of the sun! So you can imagine why physicists are having such a hard time developing this technology. However MCF currently holds the most hope for a fusion future as an experimental fusion reactor has been heavily invested  in by India, the EU, USA, Korea, Russia and Japan, which is designed to show the scientific feasibility of fusion as an energy source. It is set to have its first plasma test at the end of 2025, but will only be fully operational by 2035. It is designed to have a Q = 10, meaning it will produce ten times the amount of energy it ingests. If the reactor is deemed successful in achieving its Q value and testing the feasibility of fusion. A new fusion reactor will be built called DEMO which will be used to produce electricity, which is scheduled to be completed by the 2050s. Even though fusion shows great promise it is a technology of the future and should not be relied upon in dealing with the climate crisis, because for the moment reducing carbon emissions using fusion is just a fantasy. We cannot rely on the possible technology of the future to solve today’s problems.