Nuclear energy

Nuclear energy is another alternative source of energy instead of obtaining our energy from fossil fuels. It is widely used throughout the world although this method is primarily used in developed countries such as within the EU or in USA and Russia due to high costs and safety issues. The method uses decay of radioactive materials such as uranium to convert heat and nuclear energy into other types of energy for electricity and transport uses. It involves nuclear fission, nuclear decay and nuclear fusion although most of the nuclear energy is currently obtained from nuclear fission. The process of obtaining nuclear energy starts with mining uranium from underground and it is extracted as uranium ore which is then converted into more safe compounds and transported to nuclear energy plants. There it is converted back to uranium and uranium rods are produced. They are placed inside the reactor where their lifetime is approximately 6 years.

A lot of research has been done into nuclear energy and more efficient, safer and simpler to operate reactors are constantly being invented. Especially after the major nuclear catastrophes caused by nuclear energy generation such as Chernobyl, safety become the key primary issue of focus for further research. Providing the new plants are safe, nuclear power could contribute significantly towards mitigating the effect of high GHGs emissions and climate change. It is generally quite a clean process with little emissions and environmental impact compared to other energy obtaining methods. Figure 1 below shows CO2 emissions from various methods of obtaining energy including nuclear. It is obvious that the carbon footprint from nuclear energy is minimal.

Figure 1.

Source:Adamantiades, 2009. CO2 emissions from selected energy chains.

Nuclear power’s share of worldwide electricity production rose from less than 1% in 1960 to 16% in 1986 and that held constant up until 2005, nuclear power has seen slight decrease since (Adamantiades, 2009). However nuclear electricity generation is still concentrated in developed countries- half of the world’s reactors are in N. America and W. Europe and less than 10% in developing countries. This is shown by figure 2 below which shows the nuclear share of total electricity generation by country and thus suggests countries that utilize nuclear power the most. Regardless of the current figures, more than 40 developing countries- from Gulf Middle East to Latin American ones, have recently asked United Nations for approval of nuclear plants plans with grand schemes in mind.

Figure 2.

Source:Adamantiades, 2009. Nuclear share of total electricity generation in 2009.

Nevertheless nuclear energy also has its disadvantages. One of the main concerns is safety of the method. Three major nuclear catastphones have occurred- the Chernobyl disaster in Ukraine (USSR at the time) in 1986, Fukushima Daiichi nuclear disaster in Japan in 2011 and the Three Mile Island accident in 1979. These all present major sources of concern as the chances of such disasters occurring are very low yet they have massive consequences, which are felt to the present day. They cause all sorts of nasty mutations due to radioactivity and make massive areas of land no longer viable for any human use. Thus public attitudes towards nuclear power are not always positive. Figure 3 below shows public attitudes towards nuclear power in the US over the last part of the 20^th century. Unless the public can be assured that this method is safe, they could protest against this method of obtaining energy especially in democratic countries. The public also has concerns that civilian nuclear power may lead to facilitation and encourages research into nuclear weapons, which if used, could destroy our planet.

Figure 3.

Source:Adamantiades, 2009. Public attitudes towards nuclear power in the US, 1983-2008.

Furthermore, there remains the problem of radioactive waste. This primarily consists of unconverted uranium rods that can no longer be placed in the reactors. There are currently no permanent safe disposals of such waste and it is stored at nuclear plants in guarded areas. It has been suggested that perhaps burying it in specific monitored nuclear waste sites underground is an option however this has not been implemented to this day. Nuclear waste is especially a concern in the developing world where security remains more of an issue and thus there is the question as to whether such countries should be given the green light to construct and use nuclear energy plants.

Despite the growing interest in the industry, there were concerns about it’s further developments after the most recent disaster in Japan but even despite of the economic crisis, many countries consider nuclear energy important future energy so investments keep being made into the industry (Schiermeier, 2011). There are currently 65 nuclear plants under construction, 27 of which are in China thus proving that demand and interest in nuclear energy have not dropped (Schiermeier,2011). Although some countries such as Germany where the public remains quite strongly against nuclear energy, had to switch off 7 of its oldest plants post the Japanese disaster in order to re assess their safety and they are currently closed until further notice. They have also postponed their plans of extensions to 17 nuclear reactors.

Studies have been done whether nuclear energy could be a viable substitute for global energy produced from crude oil. It has been shown that there is both sufficient uranium available to take us way beyond 2050 if nuclear energy was to become the primary global energy source as well as the fact that over 5000 nuclear power plants that would need to be built, could be build in a short period of time required as shown by previous historical data (Brook, 2012). Thus overall whilst safety and disposal of radioactive waste remain the main issues of nuclear energy, I think it has a great potential to become the future energy in the after crude oil world.

SRES Scenarios- Climate Change Projections

SRES scenarios are often used in climate modeling and to predict what if scenarios when modeling the implication of some system on climate. SRES stands for Special Report on Emissions Scenarios which was a report produced by the IPCC first published in 2000 in the 3^rd IPCC. The 4^th IPCC in 2007 saw an update of SRES available for scientists to use. They are widely referred to in a wide range of materials such as RAMSAR report and others. Ramsar Convention is an international treaty, which seeks to encourage conservation and sustainable utilization of wetlands. The convention was named after an Iranian city- Ramsar, where it was first signed in 1971. It recognizes the essential ecological function of wetlands and their economic, cultural, scientific and recreational values. They are also widely used by hydrologists and climatologists as well as meteorologists and geologists when trying to predict the future climate or its particular aspects. They are different world scenarios that consider population growth, globalization and world economics, the cleanliness of technologies and world environmental priorities (Ramsar Report, 2002).

I mentioned them in the previous blog post in a study about geology and CCS implications so I thought I’d write a little blog post about SRES scenarios themselves too. Other examples of studies involving the use of these are the example of Nicholls’ 2004 study on how the impact of a particular climate change- sea-level rise in his case, would be affected under SRES and thus what is the climate likely to look like in the future. Nicholls used SRES to improve his original study of sea-level rise and how it would effect coastal wetlands due to increased flooding (Nicholls, 2004).

The scenarios are four scenarios which each has their own GHGs trajectories for the future where A1 and A2 has high GHGs which continue to increase beyond 2100 and B1 and B2 have mid to low levels of GHGs with rates of increase showing signs of slowing by the end of 2100. Figure 1 below summarizes these scenarios.

 Figure 1.

Source: Ramsar Report, 2002 Description of SRES scenarios.

Using full range of SRES scenarios, the atmospheric CO2 concentrations are projected to increase from the 1990 level to 475-1100 ppm by 2100. The mean global temperatures are projected to be 1.4C-5.8C higher by 2100 with variation in the increase in different regions on Earth. Generally temperatures are projected to increase the most in mid to high latitudes of the northern hemisphere. Precipitations changes are also to occur on much smaller scales of only 5-20% and also show regional variation. Although these changes could be enough for serious hydrological, ecological and global climate implications (Ramsar Report,2002). The potential implications of SRES are shown below by figure 2.

Figure 2.

Source: United States EnvironmentalProtection Agency, 2015. Projected changes over the 21^st Century in the atmospheric concentrations of 3 GHGs: CO2, methane and nitrous oxide (N2O).

The 5^th IPCC, published in 2014 updated SRES yet again now renaming them as RCPs (Representative Concentration Pathways). They are four scenarios yet again used for climate modeling and research. They also depend on GHGs emissions into the atmosphere mainly up to 2100 but also give some predictions beyond that into the 22^nd century. We have to think well beyond the 21^st century and at least about the 22^nd century as the potential effects of GHGs on the planet lag due to slow responses of global earth systems such as ocean circulation thus lagging impacts such as sea level rise which in turn also has further ability to create positive feedbacks on climate change. The four RCPs are named RCP2.6, RCP4.5, RCP6, and RCP8.5. RCP2.6 assumes the peak of GHG emissions between 2010 and 2020; RCP4.5 peak around 2040 then decline; RCP6 emissions peak around 2080 and RCP8.5 emissions continue to rise throughout the 21^st century. These are portrayed by Figure 3 below.

Figure 3.

Source. All forcing agents’ atmospheric CO2 equivalent concentrations (in ppmv) according to four RCPs.