We have seen and experienced directly or indirectly the effects of global warming on our world. In this article, we will first look at how we are causing this through the way we produce energy, which is by burning fossil fuels. And then, we will look at all the energy sources that are candidates for replacing fossil fuels and compare their advantages and disadvantages. Lastly, we will look at solar power and the reasons why we think that solar energy will be the energy of the future.
Causes of Climate Change
The Slow and Fast Carbon Cycles
There are two types of Carbon Cycles, the slow and fast carbon cycles.
The slow carbon cycle is the slow process of carbon moving from the rocks to the soil, to the ocean and finally, to the atmosphere. This is a very slow process that releases 10^13 to 10^14 grams (10–100 million metric tons) of carbon to the atmosphere every year.
The fast carbon cycle, on the other hand, is the movement of carbon through the life forms on Earth and finally to the atmosphere. It releases up to three orders of magnitude of carbon more (or 1,000 times more) in the atmosphere, at 10^15 to 10^17grams per year.
All the lifeforms here on Earth are Carbon-based. All living cells are formed from long carbon chains and rings. Even the DNA, which is called “the blueprint of life” is made of two intertwined molecules built around a carbon chain. Most importantly, the sugar which we get from the food that we eat is also made up of long carbon chains. When carbon forms these long chains, energy is stored. This way, sugar acts as the main source of energy for all living organisms on Earth.
The main components of the fast carbon cycle are the plants. They inhale carbon dioxide and use this, along with water and the energy from sunlight to form sugar. This is the main ingredient used to grow new body tissues. In the process, they also produce oxygen as waste, which is exhaled to the atmosphere.
Plantlife is such a big part of the carbon cycle such that during spring in the northern hemisphere, carbon dioxide concentrations in the atmosphere drop. This is because increased demand for carbon dioxide by the growing plants. During winter, when plants are dying and decaying, carbon dioxide concentrations in the atmosphere rise as decaying plants release the carbon stored in their bodies as carbon dioxide. This rising and falling of carbon dioxide make it seem that the Earth itself is breathing in sync with the pattern in which plants grow and die.
Humans and animals eat plants and use the sugar for energy. When this sugar is burned, the carbon combines with inhaled oxygen to form carbon dioxide, which is then released to the atmosphere, completing the carbon cycle.
Naturally, the slow and fast carbon cycles are balanced in a way to keep carbon dioxide concentrations in the atmosphere constant to trap just the right amount of heat. But since the industrial revolution, we have disturbed the carbon cycle by burning fossil fuels for energy. These fossil fuels contain the carbon from plant and animal life that took millions of years to accumulate. Without human intervention, the carbon in these should have been slowly released in the atmosphere through the slow carbon cycle. However, by burning them, we speed up this process, significantly increasing the rate at which carbon dioxide is released to the atmosphere.
Why Focus on Carbon Dioxide?
Carbon dioxide has had the biggest contribution to global warming than any other greenhouse gas. This is because of the sheer amount of it that we are dumping on the atmosphere by burning fossil fuels for energy. It comprises a total of 76% of our total greenhouse gas emissions including those that are emitted through land use (deforestation and land clearing for agriculture). 65% of those are from burning fossil fuels.
Source: IPCC (2014); based on global emissions from 2010. Details about the sources included in these estimates can be found in the Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.
At the global scale, the key greenhouse gases emitted by human activities are:
Carbon dioxide (CO2): Fossil fuel use is the primary source of CO2. CO2 can also be emitted from direct human-induced impacts on forestry and other land use, such as through deforestation, land clearing for agriculture, and degradation of soils. Likewise, land can also remove CO2 from the atmosphere through reforestation, improvement of soils, and other activities.
Methane (CH4): Agricultural activities, waste management, energy use, and biomass burning all contribute to CH4 emissions.
Nitrous oxide (N2O): Agricultural activities, such as fertilizer use, are the primary source of N2O emissions. Fossil fuel combustion also generates N2O.
Fluorinated gases (F-gases): Industrial processes, refrigeration, and the use of a variety of consumer products contribute to emissions of F-gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).
It is very clear from these data that the main cause of climate change is our carbon dioxide emissions from burning fossil fuels. This makes the world’s shift to a cleaner and better energy source all the more inevitable. This also puts solar energy at the forefront of the choices of being the energy of the future.
Nuclear Energy
Nuclear and renewable energy are the principal competitors for low-carbon electricity in most countries. There even have been many debates on which of the two will become the energy of the future, even though, not including China, most nations have been moving away from nuclear energy.
Nuclear energy is the energy in the nucleus or core of an atom. There are two ways on how nuclear energy is released: fusion and fission. In nuclear fusion, atoms combine to form larger atoms while in fission, atoms are split apart. Today’s nuclear power plants utilize fission to produce nuclear energy as this is easier, safer and more reliable.
The process of creating nuclear energy from fission is as follows:
Nuclear reactors force some Uranium atoms to break apart.
As these Uranium atoms split, they release particles called fission products.
These fission products collide into other Uranium atoms, causing them to also split. This starts a chain reaction until all of the Uranium atoms are split apart.
This process releases a large amount of heat, which is then used to boil water and drive a turbine.
Advantages of Nuclear Energy:
Less amount of fuel needed for the same amount of energy – this translates to lower production, and procurement and transportation costs.
It is more reliable – a well maintained nuclear plant can run uninterrupted by as much as 540 days.
No greenhouse gas emissions.
Disadvantages of Nuclear Energy:
Radioactive material – the fuel used in nuclear energy is Uranium, which is radioactive. This means that special precautions must be made during mining, transportation and storing it, as well as disposal of the waste materials from nuclear reactors because these can also give off harmful levels of radiation.
Water pollution – water is used to cool the nuclear fission chambers. Although water does not directly become in contact with the reactor, there is still a possibility of a fuel leak that can contaminate the water. Also, the water will still be warm when released back into its source, which disrupts the local ecosystem.
Radiation leaks – improperly installed and/or maintained nuclear power plants can release harmful amounts of deadly radiation into the environment.
Weapons proliferation – there have been fears that countries with nuclear energy are also developing nuclear weapons covertly.
Hydroelectric Energy
Hydroelectric energy is the energy from flowing water. It is usually in the form of a large dam which creates a water reservoir. The water from the dam is channeled through turbines to generate electricity. However, some forms of hydroelectric energy do not require these large dams. Some can work on small rivers, needing just a small canal to channel water through smaller turbines.
Hydroelectric energy currently leads all renewable energy technologies in terms of total global capacity. In 2015, it has generated 16.6% of the world’s total electricity, which accounts for 70% of all electricity produced by renewable energies.
Advantages of Hydroelectric Energy:
Clean – its fuel is water, so it is clean and does not emit greenhouse gases. It also does not pollute the water used.
Renewable – it relies on the natural water cycle, and therefore, is a renewable energy source.
Available at the time needed – for large dams, the flow of water through the turbines can be controlled easily based on demand.
Water supply and flood control.
Disadvantages of Hydroelectric Energy:
Disturbing fish populations – hydroelectric dams and turbines block out the fishes’ natural habitat.
Impact on water quality – hydroelectric power plants can cause low dissolved oxygen in the water, which affects riverbank habitat.
Can be impacted by drought – when there is no water, the hydroelectric power plant can’t produce electricity.
Limited available sites – building hydroelectric power plants are limited to rivers with free-flowing water, which are limited in number.
Wind Energy
Wind energy is the direct conversion of wind’s kinetic energy to electricity through the use of wind turbines. Along with solar, it is one of the frontrunners in humanity’s search for a cleaner and better energy source that can replace fossil fuels.
Like solar energy, wind energy has also been steadily increasing in terms of total global capacity. In 2017, it has generated 4.4% of the world’s total electricity. It is more prominently used in European countries, where it meets 11.6% of the total electricity demand.
Advantages of Wind Energy:
Unlimited, free fuel – wind is used to power the wind turbines which makes it a renewable energy source. Also, harvesting the kinetic energy of wind does not significantly affect currents or wind cycles in any way.
No greenhouse gas emissions.
Very negligible operations and maintenance costs.
Disadvantages of Wind Energy:
Wind turbines may be dangerous to flying animals. Many birds and bats have been killed by flying into the rotors. Experts are now conducting research to learn more about the effects that wind turbines have on habitats.
Can only be installed in remote locations – wind turbines can only be installed in very open areas without obstructions to the wind. This is why they can only be installed in remote locations. This adds transmission costs for electricity to be transmitted from the wind turbines to those that need it.
Solar PV
Solar PV (photovoltaic) is a technology that directly converts sunlight to DC electricity through the use of semiconductors. They work through the principle of the photoelectric effect which was first observed by Heinrich Hertz in 1887. This principle was only understood in 1905 when Albert Einstein published a paper regarding how it works, which eventually won him a Nobel Prize in 1921. PV modules (or more commonly referred to as solar panels) are made up of semiconductors, which gives photoelectric properties.
The smallest semiconductor unit which produces electricity is called the solar cell. A certain number of these solar cells are connected together in the form of a panel (hence, the term solar panel) to form the PV module. A PV module is a packaged, connected assembly of solar cells which is ready for use.
Advantages of Solar Energy:
Besides being clean and renewable, solar panel systems has some advantages over any other energy source out there that will most probably make solar energy be the energy of the future:
Solar Panel Systems are Technology-Based and not Fuel-Based
Fossil fuels and nuclear power plants all rely on a certain type of fuel to extract energy from, which does not improve over time. Yes, there had been improvements in how efficiently we extract energy from these fuels but this has an innovation cap. This means that there is a limit to how much it can improve. In fact, most fossil fuel power plants peaked decades ago. Another disadvantage of fuel-based energy sources is that the price of the fuel dictates the energy price, and since fuel prices are volatile, so will the price of the energy.
Solar power, on the other hand, is technology-based. This means it can only improve over time. This improvement will not only be with its quality and efficiency but also with its cost. This makes solar energy's potential very promising. It has had an unprecedented level of growth in the last decade and has shown no signs of stopping ever since.
Swanson’s Law is the observation that the solar panel costs tend to drop by 20% for every doubling of cumulative shipped volume. Historically, this has translated to costs being cut by half every 10 years. In fact, crystalline silicon solar panels (monocrystalline and polycrystalline) have fallen from $76.67 per Watt in 1977 to $0.36 per Watt in 2014.
Solar Panel Systems are a Form of Decentralized Energy Generation
Of all the other energy sources, solar energy is the only energy source that can be implemented as a decentralized energy source. Every home can produce energy right on its very roof with the only limitation being shading from nearby tall structures. This would mean that energy generation (and transmission) would be controlled by the consumers themselves instead of by a few capitalists who control the large power plants.
Growth of Solar Energy
In 2015, annual solar energy capacity grew by 50%, reaching over 74GW. This is the first time in history where the growth of solar energy exceeded those of any other fuel. This was the result of the continued boom in the industry, along with sharp cost reductions and policy support. This growth has exceeded even the most optimistic predictions.
The International Energy Agency (IEA) publishes a World Energy Outlook annually. This paper is widely recognized as the most authoritative source for global energy projections and analysis. Every year, it has predicted solar energy’s growth and has underestimated it since 2002. Auke Hoekstra, a head researcher at the Technical University of Eindhoven in The Netherlands, has pointed out that all of IEA’s previous predictions were too low compared to solar energy’s annual growth record. He summed this up in on Twitter in one chart (see image on the left).
As we can see from the graph, IEA has always predicted solar energy’s growth to be linear but the reality is that it has always grown at an exponential rate, which represents a huge disparity.
The IEA has also predicted that solar energy (solar PV along with concentrated solar), would be the top source of electricity by 2050. Given their history of underestimating solar energy's growth, it would not be impossible to achieve this even sooner.
Engr. Jet Andal has 6 years of experience in the design and installation of residential, commercial and utility-scale solar PV systems. Together, and with the use of solar energy, let us help make the world a better place. You can click here to read all of our other blogs. For aspiring solar PV engineers, you can also check out his Solar PV Engineering Ebook on Amazon on this link.
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