Replacing fossil fuels with renewable and sustainable forms of energy, may be the greatest challenge of the 21st century and possibly of world history.
Many engineers and scientists are working on developing the current technology that we have to harness the natural sources of energy to mitigate climate change. We are all aware of the severe consequences to climate change; unpredictable weather patterns, the increase in sea level which in turn will bring about more frequent flooding and the destruction to people’s homes and livelihoods. However, the research, production and development of equipment to utilise the renewable sources will need to be drastically enhanced by engineers if we have any chance at mitigating climate change and this essay will focus on the ways in which engineers are doing just that.
The most common definition of a ‘renewable source’ is an energy resource that is replaced rapidly by natural processes. Renewable sources of energy include sun, wind, tidal, hydroelectric, geothermal and biomass. These sources do not emit carbon dioxide, sulphur dioxide and other greenhouse gases that contribute to climate change. Renewable sources are said to be more sustainable but are not the most reliable sources of energy due to the long period of time it takes to start making an economic gain from them after installation.
How are some sources of renewable energy generated?
Solar power is harnessed using solar photovoltaic (PV) panels which convert the sun’s energy into electricity. The Solar PV panels absorb the sun’s rays and store it in the water or fluid inside it. The solar energy is then passed through an inverter, in turn being converted to a D.C current which is then connected to a generator. They can be installed on various scales e.g. in small hand-held appliances such as calculators, on slightly bigger scales, on the rooves of houses and on industrial scales using large areas of land as a ‘solar field’.
Although solar power is more common due to its ability to be used domestically on a smaller scale, the cost of research, development and manufacture is very high which then causes the final product to be quite expensive for people and industries to purchase. With most forms of renewable energy, including solar, there is an issue with how the energy can be stored. Currently, the electricity being generated has to be used as it is produced due to the lack of storage. On the other hand, over 486 GW of installed capacity makes solar power the 3rd largest generator of renewable energy. The annual growth rate in the use of solar power has increased by around 25% in the last 5 years making it the fastest growing source of renewable energy.
Therefore, to mitigate climate change, engineers will have to bring down the cost of solar PV panels to make them accessible to everyone which will them begin to reduce our carbon footprint.
Wind power is the power obtained by harnessing energy of the wind. When the wind blows over the blades, the air pressure on one side of the blade is significantly greater than the other. The differences in these air pressures, creates a drag and lifting force and as the lifting force is greater than the drag, a spinning effect is caused, causing the rotor to spin. The rotor blades are then connected to a generator (left), which speeds up the rotations. The energy is then converted to mechanical power turning the blades of wind turbines to power electric generators. These were traditionally used in agricultural work such as milling and pumping.
In 2018, wind power made up 24% of the world’s overall renewable energy generation and at the end of 2019, the US was home to 103GW of wind capacity with 77% of this being installed in the last 10 years. This shows the rapid growth in the production and use of wind power.
Due to the large push in the use of renewables, wind power is one of the best ways in which electricity can be produced. It does not release greenhouse gases, has a smaller carbon footprint and can potentially benefit the economy. Wind Power is also one of the few renewable energy forms which can be harnessed both offshore and onshore. However, there are some negatives in the production of wind power. Firstly, although the wind is sustainable and will never run out, the speed of the wind varies on a daily basis so there can be some uncertainty in the efficiency of wind turbines. For wind turbines to be efficient, there needs to be a sufficient quantity of wind energy which explains why wind turbines tend to be placed in areas of high land, such as on hills, and out at sea, so that there are no objects obstructing the wind from reaching the turbines.
The initial cost of installing a turbine is very high although it is gradually becoming cheaper, as engineers are beginning to design them to become more energy efficient. Firstly, an engineer conducts a site survey where they measure wind speeds over an adequate period of time. If the area is suitable, the turbines need to be bought, transported and installed in that area. The cost becomes a lot greater for offshore wind farms due to the more complex investigation that needs to go on to find out if the bedrock is adequate enough for the wind turbine. The wind turbines are then transported using ships before being installed out at sea.
Although having a high initial cost of installation and some negative impacts on wildlife, wind power is more sustainable than fossil fuels and has a low maintenance cost. As time moves on, engineers will have to find ways to make the production of wind power more efficient, especially with changing wind speeds, as the demand for energy will inevitably continue to rise.
When an atom splits into two as part of natural decay or by being split in a laboratory, the atom releases energy which is the process of nuclear fission. The nuclear reaction in which the nucleus of an atom, of low atomic mass, fuses with another atomic nucleus forming a heavier nucleus and releasing energy is known as nuclear fusion. Both forms of nuclear power can produce approximately one million times more energy per atom than the chemical energy per unit of typical fossil fuels. This shows that the waste produced from nuclear power is much less then fossil fuels being used now. Scientists have seen nuclear fission and fusion as the new possible and more sustainable way of producing energy. It has the potential to become the next major source of energy but, it does however, come with many safety, environmental and political concerns, including the potential for unsafe disposal of the radioactive substance which can cause the mutation of cells in humans.
Nuclear fission occurs in Uranium-235 as it decays naturally by alpha radiation. The uranium releases an alpha particle, or a free neutron can be fired at the U-235 nucleus and the nucleus will take in the neutron, causing it to be unstable and split instantly.
The decay of 1g U-235 atom can release around 1MW which is a very small amount of energy in terms of how much energy is need to power multiple houses. This is the same amount of energy as 3 tons of coal. To combat this issue, ‘Fast-Breed Reactors’ are used to extract Uranium because this process can make the uranium approximately 60 times more efficient as all of the uranium is used, which would be the same as providing each person with 33kWh per day.
Research into the extraction of Uranium for fuel is being undertaken all around the world, with researchers extracting uranium from both the ground and sea water. Japanese researchers have used the technique of extracting uranium from seawater which would cost $100-300 per kilogram of uranium which is much higher than the current cost of $20 per kilogram from Uranium ore. The high cost is not the only downside of using the seawater extraction method. Some researchers have questioned if the Japanese’s technique can be scaled up due to the large volume of seawater needed to make it a viable process and the immense cost of materials and stations needs to be minimised by the engineers who design them.
Although, the future of nuclear fusion is uncertain, the low volume of waste and the significant decrease in carbon dioxide emissions could see scientists using uranium as an increasing source of energy in the near future. This, however, will mean that engineers and scientists will need to find ways to mine and safely extract the uranium from the ore without causing negative impacts to the society and the environment due to contamination. Currently, another issue for the development of nuclear power is the lifetime of the plant and the infrastructure of it, from the reactor core itself to the mechanical equipment. Presently, engineers are doing research into the safe expansion of existing nuclear power plants in order to produce more energy to meet the world’s expected increase in demand. This means that we may start seeing a greater proportion of energy being generated from nuclear power stations in the future.
What can engineers do to mitigate climate change in relation to energy use and consumption both domestically and industrially? The diversity in the methods used to harness energy from renewable sources is projected to increase in the next few years. As discussed, technology is the main driver of how fast we move to renewable energies. How engineers construct and design machines that will be energy efficient and a small carbon footprint will determine how quickly we reduce our use of renewables without compromising the safety and final outcome of the products. So, to mitigate climate change, engineers must focus on improving efficiency, reducing cost and improve technologies that will ensure to harness the renewable sources that we have which will reduce carbon emissions.