WHY DO WE NEED ALTERNATIVE ENERGY?
When discussing why we need alternative energy it is important to understand the history of energy consumption and its historical link to civilisation. The production, storage and consumption of energy have been and still are essential for our survival. The very structure of our social groups from families to corporations, have focused on this very need. Our need for alternative energy which is renewable and non-polluting is underpinned by our very requirements for survival. It is most likely that our need for energy is not going to change, if anything it is only going to keep increasing.
All energy supplies have problems. The current trend for alternative energy sources is driven by a host of long-range ubiquitous problems associated with fossil fuels. Below are outlined briefly some problems of different fuel sources including alternative energy sources!
Problems with Fossil Fuels - Coal, Gas and Petroleum
Common environmental issues include contribution to climate change via greenhouse gasses, atmospheric sulphur dioxide (SO2) which is also known as acid rain; Smog and airborne particulates which contribute to lung diseases; nitrous oxide (N2O) which contributes to ozone formation at low altitudes; carbon monoxide (CO) and heavy metals. Aside from environmental issues, one of the biggest issues is the fact that fossil fuels are not renewable, they are finite.
While Natural Gas is considered the cleanest of the fossil fuels there are still many associated issues. One of the main concerns is ‘fracking’ where new deep drilling technologies break up rock formations leaving toxic fluids available to pollute groundwater.
The actual extraction of these types of fuels is as problematic and environmentally damaging as their actual consumption. Some risks associated with the production of these fuels includes: oil spills; heavy metal contamination and habitat disturbance.
Problems with Hydroelectricity
While hydroelectricity is often considered green due to the fact that it is renewable and relatively non-polluting, it does come with some fairly significant environmental costs. Hydroelectricity is generally the production of electricity from the movement of water; traditionally this is from the damming of a river to create a reservoir of water which via controlled release is used to drive turbines. Problems associated with damming and channelling water through a turbine include: reservoir stratification leading to a decline in the amount of dissolved water; habitat loss through dam construction; changing water levels in reservoir; sedimentation of the reservoir which can also lead to nutrient loading; erosion; dramatic changes in habitat for wildlife and fish.
Problems with Nuclear Energy
While much is discussed in the media regarding the dangers of nuclear energy, it is worth actually understanding a little about why it is dangerous.
An atom has at its core the nucleus. The nucleus is made up of protons (positively (+ve) charged) and neutrons (electrically neutral – no charge). Around the nucleus is a cloud of electrons (negatively (-ve) charged). Normally the number of electrons will equal the number of protons plus neutrons, thus balancing the charges and creating a neutrally charged atom.
An isotope however is an atom that has the same number of protons but a different number of neutrons. The isotope therefore has an unbalanced charge and an unstable nucleus. Due to this instability the nucleus can ‘decay’ spontaneously.
This is called radioactivity. When a nucleus decays, it breaks apart and emits radiation and particles (parts of an atom). Below three types of radioactivity are outlines, note that there are actually more than this;
- Alpha: Alpha particles are emitted from the nucleus. Alpha particles consist of two protons and two neutrons bound together into a particle. This type of particle radiation has low penetration.
- Beta: An electron is emitted. This is a high speed and high energy particle with medium penetration.
- Electron Capture: This occurs when there are too many protons in the nucleus and one of the electrons is captured by a proton to form an extra neutron in the nucleus.
As mentioned above, a half life of an isotope is the amount of time it takes for one half of the nuclei in the sample to decay. This is the common way of expressing the time for radioactive decay. Half lives of known radionuclides vary widely, with highly radioactive substances decaying much faster than those that are weak. Additionally rates of decay can and are measured precisely nor does the rate of decay vary in differing conditions. This means that it is an excellent technique for determining geological ages. If the half life is known, the parent/daughter ratio can be measured. It is this ratio that allows the calculation of the samples age. Note that the ratio refers to the percentage of atoms that decay during a half life (50%).
However the actual numbers of parent isotopes will decline continuously while the number of daughter atoms will rise in proportion. For example: If there are 100 parent isotopes and 0 daughter atoms the half life will be equal to zero. If there are 50 parent isotopes and 50 daughter atoms the half-life is 1. If there are 25 parent atoms and 75 daughter atoms, then the half life is equal to 2.
Radioactive Waste Disposal
Despite the horrors of a nuclear accident, the disposal of radioactive material is possibly one of the greatest problems with this type of energy production. This is due to the extremely long half life of the materials used. It is estimated that one reactor can produce up to 30-40 tonnes annually of waste. Currently technology has not found a way to safely store waste nuclear material. Generally, it is stockpiled in repository sites around the world.
Accidents and Safety
Nuclear fuels have been adopted in some countries however there remains a question of safety associated with that energy source. For example, storage of nuclear waste and it’s very long half-life, and risks of nuclear accidents and spills causing catastrophic damage. One very well-known nuclear disaster was Chernobyl nuclear power station disaster in the Ukraine in 1986.
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