Science As A Human Endeavour: Environmental Issues – Solar Panels
Introduction
As science progresses governments and countries are turning to renewable energy supplies to minimise their impact on the environment, as well as to conserve finite resources such as coal and natural gas. As of 2015 86% of Australia’s energy was derived from fossil fuels. The remaining 14% is renewable energy, with 7% from hydropower, 4% from wind, 2% from solar panels and 1% from bioenergy. Despite the relatively low production solar power is prominent among these as it is popularly seen as an ecofriendly addition to a house. However the environmental impacts of production may currently outweigh the benefit, relating to the SHE concept of application and limitation. It also relates to influence as governments and corporations have an interest.
Background Research
As of today there are three main types of solar panels available for purchase. The three types are polycrystalline, monocrystalline solar panels and thin film solar panels. Polycrystalline and monocrystalline solar panels are made in a very similar way. The core material of all solar panels is silicon (Si). This can be made from the treatment of silica (SiO2), which is found in sand. To convert the silica into high grade silicon quartz sand must be melted in an arc furnace at 1410° C. The intense heat removes the oxygen from the silica compound in a reduction reaction.
Heat2C + SiO2 2CO + Si
The impact of the production of silicon is one of the major draw backs of solar panels. To produce a single ton of silicon 2. 7 tons of quartz, 1. 5 tons of low ash coal and 1. 5 tons of wood is needed. Another important cost component is energy with about 13, 000 Kwh/t of silicon.
The silicon is collected as rocks. They are melted at 1, 414 ° C to form ingots. Monocrystalline cells are made from a single crystal of silicon while polycrystalline cells are made from multiple crystals melted together. This again increases the impact of solar panels as a lot of fuel is required to raise the silicon to this temperature.
The ingot is sliced with a precision saw to form wafers about 5mm thick. It is then doped (adding impurities) with phosphorous and boron. The wafers are then sealed back to back and placed in a furnace to be heated to slightly below the melting point of silicon (2, 570 degrees Fahrenheit or 1, 410 degrees Celsius) in the presence of phosphorous gas. The phosphorous atoms "burrow" into the silicon, which is more porous because it is close to becoming a liquid. The temperature and time given to the process is carefully controlled to ensure a uniform junction of proper depth.
Explanation of interaction between science and society
The constant development and designing behind the continuous improvement and progress of solar panel technology is an excellent example of the SHE aspect of development. As new methods and techniques are researched they increase the overall efficiency of the technology, as well as encouraging growth in this field of science. In 1839 the French scientist Edmond Becquerel observed and named the process by which light can be absorbed by a material and create electrical voltage the photovoltaic effect. Using Becquerel’s observation Willoughby Smith discovered that when Selenium absorbs light it becomes electrically conductive in 1873. Following on from this discovery William Adams and Richard Day found that selenium can produce electricity from light without moving parts or heat in 1876. This helped show the scientific community that solar power could be a viable source of electricity in the future.
These discoveries helped Charles Fritts when he made the world’s first solar cell by coating selenium with a thin layer of gold. This cell had an energy conversion rate of 1–2%. In 1887 Heinrich Hertz discovered the photoelectric effect. This is when light can be used to dislodge electrons from a metal to create an electrical current. This method is still used today in modern solar panels.
