Updated: Mar 20, 2018
Climate change is undoubtedly one of the biggest challenges facing humanity today. The industrial revolution and the technological advances that followed particularly in the transport industry have meant that the Earth’s average surface temperature has risen by approximately 0.84 degrees Celsius to date. Our dependence on fossil fuels has resulted in high levels of CO2 being emitted into the Earth’s atmosphere, which is resulting in a greenhouse gas effect in which the heat in the atmosphere cannot escape. CO2 prevents excess heat from reflecting back from the Earth’s surface, causing the average surface temperature to rise over time. Various technologies have been researched over the past few decades and in the following weeks Engineering First Principles will talk about each of them, including the technology behind them, examples of where they are used and their advantages and disadvantages.
Solar power is one well known solution to providing a renewable source of energy instead of burning fossil fuels. There are two different methods; photovoltaic (PV) and thermal solar power. The former harnesses the sun’s photons using solar cells on panels whilst the later converts solar power into thermal energy used to heat water.
Photovoltaic technology uses solar cells to convert energy from the sun into electricity by the photovoltaic effect, where light is absorbed causing the excitation of an electron to a higher energy state. The solar cells are made up of p-type and n-type semiconductors, joined together to form a p-n junction, creating an electric field where electrons move to the positive (p) side and holes (positive electric charge carriers equal in magnitude but opposite in polarity to electrons) move to the negative (n) side.
Source: Energy Education
When photons of a certain wavelength shine on these photovoltaic cells, energy is transferred from them to the electrons, exciting them to higher energy states, leaving behind holes. This movement of electrons creates an electric current in the solar cells.
Solar thermal energy is used for heating water to provide low-cost thermal energy. The solar energy is used to heat water using thermal collector panels. Fluid is circulated through the panels by a pump and the thermal energy generated as the fluid heats up is transferred to water storage tanks connected to the heating or cooling systems. Panels are smaller than PV ones but electricity is directly generated and energy can only be used for heating and cooling unless turbines and generators are used.
Source: Energy Bite
There are many examples of where solar panels have been implemented on a large scale around the world. In India the Cochin International Airport uses over 46,000 solar panels making the airport totally self sufficient. In Datong, China a 250 acre solar farm was built in the shape of a giant panda and it will be able to produce up to 30 million kilowatt hours of solar energy over 25 years.
Source: Panda Green Energy
The sun is an abundant source of energy, delivering 1000Wm-2 after being attenuated by the Earth’s atmosphere. Even on cloudy days when the sky is not clear, some energy can be harnessed. Using solar power results in no pollution or greenhouse gases being emitted. Solar panels require little to no maintenance and can last over 30 years. In some countries it is common for suppliers to provide feed-in tariffs that pay users for the excess energy they produce from solar panels, which is then fed back into the grid. In the UK however schemes to promote such tariffs have seen many financial cuts.
The main disadvantage to using solar power is the cost of implementation especially on a small scale. Without government incentives or lower costs, it is hard to envisage solar power being used on a large scale in the near future. In 2007 Berkley (California) introduced the FIRST scheme (Financing Initiative for Renewable Energy) which encouraged people to use PV’s. The city covered the upfront costs of solar panels, paying for installation with users paying back the cost over time through an added charge to property tax bills. The user will continue to benefit from the energy captured using the solar panels are the installation costs are paid back.
If you are interested in environmental engineering why not head over to our Types of Engineering page and check out environmental engineering using the link below:
Additionally, thank you to Nia Hughes for her contribution towards this blog series.