What can we do about such a global problem? According to the Intergovernmental Panel on Climate Change there are two major approaches for dealing with climate change: mitigation and adaptation. Mitigation refers to reducing sources and increasing sinks [4]. Adaptation is changing to deal with the effects of a changing climate. In order for any solution to be put in place it need to be an equitable and economically fair solution [4].
The unit plan presented here will focus on mitigation. The definition of mitigation when talking about climate change uses the words sources and sinks but first we need to explain the carbon cycle. Just like water, carbon also cycles. Carbon sinks include the atmosphere, photosynthesis, and ocean while sources of atmospheric carbon include greenhouse gasses emitted by respiration, deforestation and burning fossil fuels. Humans are altering the carbon cycle by releasing carbon stored for long term underground stores such (fossil fuels) and burning them for energy. Fossil fuels are fuels such as coal, oil and natural gas. Humans are moving large amounts of carbon from long term storage to the atmosphere as CO
2
.
Solutions that mitigate climate change can encourage the use of low greenhouse gas emitting energy or the capture and long term storage of carbon dioxide. Some potential alternative energy sources could be solar energy, nuclear energy, wind, hydrogen fuel cells. Carbon sequestration options include absorption towers, burning fuel in pure oxygen (to help capture the CO
2
), deep ocean storage and using biological organisms such as trees, algae, and other plants to take up the excess carbon dioxide. Alternative energy sources are also required because our current dependence on fossil fuels is not sustainable. Fossil fuels are not a renewable resource so there is a need for different energy sources before they run out and it is no longer cost effective to harvest them. Also important is the need for energy sources that do not release greenhouse gases like carbon dioxide and nitrous oxide into the environment contributing to a changing climate.
Carbon sequestration is a potential solution to carbon dioxide being put into the air from fossil fuel combustion. Carbon sequestration is the capture and storage of carbon out of the atmosphere, most likely underground under high pressure. This method could be used in industry to capture the CO
2
released and prevent it from entering the atmosphere. Carbon capture and storage has three parts which include first capturing the carbon dioxide, then moving the carbon dioxide and finally storing the carbon dioxide. Long term storage would occur in one of two places. Empty oil and gas fields or deep saline aquifer formations [5] are potential candidates for long term storage. One idea is to replace smoke stacks with absorptions towers and burning coal in pure oxygen and then using underground storage. By burning coal in pure oxygen it becomes easier to separate the carbon dioxide from the exhaust (which is a majority Nitrogen gas and other compounds) [13]. In the absorption towers one would have chemicals to isolate carbon dioxide and absorb it. The other tower would remove the carbon dioxide from the absorbing chemicals. [13] Potential engineering solutions to climate change do exist.
Alternative energy sources are those that do not use up nonrenewable natural resources or harm the environment. A short list of some alternative energy sources includes: solar, nuclear, hydroelectric, wave, biofuels, geothermal, wind, biomass, tidal and hydrogen. In 2017 renewable energy made up 11% of primary energy consumption in the United States. The breakdown for this 11% is as follows: 2% geothermal, 6% solar, 21% wind, 4% biomass waste, 21% biofuels, 19% wood, and 25% hydroelectric. [15]
Solar energy can be harnessed and used in two different ways. First is passive solar energy which may be used to heat water or directly heat a building. Passive solar energy does not require a mechanical system to work. Active solar energy uses photovoltaic cells to convert solar energy to electrical energy without the use of a turbine. There a both advantages and disadvantages to solar energy. First is that operation produces very little greenhouse gas emissions and these technologies also work anywhere there is sun. A major drawback of solar energy is that it only works when the sun is out so power is limited or unavailable at night or when it is cloudy, unless systems build a reliance on batteries.[7] In 2002 the projection for the growth of the solar energy market was that it would grow 1 gigawatt per year by 2010. By 2010 this goal was exceed by 17 times and the use of solar energy is increasing. World solar photovoltaics installation is increasing exponentially and the cost of solar panels is coming down.[16]
Nuclear power is created by the process of fission. Fission is where the nucleus of an atom is split releasing large amounts of energy. The heat energy is then used to produce steam and turn a turbine powering a generator. An advantage of nuclear is that it is such an abundant form of energy that is less polluting, especially if the nuclear waste can be reprocessed, however it also has a major drawback that a major malfunction could be catastrophic for human life and the environment.[7]
Hydroelectric energy is electricity generated by using flowing water usually from a dam to turn a turbine powering a generator. China has the world’s largest hydroelectric power plant providing electricity for the populations growing demand for power. Hydroelectric energy has advantages including not releasing any carbon dioxide in the electrical generation process once built and providing a steady supply of electricity. Disadvantages of hydroelectric energy include environmental and human impacts of damming a river and flooding the area behind it to create a reservoir.[7]
Wave energy is where the energy of ocean waves is captured at or below the surface. Waves are caused by wind moving over the surface of of the ocean in windy areas, which creates great potential to extract the energy of the waves. (ocean wave energy article). Benefits of wave energy are that they do not produce pollutants such as carbon dioxide but they are limited costal locations where large waves exist.[7]
Biofuels are fuels that come directly from living matter such as ethanol or biodiesel. Biofuels are an attractive solution because the plants used to make the biofuel take carbon dioxide out of the atmosphere even though they still release some when burned making them carbon neutral. The problem with biodiesel is that plants are energy intensive to grow and harvest and process and result in both land use changes and greenhouse gas emission during production.[7]
Geothermal power is derived by using heat stored underground to turn a turbine. Similar to the other alternative energy sources geothermal does not produce CO
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while making electricity. Disadvantages of geothermal however include that it is limited to specific geographic locations.[7]
Wind energy harnesses the power of the wind to turn a turbine. Wind turbines may stand alone or be found in wind farms. Wind energy is not only good because it does not release any CO
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, but because it is also a renewable resource. Some cons of wind energy are that it is noisy, harms wildlife and is only efficient in certain locations.[7]
Biomass energy is the direct burning of plant and animal matter for heat. Burning wood for cooking is one example of biomass being used for energy. It is considered a better alternative to fossil fuels because it releases less CO
2
than fossil fuels when burned due to the uptake of CO
2
to grow the biomass. Problems with biomass energy include things such as indoor and outdoor air pollution, extensive land use, and the potential for deforestation.[7]
Tidal energy comes from energy produced by the ebb and flow of the tides. Here water turns a turbine underwater as the tide goes in or out. A dam may be built across a bay to turn the turbine or the turbines could be placed underwater. Advantages include the production of power and the CO
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prevented from entering the atmosphere. Problems with tidal power include the disruption of the seafloor habitats and limitations to areas with significant ties.[7]
Hydrogen gas could potentially be used as a completely clean fuel. The products produced from combustion are only water vapor and warm air. Hydrogen gas may be harvested from natural gas and other fossil fuels or through electrolysis. Electrolysis is the process of using electricity to split water into hydrogen and oxygen. Like all the other alternative energies there are both pros and cons to the use of hydrogen gas as an alternative energy. Pros include the clean emissions during combustion. However generating the hydrogen gas for fuel is not a fossil fuel free process requiring either fossil fuels or other source of energy for electrolysis of other means of production. With all these potential sources of energy and even more not mentioned here there is potential to severely reduce the carbon input to the atmosphere.[7]