Dec 31, 2021
Unlimited Energy Sources That Will Help Save the World
A basic overview of renewable energy.
Many of you might recognize this:
It’s such a simple, yet, amazing idea, an endless pizza slice. An infinite food source.
I would get sick of eating pizza forever though… but that’s not the point.
You have probably heard concerns regarding our current main energy source, fossil fuels. Apart from being incredibly harmful to our environment, we simply don’t have enough to support the amounts of energy humanity will require, around 100 TW of energy.
So, it’d be perfect if, just like Soos had an infinite pizza source, we had an infinite energy source. Lucky for us, there is. This is known as *drumroll please* renewable energy!
Renewable energy is “virtually inexhaustible” as the U.S. Energy Information Administration phrases it. It’s impossible to run out of this energy since, well, the sun, water, and other sources will always be available to us. This type of energy doesn’t directly emit greenhouse gases that contribute to climate change, making it great for our current situation. It isn’t completely sustainable though, and it has many other flaws that I will discuss in this article.
Types of Renewable Energy
The following are the most used, principal, types of this renewable energy:
Hydropower
Hydropower converts energy from flowing water into electricity.
Modern hydro plants use generators and turbines. Moving water flows (from the headwater, higher elevation reservoir, to the tailwater, lower elevation water) through the turbine, causing the rotors in the electromagnetic generator (connected to the turbine) to spin. This produces electricity.
There are two types of turbines used in hydropower engineering: impulse turbines and reaction turbines.
Impulse turbines transform water energy into mechanical energy by using the kinetic energy of a jet of water, going at a high velocity.
Water shooting at the turbine buckets (the whole structure known as a runner), is regulated by a needle in the nozzle.
Reaction turbines use the combined action of pressure energy and kinetic energy to develop power. The runner chamber is filled with water completely so that a draft tube is used to recover the hydraulic head (elevation difference).
In generators, the two main components are the rotor and stator. The rotor is what is rotated by the turbine. When this rotor is magnetized, or “excited,” it creates a voltage which then goes to the stator. Specifically, the rotor generates a moving magnetic field around the stator. This induces a voltage difference between the windings of that stator, producing the alternating current output of the generator. Then a cyclical process of voltage regulation occurs. From alternating current to direct current, and vice versa, again and again until the generator begins to produce output voltage equivalent to its full operating capacity.
The powerhouses, where the generator is located, consists of the superstructure and the substructure. The superstructure has protective housing for the generator and control equipment. The substructure is the foundation of the powerhouse. This includes steel and concrete components for the draft tube, turbine stay ring and generator, etc. There is also a control room.
Hydropower is produced in two ways. Utilizing dams, or the run of river technique.
When using dams, the headwater will flow through the barrier (thanks to gravity). The potential energy from this dammed water will produce electricity when the water is released and turns the turbine, thus the generator rotors. There is also a lower accumulation of water, the tailwater, where stored water will then be pumped up to the higher level. So, when electricity is in demand, this water can be released. This is known as pumped storage.
The run of river technique uses the natural flow of water in rivers to divert a small portion of it to the turbines.
Hydropower is the most used renewable energy in the world. It is pretty reliable for a renewable source, it can be used as base-load power and to control floods. It also provides a water supply.
However, there can be a great negative impact on the environment and wildlife of the river. Catastrophes may be caused by dam failures, and CO2 is emitted during the production of these dams (due to the amounts of cement needed).
Wind Power
The wind’s motion is converted into mechanical energy in order to make electric energy.
Turbines are very tall, and they have long spinning blades. These spin as the wind blows. These are connected to an electromagnetic generator by a shaft. When the blades spin so does the shaft, producing electricity in the generator. The generator wind turbines work just like the ones in hydroelectric plants.
There are two main types of wind turbines: horizontal and vertical.
Horizontal turbines only work if the wind comes at it from the front, any other direction doesn’t affect it. It also shuts down if the wind is going too fast.
Vertical turbines work with the wind coming in any direction, at any speed. However, these aren’t as efficient as horizontal turbines.
There are also pinwheel turbines that turn so that the wind faces them, as they are more efficient like that. They have detectors that can sense the direction of the wind.
The wind is caused by atmospheric pressure, its speed varies due to geography, topography, and season. So some areas are better for turbine location than others. In windy spots, there are often wind farms, where there are many turbines lined up.
There are three main types of wind turbine establishments/wind farms being developed and used:
Land-based wind: this is the most seen, they’re the lined up huge wind turbine farms on land most of you have probably seen.
Offshore wind: this is just like land-based wind farms, except they’re offshore, in the ocean. These turbines and farms are usually a lot larger and generate more power.
Small wind: manufacturers are trying to make small/medium-sized turbines. This allows for more distribution and makes it easier to improve turbine designs.
The wind does not blow all the time though, and there are complaints about land use, loud noise, and bird disruption.
Solar Power
The conversion of the sun’s heat or light to another form of energy.
There are two ways to collect solar energy: solar photovoltaics and solar thermal.
Solar photovoltaics, or solar panels, use semiconductors to convert sunlight into direct current electricity.
There are two main types of solar panels: silicon-based and perovskites.
The classic silicon-based panel has two layers of silicon. It has one positive-charged layer and a negatively-charged one. The positive one is injected with Boron, taking away electrons, making it positive (P-Type silicone). The negative one is injected with Antimony, giving it electrons, making it negative (N-Type Silicone).
They are put one on top of the other, making a P/N junction. These different charges attract each other, the electrons from the negative silicone look for a hole to move into in the positive silicone.
Photons from the sun break the bond between the hole and the electron. The hole wants to go to the negative part, and the electron wants to go to the positive part.
The electron is constantly looking to go to the hole, however, there’s a depletion zone, in the middle, where everything is stable. This stops the electrons from moving through the P/V junction, and instead they move through the wires which lead them through the energy user and back to the silicone, where it can finally go to the hole. The same movement occurs with the hole. Then, the cycle repeats as more photons come to break the bond created.
Perovskites are more efficient, as they absorb the whole solar spectrum (unlike silicone which only absorbs visible light).
Perovskites have a crystal structure, they’re made with various combinations of elements with a chemical reaction of ABX₃. A and B are cations and X is an anion that bonds to both.
Because silicon crystals are hard to get, scientists found that perovskites can create semiconductors with similar properties to silicon. They can be tuned to ideally match the sun’s spectrum, their band gaps can be tuned by the control of compositions. There is partial or full substitution of organic or metal cations and halide anions. The electricity will then flow into the conductive layer.
Perovskites are both cheaper and less pollutant than silicon-based panels.
Solar thermal uses the heat energy of the sun to produce electricity, or for heating. These systems have two main components, reflectors (mirrors) and receivers. The sunlight is captured by the reflectors, which focus the light onto the receiver. A heat-transfer fluid is heated and circulated in the receiver. This produces steam which (with a turbine) is converted into mechanical energy, and so it powers a generator to create electricity.
As we all know, the sun doesn’t shine all the time, and it shines more in some places than others. This creates a huge problem with intermittency and efficiency.
Biomass
The energy is produced from organic matter.
The organic matter, or material, usually comes from living and/or recently living plants, and waste. These are also known as feedstocks. All feedstocks contain carbon, water, and organic volatiles.
To produce energy from feedstocks, it goes through many distinct processes, the ones that occur the most are:
Combustion: when the feedstocks are burned in the presence of air to produce heat. This heat can be used for steam to spin a turbine and power a generator to produce electricity.
Gasification: when feedstocks are put through heat, pressure, partial combustion to convert them into a combustible gas mixture known as syngas. This is used as a natural gas would, so for heat, generating electricity, etc.
Pyrolysis: when there’s a heating of feedstock without the presence of oxygen. This causes there to be no combustion, instead, decomposing takes place, producing bio-oil, bio-char, and/or syngas.
Anaerobic digestion/bio-digestion: bacteria break down organic material without air. This is captured and burned to create energy, the remaining product is digestate, which can be used as a fertilizer.
Fermentation: converts plant’s glucose to ethanol (liquid fuel) using yeast.
It’s important to keep in mind that some feedstocks are better for some processes than others. So, the process that will be used is determined by the feedstock available.
This energy source, however, is not that sustainable. Some processes, like combustion, create a lot of carbon emissions affecting the environment’s health as well as human health. Deforestation, cropland, degradation, and more can be issues associated with biomass.
There have been many innovations that fix these issues though, like the flue gas cleaning system, which filters the air so that harmful organic and inorganic substances are no longer released into the atmosphere.
Geothermal
Producing energy from the internal heat of the earth.
Radioactive decay of minerals and continual heat loss from the Earth’s original formation generates internal heat.
Geothermal wells are dug around 3–10 kilometers deep. Thanks to these, heat can be extracted using water and steam.
Hot water from underground is extracted to heat homes and buildings. It can also be brought up to a geothermal power plant to create electricity.
Another way of generating electricity is by producing steam with geothermal heat, which powers a generator.
There are three main types of geothermal power plants:
Dry steam plants use steam straight from the geothermal wells to turn the generator turbines.
Flash steam plants make steam using the really hot water from the wells and use that to turn the generator turbines. Once the steam is cooled and condenses into water, it is put back into the ground through another well. This is called the injection well. This is the most common type of geothermal power plant.
Binary cycle power plants move the heat from the hot water taken from underground to another liquid, making it turn into steam. This steam is used to turn the generator turbines.
This source of energy is great because it is reliable and consistent. It can be used as base-load power too! However, it is pretty expensive. This is due to seismic sensing, test well drilling, confirmation testing, and more. There may also be an accidental release of CO2 and hydrogen sulfide emissions, which are stored in the earth’s groundwater. Also, if geothermal heat is used irresponsibly, it can lower the earth’s internal temperature.
How we can achieve absolute sustainable energy
Although renewable energy is great, as you can see, it has many flaws. The amounts of clean energy it produces makes up for it though. We will have to use these sources because that way we will never run out of electricity, and our carbon emission will drop tremendously. We can’t run on only renewable energy. So, to achieve this goal we need to apply other sources of low-carbon emission energy and work on energy storage. Things like nuclear fusion and many other innovations that are already in development or that will come in the future, will lead us to nice, clean energy. Of course, it’s almost impossible to emit zero greenhouse gases, but the closer we are to that, the better. We still have much more to work on, regarding sustainability, but removing fossil fuels from our energy source is a HUGE step to solving our climate change crisis.
I encourage all of you readers to promote the use of renewable energy wherever you live. The world will thank you later :).
