Navigating Renewable Energy Science: The Benefits and Types

March 11, 2024

Navigating Renewable Energy Science: The Benefits and Types

With the increasing global warming exacerbated by deforestation and carbonisation, more focus is now being centred on the use of renewable energy sources. 

Case in point: The combined land and ocean temperature has soared by around 2° F in total since 1850. More alarmingly, since 1982, the rate of the globe’s temperature has surged by threefold, now increasing at 0.36 °F (0.20 °C) per decade compared to the previous pace. 

This trend of using green energy sources has been further fueled by the prevailing energy crisis aggravated by recent geopolitical and economic turbulence. 

In short, driving sustainability has now become paramount; and for a greener and more sustainable future, transforming our energy landscape by using renewable energy sources stands as a strategic imperative now. In this article, we'll delve deeper into renewable energy science. 

What is Renewable Energy?

Renewable energy, also known as clean energy, is derived from natural sources that are continuously replenished, for example, solar, biomass, wind energy, etc.

At the core of this technology lie the techniques of leveraging natural cycles or processes and generating power - heat or electricity - without depleting non-recyclable energy sources.

Tapping into these inexhaustible and recyclable energy sources is part of the global effort to decarbonise the energy sector and minimise its carbon footprint. 

In the wake of the 21st century, fossil fuel-based energy sources, such as oil, coal, and natural gas, met around 80% of the world's energy demand. These finite resources are predicted to deplete soon; It is predicted that we will run out of fossil fuels in this century. Experts predict oil to last up to five decades, natural gas up to 53 years, and coal up to 114 years. Due to renewable energy still gaining traction and not being deployed unanimously yet, the process of depleting these sources can accelerate.

Benefits of Renewable Energy: Its Impacts on Climate Change and the Environment

Renewable energy offers a range of benefits that extend across economic, environmental, and social domains, making it a critical component of a sustainable, greener future. Let's go through the benefits and how it impacts climate change and the environment:

Less Global Warming

Anthropogenic carbon dioxide and other harmful CFC gases emitted by fossil fuel-based energy sources act as a blanket that traps the heat the earth's surface radiates.

Case in point: The USA's electricity generation sector contributes to around 29% of the total global warming emissions. Among all finite resources, coal and natural gas emit most of these harmful gases.

Renewable energy can significantly reduce the impact of climate change by curbing the carbon footprint of electricity generation. 

While the life-cycle emissions range between 0.6 to 3.6 When considering the life-cycle emissions, renewables such as wind, solar, geothermal, and hydroelectric power exhibit low carbon dioxide equivalent (CO2e) values, ranging from 0.02 to 0.5 pounds of CO2E/kWh, it's only between 0.02 to 0.5 pounds per kilowatt-hour for renewable energy sources. The higher the CO2e for an energy source, the lower the volume of toxic gas it reduces while generating electricity.

Improves Human Health

The toxic particulate matter and greenhouse gases, such as sulfur dioxide, nitrogen dioxide, CFC, CO2, etc., emitted from fossil-based energy sources have been proven to be highly detrimental to human health. Long-term annihilation of these gases can cause a person to face pulmonary issues, cardiovascular diseases, neurological damage, malignancy, and more, leading to premature death. 

Case in point: According to research by Harvard University, the public health effects and the life cycle costs of the burning of coal to produce energy are as high as $74.6 billion/year. This amount has been reckoned to be equivalent to 4.36 cents per kilowatt-hour of electricity produced—about one-third of the average electricity rate for a typical US home.

Unlike finite energy sources, renewable energy sources generate power by emitting little to no air or water pollutants and consuming significantly less water. Even though geothermal energy sources emit a volume of GHG, it is negligible compared to the volume of toxic gases traditional fossil fuels emit. 

The result is improved public health, better conservation of water resources, and mitigation of the environmental and health outcomes yielded by traditional energy sources. 

Inexhaustible Energy

Renewable energy sources demonstrate the tremendous potential to significantly meet future electricity demands by acting as replenishable, inexhaustible energy sources.

Even after coming with some constraints and facing challenges, these energy sources are expected to contribute to meeting the lion's share of future energy demand worldwide. 

Case in point: According to a study conducted by NREL, by 2050, renewable energy sources are expected to meet up to 80% of the USA's energy demand. 

In addition, renewable energy sources have the potential to scale up fast. A study sponsored by the US government found that this energy can expand from three to 80 times its level reported back in 2013. The outstanding flexibility and scalability exhibited by renewable energy sources can significantly contribute to addressing future energy demands while also helping seamlessly transition to a more sustainable and low-carbon energy landscape.

Different Types of Renewable Energy Sources

Solar Energy: Harnessing the Power of the Sun

Solar energy - one of the most used renewable energy resources - traps the heat of solar radiation and turns it into power. 

In 2022, solar energy comprised around 15.9% of electricity generated by renewable sources worldwide, up from 13.5% in 2021.

Two options pathways can be adopted while harnessing solar energy - either through photovoltaic (PV) panels or through mirrors that concentrate solar radiation. This power generated as electricity can also be stored in batteries. 

Solar panels are designed based on the photovoltaic (PV) effect. The PV cells are made of semiconductors, for example, silicon, that when the sun radiates energy onto the cells, absorbs it in the form of photons. As a result, electrons in the silicon cells get excited and start moving freely from the top layer to the bottom layer of a cell. It creates a potential difference between these two layers, causing electrons to flow. The continuous flow of electrons means the generation of electricity throughout the circuit. 

The electricity can be directly used as a power source or stored in batteries as a backup. In solar panels, the most common types of batteries used are lead-acid, lithium-ion, nickel cadmium, and flow batteries.

When it comes to the orientation of the PV panel, it should be ensured it's placed in a way that it gets maximum exposure to the sun throughout the day. The standard rule is to face it south in the Northern Hemisphere or north in the Southern Hemisphere.

The latitude of the site where the panel is placed plays a pivotal role in helping decide its tilt angle. The rule of thumb is to keep the tilt angle equal to the site latitude. However, adjustments may be needed based on the geographical location and seasonal variations for optimal power generation.

On the other hand, while building a concentrating solar-thermal power (CSP) system, mirrors are used to reflect and store sunlight onto a receiver - usually a heat-absorbing fluid. The fuel, when heated to a high temperature - usually above 500 degrees Celcius - turns into steam and is used to spin a turbine or power an engine to generate electricity. 

With that said, not all countries in the world have adopted solar technology to power their households or industries. However, an approach prioritising energy mix from direct solar energy can help countries diversify their energy sources while also reducing their carbon footprint. 

Benefits

  • One of the key benefits of tapping into solar power is that the process is carbon-free.
  • Solar panels can be deployed in various forms and places - from rooftops to power large-scale industries.
  • The installation cost may seem higher. However, it's plummeting rapidly, and considering the lower operating cost and the longer lifespan of the system, solar technology is beneficial.

Limitations

  • The power generated by solar panels depends on the sunlight radiated onto it. It means that the amount of power generation can vary depending on the weather, making solar energy highly intermittent.
  • To ensure optimal performance, solar panels need regular maintenance.

Wind Power

Wind turbines - essentially, the updated version of windmills, use the kinetic energy of wind to generate power in the form of electricity.

The basic principle behind a wind turbine is to turn kinetic energy into mechanical energy which is then used to generate electricity.

A wind turbine comprises two to three propeller-like white blades, that together with the hub, form the rotor. The blades are rotated using the kinetic energy of the wind. The rotor is connected to the main shaft which spins and improves the rotational speed of the blades. The shaft is connected to a gearbox that drives a generator. The off-the-shelf induction generator, through electromagnetic induction, turns mechanical energy generated in the blades into 60-cycle AC electricity. 

When it comes to turbine design, there are two options available - upwind turbines that face into the wind and downwind turbines that face away.

Wind turbines are equipped with control systems that adjust blade pitch and yaw orientation to the wind for optimised energy generation based on the wind speed data measured and transmitted by the anemometer in the turbine. The required wind speed to make the turbine start operating varies from 8 to 16 miles per hour (mph). To avoid damage, the machine stops operating when the wind speed goes above 55 mph. 

Benefits

  • One of the key benefits of wind farms is that it they produce no greenhouse gas. The green energy produced through harnessing the power of the kinetic energy of wind doesn't toxicate the environment thus contributing to mitigating the effects of climate change.
  • Generating electricity using wind turbines involves relatively low maintenance and operating costs, making it a cost-effective alternative to traditional fossil fuel-based energy sources.
  • Wind turbines can be installed for residential power supply or industrial purposes, making wind power highly flexible.

Limitations

  • Integrating the power generated through wind turbines is highly challenging due to the intermittency it comes with. It means that how much electricity would be generated by wind turbines depends on a slew of variable factors, such as wind speed and consistency.
  • The noise and shadow flicker effect induced by wind turbines can be detrimental to patients suffering from photosensitive epilepsy and experience seizures in response to specific environmental triggers.

While solar and wind energy hold immense potential to help decarbonise the energy sector, some other sources worth mentioning include:

Geothermal Energy

In short, geothermal energy means extracting the heat stored in the rocks and fluids of Earth's crust. But, how does the Earth serve as a source of heat energy? 

In reality, the Earth's core has been radiating heat since the formation of its core. Part of this heat was generated due to the continuous decay of the Earth's radioactive materials. The high rate at which this energy is being generated makes geothermal energy a replenishable energy source. 

First off, geothermal reservoirs with high temperatures are identified, and wells (onshore and offshore) are drilled. After that, water is injected into these wells, and due to the extremely high temperature there, this water turns into steam before it returns to the ground surface.

This steam is used to drive turbines. A generator connected to the turbines then starts operating due to the force it gets from the turbines and generates electricity through electromagnetic induction. It means that, in this process, thermal energy is converted into electricity. It can be used as an energy source for residential houses or can be sold to the grid. 

Benefits

  • Geothermal power plants serve as a continuous and reliable source of renewable energy.
  • Its carbon footprint is significantly low compared to fossil fuels, contributing to a cleaner energy mix.
  • Power can be generated for 24/7 hours using geothermal energy. Its capability to act as a baseload power makes it a stable energy source.

 Limitations

  • Establishing a geothermal power plant to tap into the Earth's energy involves hefty upfront investments.
  • It may induce a slew of environmental impacts - induced seismicity, surface disturbance, earthquake, etc.

Hydro Energy

Hydropower plants operate based on the principle of using the gravitational force of water to generate electricity.

In this process, a traditional dam or channel is created to store water in an artificial lake. When a desired quantity of water is stored, it is directed to a turbine through a penstock at a high speed. 

This high flow of water spins the turbine blades. The spinning turbine shaft then starts and rotates a generator that is used to generate electricity. In this process, the kinetic energy is first turned into mechanical energy (in the generator) which is then transformed into electrical energy.

In a hydropower plant, water flow can be regulated as the demand fluctuates. 

 Benefits

  • Hydropower produces no toxic GHG while generating electricity.
  • It produces reliable and stable baseload power
  • Even though installing a hydropower plant involves a hefty upfront cost, the operating and maintenance costs are significantly low.
  • A hydropower plant has a significantly longer lifespan.

Limitations

  • Large-scale hydropower plants can cause water flow alteration, disrupt human habitation, etc., that can adversely impact downstream ecosystems.
  • Creating dams/channels requires a significant acre of land.
  • Solving the water quality and sedimentation issues with hydropower plants needs thorough strategies.
Patsy Todd

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