What is renewable energy?
In a world seeking sustainable solutions to its energy needs, the rise of renewable energy sources stands as one of the largest hopes to help mend our planet.
Unlike fossil fuels—coal, oil, and gas—which demand hundreds of millions of years to form and contribute to harmful greenhouse gas emissions when burned, renewable energy sources offer a cleaner, greener alternative.
But what exactly is renewable energy, and how does it promise to help our global energy landscape?
Renewable energy. Defined.
From the perpetual glow of sunlight to the ever-shifting currents of wind and waves, these natural resources are abundant and omnipresent and present a way out of the climate crisis if tamed and utilized.
The official definition of renewable energy by the United Nations says that renewable energy is “energy derived from natural sources that are replenished at a higher rate than they are consumed”.
But, transitioning from fossil fuels to renewables is not merely an environmental necessity but also a strategic necessity for many countries to diversify and secure the supply of energy.
The shift to more renewable energy holds the promise of significantly reducing greenhouse gas emissions and consumer prices, with renewables already proving to be a more cost-effective and job-generating solution than their fossil counterparts.
Data from the International Energy Agency unveils that EU electricity consumers saved an estimated EUR 100 billion during 2021-2023 thanks to electricity from solar and wind.
Let’s look at some of the most well-known renewable energy sources reshaping our energy paradigm.
Solar Energy
Harnessing sunlight through photovoltaic panels (PV for short) offers one of the most sustainable and cost-effective solutions that can help deliver everything from heat to cooling to electricity for residential homes to industrial complexes.
How solar energy works
Solar energy is in theory quite simple: When the sun is shining and reaches a solar panel, energy from the sunlight is absorbed by the PV cells in the panel. This energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.
More energy in store
The good news about solar is that there is plenty of if.
And despite solar energy being in high demand, we are still far from fully being able to harness the power of the sun. According to the Intergovernmental Panel on Climate Change, the rate at which solar energy is intercepted by planet earth is about 10.000 times larger than the rate at which we as humans can consume it.
The plummeting cost of solar panel manufacturing has not only made solar power affordable but often the most economical electricity option in many countries.
At the time of writing, the price of solar panels are at an all-time low thanks to China having flooded the European market with cheap yet effective solar panels. In fact, 96% of EU solar panel import comes from China.
Wind Energy
From towering onshore turbines to sprawling offshore wind farms, wind energy holds vast potential to meet global electricity demands. Despite variations in wind speed, the technical capacity for wind energy far exceeds current electricity production, offering a compelling case for further investment and innovation in this renewable realm.
How does wind energy work
Wind energy has undergone a remarkable evolution since the Danish scientist Poul la Cour in 1890 discovered that fewer rotor blades, not more, was the most effective way to harness the power of the wind.
Today, wind is captured by turning the top part of the turbine, also known as the nacelle, against the wind and adjusting its three blades at an angle that lets the flow of air to cause rotation. Once moving, a drive shaft inside the nacelle turns magnets inside a coil of wire. This generates an alternating current of electricity.
The future belongs to wind energy
As with solar, there is plenty of wind for everyone. Wind turbines have the potential to be deployed in almost every country on earth where winds are strong and consistent enough. The potential for wind is still one of the largest when it comes to renewable energy, and around 2.000 new turbines would be needed to be installed every year for the next decade to meet global targets.
The best locations for wind turbines is often at sea due to the strong winds, which simultaneously removes the issue with local communities being against having these large steel structures in their backyard – a phenomenon also known as NIMBY (not in my backyard).
Geothermal energy
Tapping into the Earth’s internal heat reservoirs, geothermal energy presents a reliable and mature technology for electricity generation. Whether harnessing naturally occurring hydrothermal reservoirs or employing enhanced geothermal systems, this renewable source offers a sustainable alternative with minimal environmental impact.
How does geothermal energy work?
With over a century of operational experience, geothermal energy stands as a testament to the enduring power of Earth’s natural resources.
The way it works is simple yet very powerful.
Small underground pathways bring underground fluids through hot rocks.
In geothermal electricity generation, this fluid can be drawn as energy in the form of heat through wells to the earth’s surface. Once it has reached the surface, this fluid is used to drive turbines that produce electricity.
The USA leads the race in terms of utilizing geothermal energy. Almost 4 GW, enough to power around 3 million homes, is being generated in the US every year.
Hydropower
Leveraging the gravitational force of water, hydropower remains not only a cornerstone of renewable energy infrastructure in many countries, but also the largest source of renewable energy at the time of writing. From reservoir-based plants to run-of-river installations, hydropower offers and very versatile solution capable of meeting diverse energy needs. While concerns over ecosystem impact persist, innovations in small-scale hydro technologies hold the promise of minimizing environmental disruption while empowering local communities.
How does hydropower work?
Hydropower has two modes:
1. Run-of-the-river systems: Here the flow and force of the water applies pressure on a turbine that in turn produces electricity.
2. Storage systems: Here water is stored in reservoirs and released when energy is needed. The volume of the water flow and the change in elevation—or fall determine the amount of available energy in moving water, so the greater the water flow and elevation, the more electricity a hydro plant is able to produce.
Ocean energy
Harnessing the untapped potential of our oceans, ocean energy represents a frontier yet to be fully explored in full. Ocean energy offers a vast reservoir of untapped energy waiting to be harnessed. In fact, more than the world’s entire energy consumption. As research and development efforts accelerate, ocean energy holds the promise of becoming a significant contributor to our renewable energy portfolio if the technology manages to harness the potential of our oceans.
How does ocean energy work?
There are currently three types of wave energy technologies being tried and tested to reach a level of large-scale commercialization, each designed to harness wave energy in different environments.
- A point absorber is a floating buoy that absorbs energy through the movement of the waves at the water’s surface.
- An oscillating wave surge converter is mounted on the seabed in shallower water, and harnesses wave energy with an oscillating flap.
An oscillating water column is a partially submerged, hollow structure which is open to the sea water below the surface and connects to an air turbine above through a chamber. As the waves rise and fall, the air in the chamber is pushed back and forth through the air turbine, generating power.
Bioenergy
Derived from organic materials such as biomass and agricultural crops, bioenergy offers a multifaceted solution to energy production. From traditional biomass use in rural areas to modern biofuel technologies, bioenergy presents a viable option for both energy access and environmental sustainability. However, careful consideration must be given to potential environmental impacts, with a focus on sustainable practices to mitigate adverse effects.
How does bioenergy work?
Biopower technologies harness the energy from renewable biomass sources to generate heat and electricity, employing methods like those utilized with fossil fuels. The energy stored in biomass can be extracted through burning, bacterial decomposition, or conversion into gaseous or liquid fuels.
By utilizing biopower, the dependency on carbon-based fuels in power plants can be reduced, thereby decreasing the carbon footprint of electricity production. Unlike certain intermittent renewable energy sources, biopower offers increased flexibility in electricity generation and contributes to the reliability of the electric grid.
However, energy created by burning biomass does create greenhouse gas emissions, but at lower levels than burning fossil fuels like coal, oil or gas. Despite this it is still considered a sustainable energy.
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