Renewable Energy

Be it on land or at sea, from the very dawn of time, mankind has harnessed wind power to perform actions that proved impossible by physical strength alone. On land, wind power was channeled by windmills to grind wheat or pump water from deep wells. At sea, wind has inflated the sails of boats and crafts of all sizes, giving humankind the chance to wonder beyond the great blue yonder.

Technological evolution and innovation were instrumental in the development of wind energy, leading to modern-day wind turbines. Based on data from a 2019 report drafted by the International Renewable Energy Agency (IRENA), wind energy currently ranks in second place among renewable energy sources with 564 GW-worth of installed capacity and counting: wind power accounts for 5% of global electricity production, a figure which has doubled over the last 10 years.

What is wind energy?

The basis of wind energy stands in harnessing wind’s power through a wind turbine, the modern-day version of old windmills. When the wind blows with adequate intensity, its power moves the blades that activate a rotor located inside a casing structure called the nacelle.

The rotor’s motion is then transferred to a gearbox that accelerates its rotation and transfers it to the alternator, tasked with transforming mechanical energy in electricity. During the entire process, a control system performs checks on all nacelle components, ensuring operations are running smoothly.

Once an electrical current is generated, it’s transferred through a power cable towards a transformer that collects all energy generated from each individual turbine of the wind farm and subsequently dispatched to the power grid.

If the earth is our home, we owe a lot to solar energy. Just to offer some perspective, solar radiation is the key element of chlorophyll photosynthesis which kickstarts the basis for life for most creatures that inhabit the planet. Solar radiation is also the origin of winds, tides and fossil fuels: the sun is the primary engine of almost all forms of energy on our planet.

Over the centuries, humankind leveraged the strong connection linking plant life and the sun, especially to learn how to manage the lifecycle of plants to transform them in edible crops. As technological progress plowed on, by the end of the nineteenth century it allowed to transform the sun’s energy in electricity through the solar cell: a device that leverages the physics phenomenon known as the photovoltaic effect.

Today, after nearly 150 years since the onset of the first photovoltaic cell, solar energy is the fastest growing renewable energy source (+24% yearly, according to the 2019 IRENA report) and its technological development follows through, delivering ever more efficient solar power plants. The global threshold of 1.000 GW-worth of installed capacity is ready to be reached and surpassed, with Asia leading the global growth trend. Hence, the sun will keep on shining and guiding the unstoppable rise of green energy.

How does solar energy work?

The core of every solar photovoltaic park is represented by solar panels. Their semiconducting coating – silica, for instance – reacts to visible light and creates energy when hit with solar radiation, thanks to the physical phenomenon known as “photovoltaic effect”. The panels are then mounted on support struts that ensure they’re correctly inclined and oriented so to fully exploit their exposure to light.

In a photovoltaic array, all solar panels are connected to an inverter, basically, a device that transforms the direct current generated by panels in alternating current which is easier to transport and use in all households. A control system is tasked with supervising over the solar park’s operations while ensuring its connection to the grid, so to guarantee the availability of all generated electricity.

One of solar energy’s trump cards is being able to release energy through other types of power plants, also known as “thermodynamic” (or concentrating), in which the sun’s rays can be transformed in electricity through a process by all accounts similar to traditional thermal power plants.

These power plants don’t feature photovoltaic panels, but rather, deploy mirrors that concentrate the sun’s rays towards a specific point, known as “collector”, containing a heat transfer fluid. The searing heat generated by the sun is more than enough to transform this fluid in steam which is, in turn, channeled to a turbine.

The mechanical energy generated by the turbine is sent to the alternator that transforms it into electricity, ready to flow through the power grid.

Water is much more than the basis of life and an essential part of our food chain and hygiene but also, one of mankind’s first forays in harnessing energy through natural resources, hence, hydroelectric power. Based on the 2019 report by the International Renewable Energy Agency (IRENA), total capacity from the world’s hydroelectric power plant amounts to 1,172 GW: about 50% of total renewable power output.

Even if hydroelectric power is the dean of renewable power sources, this hasn’t stopped R&D from increasing its efficiency. Thanks to currently available technology, 90% of water is now transformed in electricity, delivering a three-fold increase in efficiency compared to traditional power sources.

A low carbon footprint and high efficiency are the factors that concur in delivering excellent performance: along the world’s biggest renewable power plants, the top five in this ranking are powered by water.

How does hydroelectric energy work?

Hydroelectric power can count on two simple yet formidable allies: water and gravity. All types of hydroelectric power plants leverage on gravity to accelerate its flow and unleash the power carried by its kinetic energy.

In order to harness electricity from water, a reservoir is needed to store its potential energy, usually in the form of an artificial lake created by a dam located upstream.

A series of giant water mains allow water to forcefully cascade downstream, where the bulk of the power plant machinery is located. Thanks to the drop created by the water mains, water increases its speed until it makes the turbine blades spin, which in turn are mechanically connected to a generator. This is the moment for electricity to run through an alternator that lowers the intensity of the current while increasing its voltage to streamline its subsequent feeding in the power grid.

Energy storage is a catalyst for the energy transition, as it allows for greater utilization of production from renewable sources. Investments in storage systems are the only way to reduce energy costs and ensure adequacy and stability for households and businesses.

Modern storage systems contribute significantly to the flexibility and adequacy of the electricity system. They support the management of congestion and excess production, while ensuring energy coverage during peak periods.

With our eyes on the future, we are investing in innovation, with a focus on energy storage projects. Principia’s first storage project is the Battery Energy Storage System plant “Themelio” in Chalkidiki, with an installed capacity of 127 MWh (49MW). With storage through batteries, the project maximizes its operation, feeding energy into the grid even on days without sunshine.