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How electricity is generated

Would you know how to explain quickly and easily how electricity is produced?
The truth is that its origin and its journey into your home to make life as we know it work is an enigma to many, despite how close we live with the energy.

You put your finger on a switch, you press and things start to happen that, if you think about it seriously, seem like magic.

Lights that illuminate everything around you, a warmth you need to cook and keep your home warm. Lots of tools, gadgets and electronic devices working. 

As if by magic, it seems that out of completely nowhere, your home and your life are fed by kilowatts. Where's the trick?

Our intention here is simple: to explain where electricity comes from and how it reaches you, whatever its origin. For that, let's start at the beginning:


What is electricity?

It is not possible not to use it in our globalised world, but who really knows how to define it?

In a simple way, we can say that electricity is that energy capable of shining light bulbs, moving the most efficient cars and giving life to Frankenstein's monster. If we delve into the more technical concept, it is the energy generated by the movement of positive and negative electrons inside conductive materials.

And what is this? Matter, tiny little atoms, whose parts, if they are opposites, attract each other. Their positive and negative charges are complemented by creating two types of electricity: static electricity (generated by friction) and dynamic electricity (conceived by current).

It's wonderful but it's not easy to get to your home. Pressing the switch involves a process that is not at all simple. Nobody in the world can argue about whether the ability to generate electricity is the greatest invention in human history. Modern society cannot be conceived without electricity, and our lives depend on energy for many reasons.

Have you ever wondered where the electricity coming into your home comes from?


Where does electricity come from?

Electricity's journey to your socket is both very fast and very long.

Although it seems so, it is not magic. The step-by-step process is as follows:

  • Power generation: electricity is created in plants capable of obtaining electricity from primary energies. The so-called renewable primary energies are wind, solar radiation, tides and non-renewables are coal, natural gas and oil. Companies build power generation facilities and own (in whole or in part) so-called power stations and infrastructure. They sell the energy generated to the companies that market them (suppliers).  
  • Energy transmission: once the energy has been obtained and after being converted into electricity, it is transmitted by overhead power lines (suspended by towers) or underground, from the power plants to the substations. There are other elements there, called transformers, which are used to ensure an adequate electrical voltage. Substations are necessary to process the electricity and maintain the right voltage and are usually outdoors near power plants and/or in the periphery of cities. If they are not large in size, you can exceptionally find them in the city itself, inside a building. 
  • Power distribution: electricity is sent to households in the nearest area from the substations. As a receiver of energy and a consumer, you cannot choose your distributor, as one or another is assigned to you depending on the area where you live. The company you get will be responsible for ensuring that the electricity reaches your home correctly and will take care of any faults. It is also the owner of your electricity meter, and sends its readings to your supplier (which is the one that charges you).
  • Energy trading: your supplier is the one you can always choose and will always be the one that sends you the bills, since it is the one who buys the energy from the generation companies and sells it to you. The suppliers will offer you different tariffs and deals, although in Spain there is a free market where you pay according to the conditions of your contract, as in any other service tariff (mobile, Wi-Fi, etc.) and a regulated market (you pay what is established by a system designed by the government). 

"The company that makes the electricity reach your home is not the same one that charges you the bills."

What types of power plant are there?

To generate electricity, we need the energy contained in the primary materials to be released, we already know, but how do we do this?

It depends entirely on the type of power plant we are talking about, as it depends on how we obtain the energy, we will be dealing with one or the other: 

  • Conventional cycle thermoelectric plants (coal, diesel and natural gas): coal, natural gas or diesel are burned in these plants. When burned, they raise the temperature of a water tank, transforming it into steam, which causes a turbine to move. It is this movement, that of the turbine, that generates electricity by means of an alternator that transforms mechanical energy into electricity. That is, movement is transformed into electricity. Finally, the steam goes to a condenser to become water again and start the cycle again.    
  • Combined cycle thermoelectric power plants (coal, diesel and natural gas): these operate in a similar way to conventional cycle power plants. Like these, they have a turbine that moves with the steam of the heated water. But they also have a different turbine that moves with air taken from the atmosphere and heated by fossil fuels. Their great advantages over conventional cycle power plants are that they are more efficient, more flexible (they can work at full load or "at half gas" depending on the needs) and more ecological (lower emissions to the atmosphere).  
  • Nuclear power plants: in the same way as in the previous examples, the heat released by nuclear fission in a reactor heats large amounts of water at high pressure. The released steam produces electricity by passing through a turbine connected to a generator. The basic difference, apart from their high power, is the fuel they use, usually uranium. 
  • Geothermal power plantsthe system is similar to the previous ones (water is heated to emit steam that moves a turbine) but in this case the natural heat of the earth's interior is used through pipes in the subsoil. 
  • Biomass plants: in this case, the heat is generated after burning organic matter, whether vegetable or all kinds of waste (animal, industrial, agricultural and urban). 
  • Hydroelectric power plants: these do not need heat, since these types of power plants are the progression from old mills. What they do is use a major waterfall to move a hydraulic turbine. They are usually built in dams and reservoirs.
  • Wind farms: in the same way, the movement generates electricity, which in this case is created by the wind. It drives a turbine from which electricity will be obtained. 
  • Solar power plants: there are two types. What solar thermal plants do is use the heat of the sun to heat water and use the steam generated to move a turbine. What photovoltaic plants do is directly transform solar energy into electricity, thanks to photovoltaic cells. 
  • Tidal power stations: the movements of water produced by the rises and falls of the tides drive a turbine that will produce electricity through a generator.  
  • Wave power plants: similar to the above, but using waves instead of tides.

Going back to the differences between renewable and non-renewable, we will be faced with one or the other, depending on the primary energy that is being used to generate electricity. If you have to "replenish" said "fuel", it will be non-renewable but if it is not necessary because nature offers it for free, it will be renewable.

Currently the most widespread plants are non-renewable, since they use primary energies that must be extracted from the earth (including coal, natural gas, and uranium). But the future only means that increasingly, we need all the energy we consume to be renewable.

"Electricity is renewable if it is not necessary to replenish the fuel used to generate it."

How is wind power produced?

Wind power is one of the cleanest ways of generating electricity. It basically involves transforming the force exerted by the wind on the three-propeller windmills into electricity, creating mechanical energy that is transferred to a series of copper wires, where the electricity is generated.

The elements that transform wind into energy are the so-called wind turbines. These are assembled with an electric generator inside with its control systems and connection to the grid.

"Spain, along with Denmark and the Netherlands, is one of the countries with the highest rate of wind generation."

And the wind? Where does it come from?

We may never have thought about it. The sun has a number of effects on our world, and one of them is the wind. Between 1% and 2% of the solar radiation absorbed by the planet ends up turned into wind. This is because the Earth's crust transfers a greater amount of solar energy to the air, causing it to warm, become less bulky, and expand. At the same time, the coldest and heaviest air - which comes from seas, rivers and oceans - is set in motion to take the place left by the warm air. These fluctuations produce moving air and wind is nothing but moving air.

Each mass of air that moves from areas of high atmospheric pressure to areas of lower pressure through speeds proportional to the pressure differences between both areas (the greater the difference, the stronger the wind blows) is considered wind.


And the sun? How is it transformed into electricity?

The sun's energy comes from sunlight and heat. To transform them into energy, semiconductor metal sheets are needed: photovoltaic cells.

These cells are coated with a transparent glass that allows radiation to pass through and minimises heat loss, and have one or more layers of a semiconductor material. Thanks to these elements, they can manage all that solar energy.

Increasingly, we can see solar panels on the roofs of houses and buildings. These panels are fully formed by these photovoltaic cells.

It is said to be expensive to install, but the data show that the purchase pays for itself, with savings of around 30% of consumption, which in the long term (25 years) means paying between EUR 20,000 and EUR 30,000 less, making it very valuable in the medium to long term. Another advantage is that they do not need much maintenance.

And how does a solar panel work?

Basically through the sun's rays. These are composed of photons that reach the photovoltaic cells of the plate, generating an electricity field between them and thus an electrical circuit. The more intense the light, the greater the flow of electricity.

Photovoltaic cells are responsible for converting sunlight into electricity in the form of direct current and with a graduation that varies between 380 and 800 volts. The result obtained can be improved using an inverter, which is responsible for transforming this energy into alternating current, which is what we use in our homes.

Finally, this alternating current passes through a meter that quantifies it and supplies it to the general electricity grid.

"Photovoltaic solar energy will be the cheapest source of electricity in the world."

Hydraulic energy

According to NASA, one of its studies found that the origin of life could be in the electricity generated naturally on the seabed 4 billion years ago. Both water and movement are a source of life and therefore a source of energy.

In ancient times, humans already used the current of the river to move large mills. The progression of the mills resulted in hydroelectric power plants. In fact, the operation of a dam causes a river to be blocked by a concrete wall, flooding the area around the site and creating an artificial lake. Water, as a force of nature, even when held back, harbours an enormous energy potential.

The stream produced by this blockage can be converted into kinetic energy (the energy of an object in motion) if the force of gravity is used. This is very simple to understand: water falls downwards along a series of large pipes called pressure conduits. In this way, it spins the propellers of strategically placed turbines at high speed to receive the movement from the fall.

A dam can be powered by its own mechanical energy.


Tidal energy

Tidal energy is a variant of hydropower that is not as well known.

This system uses the vertical movement of seawater produced by the gravitational force exerted on it by the moon and the sun. The ebb and flow of the tide generates tidal energy.

There are currently three types of tidal energy:

  • Tidal dams: these are built at the mouths of rivers and look a lot like hydroelectric dams.
  • The difference in height between high and low tides is exploited by generating the potential energy that arises with the movement. Although they generate large amounts of energy, building and maintaining them costs a lot of money.
  • Tidal current generator: in this case, the currents turn a succession of axial turbines, similar to windmills, which generate mechanical energy. It is the simplest, cheapest method and has the least impact on nature. By not requiring a dam to be constructed, it does not alter the marine ecosystem.

"Remember, tidal energy comes from the movement of water caused by the high tide/low tide cycle"

Geothermal energy

Geothermal energy is obtained through a system that uses the heat stored on earth, either in rocks and/or hot springs, to generate energy.

The caloric energy contained under our feet is gigantic. If you excavated about 10 metres deep, you would find temperatures of approximately 17ºC throughout the year, due to the thermal inertia of the soil.

Geothermal heat pumps are used to generate this energy, extracting or transferring heat to the earth, depending on whether you want to heat the environment, cool it or get hot water.

One of the most precise techniques is the injection of liquid water into the earth's interior area to raise its temperature: the water is converted into steam and returns to the power plant full of energy and ready to be transformed into electricity.

The application of this energy depends on the characteristics of each source:

  • High-temperature resources (over 150°C) are used to generate light.
  • Below 100ºC they are used to supply electricity to heating/air conditioning systems.
  • With very low temperatures (less than 30ºC) its use goes directly for hot water.

"It is enough to dig about 10 metres to find stable temperatures of 17ºC throughout the year."

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