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Energy ABC: the key concepts around the topic of energy explained from A to Z

Do you know how much energy the average European user consumes every year? Or how the Moon can be a source of energy? For most of us, energy is imperceptibly present in our day-to-day lives.  We touch a light switch and assume that the light will turn on, but we are blissfully unaware of how or why. However, individual users have a big role in the current energy transition. ReDREAM strives to empower consumers to significantly and sustainably influence the use of energy. Its consumer-centric model hopes to put users at the centre of the energy market and aspires to give them the necessary tools to make informed decisions. But the topic of energy is complex and can sometimes be difficult to navigate. What is a kWh? Which type of lightbulb is more efficient? What is the energy grid?  If you don’t know the answer to these questions do not worry. With this simple energy alphabet, you’ll learn everything you need to know regarding energy! 

Households were one of the highest consuming sectors in 2020. According to Eurostat, the transport sector represents 28.4% of energy consumption, closely followed by households and industry which consume 28.0% and 26.1% respectively. In contrast, the agriculture and forestry sectors only account for 3.2% and the services sector for 13.7%.

According to Eurostat in 2020 the average EU citizen consumed 129 TJ of energy! This is equivalent to the energy stored in approximately 2 million disposable batteries. 

The behaviour of individual consumers can have a huge effect on overall energy consumption. Actively trying to reduce our energy consumption can help reduce the strain on the energy grid and can help us move toward a greener way of living. The less energy consumed, the less energy produced and therefore the less environmental impact. 

Blackouts can be caused by many things from small malfunctions in the electricity grids to damaged infrastructure due to extreme weather events. Most times the power outage is at the regional or national level but sometimes they can be even bigger. 

An example of this is the European blackout of 2006. The power loss started in northern Germany and spread through France, Italy, and Spain among other countries. It lasted 2h and affected over 15 million users, resulting in dozens of people being trapped in elevators and hundreds of trains being delayed!

Blackouts can create big disturbances in our day-to-day lives. Not only do we lose light, but fridges stop working, there is no heating, traffic lights can’t moderate circulation, etc. Here are some tips on how to deal with a power outage:

    1. Keep fridges and refrigerators closed to keep the cold in.
    2. Use alternative methods to refrigerate medicines or power electricity-dependent medical devices.
    3. Only use generators outdoors and away from windows.
    4. Do not use a gas stove to heat your home.
    5. Disconnect appliances and electronics to prevent damage.
    6. If safe, go to a different location for heat or cooling.

Given the current climate change situation, the transition towards more sustainable energy has become a priority. In fact, in 2009 the European Union set a target to increase the amount of renewable energy use to 20% by 2020. And we made it! According to Eurostat in 2020 22% of European energy was from sustainable sources. Now a new target has been set to increase this number to 32% by 2030.

By taking control of your energy consumption you can help reach the 2030 clean energy target. ReDREAM empowers consumers to choose where their energy comes from. Here are some examples of clean energy sources:

    1. Solar energy: harnessed from the sun using photovoltaic panels.
    2. Wind energy: transforms the kinetic energy of moving air into electricity.
    3. Geothermal energy: comes from the Earth’s interior, heat from the ground is harnessed to heat up fluids, such as water, that can then be used to generate electricity.
    4. Hydropower: it’s obtained from water moving from higher to lower elevations through rivers or reservoirs. 
    5. Ocean energy: harnessed from waves, tides, and currents.

Have you ever gone to catch the bus during rush hour and couldn’t get in because it was too full? The same thing can happen with energy consumption. If too many people consume a lot of energy at the same time, they run the risk of outpacing the grid. To help prevent this, energy companies can incentivize users to reduce their consumption in moments of great demand. For example, users involved in a demand response program could be asked to adjust the temperature of their thermostat, turn off unnecessary lights, and shift the time they use certain appliances to avoid peak demand periods.

Overstraining the grid can have severe consequences such as blackouts. To avoid this it is important that the grid stays balanced. There must be an equilibrium between the energy produced and the energy consumed. Individual users can play a big role in this. By asking your energy provider about a demand response program you can help keep the energy grid healthy and stable. Furthermore, often energy providers offer monetary compensation to consumers participating in demand response. This means that you could help reduce the strain on the grid and save some money at the same time!

Efficiency can often be defined as the ability to obtain the desired result without wasting the resources used. But how does this translate to energy? An easy way to visualize this is to think of a lightbulb. The task of this object is to generate light. However, when the lights are on lightbulbs can get hot. This heat is energy that is being wasted, it’s not serving the task of generating light. The less heat a lightbulb emits when illuminating the more efficient it is. Energy can also be lost through sound or light, depending on which device we are referring to.


It is important not to confuse efficiency with effectiveness. But what is the difference? On one hand, effectiveness is the ability to get a specific task done. On the other hand, efficiency measures how well that task is done. For example, let’s say we have two washing machines. Washing machine, A uses 1100 W to finish a washing cycle while washing machine B uses 700 W. Both machines are effective since they both have the ability to get your clothes clean. However, washing machine B is more energy efficient because it uses less energy to complete the same task.

Households are one of the highest energy-consuming sectors in the EU. Therefore, optimizing energy use in our homes can help boost the energy transition. But which elements of your home consume the most energy? Here are some statistics:


  1. Space heating alone accounts for 62.8% of a household’s energy consumption while cooling takes up 0.45% of the energy!
  2. Water heating represents 15.1% of the total energy consumption.
  3. 5% of a household’s energy does towards lighting and appliances.
  4. Cooking can represent up to 6.1% of energy consumption in European households.


Given this, can you think of any new habits you could implement in your household to make it more energy efficient? Maybe you could try switching to lower-consumption light bulbs or reducing the number of laundry loads you do in a week. These gestures might seem small, but they can have a great impact.

Flexibility can be described as the capacity to bend without breaking. For example, raw spaghetti is less flexible than cooked spaghetti. The same principle applies to energy systems. In order for a system to work, it continuously needs to maintain balance. This means that the energy supplied has to match the energy demand. However, if the system is very strict it can be easily broken. As soon as production doesn’t match demand it breaks. Adding flexibility to the energy grid can help prevent this. In this case, we are not talking about the grid being able to physically bend but being able to adapt to different scenarios.

There is more than one way to add flexibility to the grid. For example, a system that stores energy in batteries when there is a production overflow and empties them when demand increases can add flexibility to the grid. Usually, most of the grid’s flexibility comes from the supply side. Energy producers adjust the amount of energy being generated depending on the demand. But consumers can also help increase the flexibility of the grid. For example, by participating in demand response. By consuming less energy during moments of peak demand you could reduce the strain on the grid. The ReDream project aims to put users in charge of their energy consumption and allows them to do just that!

Did you know that the first electrical grid was built in 1882?! After commercialising the first incandescent light bulb in 1879, Thomas Edison set out to build a way to power those bulbs in an affordable manner. He needed to be able to distribute the electricity generated in a single place to multiple buildings. On the 4th of September of 1882, the first electrical grid was inaugurated. It extended 1 square mile and distributed electricity to 400 lightbulbs.

Edison’s first electricity grid set the tone for what would later become much more complex systems. Nowadays grids are much a lot more extensive. In fact, one of the longest electricity transmission grids, the Belo Monte-Rio de Janeiro transmission line, is 2 539km long! Furthermore, grids have become a lot more complex and can even be divided into smaller subsystems. This is the case with the electricity grid in Berlin. Berlin’s grid has three different power plants that distribute energy throughout the city via four subgrids that run at different voltages!

Have you ever wondered why bird standing on high-voltage lines don’t get electrocuted? The answer is simpler than you think. In order for electricity to flow through a circuit, there needs to be what we call a potential difference (a + side and a – side). This potential difference can also be called voltage. The bigger the voltage, the stronger the current. When a bird stands on a cable both of its feet are in contact with the same surface and are therefore at the same potential level. Since there is no potential difference between the feet of the bird, electricity doesn´t flow through it. However, if the bird were to touch two cables at the same time (or a cable and the ground) it would create a potential difference between its extremities, the current would flow through, and it would get electrocuted!

High-voltage cables are good for more than just holding birds. They are key for distributing energy and getting electricity to our homes. 

In order to transmit electricity high voltages are more sustainable than low voltages. This is because less energy is lost due to conductor resistance when we use high voltage. However, the voltage cannot be increased indefinitely. The voltage on a wire is chosen depending on the distance. The larger the distance the higher the voltage.

Incandescent light bulbs were first commercialized by Thomas Edison in 1879. At the time they were a revolution but since then their use has declined dramatically. This is because incandescent light bulbs are highly inefficient. In fact, less than 5% of the energy they use is converted into visible light!

The fact that incandescent light bulbs produce little light is important not only in terms of the energy they use but also because they can affect the rest of our household. The energy that is not transformed into light is mostly lost as heat. The heat that these lightbulbs emit can affect the temperature of the room and put additional pressure on air conditioning and ventilation systems. This is why incandescent lamps have now been replaced by other more efficient lighting systems. Here are some examples:

Halogen light bulb: It’s an upgrade from incandescent light bulbs. It follows the same principles as an incandescent lamp but is a bit more energy-efficient.

Fluorescent light bulb: It uses fluorescence to generate light. The bulb has two key elements mercury vapour and an internal phosphorus coating. When an electrical current is applied, this excites the mercury particles, causing them to emit UV light. The UV light interacts with the phosphorus coating and causes it to glow.

LED light bulb: LED blubs are electrical bulbs that produce light using light-emitting diodes (LEDs). They are more energy-efficient than incandescent lamps or fluorescent lamps. Furthermore, they provide full brightness immediately and are not damaged by frequent switching on and off.

Joules are a unit of measure for energy, work, and heat. But did you know that it is named after a scientist?  James Prescott Joule (1818-1889) was an English physicist known for his research on thermodynamics, the study of the relationship between heat, work, temperature, and energy. In particular, he worked on proving the relationship between mechanical energy and heat. The unit of energy Joule was named in his honour.

Joules (J) are important nit just because they are named after an important scientist but also because they are a key unit of measurement. However, while Joule (J) is a unit of energy measurement, we don’t commonly come across it in our day-to-day life. When talking about our energy consumption or our appliances, it is more common to talk in terms of kWh. However, it is important to understand that energy is around us in many shapes, it is not only the electricity that powers our homes. For example, when talking about energy in biological terms, we do use J as a common unit. This is especially the case in nutrition. You might have noticed that food packages often include kilocalories or Joules!

We call the measure of joules over time (J/s) a watt (w). Watts are the unit typically used to indicate the power of an appliance. For example, a standard incandescent lightbulb has a power of 60 watts. However, when we are talking about energy consumption we usually talk about kilowatts-hour (kWh). A kWh is the amount of energy you would use by keeping a 1000-watt appliance running for 1h.

Electricity is usually priced in €/kWh. Therefore, understanding what a kWh is can help you understand your energy bills. For example, let’s say that the electricity price is at 0.1€/kWh and you have a 100-watt light bulb. If you only leave the light on for 1h you will only consume 100 watts (0.1 kWh) and will therefore only be charged 0.01€. However, if you leave the light on for 10h you will have consumed 1kWh and will be charged 0.1€.

Did you know that lumens are measured in equivalence to the light emitted by a candle? The intensity of the light emitted by a common wax candle can be quantified with a unit known as candela (Latin for candle). By combining candelas with the angle of radiation of the light, we then get the amount of light being emitted. This is also known as luminous flux and is measured in lumen (lm).

Understanding what a lumen is can help you in your day-to-day life! Light bulbs are usually labelled with their light output in lumens. By checking both the power and the luminous flux (lm) of different light bulbs, you should be able to see which one is more efficient. That is which one produces more lumens while consuming less energy.

Did you know that the force that the Moon exerts on the earth is responsible for generating tides in our seas and oceans? 

These can be used as a source of energy! In fact, tides are one of the most reliable sources of renewable energy.  Tides are created by the cycles of the moon, the sun, and the earth, and they are not influenced by weather conditions. This makes them extremely predictable. So much so that we can predict tidal energy production hundreds of years in advance! Tidal turbines function in a similar way to wind turbines. But since water is denser then air, tidal devices can capture more energy!

It’s very important that we are aware of where our energy comes from and that we chose clean and sustainable energy sources. The ReDream project aims to empower users to take control of their energy consumption. This also means choosing where the energy they use comes from. 

But we also have to be aware of how our choices impact the world around us. Although tidal energy is perfect in theory, the installation of tidal turbines can alter marine ecosystems and hurt some of the biodiversity of our oceans. Research on the topic is key to reducing the impact of tidal energy extraction on the environment.

Do you know the difference between carbon neutral and net zero?

Carbon neutral means that any CO2 released into the atmosphere from a company’s activities is balanced by an equivalent amount being removed. This can be achieved by reducing carbon emissions but also by investing in carbon sinks. Carbon sinks are systems that absorb carbon from the atmosphere, such as forests, soils or oceans. A company may choose to invest in planting trees in order to counterbalance its carbon emissions.

Net zero carbon, however, means that no carbon was emitted from the beginning. Therefore, no carbon needs to be captured. For example, a building running entirely on solar energy can be said to use net-zero carbon energy. 

However, this is where it gets tricky. When we talk about net zero, we need to differentiate between net zero carbon (no carbon emitted) or net zero emissions. Net zero emissions refer to the overall balance of greenhouse gas emissions, the amount produced, and the amount absorbed.

It’s everyone’s job to help reduce our CO2 emissions and stop climate change. Individuals can contribute in small ways such as by buying electrical cars or installing solar panels in their homes. But they can also have a huge impact at a higher level. Do you know what your bank, university, or the company you work at invests in? By supporting enterprises that have a real commitment towards carbon neutrality you can help shift the balance.

More concepts coming soon!

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