Only Green Tech’s 45 Fascinating Questions & Answers


Only Green Tech has made a list of frequently asked questions and answers from all areas it deals with. Here you will learn everything you have always wanted to know about ecology and saving our planet.

When you ask a question that starts with the word “why,” you put the interlocutor in a position to think and define something. Let’s think and talk about important topics together.

1. Why do energy and work have the same unit?

Energy and work are all different physical quantities that have the same unit of measurement because they have the same nature, so their unit of measurement is the same – Joules [J].

The body has energy if it can work. Body energy is a quantity that shows how much work the body can do. The body gains energy if mechanical work is performed on it. And we all know that we can’t work if we don’t have enough energy.

2. How is energy defined?

Energy is defined as the body’s ability to work. It is the classic definition of energy, which is applicable in the world we live in, where masses are measured in kilograms, dimensions in meters, and speeds are incomparable to the speed of light.

 Today, we know that mass and energy are two manifestations of the same entity from which the whole universe is composed. Energy is a scalar quantity for which the notation E for the most time. Besides E, we can use other letters like T, Ek, Ep, etc. 

3. Is there more than one type of energy?

There are several types of energy: 

  • Mechanical energy 
  • Nuclear energy 
  • Solar energy
  • Geothermal energy
  • Hydrothermal energy
  • Hydro energy
  • Heat energy
  • Bioenergy
  • Chemical energy
  • Electrical energy
  • Magnetic energy
  • Radiant energy
  • Electromagnetic energy

Moving bodies, which are in the gravitational field or are elastically deformed, have mechanical energy. Mechanical energy can be:

1) Kinetic Ek=1/2 mV2

2) Potential Ep=m g h

The energy that bodies have when moving is called kinetic energy. For example, a river drives a water wheel, the wind drives a sailboat, and a ball hits another ball. A body has potential energy when it is at a certain height in relation to the ground. For example, a bird that flies has both types of mechanical energy. 

4. What types of energy does Only Green Tech deal with?

Only Green Tech specializes in clean and renewable energy sources. However, our main goal is to raise awareness and reduce pollution, acid rain, the green glass effect, and more. 

You can find out a lot about Solar and Wind energy by reading our blog. There a step by step instructions on home efficiency and sustainability. For example, Frequently asked questions about pellet and new heating system.

5. What is the law on energy conservation?

Energy conservation law: Energy cannot be created or destroyed but only passes from one body to another or is transformed from one form to another. The total mechanical energy of a body is equal to the sum of its kinetic and potential energy.

E = Ek + Ep = const

Within an isolated system, bodies interact with each other and move – they have potential and kinetic energy. The mechanical energy of a system is equal to the sum of the kinetic and potential energies of all the bodies that make up the system.

6. What is work?

Work is the process of transferring energy from one form to another or from one body to another. 

The symbol for work in IS is A. According to the international system of measurement units, work and energy have the same unit Joule [J] or newton-meter [Nm].

7. What is power?

Power is, by definition, the speed at which energy transforms from one form into another or the amount of work completed in a given amount of time. 

According to the international system of measurement units, the measurement unit for power is the watt [W]. 

8. How can we reduce electricity consumption?

According to Only Green tech, the best way to reduce electricity consumption is to use A+ devices, and energy-efficient lights, and lower the usage of unnecessary appliances. 

In every household, some devices use electricity for their operation. The electricity distribution firm sends out invoices for the electricity utilized at the end of each month. We can estimate how much energy we have consumed if we know the power of the devices we use and if we keep track of how long they operate. The more energy we use a device, the higher its power, and the longer we use it. Electricity consumption is listed on bills in kWh.

Home energy saving in 3 easy steps– Only Green Tech

9. What are we using energy for?

We use energy in every aspect of our life and our everyday life. Modern civilization exists because people learned how to change energy from one form to another and use it to do work.

For example, we use electric energy to use appliances like refrigerators, hair dryers, washing machines, and other household gadgets. Nuclear energy, on the other hand, is transformed into electricity and discounted for further use. 

10. What does the power industry do?

The generation, transmission, and distribution of electricity are under the purview of the power sector. Additionally, it is in charge of the electrical equipment connected to these networks, including transformers, electric motors, generators, and power electronics devices.

A sizable portion of this field deals with the conversion of direct current to alternating current and vice versa. They deal with the development of specialized systems used in aircraft and electrified railways.

Energy-saving animation- Only Green Tech

11. Why is electricity currently the most significant form of energy?

Electrical energy is undeniably the most significant form of energy used by humanity at the moment because it is relatively easy to transport and, most importantly, it can easily be converted into other useful forms of energy. 

Electricity is still currently mostly produced from fossil fuels, mainly coal. Since fossil fuels have harmful effects on the environment and are not inexhaustible, renewable energy sources are increasingly being used to produce electricity, such as:

  • Water flow and Wind energy
  • Sun energy
  • Geothermal energy

12. What energy sources does the world currently cover its energy needs?

Currently, the world covers its energy needs mainly with non-renewable energy sources:

  1.  fossil fuels (coal, oil, and natural gas) 
  2.  nuclear fuels (uranium, thorium, etc.)

A lack of energy would be disastrous since it would halt all modern technology and make manual output insufficient to meet the level of societal needs that exist today. Therefore, one of the essential prerequisites for the continuation and advancement of our civilization is the provision of enough energy.

13. What are the two main problems with non-renewable energy sources?

According to Only Green Tech’s collected data, the two main problems with non-renewable energy sources are:

  1.  Limited quantities 
  2.  Harmful to the environment

Non-renewable energy sources, as their name implies, are not replenishable, which means they will eventually run out of energy.

14. Why are fossil fuels so harmful to the environment?

Data gathered by Only Green Tech indicates that fossil fuels are extremely damaging to the environment since they:

  • they emit into the atmosphere large amounts of carbon dioxide CO2 and other gases like methane that increase the greenhouse effect, which is why there has been a global increase in temperature on Earth.
  • emit large amounts of gases (carbon monoxide, sulfur dioxide, nitrogen oxides), smoke, ash, dust, and other particles that pollute the environment into the atmosphere.

15. Why are nuclear fuels dangerous for the environment?

Nuclear fuels are not dangerous to the atmosphere, but the substances produced during the nuclear reaction remain radioactive for years and must be stored properly. So, the fission of nuclear fuels creates dangerous radioactive materials.

Nuclear or radioactive waste is waste that contains radioactive chemical elements that have no practical application. Waste can be a product of nuclear power plants that are used to supply electricity. When it gets into the environment, it contaminates everything around it.

16. Are renewable energy sources completely clean?

Renewable energy sources do not pollute the environment to the same extent as non-renewable ones, but not all of them are completely clean either. 

This is particularly true of energy derived from biomass, which, like fossil fuels, releases CO2, ash, and other pollutants during combustion but absorbs CO2 during growth, making it technically neutral in this regard.

Everything you need to know about clean energy

17. What caused the global rise in temperature on Earth?

The source of the temperature increase is global warming, which is arguably the biggest threat humanity has ever faced. In the last century, the temperature on Earth rose by about 1.1°C, and the sea level rose by 20 cm. 

It is expected that by the year 2100, the temperature on Earth will rise by about 5°C if the emission of gases that increase the greenhouse effect continues at the current intensity.

Global warming is the result of the excessive use of fossil fuels, which emit harmful carbon dioxide when burned. Carbon dioxide goes into the atmosphere and is the main culprit for the trend of increased average temperatures on Earth and climate changes that are a consequence of global warming.

Nowadays, the term global warming is commonly used to refer to the warming of the Earth’s surface caused by the enhanced greenhouse effect. The enhanced greenhouse effect is a consequence of the increased concentration of gases with the greenhouse effect in the upper layers of the atmosphere, which leads to an increase in the amount of radiation that cannot be from the Earth’s surface.

18. What are the consequences of global warming?

The consequences of global warming are:

  • the Earth’s living ecosystem is growing more and more vulnerable, and numerous plant and animal species are disappearing;
  • disturbances in food chains;
  • rising sea and ocean levels due to the melting of glaciers and glaciers;
  • increasingly frequent occurrence of storms, floods, and droughts;
  • impact on agriculture, etc.

The solution to the problem of global warming can be realized by reducing the emission of gases with the greenhouse effect, which is achieved by reducing the use of fossil fuels. Kyoto protocol all countries in the world undertake to reduce the emission of gases with the greenhouse effect.

19. What is the general trend in the world to stop the mentioned negative phenomena that cause the use of non-renewable energy sources?

To stop or at least mitigate the mentioned negative phenomena caused by the use of non-renewable energy sources and enable sustainable development, the general trend in the world is to reduce the consumption of non-renewable energy sources (fossil fuels) in two ways:

  • using renewable sources of energy instead of non-renewable
  • by improving energy efficiency

At this moment, only the combination of reducing energy consumption (by increasing energy efficiency) with the use of renewable energy sources enables the further development of energy while simultaneously preserving the environment.

20. What is sustainable development?

Sustainable development satisfies the demands of the present without endangering the capacity of future generations to satisfy their own needs. The difficulties that come with environmental risks have a particular impact on the reality of the notion of sustainable development.

Some of these challenges Only Green Tech is warning about are:

  • global warming,
  • damage to the ozone layer,
  • the greenhouse effect,
  • the disappearance of forests,
  • turning fertile land into deserts,
  • occurrence of acid rain,
  • extinction of animal and plant species.
scenic view of agricultural field against sky during sunset
Only Green Tech- Photo by Pixabay on

21. What does energy efficiency mean?

Energy efficiency means using a smaller amount of energy to perform the same job or function. For example, space heating or cooling, lighting, production of various products, vehicle operation, etc.).

Energy efficiency should not be confused with energy savings because saving always entails sacrifices, whereas efficient energy use never compromises working or living conditions. On the contrary, increased energy efficiency results in lower consumption for the same amount of product or service, resulting in monetary savings. Only Green Tech reminds us that energy efficiency measures can be implemented both in production (on the producer’s side) and in consumption (on the user’s side).

22. What is energy-saving according to Only Green Tech?

Energy saving, defined by Only Green tech, is the reduction of energy consumption by an individual as well as the entire population. That is, saving energy means using less energy in activities or tasks, so they can ultimately reduce costs.

Saving energy is important because it allows a civilization or an individual to achieve a better economic result. In turn, this can mean less waste of the planet’s resources.

23. What are renewable energy sources?

Renewable energy sources are energy sources that are found in nature and are renewed in whole or in part, are:

  1. Solar energy 
  2. Water flow energy (hydropower),
  3. Wind energy,
  4. Geothermal energy,
  5. Ocean energy (energy of sea currents and waves, the energy of tides),
  6. Landfill gas,
  7. Gas from sewage and wastewater treatment plants from the food and wood processing industries that do not contain hazardous substances, etc.
  8. Biomass, from which you can obtain:
  • solid fuel,
  • liquid biofuel (bioethanol, biomethanol, biodiesel),
  • gaseous biofuel (biogas, synthetic gas),

24. What are non-renewable energy sources?

Non-renewable energy sources are:

  1. Nuclear fuel (energy)
  2. Fossil fuels are:
  • Coal,
  • Oil,
  • Natural gas,
  • Oil shale 

Coal, oil, and natural gas are called fossil fuels. Plant and animal remains began to settle at the bottom of the ocean or on the ground many millions of years ago. Over time, those remains were covered by layers of mud, silt, and sand. In those conditions, enormous temperatures and high pressures developed, which are ideal conditions for turning the remains of plants and animals into fossil fuels.

25. From an ecological point of view, why is coal the most dangerous for the environment according to Only Green Tech?

From an environmental point of view, coal is the most dangerous source of energy for the environment, according to Only Green Tech, because it emits sulfur and some other substances into the atmosphere along with carbon dioxide. 

Sulfur in the atmosphere combines with water vapor and forms sulfuric acid, which falls on the earth in the form of acid rain. Coal is mostly made of carbon and hydrogen. When coal burns, carbon mixes with oxygen from the air and thus forms carbon dioxide. Carbon dioxide is a colorless and odorless gas, and in the atmosphere, it is one of the gases with a greenhouse effect.

Most scientists believe that the global increase in temperature is caused precisely by the release of carbon dioxide into the atmosphere.

26. Why is coal a dirty source of energy?

The less common coal also has contaminants trapped inside of it, such as sulfur, iron, and nitrogen. These pollutants are discharged into the atmosphere as coal burns.

In the atmosphere, these particles combine with steam and form droplets that fall to the ground as weak sulfuric/nitric acids. Inside the coal, there are also small particles of minerals. These particles do not burn and create ash that remains after combustion. 

A part of these particles gets caught in the vortex of gases and, together with steam, forms the smoke that comes from coal-fired power plants. Today some technologies can purify 99% of fine particles and remove 95% of impurities that cause acid rain. Also, there are more efficient coal-burning technologies, which reduce the emission of carbon dioxide into the atmosphere.

27. In what ways does oil negatively affect the environment?

Oil is a source of diverse products and derivatives and is one of the most important energy sources in the modern industrial world. 

Oil has multiple applications: to obtain propellant for various means of transportation, in the production of plastic, and asphalt, for obtaining petroleum, and various other industrially usable derivatives. 

The biggest negative consequence of the use of oil is the aforementioned global warming, which is the number one environmental problem of the modern world. During the burning of oil derivatives, large amounts of carbon dioxide are released into the atmosphere. Carbon dioxide is a gas with a greenhouse effect, and its release into the atmosphere increases the global temperature on earth.

28. Why is natural gas considered an ideal fossil fuel?

In many cases, natural gas is the ideal fossil fuel because it is quite clean, easy to transport, and comfortable to use. It is cleaner than oil and coal, so it is a solution to existing climate changes and problems with poor air quality. 

Unlike oil and coal, natural gas has a higher hydrogen/carbon ratio and emits less carbon dioxide into the atmosphere for the same amount of energy.

Natural gas consists of methane, which consists of one carbon atom and four hydrogen atoms (CH4). Methane is highly flammable and burns almost completely. After burning, no ash remains, and air pollution is very little.

29. What is liquefied natural gas?

Liquefied natural gas (LNG) is natural gas under high pressure and cooled to very low temperatures. Natural gas turns into a transparent, colorless, odorless, and tasteless liquid when cooled to -161C.

Because LNG occupies only 1/600 of the volume of natural gas in its gaseous state, that state is suitable for transportation in tankers around the world. 

Tankers carrying LNG must have double hulls and are specially designed to withstand the low temperatures of LNG. LNG itself is not flammable, and the statement “LNG tankers are floating bombs” is not correct since LNG is not flammable -it cannot explode. The evidence for this is the many incidents that have occurred, and yet a tanker with its entire contents has never exploded.

30. Fission vs. Fusion

When two or more light atoms combine to form one heavy atom, nuclear fusion causes a certain amount of energy to be released in the form of various radiations. The release of energy known as nuclear fission is the breaking of heavy atomic nuclei into two or lighter atoms.

The energy of the Sun is a consequence of the continuous nuclear fusion that takes place in its core and spreads into space in the form of radiation, so a small part of that radiation reaches the earth. The Sun uses a nuclear fusion of hydrogen atoms into helium atoms. 

 Nuclear fission is a simple process widely used in nuclear reactors to produce electricity. Nuclear energy is the energy released either by splitting one heavier atomic nucleus into two lighter atoms or by joining two lighter atomic nuclei into one heavier atom.

boiling planet
Boiling planet- Illustration of Global warming- Only Green Tech

31. What is the main problem with nuclear power plants?

The main problem with nuclear power plants is the rest of the spent fuel, which is highly radioactive waste and must be stored in special pools (water cools the nuclear fuel, and acts as a radiation shield) or in dry containers. 

Older and less radioactive fuel is packed in specialized reinforced concrete containers and kept in dry warehouses. Nuclear power plants generate trash, much like every other non-renewable energy generation process. It is hot water and radioactive garbage for them. Because they don’t produce carbon dioxide, nuclear power facilities don’t contribute to the greenhouse effect.

Radioactive waste is divided into two basic categories:

  • low-radioactive 
  • high-radioactive  

Most nuclear waste is low-radioactive waste: ordinary garbage, tools, protective suits, and others. This waste has become contaminated with a small level of radioactive powder or particles and must be stored in such a way that it does not come into contact with objects from the outside.

32. What are the benefits of renewable energy sources?

In general, the common benefits of renewable energy sources are:

  • constantly renewed 
  • impossible to use up 
  • protect the environment.

Common disadvantages of renewable energy sources are:

  • still expensive equipment
  • dependence on weather conditions.
Only green tech,
Only Green Tech

The benefits of using solar energy are its security and exceptionally silent functioning. Energy can be conserved for drying agricultural products and heating water and space. The system is very dependable and requires little maintenance. Additionally, cables and wires are not needed.

33. What is municipal solid waste?

Municipal solid waste is waste from households (domestic waste), other waste that, due to its nature or composition, is similar to household waste.

Solid waste may possess characteristics that make it potentially dangerous for the environment and human health. The majority of abandoned objects and waste materials are included in the regulatory definition of solid waste, which is broad.

The volume of waste gathered by or on behalf of local authorities and disposed of through the waste management system, according to Only Green Tech.

​​34. Why is energy of hydropower the most commonly used renewable energy source for electricity production?

The vast majority of energy obtained from renewable resources refers to the energy of watercourses because they are the oldest. Other renewable energy sources are currently negligible in terms of energy. 

The main limitation in this is expensive and long-term research, and most applications are limited to the production of electricity. The water mills and windmills used by our ancestors produced mechanical energy from a renewable energy source. The energy of watercourses is economically competitive with the production of electricity from fossil and nuclear fuels. Read more on Only Green Tech’s blog.

35. What are the advantages of hydropower plants?

The advantages of hydropower plants are:

  • They use the energy of watercourses, which is free.
  • Investment costs in the construction of a hydroelectric power plant are recovered in a period of up to ten years.
  • Because no fossil fuels are needed to run the hydroelectric power plant, the production of energy there does not produce any gases that harm the environment or heighten the greenhouse effect.

According to Only Green Tech, hydropower plants are electric power facilities that serve to convert the energy of water streams into electricity.

Energy transformation in the hydroelectric power plant takes place as follows: Potential energy of water in the reservoir – Kinetic energy of water in the pipeline – Mechanical energy in the turbine – Electrical energy in the generator.

36. What are the disadvantages of hydropower plants?

The disadvantages of hydropower plants are:

  1. During the filling of the hydro storage lake, large areas are submerged and the groundwater levels rise, which affects the entire plant and animal world and changes the biological picture of the environment.
  2. A big problem with the accumulation of water is that dam collapse can lead to major disasters.
  3. During the rotting and decomposition of plant remains underwater, gases are created that enhance the effect of the garden effect.
  4. The river brings sand and silt along its path, and as it settles in the reservoir lake over time, the lake’s depth decreases, and its purpose is lost.

37. How was wind energy used in the past, and how is it used today?

Around 600 AD B.C., Persia was the first place to identify wind as a renewable energy source. The first Persian windmills had a vertical shaft and 6-12 sails covered with reeds or canvas.

Around 1,200 years ago, they also appeared in Europe, they were used for grinding flour and pumping water, separating grains from stalks, in sawmills, etc. Later, windmills of European construction generally used a horizontal axis. Because of the use of steam engines, and subsequently electric and internal combustion engines, the use of direct mechanical windmills in Europe ended.

At the end of the 19th century, the use of windmills also began to be used for the production of electricity (wind power), but only recently in larger quantities.

38. What are the benefits of using wind energy?

The good sides of using wind energy are:

  • the high reliability of the plant’s operation
  • no fuel costs 
  • no environmental pollution

Electricity is obtained from the wind using wind turbines consisting of an arms turbine, transmission mechanism, generator, support column, and transformer through which connects to the electrical network.

39. What are the disadvantages of using wind energy?

The downsides of using wind energy are:

  • the high construction costs
  • variability of wind speed

The process by which wind energy is converted into electricity is most frequently done in generators driven by enormous three-bladed turbines perched atop tall towers; the process is sometimes referred to as the “reverse of the fan.” The principle of operation is as follows: the wind drives the turbine, which starts to spin the shaft connected to the generator, and that spin produces electricity.

40. What are the ways of direct use of solar energy?

There are several ways (technologies) of using solar energy:

  1. For electricity production, by directly converting solar energy into electricity, using photovoltaic cells (solar photovoltaic power plants). They work on the principle of the photoelectric effect, which is the most desirable way of using the Sun’s energy, but due to low efficiency (10-25%) and high price, they are currently not widely used. 
  2. They work on the principle of concentrated solar radiation, i.e., focusing (concentrating) solar energy using a mirror system into one point where a liquid is heated to a high temperature, which is used to produce electricity in generators. 
  3. Solar thermal energy systems and thermal energy are employed for space heating and the creation of hygienic hot water. It is the most straightforward and affordable way to use solar power. 

Photovoltaic cells are typically installed in locations where bringing in another energy source is impractical, such as on satellites, road signs, and the like. Additionally, they are employed to provide power to small consumers, such as pocket calculators.

Elements that use the Sun’s energy to heat water are called solar collectors (their efficiency is from 35 to 55%, and they can achieve temperatures of 30-90ºC) and are usually placed on the roofs of houses and buildings. Then for the production of heat energy that is used for various needs in industry, agriculture, etc. 

silver and black solar panels on snow covered ground
Only Green Tech- Photo by Pixabay on

41. What is the principle of operation of a photovoltaic cell?

Solar photovoltaic power plants directly convert solar energy into electricity (direct current) using photovoltaic cells, which are made of semiconductor materials. This conversion of solar energy into electricity is based on the photovoltaic effect.

The basic working principle of a photovoltaic cell is that some materials, such as silicon monocrystals, have the property of producing electricity when exposed to sun radiation (direct current).

When photons from the sun strike the surface of a photovoltaic cell, they transfer their energy to the cell and, as a result, cause the release of electrons from atoms. These released electrons then move toward N in the depleted region of the PN junction (diode) and create gaps on the P side of the semiconductor (cell), creating a potential difference that results in electricity generation. The potential difference between those two layers depends on the intensity of solar radiation.

42. What factors affect the intensity of solar radiation and thus the efficiency of photovoltaic panels?

Factors that affect the intensity of solar radiation, and thus the efficiency of photovoltaic panels:

  1. weather conditions,
  2. how high is the sun in the sky,
  3. several sunny days

Up to this point, photovoltaic solar cells have had an approximately 40% useful effect. Sunlight is reflected by an optical system or lens that concentrates on small portions of pricey photovoltaic cells because these new materials are highly expensive. If the cost of the solar cells exceeds that of the optical focusing system, the building is still justified economically. Less photovoltaic solar cell area is needed for this kind of building.

43. What are the advantages of solar photovoltaic power plants?

Only Green tech lists the advantages of solar photovoltaic power plants:

  • always available free fuel;
  • do not pollute the environment;
  • they do not release CO2 into the atmosphere;
  • do not create acid rain;
  • do not create any waste;
  • they do not pollute the soil and watercourses;
  • fit into the “peak daily load” when consumption increases during the day;
  • an additional benefit is the creation of jobs, especially during the construction phase of the solar power plant, which lasts 3-4 years;
  • it is also possible to graze herds between the photoelectric panels;
  • they do not use water for work, etc.

Only Green Tech listed only obvious advantages, there are however many more.

44. What are the disadvantages of solar photovoltaic power plants?

Only Green tech lists the disadvantages of solar photovoltaic power plants:

– energy is produced only during the day;

– the effects of the operation of the solar power plant are reduced in cloudy and rainy weather and winter when the intensity of solar radiation is several times lower than in summer;

– the big disadvantage is that they cover large areas of land. 

Only Green Tech listed only obvious disadvantages, there are however many more.

45. Can I save money by installing Solar panels?

Yes, having a few solar panels could save your home budget and lower your energy bills. Especially if you have an eclectic car and want to charge it at home.

Solar panels are still expensive to install in some developing countries. However, the final account says that in the end, you save some money.

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