Energy Sources
Level 1: Beginner
Let's go!
Introduction
Energy is an essential part of our daily lives, powering our homes, transportation, and industries. However, not all energy sources are the same, and their impacts vary widely in terms of cost, availability, and environmental consequences.This course is designed to help you understand the basics of energy sources, including renewable and non-renewable energy, their role in global energy systems, and how energy choices impact our environment. Throughout this course, you will explore different energy sources, their benefits and drawbacks, and how we can transition toward cleaner and more sustainable energy systems.
Start Course
Energy Sources Level 1: Beginner
Objectives
Modules
Exercises
Evaluation
Objectives
What will you learn?
- Understand what energy is and its different sources.
- Identify renewable and non-renewable energy sources.
- Recognize the role of energy in daily life and its environmental impact.
Modules
Module 3: Fossil fuels and decarbonization pathways
Module 1: Introduction to the objectives
Module 2: What is energy and its sources?
Module 4: Renewable energy sources
Module 5: Energy transition and policies
Module 6: Conclusions
What is energy?
Energy is the ability to do work or cause change. It is present in everything we do, from cooking food to powering transportation.Energy exists in different forms, such as heat, electricity, motion (kinetic energy), and chemical energy stored in fuels.
Figure 1. Plasma ball [1]
Energy Sources
Energy sources are categorized into non-renewable and renewable
Renewable energy sources are those that can be replenished naturally within a short time (solar, wind, hydropower, biomass, and geothermal energy). Advantages: Sustainable, low emissions, and reduces reliance on fossil fuels.Challenges: Intermittency (e.g., solar energy depends on sunlight), high initial investment.
Non-renewable energy sources are finite and take millions of years to form (coal, oil, natural gas, and nuclear energy). Advantages: reliable, high energy density.Challenges: limited supply, environmental pollution.
Figure 2. Energy sources [2]
Overview of energy sources consumption globally and in the European Union
- The world’s energy consumption has increased significantly over the past century due to population growth and industrialization.
- Fossil fuels (coal, oil, and gas) still dominate the global energy mix, but renewable energy is growing rapidly.
- The European Union has been shifting towards cleaner energy sources in line with climate goals.
Figure 3. Energy consumption by its sources [3]
Fossil fuels - What are they?
Figure 4. Use of fossil fuels [4]
Fossil fuels are natural resources formed from the remains of plants and animals over millions of years. They are non-renewable, meaning they take millions of years to form and are being consumed faster than they are replenished. Fossil fuels currently supply over 80% of the world's energy needs. The three main types of fossil fuels are coal, oil, and natural gas.
Coal, oil, natural gas
Natural gas
Oil
Coal
- Used for heating, electricity generation, and as an industrial fuel.
- Accounts for about 23% of global energy consumption.
- Often transported via pipelines or liquefied (LNG) for international trade.
- Refined into gasoline, diesel, and other fuels for transportation and industry.
- The world consumes over 90 million barrels of oil per day.
- Price is influenced by geopolitical events.
- Burned to generate electricity in power plants.
- Largest source of electricity worldwide.
- China, India, and the US are the largest consumers.
Environmental impact
Main environmental issues
Greenhouse gas emissions: CO₂ and methane (CH₄) emissions from fossil fuel combustion contribute significantly to climate change. Air pollution: Burning fossil fuels releases pollutants like sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and particulate matter, contributing to smog and respiratory diseases. Resource depletion: Fossil fuels are finite. Their resources can lasts for next 50-150 years.
How to reduce dependency on fossil fuels?
Reducing reliance on fossil fuels can lower energy costs and contribute to sustainability
- Switch to renewable energy providers ☀️
Choose electricity providers that use renewable energy sources (solar, wind, hydropower).
- Improve home energy efficiency 🏠
Seal windows and insulate homes to minimize heating and cooling costs.
- Use low-carbon transportation options 🚲
Walk, bike, or use public transport instead of driving short distances by car.
Figure 5. Energy transition [5]
Introduction to renewable energy
Definition of renewable energy
Why is renewable energy important?
- Reduces dependence on fossil fuels and lowers greenhouse gas emissions.
- Provides long-term stability in energy supply and pricing.
- Reduces air pollution and related health problems.
- Renewable energy comes from naturally replenishing sources that are virtually inexhaustible on a human timescale. It include solar, wind, hydropower, biomass, and geothermal energy.
Figure 6. Renewable energy sources [6]
'A transition to clean energy is about making an investment in our future' - Gloria Reuben
Solar energy
How solar energy works:
- Solar panels convert sunlight into electricity using photovoltaic cells.
- Solar thermal energy is used to heat water and air in buildings.
Benefits:Zero emissions, widely available, and low operational costs.Challenges:High initial cost and dependence on sunlight.
Figure 7. Solar energy [7]
Wind energy
How wind energy works:
- Wind turbines convert wind energy using rotating blades connected to a generator.
- As wind moves the blades, the generator produces electrical power.
Benefits:Renewable, zero emissions, and efficient in windy regions.Challenges: Wind speeds vary, leading to intermittent power generation. Also require space for wind farms.
Figure 8. Wind energy [8]
Hydropower
How hydropower works:
- Flowing water spins turbines to generate electricity.
- Can be instaled in dams or rivers, also as tidal energy.
Benefits:Reliable, renewable, and provides energy storage. Can generate power continuously, unlike solar and windChallenges: Impacts river ecosystems and fish migration. Also requires large infrastructure and can alter natural water flow.
Figure 9. Hydropower electricity [9]
Biomass energy
Biomass energy is generated by the combustion of organic materials such as wood, agricultural waste, and dedicated energy crops. It can be used for electricity generation, heating, and biofuels. Most common forms of biomass are wood pellets, biogas, and biodiesel.
Figure 10. Wood pellets [10]
Global and the European Union energy transition goals
Energy Transition is a shift from fossil fuels to cleaner, renewable energy sources to reduce greenhouse gas emissions and combat climate change. It involves energy efficiency improvements, electrification, and technological advancements.
Most known global energy transition commitment is
Paris Agreement: Over 190 countries committed to keeping global warming below 2°C.
Countries setting national climate targets, phasing out coal, and investing in renewables.
European Union transition goals
By 2050:
- Achieve net-zero greenhouse gas emissions, effectively making the EU climate-neutral.
By 2030:
- To reach at least 55% reduction of greenhouse gas emissions compared to 1990 levels
2050
2030
1990
Renewable energy in Lithuania, Greece, Italy, Bulgaria, and Austria energy mix
A significant gap can be noticed between share in electricity and total energy consumption. While renewable sources contribute substantially to electricity production, their share in overall energy use remains lower due to continued reliance on fossil fuels in sectors like transportation and heating.
Figure 11. Renewable energy share in countries (2023) [11]
National energy strategies in Lithuania, Greece, Italy, Bulgaria, and Austria
Lithuania
Greece
Italy
- Major investments in offshore wind and solar power; aiming for 100% renewable electricity by 2050.
- Strong push for offshore wind farms and hydrogen infrastructure; aiming for 55% renewables by 2030.
- Phasing out coal by 2028, expanding solar and wind capacity, and integrating energy storage solutions.
Bulgaria
Austria
- Gradual transition away from coal, increasing hydropower, and expanding solar energy production.
- Promote energy efficient building renovations to reduce overall demand.
Conclusions
- Energy is fundamental to modern life, powering homes, industries, and transportation.
- Fossil fuels have driven economic growth but come with significant environmental and geopolitical challenges.
- Renewable energy sources provide a sustainable alternative, but their integration requires infrastructure development and policy support.
- A diversified energy mix is essential for a resilient and reliable energy system, balancing renewables, efficiency measures, and technological advancements.
- Energy efficiency is a crucial tool for reducing costs, lowering emissions, and enhancing energy security.
Exercises
Exercise 2 Which energy source powers your home?
Exercise 1 Which are renewable energy sources?
Look around your home or neighborhood and identify main energy sources used for electricity or heating.
Evaluate different energy sources and recognize which of them are renewable.
Exercise 1.
Click only on the correct answers
Which of the following are renewable energy sources?
Solar power
Coal
Wind energy
Natural gas
Oil
Hydropower
Diesel
Biomass
Check
Exercise 2.
questions to consider?
instructions
- Write down the main energy source (e.g., electricity from the grid, natural gas, biomass, etc.).
- Based on what you’ve learned, decide whether this source is non-renewable or renewable.
- Imagine your home had to switch to a different energy source. What would be the biggest challenge in making that switch?
- What factors influence the choice of energy sources in your home?
Evaluation
Quiz
- This quiz consists of 7 multiple-choice questions related to energy sources, environmental impact, and energy transition.
- Choose the correct answer for each question (only one per question).
- The quiz helps reinforce key concepts covered in the course.
Evaluation 1/7
Evaluation 2/7
Evaluation 3/7
Evaluation 4/7
Evaluation 5/7
Evaluation 6/7
Evaluation 7/7
Certificate
Congratulations!
Certificate of Completion
To receive an Open Badge for this course, please contact the local project partner: Kaunas University of Technology.
Sources
Sources for text:
- Allcott, H., & Greenstone, M. (2012). Is there an energy efficiency gap? Journal of Economic Perspectives, 26(1), 3–28.
- Ellabban, O., Abu-Rub, H., & Blaabjerg, F. (2014). Renewable energy resources: Current status, future prospects and their enabling technology. Renewable and Sustainable Energy Reviews, 39, 748–764.
- Epstein, P. R., & Selber, J. (2020). Oil: A life cycle analysis of its health and environmental impacts. The Center for Health and the Global Environment, Harvard Medical School.
- European Commission. (2024). Energy and the Green Deal.
- European Commission. (2025). Renewable energy directive: Targets and rules. Retrieved from https://energy.ec.europa.eu/topics/renewable-energy/renewable-energy-directive-targets-and-rules_en.
- Global Wind Energy Council. (2021). Global Wind Report 2021.
- International Energy Agency (IEA). (2021). Key world energy statistics 2021: Final consumption.
- International Energy Agency (IEA). (2022). Energy Efficiency 2022. Paris: IEA.
Sources
Sources for text:
- International Energy Agency (IEA). (2025). World energy balances: Overview. Retrieved from https://www.iea.org/reports/world-energy-balances-overview/world.
- International Hydropower Association. (2020). 2020 Hydropower Status Report.
- International Renewable Energy Agency (IRENA). (2020). Renewable power generation costs in 2019.
- International Renewable Energy Agency (IRENA). (2021). World Energy Transitions Outlook: 1.5°C Pathway. Abu Dhabi: IRENA.
- Rockström, J., Gaffney, O., Rogelj, J., Meinshausen, M., Nakicenović, N., & Schellnhuber, H. J. (2017). A roadmap for rapid decarbonization. Science, 355(6331), 1269–1271.
Sources
Sources for figures and videos: [1] Plasma ball. Retrieved from https://www.pexels.com/photo/plasma-ball-illustration-414860/ [2] Energy sources. Retrieved from https://www.freepik.com/free-vector/eco-green-icons-illustration_2922398.htm#fromView=search&page=1&position=2&uuid=ecae623f-9d4a-4248-986d-d80c5fe88ce7&query=renewable+energy [3] Statistical review of world energy. Data retrieved from https://www.energyinst.org/statistical-review [4] Use of fossil fuels. Retrieved from https://www.freepik.com/free-vector/air-pollution-with-factory-cars_19167985.htm#fromView=search&page=1&position=7&uuid=ae2e92a6-f400-4e11-8b18-37803ab99bd1&query=fossil+fuels [5] Energy transition. Retrieved from https://www.freepik.com/free-vector/save-world-design-flat-style_6630796.htm#fromView=search&page=1&position=8&uuid=00d8a6ff-6dbc-4ee4-b02d-2e57178333f4&query=energy+saving [6] Renewable energy sources. Retrieved from https://www.freepik.com/free-vector/tiny-characters-village-with-windmills-solar-panels-save-planet-people-with-eco-friendly-lifestyle-flat-vector-illustration-sustainable-renewable-energy-technology-concept-banner_24644933.htm#fromView=search&page=1&position=6&uuid=c82792fe-55c2-47da-9eb9-41c31321c710&query=clean+energy
Sources
Sources for figures and videos: [7] Solar energy. Retrieved from https://www.freepik.com/free-photo/solar-panels-roof-solar-cell_21520477.htm#fromView=search&page=1&position=0&uuid=6bae5f3b-edf1-464d-a5c0-ad86557220fc&query=solar+energy [8] Wind energy. Retrieved from https://www.freepik.com/free-photo/wind-farm_1469634.htm#fromView=search&page=1&position=2&uuid=dc2d9620-26cd-417a-8f15-728156b0d16a&query=wind+energy [9] Hydropower electricity. Retrieved from https://www.freepik.com/free-vector/hydroelectric-dam-turbine-concept_39454638.htm#fromView=search&page=1&position=6&uuid=71a353ea-f29f-4f67-a176-c8b635cfb70c&query=hydro+energy [10] Wood pellets. Retrieved from https://www.pexels.com/photo/pile-of-pellets-19757403/ [11] Renewable energy share in countries. Data retrieved from https://www.eea.europa.eu/en/analysis
Level completed!
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the National Agency. Neither the European Union nor National Agency can be held responsible for them.
1.1 Energy Sources
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Transcript
Energy Sources
Level 1: Beginner
Let's go!
Introduction
Energy is an essential part of our daily lives, powering our homes, transportation, and industries. However, not all energy sources are the same, and their impacts vary widely in terms of cost, availability, and environmental consequences.This course is designed to help you understand the basics of energy sources, including renewable and non-renewable energy, their role in global energy systems, and how energy choices impact our environment. Throughout this course, you will explore different energy sources, their benefits and drawbacks, and how we can transition toward cleaner and more sustainable energy systems.
Start Course
Energy Sources Level 1: Beginner
Objectives
Modules
Exercises
Evaluation
Objectives
What will you learn?
Modules
Module 3: Fossil fuels and decarbonization pathways
Module 1: Introduction to the objectives
Module 2: What is energy and its sources?
Module 4: Renewable energy sources
Module 5: Energy transition and policies
Module 6: Conclusions
What is energy?
Energy is the ability to do work or cause change. It is present in everything we do, from cooking food to powering transportation.Energy exists in different forms, such as heat, electricity, motion (kinetic energy), and chemical energy stored in fuels.
Figure 1. Plasma ball [1]
Energy Sources
Energy sources are categorized into non-renewable and renewable
Renewable energy sources are those that can be replenished naturally within a short time (solar, wind, hydropower, biomass, and geothermal energy). Advantages: Sustainable, low emissions, and reduces reliance on fossil fuels.Challenges: Intermittency (e.g., solar energy depends on sunlight), high initial investment.
Non-renewable energy sources are finite and take millions of years to form (coal, oil, natural gas, and nuclear energy). Advantages: reliable, high energy density.Challenges: limited supply, environmental pollution.
Figure 2. Energy sources [2]
Overview of energy sources consumption globally and in the European Union
Figure 3. Energy consumption by its sources [3]
Fossil fuels - What are they?
Figure 4. Use of fossil fuels [4]
Fossil fuels are natural resources formed from the remains of plants and animals over millions of years. They are non-renewable, meaning they take millions of years to form and are being consumed faster than they are replenished. Fossil fuels currently supply over 80% of the world's energy needs. The three main types of fossil fuels are coal, oil, and natural gas.
Coal, oil, natural gas
Natural gas
Oil
Coal
Environmental impact
Main environmental issues
Greenhouse gas emissions: CO₂ and methane (CH₄) emissions from fossil fuel combustion contribute significantly to climate change. Air pollution: Burning fossil fuels releases pollutants like sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and particulate matter, contributing to smog and respiratory diseases. Resource depletion: Fossil fuels are finite. Their resources can lasts for next 50-150 years.
How to reduce dependency on fossil fuels?
Reducing reliance on fossil fuels can lower energy costs and contribute to sustainability
- Switch to renewable energy providers ☀️
Choose electricity providers that use renewable energy sources (solar, wind, hydropower).- Improve home energy efficiency 🏠
Seal windows and insulate homes to minimize heating and cooling costs.- Use low-carbon transportation options 🚲
Walk, bike, or use public transport instead of driving short distances by car.Figure 5. Energy transition [5]
Introduction to renewable energy
Definition of renewable energy
Why is renewable energy important?
Figure 6. Renewable energy sources [6]
'A transition to clean energy is about making an investment in our future' - Gloria Reuben
Solar energy
How solar energy works:
- Solar panels convert sunlight into electricity using photovoltaic cells.
- Solar thermal energy is used to heat water and air in buildings.
Benefits:Zero emissions, widely available, and low operational costs.Challenges:High initial cost and dependence on sunlight.Figure 7. Solar energy [7]
Wind energy
How wind energy works:
- Wind turbines convert wind energy using rotating blades connected to a generator.
- As wind moves the blades, the generator produces electrical power.
Benefits:Renewable, zero emissions, and efficient in windy regions.Challenges: Wind speeds vary, leading to intermittent power generation. Also require space for wind farms.Figure 8. Wind energy [8]
Hydropower
How hydropower works:
- Flowing water spins turbines to generate electricity.
- Can be instaled in dams or rivers, also as tidal energy.
Benefits:Reliable, renewable, and provides energy storage. Can generate power continuously, unlike solar and windChallenges: Impacts river ecosystems and fish migration. Also requires large infrastructure and can alter natural water flow.Figure 9. Hydropower electricity [9]
Biomass energy
Biomass energy is generated by the combustion of organic materials such as wood, agricultural waste, and dedicated energy crops. It can be used for electricity generation, heating, and biofuels. Most common forms of biomass are wood pellets, biogas, and biodiesel.
Figure 10. Wood pellets [10]
Global and the European Union energy transition goals
Energy Transition is a shift from fossil fuels to cleaner, renewable energy sources to reduce greenhouse gas emissions and combat climate change. It involves energy efficiency improvements, electrification, and technological advancements.
Most known global energy transition commitment is Paris Agreement: Over 190 countries committed to keeping global warming below 2°C. Countries setting national climate targets, phasing out coal, and investing in renewables.
European Union transition goals
By 2050:
By 2030:
2050
2030
1990
Renewable energy in Lithuania, Greece, Italy, Bulgaria, and Austria energy mix
A significant gap can be noticed between share in electricity and total energy consumption. While renewable sources contribute substantially to electricity production, their share in overall energy use remains lower due to continued reliance on fossil fuels in sectors like transportation and heating.
Figure 11. Renewable energy share in countries (2023) [11]
National energy strategies in Lithuania, Greece, Italy, Bulgaria, and Austria
Lithuania
Greece
Italy
Bulgaria
Austria
Conclusions
Exercises
Exercise 2 Which energy source powers your home?
Exercise 1 Which are renewable energy sources?
Look around your home or neighborhood and identify main energy sources used for electricity or heating.
Evaluate different energy sources and recognize which of them are renewable.
Exercise 1.
Click only on the correct answers
Which of the following are renewable energy sources?
Solar power
Coal
Wind energy
Natural gas
Oil
Hydropower
Diesel
Biomass
Check
Exercise 2.
questions to consider?
instructions
Evaluation
Quiz
Evaluation 1/7
Evaluation 2/7
Evaluation 3/7
Evaluation 4/7
Evaluation 5/7
Evaluation 6/7
Evaluation 7/7
Certificate
Congratulations!
Certificate of Completion
To receive an Open Badge for this course, please contact the local project partner: Kaunas University of Technology.
Sources
Sources for text:
Sources
Sources for text:
Sources
Sources for figures and videos: [1] Plasma ball. Retrieved from https://www.pexels.com/photo/plasma-ball-illustration-414860/ [2] Energy sources. Retrieved from https://www.freepik.com/free-vector/eco-green-icons-illustration_2922398.htm#fromView=search&page=1&position=2&uuid=ecae623f-9d4a-4248-986d-d80c5fe88ce7&query=renewable+energy [3] Statistical review of world energy. Data retrieved from https://www.energyinst.org/statistical-review [4] Use of fossil fuels. Retrieved from https://www.freepik.com/free-vector/air-pollution-with-factory-cars_19167985.htm#fromView=search&page=1&position=7&uuid=ae2e92a6-f400-4e11-8b18-37803ab99bd1&query=fossil+fuels [5] Energy transition. Retrieved from https://www.freepik.com/free-vector/save-world-design-flat-style_6630796.htm#fromView=search&page=1&position=8&uuid=00d8a6ff-6dbc-4ee4-b02d-2e57178333f4&query=energy+saving [6] Renewable energy sources. Retrieved from https://www.freepik.com/free-vector/tiny-characters-village-with-windmills-solar-panels-save-planet-people-with-eco-friendly-lifestyle-flat-vector-illustration-sustainable-renewable-energy-technology-concept-banner_24644933.htm#fromView=search&page=1&position=6&uuid=c82792fe-55c2-47da-9eb9-41c31321c710&query=clean+energy
Sources
Sources for figures and videos: [7] Solar energy. Retrieved from https://www.freepik.com/free-photo/solar-panels-roof-solar-cell_21520477.htm#fromView=search&page=1&position=0&uuid=6bae5f3b-edf1-464d-a5c0-ad86557220fc&query=solar+energy [8] Wind energy. Retrieved from https://www.freepik.com/free-photo/wind-farm_1469634.htm#fromView=search&page=1&position=2&uuid=dc2d9620-26cd-417a-8f15-728156b0d16a&query=wind+energy [9] Hydropower electricity. Retrieved from https://www.freepik.com/free-vector/hydroelectric-dam-turbine-concept_39454638.htm#fromView=search&page=1&position=6&uuid=71a353ea-f29f-4f67-a176-c8b635cfb70c&query=hydro+energy [10] Wood pellets. Retrieved from https://www.pexels.com/photo/pile-of-pellets-19757403/ [11] Renewable energy share in countries. Data retrieved from https://www.eea.europa.eu/en/analysis
Level completed!
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the National Agency. Neither the European Union nor National Agency can be held responsible for them.