Energy Resources and their Impact on Environment -7B

📘 Lecture Notes

Introduction to Environmental Science

Clean and Green Energy Resources

1. Energy and Life on Earth

Energy forms the backbone of modern civilization. Every part of human life, including transportation, industry, agriculture, communication, and household activities, relies on energy. However, the environmental impact depends on the energy source.

Energy sources are broadly classified into:

1. Renewable energy sources
2. Non-renewable energy sources

Understanding this distinction is critical for addressing climate change, pollution, and sustainable development.

A. Renewable Energy Sources

Renewable energy sources are naturally replenished and always available. They are usually cleaner and cause less environmental damage than fossil fuels.

Key Characteristics:

• Can be renewed naturally
• Sustainable over long periods
• Lower greenhouse gas emissions
• Environmentally friendly
• Will not run out

Major Types of Renewable Energy:

a. Solar energy is harnessed from sunlight through solar panels and heating systems. It is plentiful, especially in countries like Pakistan with abundant solar exposure.

b. Wind Energy uses wind turbines to transform the kinetic energy of wind into electricity. It is clean and renewable, but it relies on wind availability.

c. Hydropower is electricity produced from flowing water through dams and rivers. It is one of the oldest renewable energy sources but can affect ecosystems if not managed properly.

d. Biomass energy is derived from organic materials like plants, wood, agricultural waste, and animal residues. It helps recycle waste but can cause pollution if burned inefficiently.

e. Geothermal energy uses heat from beneath the Earth’s surface. It is dependable but limited to certain locations.

B. Non-Renewable Energy Sources

Non-renewable energy sources are finite and cannot be replenished within a human lifetime.

Key Characteristics:

• Finite resources
• Formed over millions of years
• High energy density
• Major contributors to pollution and climate change

Fossil Fuels

Fossil fuels are energy-rich substances formed from ancient plants, animals, and microorganisms over millions of years.

Major Types:

• Coal – Carbon-rich rock, widely used in power generation
• Oil (Petroleum) – Liquid hydrocarbons refined into fuels like petrol and diesel
• Natural Gas – Mainly methane, used for cooking, heating, and electricity
• Nuclear Fuels – High energy output but serious waste and safety concerns

Environmental Impacts:

• Air pollution
• Greenhouse gas emissions
• Climate change
• Smog formation
• Acid rain

Pakistan’s Energy Scenario

Pakistan faces serious energy and environmental challenges, including:

• Severe energy shortages
• Heavy dependence on imported fossil fuels
• High electricity costs and circular debt
• Escalating air pollution in cities like Lahore, Karachi, and Multan

These challenges have pushed Pakistan to prioritize clean and green energy.

Pakistan’s Green Energy Initiatives

Solar Energy:

• Utility-scale solar parks (e.g., Quaid-e-Azam Solar Park)
• Rooftop net metering for homes, industries, and universities
• Solarization of government buildings

Biomass & Bagasse:

• Sugar mills generating electricity using bagasse
• Agricultural residues used for power generation

Electric Mobility:

• Development of EV charging infrastructure
• Incentives for local electric vehicle manufacturing
• Target: 30% of new vehicles electric by 2030

Energy Use and Carbon Dioxide Emissions

Most fuels used in cars and electricity generation release carbon dioxide (CO₂):

• Petrol and diesel vehicles
• Electricity generated from coal, oil, and gas

Every human activity generates CO₂, making individuals and institutions responsible for emission control.

Greenhouse Gases and Global Warming

Greenhouse gases trap heat in the atmosphere, leading to global warming.

Major greenhouse gases include:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Water vapor
• Ozone
• Hydrofluorocarbons
• Sulphur hexafluoride

The greenhouse effect refers to the trapping of heat that the Earth tries to release back into space.

Carbon Footprint

A carbon footprint is the total amount of greenhouse gases (mainly CO₂) released into the atmosphere due to human activities.

It measures emissions from:

• Individuals (daily life, travel, food)
• Organizations and institutions
• Products and services
• Events and processes

Carbon footprint is expressed in carbon dioxide equivalents (CO₂e).

Sources of Carbon Footprint:

• Burning fossil fuels
• Industrial production
• Agriculture and food consumption
• Waste generation

Human Carbon Footprint

• A single human produces 1–15 tons of CO₂e per year
• Global average: 4–5 tons CO₂e per person
• Sustainable target:
  • ~2 tons CO₂e/person/year by 2030
  • ~1 ton CO₂e/person/year by 2050

Lifestyle matters:

• High-consumption lifestyle → large footprint
• Low-consumption lifestyle → small footprint

Carbon Credits

Carbon credits denote the reduction, removal, or avoidance of one metric ton of CO₂ (or CO₂e) from the atmosphere.

👉 1 carbon credit = 1 ton of CO₂ not emitted or removed

They are used in carbon trading and climate mitigation strategies.

A. Multiple Choice Questions (MCQs)

1. Which of the following is a renewable energy source?
   a) Coal
   b) Oil
   c) Solar energy
   d) Natural gas
   ✔ Correct Answer: c
2. Fossil fuels take how long to form?
   a) A few years
   b) Hundreds of years
   c) Thousands of years
   d) Millions of years
   ✔ Correct Answer: d
3. The main greenhouse gas responsible for global warming is:
   a) Oxygen
   b) Carbon dioxide
   c) Nitrogen
   d) Hydrogen
   ✔ Correct Answer: b
4. Carbon footprint is usually expressed in:
   a) Kilograms of carbon
   b) Tons of oxygen
   c) Carbon dioxide equivalents (CO₂e)
   d) Joules
   ✔ Correct Answer: c
5. One carbon credit represents:
   a) One tree planted
   b) One ton of coal saved
   c) One ton of CO₂ reduced or removed
   d) One unit of electricity
   ✔ Correct Answer: c

B- Descriptive Questions

Q1. Explain the difference between renewable and non-renewable energy sources with suitable examples.

Answer:
Energy sources are broadly divided into renewable and non-renewable based on their availability and ability to regenerate.

Renewable energy sources are those that can be naturally replenished and are continuously available. They are considered environmentally friendly and sustainable. Examples include solar energy, wind energy, hydropower, biomass, and geothermal energy. These sources produce little or no greenhouse gas emissions and do not run out over time.

In contrast, non-renewable energy sources are available in limited quantities and cannot be replaced within a human lifetime. These include coal, oil, natural gas, and nuclear fuels. They take millions of years to form and are the major contributors to environmental pollution and climate change.

Thus, renewable energy supports long-term sustainability, whereas non-renewable energy poses serious environmental and resource challenges.

Q2. Discuss the environmental impacts of fossil fuels and their role in climate change.

Answer:
Fossil fuels such as coal, oil, and natural gas are the most widely used energy sources worldwide. However, their use has severe environmental consequences.

When fossil fuels are burned for electricity, transport, and industrial activities, they release large amounts of carbon dioxide (CO₂) and other greenhouse gases into the atmosphere. These gases trap heat and enhance the greenhouse effect, leading to global warming and climate change.

In addition to climate change, fossil fuels cause:

• Air pollution and smog
• Acid rain
• Respiratory and cardiovascular diseases
• Environmental degradation

Because fossil fuels are non-renewable and environmentally harmful, reducing their use and shifting to clean energy is essential for environmental protection.

Q3. Describe Pakistan’s energy challenges and explain why the country is shifting toward green energy.

Answer:
Pakistan faces multiple energy-related challenges that directly affect its economy, environment, and public health.

Major challenges include:

• Severe energy shortages
• Heavy dependence on imported fossil fuels
• High electricity costs and circular debt
• Rapidly increasing air pollution in cities such as Lahore, Karachi, and Multan

To overcome these challenges, Pakistan is shifting toward clean and green energy. The country is investing in solar energy projects, rooftop net metering, biomass and bagasse-based electricity, and electric mobility.

Green energy reduces dependence on imports, lowers pollution, stabilizes energy supply, and supports sustainable development. Therefore, the transition to renewable energy is both an economic and environmental necessity for Pakistan.

Q4. What are greenhouse gases? Explain the greenhouse effect and its consequences.

Answer:
Greenhouse gases are gases in the Earth’s atmosphere that trap heat and contribute to global warming. Major greenhouse gases include carbon dioxide, methane, nitrous oxide, water vapor, ozone, and hydrofluorocarbons.

The greenhouse effect is a natural process in which these gases trap heat that the Earth tries to release back into space. While this effect is necessary to maintain Earth’s temperature, excessive greenhouse gas emissions caused by human activities intensify the effect.

The consequences of an enhanced greenhouse effect include:

• Global warming
• Climate change
• Melting of glaciers
• Rising sea levels
• Extreme weather events

Controlling greenhouse gas emissions is essential to protect the Earth’s climate system.

Q5. Define carbon footprint. Discuss its sources and significance in climate change mitigation.

Answer:
A carbon footprint is the total amount of greenhouse gases, mainly carbon dioxide (CO₂), released into the atmosphere due to human activities. It is usually expressed in carbon dioxide equivalents (CO₂e).

Carbon footprints arise from activities such as:

• Burning fossil fuels for electricity and transport
• Industrial production
• Agriculture and food consumption
• Waste generation

The significance of carbon footprint lies in its role as a measurement tool for climate impact. By calculating carbon footprints, individuals, organizations, and governments can identify major emission sources and take steps to reduce them.

Reducing carbon footprints through energy efficiency, renewable energy use, and sustainable lifestyles is a key strategy for climate change mitigation.