Environmental Management (0680) | Energy resources and the generation of electricity

Welcome to Energy Resources: Powering Our World!

Hello! In this chapter, we are going to explore where the electricity that powers our homes, schools, and cities actually comes from. Understanding energy is crucial in Environmental Management because our energy choices have massive impacts on the environment, the economy, and society.

Don't worry if some of the concepts seem technical. We will break down how each type of energy works and look at the good points (advantages) and the bad points (disadvantages) of each resource, focusing on the environmental, economic, and social consequences.

2.2 Classifying Energy Resources

The first step is to categorize the energy sources we use. We separate them based on whether we can use them forever or if they will eventually run out.

A. Non-Renewable Energy Resources

Non-renewable resources are those that are used faster than they can naturally be replaced. They are finite (limited). Once they are gone, they are gone forever.

Key Non-Renewable Resources:
- Fossil Fuels (Coal, Oil, Natural Gas)
- Nuclear Power (Using Uranium)

1. Fossil Fuels (Coal, Oil, Gas)

These fuels are formed from ancient plants and animals buried under layers of rock over millions of years (refer back to section 2.1 on formation!).

How electricity is generated:
1. The fuel (coal, oil, or gas) is burned in a furnace.
2. This heat converts water into high-pressure steam.
3. The steam pushes a turbine, making it spin.
4. The spinning turbine drives a generator, producing electricity.

Evaluation: Advantages and Disadvantages

Environmental Disadvantages:
- Huge contributor to the enhanced greenhouse effect and climate change because burning them releases massive amounts of Carbon Dioxide (\(\text{CO}_2\)).
- Releases Sulfur Dioxide (\(\text{SO}_2\)) and Nitrogen Oxides (\(\text{NO}_x\)), which cause acid rain.
- Extraction (mining or drilling) causes habitat loss and land destruction.

Economic Advantages:
- Relatively cheap to extract and transport (though prices fluctuate).
- Existing infrastructure (power stations and transport networks) is already built.

Social Disadvantages:
- Health problems for communities living near mines or power plants due to air pollution.
- Will run out eventually, creating energy instability for future generations.

2. Nuclear Power (Using Uranium)

Nuclear power stations rely on the element Uranium (a non-renewable mineral) for fuel.

How electricity is generated:
1. Uranium atoms are split in a process called nuclear fission, which releases huge amounts of heat.
2. This heat boils water to create steam.
3. The steam drives a turbine, which powers a generator.

Evaluation: Advantages and Disadvantages

Environmental Advantages:
- Releases no greenhouse gases or acid rain pollutants during operation (it is carbon-free).
- Needs only a very small amount of fuel for a huge amount of energy output.

Environmental Disadvantages:
- Produces highly dangerous radioactive waste that remains hazardous for thousands of years. Safely disposing of this waste is difficult and expensive.
- Risk of catastrophic accident (e.g., Chernobyl or Fukushima) releasing radiation.

Economic Disadvantages:
- Extremely high initial building costs and very high costs to safely shut down (decommissioning) old power plants.

B. Renewable Energy Resources

Renewable resources are those that are naturally replenished (replaced) over a short timescale, or are resources whose supply is essentially endless.

Key Renewable Resources:
- Biofuels, Geothermal, Hydro-electric, Tidal, Wave, Solar, Wind.

1. Hydro-electric Power (HEP)

HEP uses the kinetic energy of moving water, often captured by building a large dam.

How electricity is generated:
1. A dam is built across a river to create a large reservoir of stored water.
2. Water is released through pipes (penstocks) where its force spins turbines.
3. The turbines power generators.

Did you know? This process is simply converting gravitational potential energy into kinetic energy, and finally into electrical energy!

Evaluation: Advantages and Disadvantages

Environmental Disadvantages:
- The reservoir floods large areas of land, destroying habitats and ecosystems (e.g., the Three Gorges Dam flooded historical sites).
- Changes the river flow, affecting ecosystems downstream.
- Traps river sediment, impacting soil fertility further down the river.

Social Disadvantages:
- Requires the displacement of people and communities whose homes are flooded by the reservoir.

Advantages (Environmental & Economic):
- Very reliable and controllable (water release can be regulated).
- Zero \(\text{CO}_2\) emissions during operation.
- Can also be used for flood control and irrigation supply.

2. Wind Power

Wind farms (onshore or offshore) capture the kinetic energy of the wind.

How electricity is generated:
1. Wind turns the large blades of the turbine.
2. The blades are connected to a gearbox and then to a generator.

Evaluation: Advantages and Disadvantages

Environmental Disadvantages:
- Visual pollution (some people find large wind farms ugly).
- Can kill flying animals, especially birds and bats.

Economic Disadvantages:
- Intermittent: only works when the wind is blowing. A backup energy source is always needed.

Advantages:
- Zero \(\text{CO}_2\) or pollution during operation.
- Running costs are very low once installed.

3. Solar Power

Solar power captures energy directly from the sun.

How electricity is generated:
1. Photovoltaic (PV) cells (solar panels) convert sunlight directly into electricity.
2. Alternatively, Concentrating Solar Power (CSP) uses mirrors to focus heat onto water pipes to create steam, which then drives a turbine.

Evaluation: Advantages and Disadvantages

Economic & Social Disadvantages:
- Intermittent: only works during the day and less efficiently when cloudy.
- Requires large areas of land (solar farms) to generate meaningful amounts of power.

Advantages:
- Perfect for use in remote areas where grid connection is difficult.
- No pollution or \(\text{CO}_2\) emissions during use.
- Renewable and unlimited "fuel" source (sunlight).

4. Geothermal Power

This energy comes from the heat stored inside the Earth, often near volcanic or tectonic plate boundaries.

How electricity is generated:
1. Cold water is pumped deep underground to hot rocks.
2. The water turns into high-pressure steam.
3. The steam returns to the surface and drives a turbine/generator.

Evaluation: Advantages and Disadvantages

Environmental Disadvantages:
- Only available in specific geological locations (e.g., Iceland, New Zealand).
- Can sometimes release small amounts of sulfur gases from underground.

Advantages:
- Highly reliable (the Earth's heat is constant, unlike sun or wind).
- Low operating costs and zero \(\text{CO}_2\).

5. Biofuels (Bioethanol, Biogas, Wood)

Biofuels are created from recently living biological materials, such as wood, plant residues, or purpose-grown crops (like sugarcane for bioethanol).

How electricity is generated:
1. The biomass (wood chips, biogas, etc.) is burned in a combustion plant.
2. This creates heat, driving the standard steam-turbine-generator process.

Key concept: Carbon Neutral? Biofuels are often considered "carbon neutral" because the \(\text{CO}_2\) released when they burn is theoretically equal to the \(\text{CO}_2\) the plants absorbed while growing. However, this relies on sustainable harvesting and replanting.

Evaluation: Advantages and Disadvantages

Environmental Disadvantages:
- Can lead to deforestation if wood is unsustainably harvested.
- Growing crops for fuel requires large areas of land, fertilizers, and water.

Social Disadvantages:
- Creating fuel crops can compete with food crops, potentially driving up food prices and causing food shortages (especially bioethanol).

Advantages:
- Can be a way to manage and utilize organic waste.
- Reduces dependence on fossil fuels.

6. Tidal and Wave Power

These methods capture the energy of moving water in the ocean, driven by the gravitational pull of the moon (tides) or wind (waves).

How electricity is generated:
- Tidal barrages: A large dam across a river estuary captures high tide water, which is then released through turbines.
- Wave devices: Floating or seabed devices capture the up-and-down motion of waves to drive hydraulic systems attached to generators.

Evaluation: Advantages and Disadvantages

Advantages:
- Highly predictable (especially tides, which follow a strict schedule).
- Zero \(\text{CO}_2\) emissions.

Disadvantages:
- Very high initial construction costs for tidal barrages.
- Tidal barrages drastically change the habitat of the estuary, affecting fish and bird life.
- Wave power technology is still relatively new and often unreliable due to the harsh marine environment.

Summary: Comparing Environmental, Economic, and Social Impacts

When studying energy resources, the exam often asks you to compare them using the three sustainability pillars: Environmental, Economic, and Social (E-E-S).

Environmental Impacts (Pollution and Ecosystem Damage)

Worst Offenders (High \(\text{CO}_2\), Acid Rain, Habitat Loss):

- Fossil Fuels: Massive \(\text{CO}_2\) release, acid rain, and mining destruction. - HEP: Causes large-scale habitat loss through flooding.

Cleanest (Zero \(\text{CO}_2\) Emissions during operation):

- Nuclear, Wind, Solar, Tidal, Geothermal.

Unique Problems:

- Nuclear: Toxic radioactive waste. - Wind: Visual pollution and bird deaths. - Biofuels: Requires large amounts of land and water, potentially leading to deforestation.

Economic Impacts (Cost and Reliability)

High Reliability / Low Running Costs:

- Fossil Fuels: Historically cheap running costs. - HEP & Geothermal: Consistent output, low ongoing costs.

High Initial Costs (But long lifespan):

- Nuclear, HEP, Tidal. These require large, expensive infrastructure projects.

Intermittency (Reliability Issue):

- Wind and Solar. Output fluctuates, requiring expensive storage or backup power systems.

Social Impacts (Community and Health)

Negative Social Impact:

- Fossil Fuels: Air pollution leads to respiratory health issues. - HEP: Forced displacement of local people due to reservoir creation. - Biofuels: Competition between fuel crops and food crops.

Positive Social Impact:

- Renewables (especially Solar/Wind): Can provide decentralized energy access to rural communities (improving quality of life and health).