Unit 14: Renewable Energy

What defines renewable energy?

Energy that can be generated continuously without running out.

What are five main types of renewable energy?

Hydropower, Wind, Solar, Biomass, and Geothermal.

What is an example of small-scale renewable energy use?

Solar panels on rooftops or small wind turbines for homes or communities.

What is an example of utility-scale renewable energy?

Large solar or wind farms providing power to a regional grid.

Why might siting be an issue with renewable energy?

Ideal locations for renewable energy don’t always match where energy demand is highest.

What is one advantage of local power generation?

Greater energy independence and lower transmission losses.

What is one advantage of regional power generation?

Economies of scale and the ability to supply power to large areas.

What is the world’s largest renewable source of electricity?

Hydropower is the largest source of renewable electricity.

How does hydropower generate electricity?

Stored water behind dams flows through turbines, converting potential energy to kinetic energy, which is used to generate electricity.

What is a major environmental benefit of hydropower?

Produces no carbon emissions during electricity generation.

Why is hydropower cost-effective long term?

Low operating costs after the dam is built, making it cheaper over time.

Why is hydropower considered a consistent energy source?

Water flow is predictable, especially in large reservoirs.

What is one major environmental drawback of hydropower?

Destroys ecosystems and wildlife habitats through flooding.

How can hydropower affect water quality?

Changes temperature, oxygen, and sediment levels, harming aquatic life.

What is a social impact of building large dams?

Displaces people—e.g., Itaipu Dam displaced 10,000 families.

What geologic risk is linked to hydropower dams?

Can trigger earthquakes or landslides due to the mass of stored water.

What is the world's largest power-generating station?

Three Gorges Dam (China) with a capacity of 22,500 MW.

What is the environmental impact of the Three Gorges Dam?

It has a major impact on ecosystems and communities, despite providing clean energy.

What is the second-largest dam by volume and where is it located?

Itaipu Dam, located on the Paraná River between Brazil and Paraguay.

What were the social and environmental impacts of the Itaipu Dam?

Displaced 10,000 families and submerged one of the world’s largest waterfalls.

What percent of global electricity comes from hydropower?

16% of global electricity is produced from hydropower.

How important is hydropower in Canada’s energy mix?

The 3rd largest hydro producer, generating about 60% of its electricity from water.

How much of the U.S. electricity comes from hydropower?

About 6%

Why is future hydropower expansion limited in some regions?

Most rivers are already dammed, limiting new dam potential,

What is micro-hydro power and where is it useful?

Small-scale hydro systems ideal for rural or remote areas, especially in developing regions.

What is the first step in harnessing tidal energy?

Tidal turbines are placed in areas with high tidal movement

How is mechanical energy generated in tidal systems?

High tides rotate the turbine

What converts mechanical energy into electricity?

A generator and a transformer

How is the electricity from tidal energy systems transmitted?

Through power cables to nearby areas

What is the function of a solar photovoltaic (PV) system?

Capture solar energy and convert it into electricity using the photovoltaic effect.

How does a solar cell produce electricity?

• Semiconductor materials (like silicon) absorb sunlight (photons).

• Electrons are freed, creating an electric current that can be used to power devices.

What are the two main scales of PV system installations?

• Local systems serve individual buildings, sometimes feeding extra power into the grid.

• Utility-scale installations supply large amounts of electricity to regional power grids.

What are key siting considerations for PV systems?

• They require adequate sunlight for optimal performance.

• Clouds or nighttime reduce energy production, since panels depend on sunlight.

How does a Concentrated Solar Thermal (CST) system work?

• Reflectors (heliostats) focus sunlight onto a central collector.

• This heats the collector to produce high-temperature steam, which drives a turbine to generate electricity.

What is the main purpose of solar cooking in the developing world?

To reduce indoor air pollution and deforestation by decreasing the need for traditional wood fires.

How does a solar cooker work?

Mirrors focus sunlight onto a small cooking area, using solar heat to cook food without firewood or fossil fuels.

What is the goal of passive solar design?

To use building materials and structure to maximize solar gain and natural airflow, reducing energy use.

How does passive solar design improve energy efficiency?

It absorbs and retains heat from the sun, lowering the need for mechanical heating/cooling systems.

Which country leads in solar panel production?

China is the leader in solar panel production.

Which country has the most installed solar energy capacity, despite having less sunlight?

Germany has the most installed solar energy capacity, even with less sunlight than places like the California desert.

What is the current efficiency of solar panels?

Around 20%, but emerging technologies could push it up to 50% in the future.

How are solar panel prices changing?

Are falling rapidly, making solar energy more affordable.

What is a barrier to solar energy expansion?

Cost is a major barrier as solar energy is not yet cost-competitive with fossil fuels in many regions.

Why is sourcing materials for solar panels challenging?

Solar panels depend on rare or difficult-to-source materials, which can be a limitation.

How does weather affect solar energy production?

Solar energy production is weather-dependent and can be affected by cloudy conditions and time of day.

What environmental impact can large solar farms have?

Large solar farms can cause habitat disturbance, disrupting local ecosystems.

What is a concern regarding solar panel disposal?

There are concerns about the recycling and disposal of solar panels at the end of their lifespan.

How do wind turbines work?

Wind turbines capture energy from the wind and convert it into electrical energy.

What is the energy capacity of a large wind turbine?

Can generate 2 megawatts (MW) of power, enough to supply 500 homes.

How tall can large wind turbines be?

Can reach up to 400 feet in height.

What is a wind farm?

A group of wind turbines located in the same area to generate electricity.

What is the capacity of the St. Joseph Wind Farm?

138 MW project with 60 turbines, each with a 2.3 MW capacity.

What is the capacity of the St. Leon Wind Farm?

Has 73 turbines, each producing 1.65 MW and can supply electricity for over 40,000 homes.

Where are wind farms most effective?

Require windy locations with consistent, strong winds, so they’re not suitable everywhere.

Why are the windiest areas often challenging for wind farms?

Often far from populated regions, making it harder to transport power to consumers.

What environmental concerns do wind farms present?

Can affect bird populations due to turbine blades, requiring careful site selection to minimize ecological damage.

What is the public's attitude toward wind farms?

Many people support clean energy but oppose wind farms near their homes due to aesthetic concerns (NIMBY - Not In My Backyard).

How do offshore wind farms help with land use?

Placed in oceans, reducing land use conflicts.

How is wind power becoming more competitive?

Cost-competitive with fossil fuels, making it a more affordable energy source.

Where is wind energy most commonly found?

Most common in windy coastal regions, open plains, and offshore locations.

What are biomass fuels?

Are organic materials like wood, crop residues, and animal dung used as fuel.

How were biomass fuels historically used?

Traditionally used for heating and cooking and are still widely used in developing countries.

Why are biomass fuels considered hypothetically carbon neutral?

Plants absorb CO₂ while growing, which offsets emissions when burned.

What is an advantage of biomass fuels in terms of availability?

Are widely accessible and renewable, making them a reliable energy source.

What environmental issue is associated with the overuse of biomass fuels?

Deforestation causing habitat loss and soil degradation.

How can burning biomass fuels affect health?

Burning wood and dung in poorly ventilated homes releases harmful pollutants, leading to indoor air pollution.

Why is biomass burning inefficient?

Burns quickly and inefficiently, wasting energy and reducing its overall effectiveness.

How can biomass fuel use be improved in homes?

Efficient stoves can reduce indoor air pollution and increase fuel efficiency.

What is meant by sustainable harvesting in biomass use?

Involves managing forests properly to prevent deforestation while using biomass fuels.

What are some modern forms of biomass energy?

Includes biofuels (e.g., ethanol, biodiesel) and biogas for cleaner energy production.

What is ethanol and how is it produced?

Renewable biofuel made by fermenting plant-based sugars into alcohol.

What are the primary sources of ethanol production in the U.S. and Brazil?

• In the U.S., ethanol is primarily produced from corn.

• In Brazil, ethanol is mainly produced from sugarcane.

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What are the steps involved in ethanol production?

1. Extraction

2. Fermentation

3. Distillation

What is step “extraction” in ethanol production?

Sugars are extracted from plant materials.

What is step “fermentation” in ethanol production?

Microorganisms (e.g., yeast) convert sugars into ethanol and carbon dioxide.

What is step “distillation” in ethanol production?

Ethanol is separated and purified for use as fuel.

How is ethanol commonly used as a fuel?

Often mixed with gasoline in blends like E10, E15, or E85, and helps reduce greenhouse gas emissionscompared to fossil fuels.

What is the food vs. fuel debate related to ethanol production?

Concerns how ethanol production competes with food crops, potentially driving up food prices.

What are some challenges of ethanol production?

• Energy-intensive production process.

• Land use and water consumption for growing crops.

• Competition with food crops for resources.

What is cellulosic ethanol and what are its sources?

Made from non-food plant material, such as switchgrass, wood chips, and agricultural waste.

What are the advantages of cellulosic ethanol?

• Reduces competition with food crops.

• Can be produced from plants that grow on marginal lands, unsuitable for food production.

What are the challenges associated with cellulosic ethanol?

• Breaking down cellulose into fermentable sugars is difficult.

• Energy-intensive conversion process.

What are algae-based biofuels and their sources?

Made from microalgae that produce lipids (oils), which can be converted into biofuels.

What are the advantages of algae-based biofuels?

• Can be grown in controlled environments (e.g., tanks, ponds).

• Consumes CO₂ from fossil fuel combustion, helping to reduce emissions.

• Higher biomass yield than land-based plants.

What are the challenges of algae-based biofuels?

• High production costs and technological barriers.

• Still in research and development, with large-scale feasibility not yet achieved.

What is biodiesel and what are its sources?

Made from plant oils (e.g., soybean, canola) and animal fats.

What is the production scale of biodiesel?

Large industrial facilities or small-scale operations.

What are the advantages of biodiesel?

• Lower energy demand compared to ethanol production.

• Compatible with existing diesel engines (can be used as a blend or pure).

• Biodegradable and non-toxic, reducing environmental impact.

What are the challenges associated with biodiesel?

• Land use concerns, as it requires agricultural land for oil crops.

• Production cost can be higher than fossil diesel.

• Limited cold-weather performance (can gel in low temperatures).

Which country is the largest producer of biofuels globally, and what do they primarily produce?

The United States is the largest producer of biofuels globally, primarily producing ethanol from corn.

What does Brazil primarily produce for biofuels, and what is notable about their biofuel program?

• Primarily produces ethanol from sugarcane.

• An ethanol-based fuel program operational for decades.

Which countries or regions are other significant contributors to global biofuel production?

• European Union focuses on biodiesel production from vegetable oils.

• China and India are increasing biofuel production, primarily for domestic energy consumption.

What is the primary energy source for geothermal heat pumps?

Energy derived from deep within Earth's interior.

How do geothermal heat pumps function in regulating building temperatures?

By using the ground's stable temperature. They can heat and cool buildings by transferring heat to or from the ground.

How do geothermal heat pumps work to regulate temperature in buildings?

• Just below Earth's surface, the temperature stays relatively constant around 50-60°F (10-15°C).

• Geothermal heat pumps transfer heat to or from the ground to regulate the temperature of buildings, depending on the season.

What are the advantages of using geothermal heat pumps?

• Energy-efficient for both heating and cooling.

• Environmentally friendly, as it uses renewable energy from the Earth’s natural temperature.

Where is geothermal power generation commonly found?

Is commonly found in geothermal zones within volcanically and tectonically active areas.

What temperature range is typically found deep below the surface in geothermal power generation zones?

250−300°F (121−149°C) deep below the surface, providing substantial energy for geothermal power generation.

How is energy extracted for geothermal power generation?

• Wells are drilled to access hot underground reservoirs.

• Fluid or brine is circulated through the reservoir to capture the heat.

How is captured geothermal energy used?

• Used in direct heat applications.

• It can also be converted into electricity through geothermal power plants.