Renewable and nondepletable energies

Topic 18 part 4

Renewable energy from biomass

Biomass– Wood– Charcoal– Peat– Manure

Biodiesel Ethanol Methane from livestock

Energy from Biomass

Is biomass really renewable?-If harvested sustainably

-Wood is often converted into charcoal and sold in urban areas

(Haiti deforestation and resulting problems)

-Solution research

Wood: Advantages and Disadvantages

-there’s a large potential supply, if it’s used sustainably

-doesn’t cost too much-no net carbon dioxide

released if it is harvested sustainably

-plantations can restore degraded land

-can put agricultural and urban waste to good use

-easily becomes nonrenewable when not harvested carefully

-if not harvested renewably, it releases a lot of carbon dioxide

-burning causes pollution of air and water

-plantations & cutting down trees cause habitat and biodiversity loss

-plantations could compete with land that should be used to grow crops

Biodiesel• diesel fuel made

vegetable oil extracted from renewable resources

 

http://www.youtube.com/watch?v=8omdRWbRaIs

Advantages and Disadvantages

Figure 17-29 from Miller Textbook

Biodiesel from microalgae

Benefits:Less land useLess soil disturbanceDecreased fossil fuel useMay be grown in waste water

Ethanol•Made of corn alcohol in its purest form

•Can be mixed with unleaded gasoline

•Comes in forms of E10, E85 and midrange•E10: 10% ethanol, 90% gasoline can be used by all cars•E85: 85% ethanol, 15% gasoline requires flexible fuel vehicles that are designed to run on ethanol •Midrange fuels: can be used on traditional car with some modifications

Advantages• Would help reduce foreign oil dependence • Producing 7.5 billion gal of ethanol would

reduce oil consumption by 80,000 gal per day

• Domestic production = boost for economy• Cleaner burning

• Reduces smog forming emissions and carbon monoxide emissions

• Flexible fuel vehicles can also run on gasoline

Disadvantages: Currently produced mainly from corn; there are still greenhouse gas emissions.

Methane biogas Anaerobic digestion of organic material Methane capture Burn in an internal combustion engine to turn a

turbine

Benefits?

Nondepletable sources of energy

• Solar

• Geothermal

• Wind

• Water

Hydroelectricity

• Conventional• Run-of-the-river• Tidal

Conventional (impoundment)

Environmental Effects

• Once constructed, no direct energy waste • Fundamentally alters ecosystem, stress to aquatic

and streamside life on either side of dam• Disables fish migration and access to spawning

grounds• Lower amounts of dissolved oxygen in water• Prevents flooding• Build of of nutrients

Run-of-the River

Cost/Efficiency

• Large initial investment to build plant• Low maintenance costs • Long lifetime for plants - around 50 years

(compared to 25 years for a typical fossil fuel plant)

• Very high efficiency– 90% of available energy converted to electricity

compared to ~50% in fossil fuel plants

Current Global Uses

Itaipú Dam• Paraná River on border of

Brazil and Paraguay• In 2000, generated 93,428

GWh of electricity • In 2000, provided 20% of

energy supply for Brazil and 94% in Paraguay

http://www.worldtourismplace.com/wp-content/uploads/2010/12/beautiful-itaipu-dam.jpg

Tidal energy

BARRAGE: dam built across bay, opens and lets in high tide, closes, then reopens at low tide

Solar energy from your readings…

1. What is the difference between passive and and active solar energy?

2. How do solar water heating systems work?3. How do photovoltaic systems work?4. What is concentrating solar thermal electricity

generation?5. What are the advantages of active solar

systems?6. What are the drawbacks of active solar

systems?

Geothermal energy from your readings…

1. What is geothermal energy?

2. In what way can this be unsustainable?

3. How can geothermal energy be converted into electricity?

4. What are ground source heat pumps and how do they work? Are these true geothermal?

Wind energy from your readings…

1. How could you make an argument that wind energy is actually solar energy?

2. How can wind energy be converted into electricity?

3. What are the advantages to using wind energy?

4. What are the drawbacks to wind energy?

Wind energy and the environment

• Benefits • Impacts

Reduce sulfur dioxide emissionsReduce carbon dioxide emissions

Reduce mercury emissions

Reduce particulate emissions

Reduce need for mining & drilling

Negative aesthetic effect

Harmful to birds

Changes in land use

Habitat fragmentation

Hydrogen fuel cells from your readings…

1. What is the difference between a battery and a fuel cell?

2. What are the challenges of manufacturing hydrogen fuel cells?

3. What are the advantages to using hydrogen fuel cells?

4. What are the drawbacks to using hydrogen fuel cells?