Is biomass really renewable? -If harvested sustainably -Wood is often converted into charcoal and sold in urban areas (Haiti deforestation and resulting problems)Haiti deforestation 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 use Less soil disturbance Decreased fossil fuel use May 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
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
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
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 BenefitsImpacts Reduce sulfur dioxide emissions Reduce 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?