Achieving Energy Sustainability February 23, 2015 Mr. Alvarez Renewable Energy Renewable Energy- can be rapidly regenerated, and some can never be depleted, no matter how much of them we use. Potentially Renewable- An energy source that can be regenerated indefinitely as long as it is not overharvested Ex: Biomass Energy Nondepletable- An energy source that cannot be used up Ex: Wind, Solar, Geothermal, Hydroelectric and Tidal 1
Energy Conservation Energy Conservationfinding ways to use less energy Ex: Lowering household thermostat when not home Energy Efficiencygetting the same result from using a smaller amount of energy. Ex: Buying Energy Star Appliances Government Facilitated Conservation Government taxing of electricity, oil and natural gas Discourages usage Governments can offer tax rebates or tax credits for retrofitting a home or business to operate on less energy Incentive for homeowners to update old appliances and insulation Tiered Rate System- Customers pay low rate for the first increment of electricity they use and pay higher rates as their use goes up Light Bulbs Switch light bulbs to Compact-Fluorescent Light Bulbs (CFL s) CFL s use ¼ as much energy as incandescent bulbs LED (Light-emitting diode) bulbs use 1/6 energy 2
Peak Demand Peak Demand- the greatest quantity of energy used at any one time Many energy companies have an extra backup source of energy available to meet the peak demand Usually Natural Gas-Fired Generators Variable price structure- utility customers can pay less to use energy when demand is lowest and more during peak demand. Sustainable Design Sustainable Design- Improving the efficiency of the buildings we live and work in. Passive Solar Design- a technique that takes advantage of solar radiation to maintain a comfortable temperature in the building Using passive solar energy can lower your electricity bill without the need for pumps or other mechanical devices. Building the house with windows along a south-facing wall which allows the Sun s rays to warm the house would be an example. 3
The California Academy of Sciences Uses 30% less energy than the quantity it is allowed to use under federal code requirements Includes Passive Solar Design, radiant heating, solar panels, and skylights Natural light fills 90% of the office space Windows, louvers, and skylights open as needed to allow air to circulate Captures the ocean breezes and ventilates building Recycled denim insulation in the walls and Soil-covered rooftop garden provide insulation that reduces heating and cooling costs Living Green Roof grows native plants and captures 13.6 million liters (3.6 million gallons) of rainwater used to recharge groundwater stores 4
Cost of Electrical Production VERY IMPORTANT!!! There is no Silver Bullet every source has upsides, downsides, limitations Source diversity = resiliency Benchmark for renewables must beat to be financially competitive (& economically sustainable) Modern Carbon vs. Fossil Carbon Modern Carbon- Carbon in biomass that was recently in atmosphere Biomass- The total mass of all living matter in a specific area The carbon found in biomass was in the atmosphere as carbon dioxide, taken in by the tree, and by burning it we put it back into the atmosphere Fossil Carbon- Carbon in Fossil Fuels Burning coal is carbon that has been buried for millions of years and was out of circulation until we began to use it. This results in a rapid increase in the concentration of carbon dioxide in the atmosphere. Ultimate Goal is to be Carbon Neutral 5
Solid Biomass- Low Technology Solid Biomass- Wood, Charcoal and Manure Used to heat homes and a fuel for cooking Tree removal can be sustainable, however: Often leads to soil erosion, increased water temps, and habitat fragmentation Burning manure removes harmful microorganisms from surroundings All lead to indoor air pollution: Increased particulate matter and other pollutants that cause reparatory illnesses and cancers Also release Carbon Monoxide and Nitrogen Oxides (NOx) which lead to smog Biofuels- High Tech Biofuels- Ethanol, Biodiesel and Biogas are used in replacement of Gasoline and Diesel Fuels Ethanol- an alcohol, the same one found in alcoholic beverages, comes from fermented sugars Biodiesel- a substitute for regular petroleum diesel, is extracted oil from sources Biogas- typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Ethanol In United States, usually produced from corn and cornbyproducts Can also be produced from sugarcane, wood chips, crop waste or Switchgrass Corn must be replanted every year Sugarcane must be replanted every six years Switchgrass is perennial (farmers can harvest without replant) 10% ethanol (gasohol) reduces gas mileage 2-3% E-85 (85% ethanol) reduces gas mileage by 1/3 Switchgrass, woodchips and crop waste are composed of cellulose which must be broken down into sugars Very energy-intensive 6
Biodiesel Can be extracted from soybeans, or from processed vegetable oil Any Diesel vehicle can run on B-20 80% petroleum diesel 20% Biodiesel Diesel vehicles can be converted to 100% straight vegetable oil (SVO) Obtained as a waste product from restaurants and filtered for use as a fuel (unlikely enough to power all vehicles) Certain Algae species can produce Biodiesel Photosynthetic microorganisms that can be grown anywhere, even in brackish waters, rooftops or other non-agricultural waters Use the least amount of energy and fertilizer per quantity of fuel out of all biofuel options 15-300 times more fuel per area than conventional biodiesel crops Biofuel Downsides Crops for Fuel vs. Crops for Food (takes food away from people) Agricultural expansion land footprint deforestation (esp. soy & palm in the tropics) Crops have fossil fuel input (mechanized monoculture uses lots of fuel/fertilizer/pesticide) One More Biofuel: Biogas Organic wastes go in bacteria convert to methane biogas harvested for use. 7
Hydroelectricity Hydroelectricity- Electricity generated by the kinetic energy of moving water Moving water, either falling over a vertical distance or flowing with a river or tide spins a turbine just as steam would in a coal-fired plant Second most common form of renewable energy in the United States and in the world Types Include: Run-of-the-River Water Impoundment Systems Tidal Systems Run of the River Run-of-the-river- water is retained behind a low dam and runs through a channel before returning to the river (water wheels) Pros: Relatively little floodplain occurs upstream and seasonal changes in river flow not disrupted Cons: Generally small, and rely on natural water flow which means that electricity generation could be intermittent Water Impoundment Systems Water Impoundment- Storing water in a reservoir behind a dam 8
Pros and Cons of Water Impoundment Pros Once built, require minimal amounts of fossil fuels Can provide recreational and economic opportunities Controls downstream flooding Generates large quantities of electricity No air pollution No waste products No CO 2 emissions Cons Reservoir floods can flood land with agricultural, aesthetic or archeological value Reservoirs are warmer and contain less dissolved oxygen Certain organisms cannot survive Organisms die, decompose which leads to more CO 2 and CH 4 Conversely, great home for disease carrying parasites such as mosquitos Disrupts fish migration Siltation- the accumulation of sediments on the bottom of the reservoir which decreases life of the dam Solar Energy Advantages: After construction, no cost to generate electricity No air pollution, water pollution, CO2 production during operation HUGE potential Disadvantages: Manufacturing requires lots of rare metals Manufacturing photovoltaic cells requires a great deal of energy, water and involves a variety of toxic metals and industrial chemicals that can be released into the environment High initial cost; geographically limited; inconsistent Limited lifespan of PV cells and batteries (disposal) 9
Household Solar Thermal Heating Household Solar PV Panel Electricity Concentrated Solar Thermal Plants Distributed Pipes vs. Central Tower 10
Geothermal Energy Geothermal Energy- using the heat from natural radioactive decay of elements deep within Earth as well as heat coming from Earth. Small-scale (Household): Heats individual homes by closed-loop circulation Pro: Can be done anywhere; free heating/cooling! Con: Only works for small buildings Large-scale (Electricity Generation): Pumps water down very deep to be heated Pro: very cheap; no emissions; large potential Con: Only usable where magma is close to surface Small-Scale Geothermal ( Ground Source Heat Pump ) Large-Scale Geothermal Wind Energy Using kinetic energy of wind to spin a blade, which spins a turbine Pros: HUGE potential very low impact on Environment best in rural areas w/ frequent wind Cons: Not usable everywhere kills birds construction cost & metals public resistance 11
Wind Turbines & Wind Farms 12
Hydrogen Fuel Cells Not a SOURCE of energy but a METHOD OF STORAGE (like a battery) OTHER SOURCE must separate Hydrogen in to H 2 gas H 2 stored & later combined w/ O 2, generating flow of e - (Reaction Layer) Hydrogen Fuel Cell Car Pros and Cons of Hydrogen Pros 80% Efficient in turning potential energy of hydrogen and oxygen into electricity Fossil Fuels are 35-50% efficient Only by-product is water Potential to use solar or wind energy to produce hydrogen Cons Right now, more energy is expended by generating hydrogen than saved Fossil fuels used to generate H 2 gas Hydrogen gas distribution methods are needed Vehicles would need larger fuel tanks to have the same mileage range as gasoline-powered vehicles Tank rupture could lead to fire or explosion 13
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