Energy Notes- Ecology Fossil Fuels, Nuclear Energy

Energy Sources and Consumption Energy sources used to be local Now they are worldwide Fossil fuels Nuclear energy Electricity Energy consumption is different between developing and developed nations 20% of world’s population use 60% of the world’s energy sources

Energy consumption in the US Industries (production) use the most Heating, cooling, and illuminating building is 1/3

Fossil Fuels Combustible deposits in the Earth’s crust Composed of the remnants (fossils) of prehistoric organisms that existed millions of years ago Includes coal, oil (petroleum) and natural gas Non-renewable resource Fossil fuels are created too slowly to replace the reserves we use

How Are Fossil Fuels Formed? 300 million years ago Climate was mild Vast swamps covered much of the land Dead plant material decayed slowly in the swamp environment

How Are Fossil Fuels Formed Over time, layers of sediment accumulated over the dead plant material Coal Heat, pressure and time turned the plant material into carbon-rich rock (coal) Oil Sediment deposited over microscopic plants Heat pressure and time turned them into hydrocarbons (oil) Natural Gas Formed the same way as oil, but at temperatures higher than 100 °C

Coal Occurs in different grades Lignite Subbitumimous Bituminous Based on variations in heat and pressure during burial Lignite Subbitumimous Bituminous Anthracite Most, if not all, coal deposits have been identified Primarily in northern hemisphere

Coal US has 25% of world’s coal supplies Known coal deposits could last 200 years At present rate of consumption

2 Types of Coal Mining Surface mining (right) Subsurface mining Chosen if coal is within 30m of surface mineral and energy resources are extracted near Earth’s surface by first removing the soil, subsoil, and overlying rock strata Subsurface mining Extraction of mineral and energy resources from deep underground deposits

Environmental Impacts of Mining Coal Surface Mining Control and Reclamation Act (1977) Requires filling (reclaiming) of surface mines after mining Expensive! Reduces Acid Mine Drainage Requires permits and inspections of active coal mining sights Prohibits coal mining in sensitive areas Mountaintop Removal Fills valleys and streams with debris

Environmental Impacts of Burning Coal Releases large quantities of CO2 into atmosphere Greenhouse gas Releases other pollutants into atmosphere Mercury Sulfur oxides Nitrogen oxides Can cause acid precipitation

Making Coal Cleaner Fluidized Bed Combustion (below)

Oil and Natural Gas Oil and gas provide 60.6% of world’s energy

Petroleum Refining Numerous hydrocarbons present in crude oil (petroleum) are separated Based on boiling point Natural gas contains far fewer hydrocarbons than crude oil Methane, ethane, propane and butane

Oil and Natural Gas Exploration Oil and natural gas migrate upwards until they hit impermeable rock Usually located in structural traps

Oil Reserves Uneven distribution globally More than half is located in the Middle East

Natural Gas Reserves Uneven distribution globally More than half is located in Russia and Iran

Environmental Impacts of Oil and Natural Gas Combustion Increase carbon dioxide and pollutant emissions Natural gas is far cleaner burning than oil Production Disturbance to land and habitat Transport Spills- especially in aquatic systems Ex: Alaskan Oil Spill (1989), BP oil spill (2010)

Day 2: Nuclear energy

Nuclear Energy

New York Times http://www.nytimes.com/2012/02/28/world/asia/japan-considered-tokyo-evacuation-during-the-nuclear-crisis-report-says.html?_r=1&ref=todayspaper http://abcnews.go.com/ThisWeek/video/nuclear-meltdown-13126566

Introduction to Nuclear Energy Energy released by nuclear fission or fusion Nuclear fission Splitting of an atomic nucleus into two smaller fragments, accompanied by the release of a large amount of energy Nuclear fusion Joining of two lightweight atomic nuclei into a single, heavier nucleus, accompanied by the release of a large amount of energy

Atoms and Radioactivity Nucleus Comprised of protons (+) and neutrons (neutral) Electrons (-) orbit around nucleus Neutral atoms Same # of protons and electrons

Radioactive Isotope Unstable isotope Radioactive Decay Example Emission of energetic particles or rays from unstable atomic nuclei Example Uranium (U-235) decays over time to lead (Pb-207) Each isotope decays based on its own half-life

Nuclear Fission U-235 is bombarded with neutrons The nucleus absorbs neutrons It becomes unstable and splits into 2 neutrons 2-3 neutrons are emitted and bombard another U-235 atom Chain reaction

Nuclear Fission Nuclear Fuel Cycle processes involved in producing the fuel used in nuclear reactors and in disposing of radioactive (nuclear) wastes

How Electricity is Produced

http://www.nrc.gov/info-finder/reactor/

Pros and Cons of Nuclear Energy Less of an immediate environmental impact compared to fossil fuels

Pros and Cons of Nuclear Energy Pros (continued) Carbon-free source of electricity- no greenhouse gases emitted May be able to generate H-fuel Cons Generates radioactive waste Many steps require fossil fuels (mining and disposal) Expensive

Cost of Electricity from Nuclear Energy Cost is very high 20% of US electricity is from Nuclear Energy Affordable due to government subsidies Expensive to build nuclear power plants Long cost-recovery time Fixing technical and safety issues in existing plants is expensive

Safety Issues in Nuclear Power Plants Meltdown At high temperatures the metal encasing the uranium fuel can melt, releasing radiation Probability of meltdown or other accident is low Public perception is that nuclear power is not safe Sites of major accidents: Three Mile Island Chornobyl (Ukraine)

Three-Mile Island 1979- most serious reactor accident in US 50% meltdown of reactor core Containment building kept radiation from escaping No substantial environmental damage No human casualties Elevated public apprehension of nuclear energy Led to cancellation of many new plants in US

Chernobyl 1986- worst accident in history 1 or 2 explosions destroyed the nuclear reactor Large amounts of radiation escaped into atmosphere Spread across large portions of Europe

Fukushima Daiichi nuclear complex http://www.pbs.org/wgbh/frontline/film/japans-nuclear-meltdown/

Film clips Meltdown at Chernobyl http://www.youtube.com/watch?v=Exh4n88WoO4&feature=fvsr&safety_mode=true&persist_safety_mode=1&safe=active http://www.youtube.com/watch?v=A62au7Avq1E&safety_mode=true&persist_safety_mode=1&safe=active

Chernobyl Radiation spread was unpredictable Radiation fallout was dumped unevenly Death toll is 10,000-100,000

Radioactive Waste Low-level radioactive waste- Radioactive solids, liquids, or gasses that give off small amounts of ionizing radiation High-level radioactive waste- Radioactive solids, liquids, or gasses that give off large amounts of ionizing radiation

Radioactive Wastes Long term solution to waste Deep geologic burial –Yucca Mountain As of 2004, site must meet EPA million year standard (compared to previous 10,000 year standard) Possibilities: Above ground mausoleums Arctic ice sheets Beneath ocean floor

Radioactive Waste Temporary storage solutions In nuclear plant facility (require high security) Under water storage Above ground concrete and steel casks Need approved permanent options soon.

Case-In-Point Yucca Mountain 70,000 tons of high-level radioactive waste Tectonic issues have been identified

Decommissioning Nuclear Power Plants Licensed to operate for 40 years Several have received 20-year extensions Power plants cannot be abandoned when they are shut down Three solutions Storage Entombment Decommissioning (dismantling)