4.02.15 (lecture) Notes PDF

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Prof. Joel Meyer...

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The Environment and Energy Sources 4.02.15 Lecture Notes Opening Class Discussion: Why is coal cheap?  A lot of it  Easy to extract  Externalities (pollution, effects on ecosystem) are not included in the price  Like most fossil fuels, coal is subsidized Fracking  Earthquakes  More environmentally friendly, but not regulated enough  Requires a lot of water  What kind of water is used for fracking? o Engineers are working so that less clean water is necessary for fracking  Pollution of groundwater  Debate hinges on the extent of regulation and the weighing of costs and benefits  Alternatives to fracking?? Oil will not run out, question is when will it be economically not worth it to extract it (too deep) I. Why care? Energy important in human successes  1800: Italy – electricity from wet-cell battery Historically  Most energy sources were from wood  Peak on petroleum, natural gas, and coal  Nuclear peaked at some point, but now has plateaued or even gone down II. History of human energy use Energy is useful and limited  Humans appropriate ~32% of the Earth’s total NPP o Human appropriated NPP (HANPP) varies regionally o HANPP often >>> NPP – must be subsidized with NPP from other regions o Using fossil fuels to import energy from another point in time (because HANPP exceeds current NPP)  Additional sources of energy required Costs of energy  $120 billion per year, external costs of fossil fuels (National Research Council)  ~20 lbs of coal/day (gone down recently because of fracking)  Coal mining leads to 6000 deaths/year in China  Pollution from coal about ~1 million deaths/year in China  Flooding of ash sludge in Tennessee http://www.nytimes.com/2008/12/27/us/27sludge.html?_r=0 III. Sources of Energy (historical and current) Fossil fuels: formation  Woody terrestrial vegetation dies and falls onto swamp or marine organisms fall/sink to ocean floor  Anaerobic conditions – organic matter is not fully oxidized – formation of kerogen

 Under conditions of high heat and pressure, coal, thermogenic natural gas, and crude oil is formed from kerogen  “Fossil fuels” – free energy from a long time ago o Essentially nonrenewable in the context of the time-scale it takes to create o Are we using this energy in a good way? Other fossil fuels  Oil and tar sands: dense, hard, oil substances that can be mined from the ground o Tar is left behind when the lighter components of oil is volatilized o Has to be extracted from sand that is also mixed in  Shale oil: sedimentary rock filled with organic matter that was not buried deeply enough to form oil  Methane hydrates: methane trapped in ice crystals; occur under the seafloor and elsewhere o Methane frozen, found in the bottom of the ocean o Warmed, would provide a large source for methane gas  Extraction feasibility depends on price Oil  Technology limits how much oil can be extracted, but economics determines how much oil will be extracted  Rate of new petroleum finds has been steadily diminished  Fracking offers new extraction ability  Energy returned on energy invested (EROI): energy used to produce a unit of fuel divided by the energy contained in that unit  Historically, EROI was 1:25  Today, best fields are 1:10  US fields and off-shore 1:3  Tar sands in Canada 1:1.5  Tar sand production is not economically feasible anymore; may decrease in the following years  Secondary extraction of oil: injection of seawater into ocean floor to push oil up  Useful for many things  Dollar value of crude oil had been pretty stable from 1880 to 1970 o Peaked with the OPEC oil embargo and the Iranian Revolution and then plummeted with the Iraq invasion of Kuwait o US depends on imported oil o Legislation was passed to improve fuel efficiency of cars starting from 1980s Coal  Anthracite: highest heat content  (sub) Bituminous coal: lower, contains more sulfur and nitrogen  Lignite: lowest heat content, but very abundant  Peat (soft)  lignite  bituminous  anthracite  40-90% carbon by weight o Efficient burning – carbon dioxide o But leftover large volume of ASH  Negative impacts: o Habitat destruction from strip mining, mountaintop removal  Used to do a lot of shaft mining, but US converted to other types of mining because subsurface mining is extremely hazardous o Erosion from strip mining o Chemical runoff from strip mining through acid drainage  Sulfur, metal, acidic o Human health risks for workers from subsurface (aka shaft) mining

 Step 1: the forest and topsoil is removed from the area to be mined (aka deforestation and removal of geological layers) o Scraping off the layers of the mountain that doesn’t contain coal  Step 2: dynamite is used to dislodge the overburden (rock above the coal), which is then placed in the adjacent valleys o Mountaintop mining = valley fill  Step 3: draglines (large machines that scrape coal) excavate lower layers of coal  Step 4: re-grading begins as coal excavation continues  Step 5: once coal removal is complete, final re-grading takes place and the area is re-vegetated o In principle, after all this, soil is added and the ecosystem is supposed to function similarly to before o Realistically, ecosystems are not being rebuilt effectively; forest ecosystems do not reemerge and rivers are destroyed o Artificial stream percolate the metals and sulfates (??) Coal – economics and policy  Energy content/volume low – significant transportation costs diminish EROI  Use in US currently in decline – but not elsewhere!  http://www.economist.com/news/briefing/21569037-why-worlds-most-harmful-fossil-fuel-beingburned-less-america-and-more-europe Mountaintop Mining Consequences  Streamwater sulfate concentrations – decrease in biodiversity  WV stream condition index decreases  Studies done to see if these affect human health in the area Natural gas  Composed of methane and other gases  Thermogenic (fossil fuel); ~60 years left  Biogenic: small-scale renewable “Fracking” (hydraulic fracturing) highly controversial; e.g., Dimock Pennsylvania  Permits much greater recovery of gas, esp. from shale  2005 federal loophole exempting fracking from environmental regulation  Concerns regarding groundwater contamination  HOW? Combination of two techniques – horizontal drilling and hydraulic fracturing o Gun charges blast holes through the well-casing and into the surrounding rock o Sand, water, and chemicals pumped in at high pressure further fracture the rock o Gas escapes through fissures propped open by sand particles and up to the surface  Greenhouse gases (burning natural gases) vs. human health risks (particulate matter from burning coal) Nuclear Power  Fukushima accident shut down all nuclear power in Japan (affected public opinion in many other countries)  http://www.world-nuclear.org/info/Safety-and-Security/Safety-of-Plants/Fukushima-Accident/  Germany shut down a lot of nuclear power  Plants are not being built as a response to Fukushima  Fossil fuels is becoming cheaper  When plants are getting too old? o New ones or let it die?  Chernobyl associated with child thyroid cancer and Cesium-137 deposition  Plants built over time have varying levels of security Water disposal is a major concern  Radioactivity produced as a by-product stays for a long time

 Stored underwater or else they will catch on fire o After a few years, they can stored in dry storage  Uranium oxide ~ 3-5 years  Hot fission products ~ 300 years  Long-lived actinides such as plutonium ~ more than 100,000 years  ~130 sites, > 70,000 tons  We haven’t been coming up with a long-term place to put the nuclear waste Spent fuel disposal  Getting materials our of the biosphere (suggestions and realistic solutions) o Deep sea burial o Outer space o Transmutation (can be stolen and used to make nuclear weapons) o Geologic emplacement  1982 Nuclear Waste Management Act o Mandated that the Department of Energy would develop a repository o 1987 Yucca Mountain Nevada selected; 2009: removed! o EPA set standards for performance – must protect environment from significant exposure for 1 million years o Spent 9-10 billion dollars so far on research…significant concerns remain o Ongoing legal disputes with Nevada over the location  What can be done with the waste? o Burial: Yucca-like underground storage at an undetermined location  Money is in the bank, but science and politics have yet to align o Surface storage: concrete-and-steel casks at reactor sites  Not a long-term solution, although, after 100 years, the waste would be easier to bury o Recycling in reactors: turns waste into more power but at a cost  Poses risk of pollution in reprocessing and requires a fleet of a new type of nuclear reactor...