ENV200 Chapter 13 Notes

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School of Environment
Romila Verma

CHAPTER 13 – ENERGY [13.2] FOSSIL FUELS ­ Fossil fuels = organic (carbon-based) compounds derived from decomposed plants, algae, and other organisms buried in rock layers for hundreds of millions of years o Most of the richest deposits date to about 286 million to 360 million years ago Coal resources are vast ­ World coal deposits are ten times greater than oil and gas resources combined o Total coal resource is estimated to be 10 trillion metric tons o Almost all the world's coal is in North America, Europe, and Asia ­ Coal mining = dirty, dangerous activity o Underground mines are notorious for cave-ins, explosions, black lung disease o Surface mines (called strip mines) are cheaper and generally safer  Strip mines = large machines scrape off overlying sediment to expose coal seams o Mountaintop removal = the whole top of a mountain ridge is scraped off to access buried coal  One of the most environmentally destructive methods of coal mining  Valley fill = waste rock is pushed into nearby valleys, which buries forests, streams, farms, and sometimes whole towns ­ Coal burning releases huge amounts of air pollution (e.g., 2O ,2SO , NOx, CO, hydrocarbons, mercury, arsenic, chromium, lead, uranium) o Largest single source of acid rain in many areas o Sulfur and nitrogen oxides combine with water in the air to form sulfuric and nitric acids ­ Coal burning plants emit radioactivity from uranium and thorium o Making gas or liquid fuels out of coal is dirtier and more expensive than burning the coal directly o Both coal-to-liquid and coal-to-gas are environmentally disastrous ­ Coal ash sludge contains dangerous levels of arsenic, mercury, and toxic hydrocarbons Coal may be on the way out ­ Coal is providing less of our electricity o Federal regulations are part of this decline  EPA will slash the allowable mercury, arsenic, chromium, and fine particulates emissions from coal-fired power plants  Delayed for decades by owners of old power plants, who argued that their facilities were about to be closed anyway and so they shouldn't have to install expensive pollution control equipment  EPA will limit carbon emissions from power plants  Coal-fired power plants must install expensive carbon capture and storage equipment ­ Coal prices are increasing while solar costs are decreasing o Solar panel prices are decreasing o Mercury limits and carbon-mitigation policies are increasing the price of coal ­ Natural gas supplies are growing and prices are falling o Gas is more versatile and cleaner burning than coal ­ There are cleaner ways to generate energy from coal o Gasification = heating a coal slurry at high pressure in the presence of almost pure oxygen  Coal reacts with oxygen and breaks down into a variety of gases (e.g., hydrogen, 2O )  Gases are cooled, separated, and purified of contaminants (e.g., sulfur, mercury, arsenic)  Carbon dioxide can be captured and used for industrial processes or stored in geological formations ­ China and India have very large coal resources and burn about half of all coal mined annually in the world Have we passed peak oil? ­ Worldwide production of crude oil was predicted to peak in the 1970s o Global production has not yet slowed significantly o Many oil experts expect that we will pass this peak in the next few years ­ Proven oil reserves = commercially extractable liquid oil using currently available technology o Middle Eastern countries have more than half of the proven world supplies o Consumption rates continue to climb both in developed countries and in the fast-growing economies  Competition is growing for global oil and gas supplies Extreme oil and tar sands have extended our supplies ­ Estimates of recoverable oil supplies have expanded dramatically as new techniques have developed for obtaining oil from evermore extreme places o Deep ocean oil wells = drilling in deep waters and then below the seafloor o Tar sands = composed of sand and shale particles coated with bitumen  Bitumen = a viscous mixture of long-chain hydrocarbons  Shallow tar sands are excavated and mixed with hot water and steam to extract the bitumen  Deeper tar sands are injected with superheated steam melt the bitumen, then pumped to the surface like liquid crude oil, then cleaned and refined to be useful  Larger than conventional liquid oil reserves  May emit more CO t2an coal depending on how much energy is used to extract and refine oil from tar sands  There are severe environmental costs  Creates toxic sludge  Releases greenhouse gases  Consumes or contaminates water  Destroy the boreal forest in Canada ­ Pipelines carrying tar sands oil have a much higher rupture rate than those for conventional oil o The residual sand is more abrasive o The oil is more acidic and corrosive o Must be heated to higher temperatures in order to be shipped ­ United States has large supplies of unconventional oil o Oil shales = fine-grained sedimentary rock rich in solid organic material called kerogen  Kerogen can be heated, liquefied, and pumped out like liquid crude oil  There are severe environmental costs  Uses vast amounts of water  Releases much more carbon dioxide than burning an equivalent amount of coal  Creates enormous quantities of waste o Rock matrix expands when heated Natural gas is growing in importance ­ Natural gas (e.g., mostly methane) is the world's second largest commercial fuel o Burns more cleanly than either coal or oil o Produces less CO2compared to coal o May help reduce global warming ­ More than 50% of proven natural gas reserves are in the Middle East and the former Soviet Union ­ Gas consumption rates are less than oil consumption rates ­ Large amounts of methane are known to occur in relatively shallow sedimentary beds ­ Methane can be extracted from “coal-bed” methane deposits or shale gas o Requires many closely spaced wells and directional drilling o Fracking = hydraulic fracturing  Mixture of water, sand, and various chemicals is pumped into the ground and rock formations at extremely high pressure  Pressurized fluid cracks sediments and releases the gas  Fracturing rock formations disrupts aquifers and contaminates water wells  Drilling companies refuse to reveal the chemical composition of the fluids used in fracking  Petroleum distillates, hydrochloric acid, or sodium hydroxide are often used  Many of these chemicals are known to be toxic to humans and wildlife ­ Methane emissions from shale gas well are greater than those from conventional gas wells o Climate footprint of shale gas is greater o Natural gas supply may not help combat global climate change after all [13.6] WIND AND SOLAR ENERGY ­ Renewable sources could supply all the energy we need o Solar energy is the most abundant and ubiquitous renewable resource o Wind power is the second most abundant and ubiquitous renewable resource ­ Advantages o Prices are decreasing because of engineering developments and mass production o Creates more jobs, takes up less land, and keeps more money at home o Does not emit CO2that disrupts our global climate o Can be tied together over a wide geographical area to create a steady, dependable, affordable electrical supply o Much shorter planning and construction times than fossil fuel or nuclear power plants o Modular = a few or a lot more turbines or solar panels can be added if loads
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