What happens to the steam? The steam that has passed through the power station's turbines has to be cooled, to condense it back into water before it can be pumped round again. This is what happens in the huge "cooling towers" seen at power stations.
Alternative way of cooling Some power stations are built on the coast, so they can use sea water to cool the steam instead. However, this warms the sea and can affect the environment
Three major coal producing areas in the United States Millions of Short Tons Amount produced in millions of short tons 2006
What are the advantages of using Coal? It is cheap There is lots of it (enough for hundreds of years) Can produce large amounts of electricity all in one location It is easily and safely transported Supplies are readily available and local Little need to rely on outside sources
What are the disadvantages of coal? Severe land disturbance occurs when mining for it High carbon and sulfur dioxide emissions Contributes to acid rain which affects waterways Releases radioactive particles and toxic mercury into the air Threat to human health
What is crude oil? Crude oil (petroleum) is a thick liquid containing hydrocarbons that we extract from underground deposits and separate into products such as gasoline, heating oil and asphalt. Only 35-50% can be economically recovered from a deposit.(by conventional pumping) Only 35-50% can be economically recovered from a deposit.(by conventional pumping) About 10-25% more can be recovered from expensive secondary extraction techniques. (involves injecting steam into well) About 10-25% more can be recovered from expensive secondary extraction techniques. (involves injecting steam into well) This lowers the net energy yield.
What are reserves? Estimated reserves are educated guesses about how much oil or natural gas is left and where it may be found. Proven reserves are exact amounts of oil that can be economically obtained from a field. Proven reserves are determined only after drilling.
Core Case Study: How Long Will the Oil Party Last? We have three options: Use or waste less oil. Use or waste less oil. Use something else. Use something else. Continue to utilize shale-oil and other “unconventional” oil sources and technologies Continue to utilize shale-oil and other “unconventional” oil sources and technologies Figure 16-1
OIL Refining crude oil: Based on boiling points, components are removed at various layers in a giant distillation column. Based on boiling points, components are removed at various layers in a giant distillation column. The most volatile components with the lowest boiling points are removed at the top. The most volatile components with the lowest boiling points are removed at the top. Figure 16-5
OIL Twelve OPEC (Organization of Petroleum Exporting Countries) have 78% of the world’s proven oil reserves and most of the world’s unproven reserves. After global production peaks and begins a slow decline, oil prices will rise and could threaten the economies of countries that have not shifted to new energy alternatives.
So what is up with the oil prices? There’s too much supply. “ Continued growth in U.S. shale production and increase in non-OPEC countries oil exports have led to excess capacity,” says Fortune magazine And too little demand. “At the same time, demand for oil in places like Europe, Asia, and the US began tapering off, thanks to weakening economies and new efficiency measures”
Prudhoe Bay on Alaska’s North Slope is the highest yielding oil field in the United States, typically producing approximately 400,000 barrels per day.
Keystone Pipeline The basics are easy enough: The proposed pipeline would carry 830,000 barrels of oil per day from Canada's oil sands down to Nebraska. Supporters argue that building it will create jobs and bolster the flow of crude from a friendly neighbor. Opponents say all that extra fossil fuel will exacerbate global warming. The Obama administration, which has final say over the project, has wavered on a decision.
Drilling on the Arctic National Wildlife Refuge: The big debate The controversy over oil drilling in ANWR continues with no resolution in sight. So, what are public opinions on drilling? It depends on whom you ask:
Many Alaskans favor ANWR oil drilling as it would strengthen the Alaskan economy and provide jobs. The Inupiat Eskimos are open to drilling, so long as it can be done in an environmentally safe manner and they have say into the process and revenues. The Gwich'in Indians are opposed to drilling in ANWR. During July 2008's high gas prices, the Pew Center found that the U.S. public increasingly favored opening ANWR to drilling -- 53 percent favored it, 43 percent opposed it and 7 percent were undecided [source: Pew Center].
Fig. 16-7, p. 363 Trade-Offs Conventional Oil AdvantagesDisadvantages Ample supply for 42–93 years Need to find substitutes within 50 years Low cost (with huge subsidies) Artificially low price encourages waste and discourages search for alternatives High net energy yield Easily transported within and between countries Air pollution when burned Low land use Releases CO 2 when burned Technology is well developed Efficient distribution system Moderate water pollution
Transporting oil is usually safe, but accidents do happen!!!
Heavy Oils from Oil Sand and Oil Shale: Will Sticky Black Gold Save Us? Heavy and tarlike oils from oil sand and oil shale could supplement conventional oil, but there are environmental problems. High sulfur content. High sulfur content. Extracting and processing produces: Extracting and processing produces: Toxic sludge Uses and contaminates larges volumes of water Requires large inputs of natural gas which reduces net energy yield.
Oil Shales Oil shales contain a solid combustible mixture of hydrocarbons called kerogen. Figure 16-9
Natural Gas Natural Gas is the fastest growing fossil fuel in use today and comprises 25% of global commercial energy consumption. Natural Gas is the fastest growing fossil fuel in use today and comprises 25% of global commercial energy consumption.
Formation Natural Gas consists primarily of methane, CH 4 and typically includes varying amounts of other volatile hydrocarbons. The main type of natural gas is called thermogenic because it results from compression and heat deep underground.
Fig. 16-2, p. 357 Oil and natural gas Floating oil drilling platform Oil storage Coal Contour strip mining Oil drilling platform on legs Geothermal energy Hot water storage Oil well Pipeline Geothermal power plant Gas well Valves Mined coal Pump Area strip mining Drilling tower Pipeline Impervious rock Underground coal mine Natural gas Water Oil Water is heated and brought up as dry steam or wet steam Water Coal seam Hot rock Water penetrates down through the rock Magma
Extraction Most gas extracted commercially is thermogenic and is found above deposits of crude oil or seams of coal. Many of the most accessible reserves have been tapped by wells and used already.
Fracturing techniques One popular method is to pump salt water under high pressure into the rocks to crack them. Sand or small glass beads are inserted to hold the cracks open once the water is withdrawn.
NATURAL GAS Russia and Iran have almost half of the world’s reserves of conventional gas, and global reserves should last 62-125 years. Natural gas is versatile and clean-burning fuel, but it releases the greenhouse gases carbon dioxide (when burned) and methane (from leaks) into the troposphere.
Fig. 16-11, p. 368 Trade-Offs Conventional Natural Gas AdvantagesDisadvantages Ample supplies (125 years)Nonrenewable resource High net energy yield Releases CO 2 when burned Low cost (with huge subsidies) Methane (a greenhouse gas) can leak from pipelines Lower CO 2 emissions than other fossil fuels Difficult to transfer from one country to another Moderate environmental impact Shipped across ocean as highly explosive LNG Easily transported by pipeline Sometimes burned off and wasted at wells because of low price Low land use Good fuel for fuel cells and gas turbines Requires pipelines Less air pollution than other fossil fuels