Chapter 16 Nonrenewable Energy Resources Energy resources 99

Chapter 16 Nonrenewable Energy Resources

Energy resources 99% of energy used to heat the earth and all the buildings comes from the sun The sun also creates renewable energy resources – wind, flowing water, biomass

The rest The last 1% comes from fuel resources Fossil fuels make up the vast majority Petroleum, coal, and natural gas A small portion also comes from nuclear sources

Is it getting hot in here? Which energy source has the highest net energy ratio for space heating? Passive solar, yes, just letting in sunlight to warm a room is the most efficient § Which energy source has the highest net energy ratio for high-temperature industrial uses? § coal

Beep, Beep The highest net energy ratio for transportation Natural gas Unfortunately, current NG cars have limited driving ranges and limited fueling sites.

Oil and Natural Gas Floating oil drilling platform Oil drilling platform on legs Gas well Coal Oil storage Oil well Valves Pipeline Mined coal Geothermal Energy Hot water Contour storage strip mining Geothermal power plant Area strip Pipeline mining Drilling tower Pump Underground coal mine Water is heated and brought up as dry steam or wet steam Impervious rock Natural gas Oil Water penetrates down through the rock Coal seam Hot rock Water Magma Fig. 14. 11, p. 332

What is this stuff? Petroleum is a gooey liquid consisting of primarily hydrocarbons Also called crude oil (or just oil) Oil is widely used because it is cheap, easily transported and has a high net energy yield Through distillation we produce many products - asphalt, heating oil, diesel, gasoline, grease, wax, natural gas

Shifts in energy usage worldwide During the 20 th century Coal use dropped from 55 to 22% Oil increased from 2 to 30% Natural gas rose from 1 to 23% Nuclear rose from 0 to 6% Renewable (wood and water ) dropped from 42 to 19%

Way to go US The U. S. is the world’s largest energy consumer We use 25% of the world’s energy (even though we only have 4. 5% of the total population) India with 17% of the population only uses 3% of the world’s commercial energy 91% of the U. S. ’s energy in nonrenewable

Energy Net energy refers to the amount of useful energy minus the energy needed to find, extract, process, concentrate, and transport to the users Nuclear energy has a low net energy ratio because it is expensive to extract and process uranium, convert it into a fuel, build and operate the plant, and dismantle and deal with radioactive plants and waste

Oil, Oil everywhere and not a drop to drink Extracted as crude oil or petroleum, a thick liquid consisting of hydrocarbons, and some sulfur, oxygen and nitrogen impurities Produced from decayed plant and animal material over millions of years

Oil continued Normally crude oil is not found in underground pools, but is spread out in the pores and cracks within rock deep beneath the ground Primary recovery – drill a hole and pump out the light weight crude that fills the hole

Oil continued Secondary recovery – pumping water into the well to force oil out of the pores The oil and water mixture is separated after pumping Only about 35% of the oil is removed by primary and secondary recovery

Oil continued Tertiary recovery – either a heated gas or a liquid detergent is pumped into the well to help remove more oil Tertiary is expensive

Oil continued At the refinery oil is converted into petrochemicals and used as a resource to create industrial organic chemicals, pesticides, plastics, synthetic fibers, paints, medicines and more. OPEC – organization of petroleum exporting countries control 67% of the worlds oil and maintain control over pricing

Ticket to Ride Most oil in the US is used for transportation Gasoline Diesel Lubricant oil and grease Some as LNG

Gases Gasoline Aviation fuel Heating oil Heated crude oil Diesel oil Naphtha Furnace Grease and wax Asphalt Fig. 14. 16, p. 337

Advantages Ample supply for 42– 93 years Low cost (with huge subsidies) High net energy yield Easily transported within and between countries Low land use Disadvantages Need to find substitute within 50 years Artificially low price encourages waste and discourages search for alternatives Air pollution when burned Releases CO 2 when burned Moderate water pollution Fig. 14. 21, p. 340

Oil continued Oil shale is a fine grained sedimentary rock containing solid combustible organic material (waxy hydrocarbons) called kerogen Shale oil is made from heating oil shale Tar sand contains bitumen (a high sulfur heavy oil) another combustible organic material Both are more expensive than crude recovery because it requires more energy, land disruption, and are more difficult to extract, produce roughly the same oil but with lower net energy yield

Oh, Canada There is a lot of shale oil and tar sands in North America, particularly in Canada. As the price of crude oil goes up, the value of this heavy oil also goes up and becomes economically profitable to extract. Unfortunately, almost all vegetation above the reserves must be removed to obtain these resources, so the environmental cost is very high

Domestic Oil US extraction of oil has decreased since 1985, thus increasing our reliance on other countries Switching to alternative fuels sources helps maintain our economic independence

Advantages Moderate existing supplies Large potential supplies Disadvantages High costs Low net energy yield Large amount of water needed to process Severe land disruption from surface mining Water pollution from mining residues Air pollution when burned CO 2 emissions when burned Fig. 14. 25, p. 342

Natural Gas Mostly CH 4 methane with some ethane, propane and butane and small amounts of hydrogen sulfide (toxic) LPG (liquefied petroleum gas) the propane and butane are removed from natural gas and stored under pressure

How long will it last? Natural gas should last about 125 years worldwide About 75 years in the US Overall about 200 -300 years with rising prices, better technology, and more discoveries

Advantages Disadvantages Ample supplies (125 years) Releases CO 2 when burned High net energy yield Methane (a greenhouse gas) can leak from pipelines Low cost (with huge subsidies) Less air pollution than other fossil fuels Lower CO 2 emissions than other fossil fuels Shipped across ocean as highly explosive LNG Sometimes burned off and wasted at wells because of low price Moderate environmental impact Easily transported by pipeline Low land use Good fuel for fuel cells and gas turbines Fig. 14. 26, p. 342

The future of power plants There is currently being developed a combined cycle natural gas electric power plant with 60% efficiency This is much better than 32 -40% efficiency of others (coal, oil, nuke) What other reasons make it better?

Coal Solid fuel of combustible carbon, most formed 285 -360 million years ago Peat – 1 st, low heat content Lignite – 2 nd, low heat and low sulfur Bituminous Coal – 3 rd, high heat and abundant supply, high sulfur Anthracite – 4 th, high heat, low sulfur, limited supply

Increasing heat and carbon content Increasing moisture content Peat (not a coal) Lignite (brown coal) Bituminous Coal (soft coal) Anthracite (hard coal) Heat Pressure Partially decayed plant matter in swamps and bogs; low heat content Low heat content; low sulfur content; limited supplies in most areas Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content Highly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areas Fig. 14. 27, p. 344

Coal for energy Coal provides about 22% of the commercial energy in the world It is used to create 62% of the worlds electricity 75% of the worlds steel China is the largest user followed by US US creates 52% of energy with coal

Advantages Ample supplies (225– 900 years) High net energy yield Low cost (with huge subsidies) Disadvantages Very high environmental impact Severe land disturbance, air pollution, and water pollution High land use (including mining) Severe threat to human health High CO 2 emissions when burned Releases radioactive particles and mercury into air Fig. 14. 28, p. 344

The cost of coal Land disturbance Air pollution (especially sulfur dioxide) Co 2 emissions Water pollution Electricity production (coal) is the second largest producer of toxic emissions The most deadly emission is mercury

Wonderful coal 60, 000 babies annually are born with brain damage due to mercury exposure, typically from pregnant mothers eating mercury in fish Coal also releases more radioactive particles into the atmosphere than nuclear power plants Also, acid rain and methane release

Coal in the US Air pollutants kill thousands (estimates are from 60, 000 – 200, 000) Cause at least 50, 000 cases of respiratory disease Cost several billion dollars in property damage

The good news Fluidized bed combustion is reducing the amount of pollution Hot air is blown under a mix of crushed limestone and coal while it is burnt This removes most sulfur dioxide, reduces Nox and burns the coal more efficiently and cheaply

Flue gases Coal Limestone Steam Fluidized bed Water Air nozzles Air Calcium sulfate and ash Fig. 14. 29, p. 345

Coal gasification Solid coal can be converted into synthetic natural gas (SNG) It can also be made into synfuels (liquids) through coal liquefaction Neither is expected to play a major role in our future energy needs

Raw coal Remove dust, tar, water, sulfur Air or oxygen Raw gases Steam 2 C + O 2 Coal Pulverizer CO + 3 H 2 2 CO CH 4 + H 2 O Methane (natural gas) Recover sulfur Clean Methane gas Recycle unreacted carbon (char) Slag removal Pulverized coal Fig. 14. 30, p. 345

Advantages Disadvantages Large potential supply Low to moderate net energy yield Vehicle fuel Higher cost than coal High environmental impact Increased surface mining of coal High water use Higher CO 2 emissions than coal Fig. 14. 31, p. 346

Nuclear Energy Uranium 235 and plutonium 239 are split (nucleus) to release energy The reaction rate is controlled The energy heats water and turns it to steam Steam spins turbines connected to generators which create electricity

LWR light water reactors All US reactors are of this type, so know it

Small amounts of Radioactive gases Uranium fuel input (reactor core) Containment shell Waste heat Emergency core Cooling system Electrical power Steam Control rods Turbine Heat exchanger Hot coolant Hot water output Condenser Pump Coolant Black Moderator Useful energy 25 to 30% Generator Water Pump Cool water input Pump Waste heat Coolant passage Pressure vessel Shielding Periodic removal and storage of radioactive wastes and spent fuel assemblies Periodic removal and storage of radioactive liquid wastes Waste Water source heat (river, lake, ocean) Fig. 14. 32, p. 346

Nuclear is out of favor (unless you ask Bush) The US has not ordered a new nuclear facility since 1978, and 120 ordered since 1973 were cancelled Most countries are phasing out nuclear plants or are not continuing to expand their programs, except China who is trying to move away from dependence on coal

Why is nuclear not meeting expectations? Multi-billion dollar cost of construction Strict govt. safety regulations High operating costs More malfunctions than expected Poor management Public concern after Chernobyl, and Three Mile Island Investor concern about economic feasibility

Advantages Large fuel supply Low environmental impact (without accidents) Disadvantages High cost (even with large subsidies) Low net energy yield Emits 1/6 as much CO 2 as coal High environmental impact (with major accidents) Moderate land disruption and water pollution (without accidents) Catastrophic accidents can happen (Chernobyl) Moderate land use Low risk of accidents because of multiple safety systems (except in 35 poorly designed and run reactors in former Soviet Union and Eastern Europe) No acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants Spreads knowledge and technology for building nuclear weapons Fig. 14. 35, p. 349

Coal Ample supply High net energy yield Very high air pollution High CO 2 emissions 65, 000 to 200, 000 deaths per year in U. S. High land disruption from surface mining High land use Low cost (with huge subsidies) Nuclear Ample supply of uranium Low net energy yield Low air pollution (mostly from fuel reprocessing) Low CO 2 emissions (mostly from fuel reprocessing) About 6, 000 deaths per year in U. S. Much lower land disruption from surface mining Moderate land use High cost (with huge subsidies) Fig. 14. 36, p. 349

Chernobyl In the former Soviet Union, April 26, 1986 the reactor core went out of control and exploded sending a cloud of radioactive dust into the atmosphere 3, 576 – 32, 000 people died 400, 000 forced to evacuate 62, 000 square miles still contaminated More than 500, 000 people exposed to high level radiation Cost the govt. $385 billion

Three Mile Island March 29, 1979 in Harrisburg, Penn. Coolant failed and core melted Radioactive material escaped into air 50, 000 people evacuated Luckily the radiation release was believed to be too low to cause death or cancer Cleanup has cost $1. 2 billion so far

What do we do with the waste? Low level radioactive waste must be stored for 100500 years until it reaches a safe level (does not give off harmful ionizing radiation) This was done by sealing the waste in steel drums and dumping it in the ocean Today some countries (US) stores the waste at govt. run landfills, but no one wants to live anywhere near them

Waste container 2 meters wide 2– 5 meters high Several steel drums holding waste Steel wall Lead shielding Fig. 14. 38 a, p. 351

Up to 60 deep trenches dug into clay. As many as 20 flatbed trucks deliver waste containers daily. Barrels are stacked and surrounded with sand. Covering is mounded to aid rain runoff. Clay bottom Fig. 14. 38 b, p. 351

And the bad stuff? High level radioactive waste must be stored for 10, 000 to 240, 000 years until it reaches a safe level Currently most is stored at the reactor site, sealed in drums, in pools of water

Proposed methods of disposal Bury deep underground – this is the leading strategy currently Shoot it into space/Sun Bury it deep in the Antarctic ice sheet Dump it into descending subduction zones Bury in deep mud deposits on ocean floor Convert into less harmful isotopes (currently we do not have the technology)

Fig.

Radioactive contamination The EPA suggests that there are 45, 000 sites in the US (20, 000 belong to the DOE) It is expected to cost over $230 billion over the next 75 years More than 144 highly contaminated weapons construction sites will never be completely cleaned