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Energy Resources 03/19/
Types: non-renewable or exhaustible : a resource which exists in a fixed amount in various places in the Earth's crust. energy resources: coal, oil, natural gas, nuclear **may not be completely exhausted, but economically depleted , cost of extracting is greater than the monetary profit ** Some of these can have their supplies extended by Reusing and/or Recycling ** depletion time: the time it takes to use a certain fraction, usually 80%, of the known or estimated supply of a non-renewable resource perpetual : a resource that is essentially inexhaustible on a human time scale energy resources: solar energy, wind, hydropower, geothermal renewable or potentially renewable : a resource which can be replenished fairly rapidly through natural processes on a human time scale (hours or years or decades) energy resources: Biomass (trees, other plants, animals)
approximately 5% of world consumes 25% of world’s energy Non-Renewable Energy Resources: Fossil Fuels: coal: solid combustible mixture of organic compounds, with water, sulfur andnitrogen compounds. It forms from the remains of plants subjected to heat & pressure over millions of years. (swamps) * 30-98% carbon by weight Who controls it (where is it)? most abundant fossil fuel (~ 1 quadrillion metric tons) U.S., Russia, China, & India have 66% of proven reserves & ~ 85% of estimated undiscovered reserves (in swamps) U.S. alone has about 24% of global reserves provides ~ 21% of world's commercial energy, 65% of world's electricity, & to make 75% of world's steel How long will it last? at current usage rate, identified reserves will last 225 years if usages rate increases 2% per year 65 years add in unidentified reserves at current rate 900 years at increased rate (2%/year) 149 years Advantages Disadvantages
oil(crude oil): gooey liquid consisting of hydrocarbon compounds & smaller amounts of oxygen, sulfur and nitrogen (from organic marine sediments) * refined into: heating oil, diesel fuel, jet fuel, gasoline, tar, etc Who controls it (where is it)? OPEC (Oil Producing and Exporting Countries) has 67% of known reserves o (Saudi Arabia 26%, other Middle East countries ~64%) US has ~ 3% of known world reserves o (uses 26% extracted/year) US imports ~55% of oil it uses (was 36% in 1973) World reserves estimated at about 1 trillion barrels How long will it last? identified reserves at current usage rates ~ 53 years o (current usage rate is ~25 billion barrels/year) if usage rate increases 2%/year ~ 42 years add undiscovered oil, could add 20-40 years Advantages Disadvantages Ample supply (~50 years) Low cost (with subsidies), high net energy yield, easily transported, low land use Technology well developed, efficient distribution system Need to find substitute within 50 years Air pollution when burned, releases CO2 when burned, moderate water pollution, artificially low price (in some places) encourages waste and discourages search for alternatives
Natural gas : underground deposits of gases consisting of 50-90% by weightmethane gas & small amounts of heavier gaseous hydrocarbon compounds such as propane & butane. Who controls it(where is it)? Russia & Kazakhstan have ~ 42% of world's reserves other countries, Iran, Qatar, Saudi Arabia, Algeria, Nigeria, & Venezuela about 34% US has about 3% of world’s resources world reserves estimated at about 140 trillion cubic meters How long will it last? at current usage rate, known reserves 200 years if rate increases 2%/year 80 years add in undiscovered reserves up to 325 years Advantages Disadvantages Ample supplies High net energy yield, low cost (with subsidies) Less air pollution and lower CO emissions that other fossil fuels, moderate environmental impact, low land use, good for fuel cells and gas turbines Releases CO2 when burned Difficult to transfer across oceans, Methane (greenhouse gas) can leak out, Often burned and wasted at wells because of low price, Needs pipeline distribution system
Renewable Energy Resources: solar: direct radiant energy from the sun *Advantages for use in heating a home: energy is free, Net energy is moderate to high, relatively quick instillation, No CO2 emissions, Very low air and water pollution, Very low land usage, Moderate costs *Disadvantages for use in heating a home: Need access to sun 60% of time, blockage of sun by other structures, Need heat storage system, high cost(active system), Active collectors unattractive Passive: using sunlight to control heat, with help of things like windows and roofs Active: using sunlight to heat water to power pumps that create heat *Advantages for use in generating electricity: Moderate to high net energy, Low to moderate environmental impact, No CO 2 emissions, Relatively quick installation, Reduces dependence on fossil fuels *Disadvantages for use in generating electricity : Need access to sun, low efficiency, Need storage system or backup, High land use, high costs, DC current must be converted to AC hydropower: electrical power produced by falling or flowing water supplies about 6% of world's commercial energy, 4% in U.S. supplies 20% of world's electricity, 10% in U.S ., 99% in Norway *Advantages: Moderate to high net energy, High efficiency, Low-cost electricity, Long life span, Low CO2 emissions, Provides water for other uses (recreation, irrigation, flood control)
*Disadvantages: High construction costs, High environmental impact (by flooding natural areas, converting land habitat to lake habitat, changing water flow dynamics, sediment dynamics, etc.), May increase CO 2 emissions from decaying biomass in reservoir wind: electricity generated from using wind power (wind turbines) in 2001 worldwide production was enough to meet electricity needs of 7 million homes 18% of electrical needs met with wind power in Denmark large future potential with advancing technology *Advantages: Moderate to high net energy, High efficiency, moderate capital costs, Low electricity costs, Low environmental impact, No CO emissions *Disadvantages: Steady winds needed(desirable), Backup systems needed if no wind, High land use for wind farm system, Visual pollution, Some noise pollution, May interfere with flight of migratory birds geothermal: heat transferred from underground by either dry steam, wet steam, or hot water(heated on its own by crust or from volcanic activity) *Advantages: Very high efficiency, Moderate net energy, Low CO 2 emissions, Low cost, Low land use or disturbance, Moderate environmental impact *Disadvantages: Scarcity of suitable sites, Depleted if used too rapidly, Moderate to high local air pollution biomass : primarily trees, but other plants (corn and others) are being used more and more
Agricultural Resources 03/19/
Soil: the main agricultural resource, since without soil there are few plants and thus little agriculture *A complex mixture of inorganic minerals, decaying organic matter, water, air, and living organisms it varies widely in texture, structure, fertility, acidity, and amount _the problem isn't that there is not enough soil, but not enough in the right places that is good enough for agriculture (arable)_ AND that too much of what is arable is being lost or degraded Soil Erosion: * the movement of soil components by wind and water , often increased by human activities which reduce vegetation cover * leads to loss of soil fertility & increased sediment in lakes, rivers and other water systems * some estimate that topsoil is eroding faster than it forms on ~38% of the world’s crop land * nearly 40% of the world's arable land is seriously degraded by erosion, salinization, and water logging; and food production has been reduced on 16% of world's arable land * in the U.S. about 1/3 of the original topsoil has been lost by erosion ; although the rate of loss has slowed in recent years because of conservation efforts
Desertification: the conservation of marginal lands to desert-like conditions with a drop of 10% or more in productivity * caused by overgrazing, soil erosion, prolonged drought * most severe in areas near the world's major deserts which are over used by the local peoples EX: Sahel in Africa *** Salinization:** process by which soil accumulates too much salt to be productive because of toxicity * stunts crop growth, lowers crop yields, kills plants and makes the soil unusable * most severe on irrigated lands in drier climates; 21% of world's irrigated cropland has reduced yields from salinization, with a another 30% threatened * over watering or waterlogging the soil can also lead to reduced productivity and lowered fertility because of salinization *** Soil Fertility:** * plants eventually use-up the nutrients in the soil and if not replenished by decaying plants, then it must be done another way; Usually with organic or inorganic fertilizers
* ocean fisheries supply about 7% of the world's food * Types of Agriculture: Subsistence agriculture: primarily to provide food for direct consumption by the farmer and family * 3 types: Shifting cultivation , Pastoral nomadism , Intensive subsistence agriculture Commercial Agriculture: production of food/products primarily for sale off the farm * 7 types: Mixed crop & livestock farming , Dairy farming , Grain farming , Livestock ranching , Mediterranean agriculture ,
Commercial gardening & fruit farming , Plantation farming "Green Revolutions" : introduction of scientifically bred or selected varieties of grain (rice, wheat, corn) that, with high enough input of chemicals and water, can greatly increase crop yields * Yields can be 2 to 5 times that of traditional strains of the grains, on the sameamount of land. And often more than one crop per year can be harvested in some areas (multiple cropping). Results: * in the U.S., crop yields have more than doubled since 1950 with these techniques and new plants; with only .03% of the world's farm labor force, the U.S. produces 17% of the world's grain. * World grain production tripled between 1950-1990. BUT: ***** population growth is outpacing food production and distribution in some areas, especially in Africa * still large numbers of people (~ 800 million) are Undernourished (do not get enough food to meet basic energy needs)
Atmospheric Resources 03/19/
COMPOSITION OF THE ATMOSPHERE
* a mixture of discrete gases with solid and liquid particles suspended in it * Some components are fairly stable while others vary spatially and temporally ** constant Gases (found in same proportions within lower atmosphere) Constant Gases : 3 gases make-up just under 100% of the atmosphere (First 50 miles) Nitrogen (N) ~ 78% Oxygen (O2) ~ 21% Argon (Ar) ~.9% **** variable Gases (present in differing amounts spatially and/or temporally)** Variable Gases : 3 which influence weather and life systems Carbon Dioxide (CO2) Water vapor (H2O) Ozone (O3) Methane (CH4)
** Carbon dioxide : absorbs radiant energy emitted by earth (traps in heat) ** water vapor : quite variable throughout atmosphere (affects humidity) 4% by volume in tropics to < 1% in deserts source of clouds and precipitation absorbs radiant energy & important in energy transfer Water is only substance found in all 3 states (solid, liquid, gas) ** Ozone: concentrated in the stratosphere (10-50 km above surface) absorbs damaging ultraviolet (UV) radiation formation is by splitting an O 2 molecule with shortwave radiation and the single O atoms combining with an O 2 OZONE "HOLE" (Thinning) Thought to be caused by increasing amounts of chlorofluorocarbons, CFC’s, in the atmosphere CFC's are a family of chemicals used as coolants (Freon), propellants in aerosol cans, cleaners for computer chips, sterilants, fumigants, bubbles in foam insulation & packaging UV radiation breaks apart the CFC molecules and the chlorine atom then reacts with an O3 molecule breaking it apart (the chlorine atom takes away one of the oxygen atoms, then the new O2 cannot block out UV radiation) ozone layer thinning is primarily around the Antarctic & Arctic areas (because the chlorine builds up over winter then it’s always light out for an entire season and thus more vigorously breaks apart ozone ) ozone layer may be reduced by at much as 50% around the Antarctic and 11-38% around the Arctic area 1% loss of O3 leads to a 2% increase in UV radiation at the earth’s surface ** Consequences (of less ozone) :
if the T° increases with altitude it's called an inversion o happens mainly around cities a change in T° with a change in altitude is called the lapse rate or the Temperature lapse rate Layers of the Atmosphere: 2 general regions : based on chemical composition Homosphere : uniform chemical composition; from surface to a height of 80 - 100 km (50 - 63 mi) Heterosphere : changing chemical composition; from top of homosphere upwards 4 main layers: based on temperature: Homosphere: (Humans have an affect on) Troposphere : T° usually deceases with increasing altitude; from surface to average height of 12 km (7.5 mi or 40,000') 8-10 miles Where we live Where the greenhouse gasses are: CO2, Methane, Water Vapor
Stratosphere : T° stays constant or increases with altitude (because sunlight is absorbed by ozone); contains the ozone layer(ozonosphere) ; very little H 2 O Heterosphere: (Humans don’t have much affect on) Mesosphere : T° decreases with increasing altitude; between ~ 50 & 80 km (31 & 50 mi) Thermosphere : T° increases dramatically with altitude; T°'s may reach upwards of 900°C (1650°F); area above 80 km (50 mi) CLIMATE CHANGE: EVIDENCE & TIMING ** Variations in climate on many different time scales from decades to millions of years, & the possible causes of such variations * climate system; the interaction of the atmosphere, lithosphere, biosphere, & hydrosphere * when change occurs in one sphere, it affects the other spheres Evidence of Climate Change Seafloor sediments, Oxygen isotope analysis,
