class notes

43
Dr. Mahmud Faculty: HMd Class Note 8 Renewable and Non- renewable energy ENV 107: Environmental Science Fall 2015

Upload: akib-zabed-washak

Post on 14-Jul-2016

222 views

Category:

Documents


0 download

DESCRIPTION

fdg

TRANSCRIPT

  • Dr. MahmudFaculty: HMd

    Class Note 8

    Renewable and Non-renewable energy

    ENV 107: Environmental ScienceFall 2015

    Dr. Mahmud

  • Dr. MahmudIntroductionHuman society, like all living organisms, is dependent on a continuous flow of energy for survival.This need for energy has increased dramatically with increased technology and population.The average North American uses 4.8 times as much energy as the global per capita average and 40 times as much energy as the typical individual in Bangladesh.This massive use of energy has brought material prosperity to the industrialized world, but at a substantial cost to the environment.Where will the energy come from in the future? How will we manage the environmental impacts?

    Dr. Mahmud

  • Dr. MahmudEnergy History Burning wood was the earliest human energy resource. Muscle power provided by domestic animals has been important since dawn of agriculture 10,000 years ago. Wind and water power have been around almost as long. Switch to coal power in 1800s due to diminishing wood supplies & invention of steam engine. Switch to oil in 1900s because easier to ship, store, & burn.

    Dr. Mahmud

  • Dr. MahmudThe development of energy sources has in large part supported the development of civilization.

    Dr. Mahmud

  • Dr. Mahmud

    Dr. Mahmud

  • Dr. MahmudNote how the mix of primary sources has changed over the years and how the total amount of energy consumed has continued to grow. Note also the skyrocketing increase in use of oil after World War II (1945) as the private car became common.

    Dr. Mahmud

  • Dr. MahmudWorld Energy Use

    Dr. Mahmud

  • Dr. MahmudEnergy types

    Non-renewable : Oil, Gas, Coal, Nuclear powerRenewable : Solar, Hydropower, Biomass, Wind, Tidal, etc.The fossil fuels (coal, oil, natural gas) formed over geological time from the remains of plants and animals buried under layers of sedimentary rock.People are consuming fossil fuels millions of times faster than they are forming.

    Dr. Mahmud

  • Dr. MahmudCarbon Cycle

    Dr. Mahmud

  • Dr. MahmudPower PlantsSupplying the People with ElectricityA large portion of the energy sector is devoted to supplying consumers with electricity to run electrical appliances, lighting, heating, and so forth. Most commercial power plants are described by the type of primary energy used to operate the turbine driven generators.

    Dr. Mahmud

  • Dr. MahmudPower PlantsMost utilities that generate electricity must have a larger generating capacity than is actually needed much of the time.The surplus capacity provides a reserve to meet fluctuation in peak demand or to cover repair and maintenance downtime for power plants or portions of the electrical grid.Brownouts and blackouts can occur that disrupt society if demand of energy exceeds supply.

    Dr. Mahmud

  • Dr. MahmudWorld Electricity Generation

    Dr. Mahmud

  • Dr. MahmudCoalCoal is much more abundant than oil and more evenly distributed throughout the world.The worlds known coal supply could last about two hundred years at current consumption rates, much less time if it is used as a replacement when the oil resource is exhausted.

    Dr. Mahmud

  • Dr. MahmudProblems with CoalMiningBetween 1870 and 1950, more than 30,000 coal miners died of accidents and injuries in Pennsylvania alone.Several thousands have died of respiratory diseases. (black lung disease)Strip mining often makes the land unfit for other uses; reclamation efforts often superficial.Land subsidence might occur water pollution

    Dr. Mahmud

  • Dr. MahmudProblems with CoalAir PollutionBurning releases radioactivity and toxic metals into the atmosphere.Burning releases sulfur oxides and nitrogen oxides - acid rainBurning releases carbon dioxide global warming

    Dr. Mahmud

  • Dr. MahmudEnvironmental Impacts of the Coal Fuel Cycle

    Dr. Mahmud

  • Dr. MahmudOil Petroleum is formed very similar to coal Mostly marine organic material buried in sediment and subjected to high pressure and temperature.Oil Pool usually composed of individual droplets or thin film permeating spaces in porous sandstone or limestone. Proven reserves used at current consumption rate estimated to last 45 years.

    Dr. Mahmud

  • Dr. MahmudOil Reserve

    Dr. Mahmud

  • Dr. MahmudUnconventional Oil ResourcesOil Shales and Tar SandsEstimates of total oil supply usually do not reflect large potential from unconventional oil sources:

    - shale oil Fine grained sedimentary rock rich in solid organic materials, named as Kerogen. Kerogen can be liquidified and extracted.- tar sand bituminous semi-solid sand.Could potentially double total reserve, but currently expensive and environmentally damaging to extract.

    Dr. Mahmud

  • Dr. MahmudNATURAL GAS

    Worlds third largest commercial fuel.Produces half as much CO2 as equivalent amount of coal.Most rapidly growing energy source because its convenient, cheap, & clean.Difficult to ship long distances, and to store in large quantities.Usually Oil and gas stay together. Current reserves represent roughly 60 year supply at present usage rates.

    Dr. Mahmud

  • Dr. MahmudUnconventional Gas SourcesMethane hydrate - Small individual molecules of natural gas trapped in a crystalline matrix of frozen water.Deposits in arctic permafrost & beneath deep ocean sediments.Thought to hold 10,000 gigatons of carbon, or twice as much as combined amount of all traditional fossil fuels. Difficult to extract, store, and ship. Also presents risk of released methane gas - global warming

    Dr. Mahmud

  • Dr. MahmudNuclear PowerNuclear power supplies about 6.5% of the worlds commercial energy, but supplies a much larger percentage of electrical generation in some industrial countries.Growing public concerns about safety, and the high cost of nuclear power, are changing the earlier interest for nuclear-generated electricity in many countries.Since 1978, there have been no new nuclear plants ordered in the U.S. but other countries like China and India have continued developing their nuclear capacity.

    Dr. Mahmud

  • Dr. MahmudProblems with Nuclear EnergyNuclear wasteLow level wastesHigh level wastesAccidentsChernobyl (1985)Three Mile IslandRancho SecoBrowns FerryDiablo Canyon

    Dr. Mahmud

  • Dr. MahmudDisposal ProblemsProposals to dispose of waste include:Rocket loads of waste launched into the sunDeep sea burialBurial in Antarctic glaciersBurial in stable geologic zones

    Dr. Mahmud

  • Dr. MahmudRENEWABLE ENERGYAlternative energy sources are usually renewable, sustainable or potentially sustainable, and environmentally benign.The alternative energy sources include:Hydroelectric powerBiomass fuelsSolar powerGeothermal powerWind powerOcean energy

    Dr. Mahmud

  • Dr. MahmudHydropowerHydroelectricity is the fourth largest global source of commercial energy production and consumption.After dam construction is complete, it is a relatively cheap and very clean method of generating electricity.

    Dr. Mahmud

  • Dr. MahmudHydropowerDespite the advantages, there are several drawbacks:Initial construction is very expensiveFlooding large tracts of land destroys natural habitats and dislocates indigenous peopleReservoirs have relatively short life spans due to sedimentationReservoirs modify water quality and reduce nutrient cycling

    Dr. Mahmud

  • Dr. MahmudThe Future of HydropowerSmall-scale hydropower facilities may be more compatible with the natural environment because large-scale hydropower can disrupt water flow and damage the natural environment.Courtesy of Warren Gretz/National Renewable Energy Laborator

    Dr. Mahmud

  • Dr. MahmudBiomass

    Dr. Mahmud

  • Dr. MahmudBiomassThe total power needs for the Mason-Dixon Dairy, located in Pennsylvania, are obtained as a byproduct of cow manure, and nutrients are recycled in the process. Excess power, nearly half of what is produced, is sold to the local utility.

    Dr. Mahmud

  • Dr. MahmudSolar EnergyMuch of the energy we use at present is indirect solar energy.While people currently harness about 13 terawatts of energy, the sun delivers about 80,000 terawatts to the Earth.Direct solar energy is dilute, diffuse, and intermittent.The large amount of solar energy available could potentially solve many of our current energy problems.

    Dr. Mahmud

  • Dr. MahmudSolar Energy

    Dr. Mahmud

  • Dr. MahmudSolar energy to heat houses and water

    Dr. Mahmud

  • Dr. MahmudEnvironmental Advantages andDisadvantages of Solar EnergySunlight is a fairly perfect abundant, renewable energy resourceThe main obstacle to using solar energy is its dispersed nature and intermittency.Large tracts of solar power plants can be disruptive to ecosystems like the desert biota.Production and deployment of solar cell arrays use fossil fuels and other poisonous chemicals.

    Dr. Mahmud

  • Dr. MahmudWind Power Estimated wind power could produce fifty times current nuclear generation. Wind farms are large concentrations of windmills in open plains, on mountain ridges, or at sea. (By 2030 Denmark plans to generate of nations power this way.)Problems Windmills kill birds Large need large areaWindmills may degrade areas scenic resources

    Dr. Mahmud

  • Dr. MahmudWind Power

    At present, wind power generates less than 1.5-2% of the worlds electricity but its use is growing rapidly.The cost of wind-derived electricity has dropped dramatically in the last decade.Wind farms now generate electricity at competitive prices.

    Dr. Mahmud

  • Dr. MahmudGeothermal EnergyThe energy from Earths hot interior can be used to heat buildings directly or to generate electricity.Geothermal field, located in The Geysers, CA

    Dr. Mahmud

  • Dr. MahmudGeothermal EnergyThere are four basic types of geothermal deposits:Hydrothermal reservoirsGeopressured brinesMagmaHot, dry rockDisadvantages of Geothermal EnergyGeothermal energy operationsrequire large quantities of watermay release hazardous substances.

    Dr. Mahmud

  • Dr. MahmudOcean EnergyCommercial ocean energy developments have been based on both the movement of water and on its temperature.Both wave action and tidal flows have been used to generate electricity.Ocean thermal energy conversion used the temperature difference between deep ocean water and solar-heated surface water to run a turbine and generate electricity.

    Dr. Mahmud

  • Dr. Mahmud

    Dr. Mahmud

  • Dr. MahmudEnergy StorageA major obstacle to the widespread use of alternative energy is the problem of energy storage and transportation.Most electricity is used as soon as it is generated.Unlike most alternative energy sources, fossil fuels are compact, storable, and transportable.

    Dr. Mahmud

  • Dr. MahmudEnergy ConservationThe simplest and cheapest way of stretching our energy resources and mitigating energy-related problems is through energy conservation and energy efficiency.A big component of energy conservation is reducing fossil fuels (coal, oil, and natural gas).Bangladesh : Gas???...people keep their gas burner open to save a match stickno metering system at all !!

    Dr. Mahmud

  • Dr. MahmudSaving EnergyEnergy can be saved by:Not converting it from one form to another unnecessarilyIncreasing the efficiency of energy conversionsNot transporting energy unnecessarilyIncreasing the efficiency with which energy is transportedEncouraging conservation

    Dr. Mahmud