Chapter 14 3 renewable energy for transportation
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Chapter 14.3 Renewable Energy for Transportation - PowerPoint PPT Presentation

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Chapter 14.3 Renewable Energy for Transportation. BIOFUELS complex organic matter (mainly plants) can be processed to make fuels for vehicles ethyl alcohol production has doubled since 2000 biodiesel industry has grown 3x in the same time period. ethanol.

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Chapter 14 3 renewable energy for transportation
Chapter 14.3Renewable Energy for Transportation


    • complex organic matter (mainly plants) can be processed to make fuels for vehicles

    • ethyl alcohol

      • production has doubled since 2000

    • biodiesel

      • industry has grown 3x in the same time period


  • produced by the fermentation of sugars and starches (usually grain, sugar cane, or sugary fruits)

  • production costs make ethanol more expensive than gasoline until oil costs more than $55 per barrel

  • corn-based fuels provide another market for the crop

  • 2005-06: 4.3 billion gallons of ethanol used for fuel in U.S. (accounting for 14% of corn crop)

  • production credit of 51 cents per gallon helps to make ethanol competitive

Ethanol benefits
ethanol benefits?

  • with corn cropland needed for animal feed and export, there is very little room for expansion of ethanol industry

  • questionable energy efficiency of corn-based ethanol:

    • requires fossil fuel energy to produce, transport, and process corn

    • recent analysis suggests that replacing gasoline with ethanol reduces greenhouse gas emissions only 13%

    • with negligible environmental benefits, main reason for using ethanol is to reduce dependence on oil

  • production of ethanol from sugar is much less costly

Ethanol as substitute
ethanol as substitute

  • mixtures of alcohols and gasoline should help countries meet their domestic fuel demands as demand continues to rise

  • ethanol works as a substitute for methyl tertiary butyl ether (MTBE)

    • MTBE is a petroleum derivative that has been used to make fuel burn cleaner

    • both ethanol and MBTE improve air quality when they are a part of reformulated gasoline

    • many metropolitan areas depend on these additives to help them meet Clean Air Act standards

    • unfortunately, MBTE is a carcinogen in animals and has been showing up in water supplies


  • mix of 20% soybean oil in normal diesel fuel, but any natural oil or fat can be mixed with an alcohol to make the fuel

  • sales have reached 75 million gallons, which is comparable to diesel from fossil fuels (partly due to a sizeable tax credit)

  • potential exists for most any organic waste to be converted to biodiesel

    • Ex. factory in Missouri converts wastes from Butterball turkey-processing plant to biofuels

Hybrid electric vehicles
hybrid electric vehicles

  • combine a conventional gasoline engine and a battery-powered electric motor to achieve substantial improvements in fuel economy

  • examples:

    • Toyota Prius—55 mpg

    • Honda Insight—56 mpg

  • most of today’s hybrids are versions of standard gasoline engines, combined with a large battery

    • two electric motors work as generators that charge the battery as the car slows down

    • car starts out under electric power, then kicks on gasoline engine as speed increases

    • at stops and down hills, gasoline engine shuts off


  • conventional car engines can be run on hydrogen gas in the same manner as they are now able to run on methane

    • neither carbon dioxide nor hydrocarbon pollutants are produced

    • main byproduct is water vapor, along with some nitrogen oxides (NOx)

  • problem with hydrogen is that it is extremely abundant as an element, but not in the energy-rich gas form

    • can be extracted from water, but requires input of significant amounts of energy

Production of hydrogen
production of hydrogen

  • plants have split water for millions of years to provide H ions for photosynthesis

  • 2 proposed methods of mimicking plants:

    • 1. use a catalyst (titanium dioxide is receiving most attention) to absorb visible light and split water

      • has worked with an efficiency of 8.5% (reaching 10% would achieve the DOE’s standard as a useful catalyst)

    • 2. pass an electrical current through water and cause the water molecules to dissociate (electrolysis)

      • some suggest that solar energy (collected by solar troughs) in the southwest U.S. should be used to power electrolysis

      • hydrogen produced could then be transported via underground pipelines (some of which already exist)

Fuel cells
fuel cells

  • an alternative to burning hydrogen in internal combustion engines is using it in fuel cells

    • fuel cells would produce electricity and power an electric motor

    • hydrogen or some other fuel is chemically combined with oxygen to create an electrical potential

    • to power vehicle, fuel cells are combined into a fuel cell stack

    • vehicle would require: a hydrogen storage device, a cooling system, and a device to force oxygen into the fuel cells

  • obstacles include high cost and lack of infrastructure for hydrogen refueling