Renewable Transportation

PRODUCING ENERGY FROM BIOMASS Plant materials Animal wastes (#2) burned to provide heat or electricity Can be converted into gaseous or liquid biofuels

Converting Plants and Plant Wastes to Liquid Biofuels: An Overview Motor vehicles can run on ethanol, biodiesel, and methanol produced from plants and plant wastes. The major advantages of biofuels are: Crops used for production can be grown almost anywhere. There is no net increase in CO2 emissions. Widely available and easy to store and transport.

Case Study: Producing Ethanol Crops such as sugarcane, corn, and Switchgrass can be fermented to ethanol. Also, agricultural, forestry, and municipal wastes Switchgrass can remove CO2 from the troposphere and store it in the soil.

Case Study: Producing Ethanol 10-23% pure ethanol makes gasohol which can be run in conventional motors. (blend of ethanol and unleaded gasoline) Ethanol (E85) is a mixture of 85% ethanol and 15% gasoline. fuel for flexible-fuel vehicles. Biodiesel is made by combining alcohol with vegetable oil made from a variety of different plants. Biodiesel from algae. Less land, not competing as a food source.

Some reduction in CO2 emissions Lower driving range Trade-Offs Ethanol Fuel Advantages Disadvantages Large fuel tank needed Some reduction in CO2 emissions Lower driving range Low net energy (corn) High net energy (bagasse and switchgrass) Much higher cost Corn supply limited Reduced CO emissions May compete with growing food on cropland Figure 17.27 Trade-offs: general advantages and disadvantages of using ethanol as a vehicle fuel compared to gasoline. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Can be sold as gasohol Higher NO emissions Potentially renewable Corrosive Hard to start in cold weather Fig. 17-27, p. 407

Slightly increased emissions of nitrogen oxides Trade-Offs Biodiesel Advantages Disadvantages Reduced CO emissions Slightly increased emissions of nitrogen oxides Reduced CO2 emissions (78%) Higher cost than regular diesel Reduced hydrocarbon emissions Low yield for soybean crops Better gas mileage (40%) May compete with growing food on cropland High yield for oil palm crops Figure 17.29 Trade-offs: general advantages and disadvantages of using biodiesel as a vehicle fuel compared to gasoline. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Loss and degradation of biodiversity from crop plantations Moderate yield for rapeseed crops Potentially renewable Hard to start in cold weather Fig. 17-29, p. 408

Hybrid Vehicles Hybrid gasoline-electric engines with an extra plug-in battery could be powered mostly by electricity produced by wind and get twice the mileage of current hybrid cars. How does a Prius work?

Fuel-Cell Vehicles Video Fuel-efficient vehicles powered by a fuel cell that runs on hydrogen gas are being developed. Combines hydrogen gas (H2) and oxygen gas (O2) fuel to produce electricity and water vapor (2H2+O2  2H2O). Emits no air pollution or CO2 if the hydrogen is produced from renewable-energy sources. Hydrogen comes from electrolysis of water.

Body attachments Mechanical locks that secure the body to the chassis Air system management Universal docking connection Connects the chassis with the drive-by-wire system in the body Fuel-cell stack Converts hydrogen fuel into electricity Rear crush zone Absorbs crash energy Drive-by-wire system controls Cabin heating unit Side-mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors Hydrogen fuel tanks Front crush zone Absorbs crash energy Figure 17.8 Solutions: prototype hydrogen fuel-cell car developed by General Motors. This ultralight and ultrastrong car consists of a skateboard-like chassis and a variety of snap-on fiberglass bodies. It handles like a high-speed sports car, zips along with no engine noise, and emits only wisps of warm water vapor and heat—no smelly exhaust, no smog, no greenhouse gases. General Motors claims the car could be on the road within a decade, but some analysts believe that it will be 2020 before this and fuel-cell cars from other manufacturers will be mass produced. (Basic information from General Motors) Electric wheel motors Provide four-wheel drive; have built-in brakes Fig. 17-8, p. 390

Converting to a Hydrogen Economy Iceland plans to run its economy mostly on hydrogen Produced via hydropower, geothermal, and wind energy Doing this in industrialized nations is more difficult. In the U.S. we would need the infrastructure for hydrogen-fueling stations 12,000 needed at $1 million apiece High cost of fuel cells.