Chapter 9

Automobile Emissions Controls

Stationary Emissions Control

Cost of Emissions Controls

Thermal Pollution from Energy Generation

Ecological Effects of Thermal Pollution

Cooling Towers

Using Waste Heat

Energy in the News

Thursday Energy Roundtable at SIPA Cancelled: Not yet rescheduled

Automobile Emissions Controls

Emissions can be controlled in several ways

Change the fuel used by the car

Change the way that the engine burns the fuel

Decrease the use of cars by subsidizing mass transit

Changing the Fuel

What are other names for methanol, ethanol and compressed gas?How are they made? Other drawbacks of these fuels?

The Newest Fuel: Nitrogen

Newest alternative fuel(reported this Monday)

Works by using decompression of Liquid nitrogen toPush pistons and runThe car engine.

No pollutants at all, BUTTechnology not mature.

Changing the Burning ProcessMore efficient cars emit less CO2 per mile traveled. (In the 1970s, estimated that could runAll cars on ethanol and methanol derived from Fermented biomass if all cars averaged 60 milesPer gallon.) Number is out of date, but at some gas mileageIt is possible to run all cars on renewable sourcesOf hydrocarbons.

Amory Lovins: using the best technology:Could potentially build cars That get 150 miles per gallon.

Positive Crankcase Ventilation

At the edges of the combustion Chamber of the engine (above the piston tops), there is a thin layer of gasoline that doesNot burn up. This gasolineConstitutes an air pollutant(what is its classification?)

To keep gasoline from returning toThe air, this gasoline is recirculatedBack into the combustion chamber.

Exhaust Gas Recirculation

Exhaust gases areRemoved from theCrankcase and thenRecirculated back intoThe carburetor.

Other Pollution Controls

Minimize CO and hydrocarbons by improving burningOf the fuel. To improve burning: use leaner fuels and increaseTemperatures in the combustion chamber.

Leaner fuels: means mixture of air plus fuel has moreAir and less fuel.

But leaner fuels increase Nox formation because Burning is at higher temperatures and more oxygen isAvailable to form Nox.

Catalytic converters: help to get around these problems.They require unleaded gasoline.

Automobile Emissions Standards

Standards met by using catalytic converters, engineRedesign and additives (MBTE, other oxidants).

Mass TransitShin Kan Sen (Bullet Train), TGV (Train Grande Vitesse)Both are MAGLEV (magnetic levitation) trainsTravel at up to 300 km/hr (180 mph)

Shin Kan Sen: Trains leave every 3 hours: Tokyo-KyotoTGV-not so often

Buses like subways(pay fare before getting on in enclosed area)Most efficient form of public transportExist in Brazil

Biggest problem: Load factorIf not used enough, mass transit is LESS energy efficient than cars90% of public funds in US used to build highways

True Energy Use by Transportation

In theory, a trainIs 15 times moreEnergy efficient thanA car.

Considering loadFactors, what is The more typical Ratio of efficiency?

What is the most Energy efficientTransportation?

Reducing Pollution from Stationary Sources

How pollution is reduced;

1) Change the fuel

2) Change how the fuels burns

3) Remove pollutants after burning

Other methods don’t really reduce overall pollution, theyShift it in time or in space, what are these methods?

Shifting the Pollution in SpaceSudbury Ontario: giant astrobleme-Worlds biggest Ni mineOne of two oldest meteorite impact structures: 1.8 Ga (1800 Ma)(Canadian Nickels)

Ni is a heavymetal; large quantitiesAre poisonous to people and plants.

What did building aTaller smoke stack at Sudbury do to thelandscape?

(Dumping the slag)

Shifting the Pollution in Time

Why does shifting the time at which emissions are madeAffect the resulting air quality? (Ozone for example).

Other strategies not so nice. (At U.S. Mexican border).El Paso area?

Removing the Pollution

Mary Walton invented an early pollution control deviceFor factories.

Power Plant Pollution Control

What is beingRemoved byThe electrostaticPrecipitator?

By the wet Scrubber?

Fluidized Bed Combustion

Key Reaction:

CaO (lime) + 1/2O2 +SO2

= CaSO4 (calcium sulfate)

Limestone = CaCO3

What else besides calcium sulfateIs emitted by Fluidized Bed Combustion (FBC)?

FBC reduces NOx by loweringTemperature of burning

Cleaning the Coal by Crushingand Settling

FeS2 or pyrite (fools gold):Very dense.Can separate from coal using Settling techniques. Why?

This cleans the coal of partOf its sulfur. Remaining sulfur: chemicallyBonded with the coal.

Cost of Pollution Controls

Cost of pollution controlsLeft: normalized to 100%Cost for all pollution ControlsRight: as a percentage ofTotal power plant cost(only one line is relevant)Actual cost: typicallyAbout 1/3 of plant cost

Physics of Waste Heat

Q = m* c* deltaT

Q is heat added, m is mass, c is specific heatDelta T is the temperature change

What is waste heat?Why do you get always get waste heat whenYou generate power using a heat engine?

Waste Heat and Water Use

Which users areIncreasing their water consumption the most?

1855 to 1980?1980 to 2000?

(Graph is for theUnited States)

Why?

Waste Heat from Power Plants

Which portion of the waste heat goes to heat up waterIn a water-cooled plant? Which plant type generatesThe most waste heat per unit of power output?

Dissolved Oxygen in Water vs T

How does the amountOf dissolved oxygen inThe water change as aFunction of temperature?

Why?PV=nRT

Oxygen Consumption of Fish vs T

Why do fish need more oxygenAs the temperature of the waterIncreases?

Given the solubility of oxygenIn water as a function of temperature(in the previous slide), what happens to the fish if the water gets too hot?

Why would it be difficult to publishThis graph?

Fish: Response to TemperatureSolid dot:Upper lethalLimit for aGiven species

Open dot:Best T for spawning

Solid blocks:PreferredTemperatureRange

Temperature and Growth of Food Animals

What is the optimumTemperature forHens, catfish, shrimp?

Thermal Pollution from Power Plants

Eutrophication:Natural aging ofLakes

Promoted by wasteHeat from powerPlants.

Why?

Natural Draft Cooling Tower

Why does this coolingTower lack a fan?

Mechanical Draft Cooling Tower

Why does this towerNeed a fan?

(Active vs PassiveCooling Tower)

Air to Liquid Heat Exchanger

What is theHeat being Extracted from?

Why?

Recuperator: Also extracts heat

Why is it useful to heat incomingAir and cool outgoing air(this is a heat engine)?

Uses of Waste HeatCogenerationAquacultureGreenhouse heatingDesalination of seawaterIncrease crop growth in cold seasonPreheat airOther??