ppt - Chapter 9

Report
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 to
Push pistons and run
The car engine.
No pollutants at all, BUT
Technology not mature.
Changing the Burning Process
More efficient cars emit less CO2 per mile traveled.
(In the 1970s, estimated that could run
All cars on ethanol and methanol derived from
Fermented biomass if all cars averaged 60 miles
Per gallon.)
Number is out of date, but at some gas mileage
It is possible to run all cars on renewable sources
Of 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 does
Not burn up. This gasoline
Constitutes an air pollutant
(what is its classification?)
To keep gasoline from returning to
The air, this gasoline is recirculated
Back into the combustion chamber.
Exhaust Gas Recirculation
Exhaust gases are
Removed from the
Crankcase and then
Recirculated back into
The carburetor.
Other Pollution Controls
Minimize CO and hydrocarbons by improving burning
Of the fuel.
To improve burning: use leaner fuels and increase
Temperatures in the combustion chamber.
Leaner fuels: means mixture of air plus fuel has more
Air and less fuel.
But leaner fuels increase Nox formation because
Burning is at higher temperatures and more oxygen is
Available to form Nox.
Catalytic converters: help to get around these problems.
They require unleaded gasoline.
Automobile Emissions Standards
Standards met by using catalytic converters, engine
Redesign and additives (MBTE, other oxidants).
Mass Transit
Shin Kan Sen (Bullet Train), TGV (Train Grande Vitesse)
Both are MAGLEV (magnetic levitation) trains
Travel at up to 300 km/hr (180 mph)
Shin Kan Sen: Trains leave every 3 hours: Tokyo-Kyoto
TGV-not so often
Buses like subways(pay fare before getting on in enclosed area)
Most efficient form of public transport
Exist in Brazil
Biggest problem: Load factor
If not used enough, mass transit is LESS energy efficient than cars
90% of public funds in US used to build highways
True Energy Use by Transportation
In theory, a train
Is 15 times more
Energy efficient than
A car.
Considering load
Factors, what is
The more typical
Ratio of efficiency?
What is the most
Energy efficient
Transportation?
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 donā€™t really reduce overall pollution, they
Shift it in time or in space, what are these methods?
Shifting the Pollution in Space
Sudbury Ontario: giant astrobleme-Worlds biggest Ni mine
One of two oldest meteorite impact structures: 1.8 Ga (1800 Ma)
(Canadian Nickels)
Ni is a heavy
metal; large quantities
Are poisonous to
people and plants.
What did building a
Taller smoke stack at
Sudbury do to the
landscape?
(Dumping the slag)
Shifting the Pollution in Time
Why does shifting the time at which emissions are made
Affect 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 device
For factories.
Power Plant Pollution Control
What is being
Removed by
The electrostatic
Precipitator?
By the wet
Scrubber?
Fluidized Bed Combustion
Key Reaction:
CaO (lime) + 1/2O2 +SO2
= CaSO4 (calcium sulfate)
Limestone = CaCO3
What else besides calcium sulfate
Is emitted by Fluidized Bed
Combustion (FBC)?
FBC reduces NOx by lowering
Temperature of burning
Cleaning the Coal by Crushing
and Settling
FeS2 or pyrite (fools gold):
Very dense.
Can separate from coal using
Settling techniques. Why?
This cleans the coal of part
Of its sulfur.
Remaining sulfur: chemically
Bonded with the coal.
Cost of Pollution Controls
Cost of pollution controls
Left: normalized to 100%
Cost for all pollution
Controls
Right: as a percentage of
Total power plant cost
(only one line is relevant)
Actual cost: typically
About 1/3 of plant cost
Physics of Waste Heat
Q = m* c* deltaT
Q is heat added, m is mass, c is specific heat
Delta T is the temperature change
What is waste heat?
Why do you get always get waste heat when
You generate power using a heat engine?
Waste Heat and Water Use
Which users are
Increasing their
water consumption
the most?
1855 to 1980?
1980 to 2000?
(Graph is for the
United States)
Why?
Waste Heat from Power Plants
Which portion of the waste heat goes to heat up water
In a water-cooled plant? Which plant type generates
The most waste heat per unit of power output?
Dissolved Oxygen in Water vs T
How does the amount
Of dissolved oxygen in
The water change as a
Function of temperature?
Why?
PV=nRT
Oxygen Consumption of Fish vs T
Why do fish need more oxygen
As the temperature of the water
Increases?
Given the solubility of oxygen
In 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 publish
This graph?
Fish: Response to Temperature
Solid dot:
Upper lethal
Limit for a
Given species
Open dot:
Best T for
spawning
Solid blocks:
Preferred
Temperature
Range
Temperature and Growth of Food
Animals
What is the optimum
Temperature for
Hens, catfish, shrimp?
Thermal Pollution from Power Plants
Eutrophication:
Natural aging of
Lakes
Promoted by waste
Heat from power
Plants.
Why?
Natural Draft Cooling Tower
Why does this cooling
Tower lack a fan?
Mechanical Draft Cooling Tower
Why does this tower
Need a fan?
(Active vs Passive
Cooling Tower)
Air to Liquid Heat Exchanger
What is the
Heat being
Extracted from?
Why?
Recuperator: Also extracts heat
Why is it useful to heat incoming
Air and cool outgoing air
(this is a heat engine)?
Uses of Waste Heat
Cogeneration
Aquaculture
Greenhouse heating
Desalination of seawater
Increase crop growth in cold season
Preheat air
Other??

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