Energy and the Environment

Energy and the Environment

Fall 2013Instructor: Xiaodong Chu

Email ： [email protected] Tel.: 81696127

mailto:[email protected]

Flashbacks of Last Lecture

• Air pollution – Air-quality modeling– Photo-oxidants– Acid deposition

• Water pollution• Land pollution

Primary Pollutants

COCO CO2CO2Secondary Pollutants

SO2SO2 NONO NONOCH4 and most

other hydrocarbonsCH4 and most

other hydrocarbons

SO3SO3

Most suspended particlesMost suspended particles H2O2H2O2

H2SO4H2SO4

PANsPANsMost NO3

– and SO42– saltsMost NO3

– and SO42– salts

Natural Source Stationary Human Source

Human Source

Mobile

NO2NO2

O3O3

HNO3HNO3

Sources and Types of Air Pollutants

Air Pollution Cases: Smog And Haze

Industrial Smog

• Chemical composition of industrial smog• How pollutants are formed from burning coal

and Oil, leading to industrial smog?

Ammonium sulfate [(NH 4 )2SO4]

Ammonia (NH3)

Sulfuric acid (H2SO4)

Water vapor (H2O) Carbon monoxide (CO) and carbon

dioxide (CO2)Sulfur trioxide (SO3)

Oxygen (O2)

Sulfur dioxide (SO2)

Burning coal and oil

Oxygen (O2)

Sulfur (S) in coal and oil Carbon (C) in coal and oil

Photochemical Smog

• Photochemical Smog– Chemical composition– Sources

• VOCs + NOx + Heat + Sunlight yields

– Ground level O3 and other photochemical oxidants

– Aldehydes– Other secondary pollutants

PANS and other pollutantsVolatile organic compounds (VOCs)

Ozone (O3)

Oxygen (O2)

Nitric oxide (NO) + Oxygen atom (O)

Water vapor (H2O)

Hydrocarbons UV radiationPeroxyacyl nitrates (PANs) Nitrogen dioxide (NO2)

Oxygen (O2)

Nitric oxide (NO)

Oxygen (O2) Burning fossil fuels

Nitrogen (N) in fossil fuel

Ingredients of Photochemical Smog

• Three main ingredients of photochemical smog– High automobile traffic volume – Plenty of sunlight– Very stable atmosphere

• Temperature inversion

• A temperature inversion occurs when cold air is trapped near Earth’s surface by a layer of warmer air

• Polluted air can then be trapped near Earth’s surface

Temperature Inversion

• Temperature inversions can occur during cold, cloudy weather in a valley surrounded by mountains

• Frequent and prolonged temperature inversions can also occur in an area with a sunny climate, light winds, mountains on three sides, and the ocean on the other – A layer of descending warm air from a high-pressure system

prevents ocean-cooled air near the ground from ascending enough to disperse and dilute pollutants

Temperature Inversion

Continental Surface Visibility (Human Observers)

NOAA NCDC Global Summary of the Day (SOD) 7000 Observations

Low Visibility High Visibility

February 2001 12

Regional Haze• Regional haze is visibility impairment that is produced by many

sources and activities which emit fine particles and their precursors and which are located across a broad geographic area

• Pollutants come from a variety of natural (e.g., windblown dust, soot from wildfires) and manmade (e.g., motor vehicles, electric utility and industrial fuel burning) sources. Some haze-causing particles are directly emitted to the air while others are formed when gases emitted to the air form particles as they are transported.

• Haze is caused when sunlight encounters tiny pollution particles in the air. Some light is absorbed by particles. Other light is scattered away before it reaches an observer. More pollutants mean more absorption and scattering of light, thus reducing the clarity and changing the color of what one sees. Some types of particles, such as sulfates, scatter more light than others, particularly during humid conditions.

Regional Haze

• Regional haze arises when the contributions of many individual sources are mixed together during long range transport

• The resulting spatially uniform hazy air mass can cover multi-state areas in excess of 1000 km in size

14

Global Pattern of Haze Based on Visibility Data

• A rough indicator of PM2.5 concentration is the extinction coefficient corrected for weather conditions and humidity. There are over 7000 qualified surface-based visibility stations in the world.

• The June-August haze is most pronounced in southeast Asia and over sub-Saharan Africa where the seasonal average PM2.5 is estimated to be over 50 g/m3.

• Interestingly, the industrial regions of the world such as eastern North America, Europe and China-Japan exhibit only moderate levels of haze during this time.

Case Study: Los Angeles Air Quality

Photochemical smog in downtown Los Angeles, California (USA)

Ingredients of Photochemical Smog

• Due to the lack of efficient public transportation, residents there depend on their cars

• Los Angeles’ climate is dominated by the Eastern Pacific High – Subsidence also produces clear condition and hence more

sunlight – Subsidence produces compression heating of the air, and

the temperature is often higher at a few hundred feet level than at surface – an inversion condition, an absolutely stable condition

• The topography of Los Angeles – a basin also helps to trap air pollutants

Valleys Trap PollutantsL.A. is in a basin surrounded by mountains that trap pollutants and usually has onshore flow that creates frequent inversions.

Pollutants can only escape through narrow canyons

Sources of Smog in Los Angeles

Typical Daily Concentration Variation of Smog Chemicals

Case Study: Asia Brown Cloud• Particles from airborne

pollution, such as the "Giant Brown Cloud," can travel all around the globe. In April of 2001, NASA satellites saw a massive dust storm appear over China. The densest portion of the aerosol pollution traveled east over Japan, the Pacific Ocean, and, within a week, the United States.

—— NASA

Clearing forest and burning fossil fuels • Clearing and burning forest for planting crops• Burning of coal, diesel, and other fossil fuels in

industries , vehicles and homes

Asia Brown Cloud: Causes

Asia Brown Cloud: Chemical Composition

Dust, smoke and compounds

• 1/3 of it is dust, smoke, and ash• Rest is acidic compounds, soot, toxic metals

(mercury and lead), hundreds of organic compounds and fly ash

South Asia

• Much of India, Bangladesh• South of China• Open Sea east of this area

Asia Brown Cloud: Areas Impacted

Environment and health

• Photosynthesis has been reduced by 7-10%• Acid in the haze fall to the surface and damage

crops, trees, and aquatic life

Asia Brown Cloud: Impacts

Farmers’ method of clearing the land• Indonesian farmers carry out the “slash-and-burn”

method to make land for crop-planting• Setting fire to large pieces of land to burn down trees

and leave only bare ground• Cheapest and fastest way to obtain clear land• Serious implications – severe haze contaminates air

in neighbouring countries

Case Study: 1997 Southeast Asian Haze: Causes

Large Corporations: Timber and palm plantations• Corporations want the cheapest way to clear space

to start plantations – save money• Employ workers to set forest-fires• Inconsiderate and unethical in the long run• Damage the environment

1997 Southeast Asian Haze: Causes

1997 Southeast Asian Haze: Impacts

TOMS for 1997 Southeast Asian haze

Environment• Disruption in ecosystem

– Flora and fauna burnt and lost– Endangers more species of animals– Destroys rare species of organisms

• Pollute the air – pollutants blown to neighboring countries (transboundary pollution)


• Fires produce greenhouse gases– Sulphur Dioxide– Ozone– Nitrogen Dioxide– Carbon Monoxide

• Affects atmosphere negatively• Speeds up global warming

– Shifting climate changes– Unpredictable weather


Environment (cont’d)

Health

• Triggeres off health conditions– Respiratory related problems– Asthma attacks– Bronchitis– Coughing / wheezing– Runny noses– Sore throats– Eye / skin irritation– Heart conditions


Health (cont’d)

• Haze particles (Ozone, Sulphur Dioxide) cause damage to lungs and hearts

• Particulate Matter 10 (PM10) cause lungs to function at decreased rate – shortness of breath


Tourism

• Flights disrupted (13 cancelled) and delayed• Tourists shun countries affected by haze• Tourists stranded at the airport as they have already

checked out of hotels• Unsatisfied and unhappy about their vacations


Economy

• Surge in medical costs– Treatment of cough– Other haze-related illnesses

• More people ill; less people turn up for work – reduce efficiency of different industries during that period

• Retailers and recreation businesses affected – most people try to stay at home during the haze period


Laws and Regulations Can Reduce Outdoor Air Pollution

• United States– Clean Air Acts: 1970, 1977, and 1990 created regulations

enforced by states and cities• EPA

– National ambient air quality standards for 6 outdoor pollutants– National emission standards for 188 hazardous air pollutants

(HAPs)• Toxic Release Inventory (TRI)

The Clean Air Act• Authorizes EPA to set limits

on amount of specific air pollutants permitted

• Focuses on 6 pollutants:– lead, particulate matter,

sulfur dioxide, carbon monoxide, nitrogen oxides, and ozone

• Act has led to decreases

Laws and Regulations Can Reduce Outdoor Air Pollution

• Good news in developed countries– Decrease in emissions– Use of low-sulfur diesel fuel

• Cuts pollution

• Less-developed countries– More air pollution

Case Study: U.S. Air Pollution Can Be Improved

• Rely on prevention of pollution, not cleanup• Sharply reduce emissions from power plants,

industrial plants, and other industry• Raise fuel-efficiency for cars, SUVs, and light

trucks• Better regulation of emissions of motorcycles

and two-cycle gasoline engines

Case Study: U.S. Air Pollution Can Be Improved

• Regulate air pollution for oceangoing ships in American ports

• Regulate emissions at U.S. airports• Sharply reduce indoor pollution• Increased and more accurate monitoring of air

pollutants

There Are Many Ways to Reduce Air Pollution

• There are ways to deal with– Stationary source air pollution– Motor vehicle air pollution

• New cars have lower emissions

Stationary Source Air Pollution

Motor Vehicle Air Pollution

Documents

Energy and the Environment