AGE 3118: Environmental

Engineering & Energy Studies

COURSE TUTOR: ING. Dr. KEMOH BANGURA

DEPARTMENT OF AGRICULTURAL ENGINEERING,

NJALA UNIVERSITY
 Introduction
• Environmental engineering is a field that
uses scientific and engineering principles to
improve the environment and protect
human health. Environmental engineers
use their knowledge of biology, chemistry,
ecology, and other subjects to design
systems and solutions that address a wide
range of environmental issues
 Environment and its components

The environment is made up of living and

non-living components:

• Biotic: Living organisms like animals,

plants, forests, birds, and insects

• Abiotic: Non-living components like air,

water, land, sunlight, rocks, and clouds
 Importance of environmental engineering
• The goal of environmental engineering is to ensure that societal
development and the use of water, land and air resources are
sustainable. This goal is achieved by managing these resources so that
environmental pollution and degradation is minimized.

• Environmental engineers work to improve the environment by:

o Designing systems for water supply and wastewater treatment

o Managing water and air pollution
o Improving recycling and waste disposal
o Developing plans to prevent waterborne diseases
o Evaluating hazardous-waste management systems
o Assessing the environmental impact of construction projects
o Studying the effects of technological advances on the environment
 The Earth’s Spheres
• The atmosphere, hydrosphere, lithosphere, and biosphere are the
four major spheres of Earth, and the water cycle connects them all:
Atmosphere
• The layer of gases that surrounds the Earth, made up of nitrogen,
oxygen, carbon dioxide, argon, and other trace gases. The
atmosphere is where weather patterns like rain, wind, and storms
form.
Hydrosphere
• All the water on Earth, including oceans, lakes, rivers, ice, and snow.
Lithosphere
• The rocky Earth, including mountains, sand, and minerals. The
lithosphere extends from the ground to the Earth's core.
Biosphere
• All living organisms on, in, and around Earth, including plants,
animals, and humans.
The water cycle, also known as the hydrologic cycle, is the process by
which water moves between these spheres in many ways:

• Evaporation: Water from oceans and other bodies of water evaporates

into the atmosphere as water vapor.
• Condensation: Water vapor in the atmosphere cools and condenses
into liquid droplets, forming clouds.
• Precipitation: Clouds release water as rain, snow, or sleet.
• Runoff: Rainwater that falls on land flows into rivers and streams,
eventually making its way back to the oceans.
• Groundwater: Some rainwater sinks into the ground and becomes
groundwater, which is part of the lithosphere.
• Transpiration: Plants release water into the atmosphere through
transpiration.
• Respiration: Animals release water into the atmosphere through
respiration.
• Excretion: Animals excrete water, which can enter the hydrosphere or
geosphere.
 Water supply and quality management
• Water quality is a measurement of how clean water is for living things,
including humans. Drinking water quality standards include color, turbidity, pH,
and taste and odor.
• Water supply and quality management involves a number of aspects,
including:

Water quality standards

• These standards include criteria to protect water uses, resistance to
degradation requirements, and designated uses.
Water quality parameters
• These parameters include temperature, pH, dissolved oxygen, electrical
conductivity, and total dissolved solid.
Water quality monitoring
• This involves taking samples and analyzing them in accredited
laboratories. Monitoring can be done in two ways: check monitoring and
audit monitoring.
Water quality management systems
• These systems can include automatic measurement of turbidity, electrical
conductivity, and residual chlorine.
 Water supply and quality management
Drinking water quality regulations
• These regulations can be developed by setting limits for
parameters, monitoring frequency, and considering
resources.
Non-point pollution
• This is pollution caused by poor drain sanitation,
uncollected waste, and the use of chemicals in agriculture.
 Pollution and control
• Pollution can have many negative effects on the environment and
human health, including:
Air pollution
• Can cause health problems for humans and other living beings,
damage the climate, and harm materials. Smog, for example, can
damage human health and ecosystems, and lead to economic costs.
Soil pollution
• Can affect soil fertility, which can jeopardize food security and human
health. People can be exposed to contaminated soil directly, or
indirectly through contaminated food and drinking water.
Water pollution
• Can negatively impact the use of water bodies, such as lakes, rivers,
oceans, aquifers, reservoirs, and groundwater.
Noise pollution
• Can cause hearing loss, sleep disturbances, hypertension, and
cardiovascular issues.
 Control of air, soil, water and noise pollution
There are several technologies that can be used to control air, water, soil,
and noise pollution, including:

Air pollution
• Electrostatic precipitators and catalytic converters can remove or change
harmful emissions from vehicles and industries. Other strategies include
avoiding emissions, restricting them, or using end-of-pipe technologies.
Soil contamination
• Bioremediation uses microorganisms to break down pollutants, while
phytoremediation uses plants to absorb or degrade
contaminants. Bioventing and biosparging are techniques that use air to
stimulate microorganisms to break down organic contaminants.
Water pollution
• Filtration and biological processes can clean wastewater before it enters
natural waterways. Other technologies include oxidation, chlorination,
and ion exchange.
Control of air, soil, water and noise pollution

Noise pollution
• Soundproofing materials and barriers can reduce the impact
of noise from transportation and industries. Noise pollution is
generally considered to be any sound that is over 85
decibels.
Waste management
• Recycling and waste-to-energy systems can convert waste
into reusable resources or energy, minimizing the need for
landfills.
 Other environmental concerns
• Greenhouse effect,
• Ozone layer depletion,
• Photochemical smog,
• Acid rain,
• Radioactive pollution and
• Arsenic pollution.
• Waste from power generating industries
• Environmental damage from extraction, transport and use of fossil fuels,
and the ‘green house effect
• Ozone depletion and acid rain
• Fuel wood use and deforestation
• Environmental effects of nuclear and electromagnetic radiation in
industries
• Effect of climate change on machinery use and land degradation
• Effect of post-harvest operations on the environment
• Environmental impact of hydro-construction
 Greenhouse effect
• The greenhouse effect is a process that occurs when gases in the Earth's
atmosphere trap heat from the sun, making the planet warmer than it
would be without an atmosphere.

• Greenhouse gases include: Carbon dioxide, Methane, Water, Nitrous

oxide, Ozone, and Chlorofluorocarbons (CFCs).

• Carbon dioxide is the most important greenhouse gas because it absorbs

and radiates heat. Plants remove carbon dioxide from the atmosphere
through photosynthesis, which turns sunlight into energy and transforms
carbon dioxide and water into sugar and oxygen.

The effects of the greenhouse gases include:

Climate change
Greenhouse gases cause climate change, which can lead to:
• Extreme weather
• Food supply disruptions
• Increased wildfires
• Changes in typical weather patterns
• Species extinction, migration, or growth
 Greenhouse gas effects
Health effects
• Greenhouse gases contribute to respiratory disease from
smog and air pollution.
Environmental effects
The greenhouse effect can lead to:
• Thawing of glacial masses
• Flooding of islands and coastal cities
• More devastating hurricanes
• Desertification of fertile areas
 Measures to reduce greenhouse gas emissions
There are many ways to reduce greenhouse gas emissions, including:

Using renewable energy

• Renewable energy sources like solar, wind, and water power are replenished
by nature and don't release greenhouse gases into the atmosphere.
Reducing energy use
You can reduce your energy use by:
• Using energy-efficient appliances
• Using LED light bulbs
• Washing clothes in cold or warm water
• Line-drying clothes
• Replacing your oil or gas furnace with an electric heat pump
Reduce car use: You can reduce your car use by:
• Walking or biking instead of driving
• Taking public transportation
• Buying an electric vehicle
• Limiting air travel
 Measures to reduce greenhouse gas emissions
Limit air travel: You can limit air travel by:
• Taking the train or bus instead of flying
• Telecommuting
Support green spaces; You can support green spaces by:
• Encouraging local officials to invest in sustainability
• Supporting parks and healthy ecosystems

Reducing food waste: You can reduce food waste by:

• Having a waste management plan
• Reusing, repurposing, or donating materials
• Recycling
• You can reduce food waste by composting it.
In agriculture; You can reduce greenhouse gases in agriculture by:
• Using livestock feed additives
• Practicing rotational grazing
• Managing manure/fertilizer
 Ozone layer depletion
Ozone layer depletion is the gradual thinning of the Earth's ozone layer in the
stratosphere. It's caused by the release of ozone-depleting substances (ODS)
from human activities, such as:
• Refrigerators and air conditioners, Fire extinguishers, Foam blowing
agents, Electrical equipment, Industrial solvents, Cleaning solvents,
Aerosol spray propellants, Fumigants

Ozone depletion has several consequences, including:

 Increased UV radiation: The ozone layer protects life from the sun's
harmful ultraviolet (UV) radiation. When the ozone layer thins, more UV
radiation reaches the Earth's surface.
 Health issues: Increased UV radiation can cause: Skin cancer, Eye
cataracts, Genetic damage, Immune system damage, Sunburns and Quick
aging
 Damage to marine organisms, plants, and plastics: Increased UV
radiation can damage these organisms, plants, and plastics
 Measures to reduce Ozone layer depletion
Here are some ways to reduce ozone layer depletion:

Avoid ozone-depleting substances: Avoid using products that contain

CFCs (chlorofluorocarbons), halogenated hydrocarbons, methyl bromide,
or nitrous oxide.
Use eco-friendly products: Use eco-friendly household cleaning
products and avoid using pesticides.
Maintain air conditioners and refrigerators: Regularly inspect and
maintain air conditioners and refrigerators to prevent refrigerant leakage.
Reduce car use: Limit the use of private vehicles, and consider walking,
biking, carpooling, or using public transportation.
Use clean energy: Use electricity from clean energy sources.
Recycle: Recycle.
Reduce greenhouse gas emissions: Take actions to reduce
greenhouse gas emissions to help protect the ozone layer and minimize
the effects of climate change.
Support the Montreal Protocol: The Montreal Protocol is an
international treaty that aims to protect the ozone layer by phasing out the
production and consumption of ozone-depleting substances.
 Photochemical smog
• Photochemical smog is a mixture of pollutants that are
formed when nitrogen oxides and volatile organic
compounds (VOCs) react to sunlight, creating a brown haze
above cities. It tends to occur more often in summer,
because that is when we have the most sunlight.

• Photochemical smog is a result of the burning of fossil fuels

and automobile fuels that emit NO2 and hydrocarbons

• Photochemical smog can have a tremendous impact on

humans, animals, plants, and materials. The harmful
substance can hinder photosynthesis, thus inhibiting plant
growth. Moreover, ozone can negatively affect various
compounds like rubber, paint, and dyed fibers. It may
damage their duration and quality.
 Measures to reduce Photochemical smog
Here are some ways to reduce photochemical smog:

• Use less fossil fuels: Use non-polluting or renewable energy sources like
wind, nuclear, or hydroelectric power.
• Drive less: Walk, bike, carpool, or use public transportation when
possible.
• Maintain your car: Keep your car in good repair, change the oil regularly,
and inflate tires to the proper level.
• Use cleaner burning gasoline: Use cleaner burning gasoline and meet
new emission standards.
• Fuel up during cooler hours: Fuel up during the night or early morning to
prevent gas fumes from heating up and producing ozone.
• Use catalytic converters: Use catalytic converters in automobiles to
prevent the release of NO2 and hydrocarbons into the atmosphere.
• Use electric or hand-powered lawn equipment: Avoid gas-powered yard
equipment, like lawn mowers.
• Use low-VOC paints: Avoid products that release high levels of VOCs.
• Plant trees: Plant and care for trees.
• Raise public awareness: Raise public awareness about the
environmental impact.
 Acid rain
• Acid rain is a general term for any form of precipitation that contains
acidic components, such as sulfuric or nitric acid. It can fall to the
ground as rain, snow, fog, hail, or even dust.

• Acid rain is caused by human activities, such as burning fossil fuels,

manufacturing, oil refineries, electricity generation, and vehicles. These
activities release sulfur and nitrogen oxides into the atmosphere.

Acid rain can have many adverse effects on the environment and human
health, including:

• Ecosystems: Acid rain can harm aquatic life, forests, and other
vegetation. It can also damage soil biology and chemistry.
• Water: Acid rain can pollute surface waters and aquatic animals. For
example, acid rain can kill phytoplankton in lakes, which can then lead
to the death of insects that eat the phytoplankton.
• Buildings and statues: Acid rain can cause stone buildings and
sculptures to weather, and paint to peel.
 Acid rain
• Steel structures: Acid rain can corrode steel structures,
such as bridges.
• Human health: Acid rain can have impacts on human
health.
• Ocean acidification: Acid rain can contribute to ocean
acidification.
• Nitrogen pollution: Acid rain contains nitrogen, which can
impact ecosystems. For example, nitrogen pollution in
coastal waters can contribute to declining fish and shellfish
populations.
 Measures to reduce acid rain
There are several ways to reduce acid rain, including:

Reduce emissions
• Governments and corporations can reduce the amount of pollutants
released into the atmosphere by factories and transportation.
Use renewable energy
• Renewable energy sources like solar, wind, and water power produce
less pollution than fossil fuels.
Use less energy
• Individuals can reduce their energy consumption by turning off lights and
electronics when not in use, using air conditioning only when needed,
and turning down the thermostat when leaving the house.
Use alternative transportation
• Individuals can use public transit, carpool, or walk or bike to get around.
Plant trees
• Trees absorb carbon dioxide and other pollutants from the air.
 Measures to reduce acid rain

Restore damaged ecosystems

• Restoration programs can help restore ecosystems damaged by
acid rain. These programs can include liming, which neutralizes the
acidity of soil or water, or introducing plants and animals that can
tolerate acidic conditions.

International agreements
• International agreements can help reduce acid rain by exchanging
scientific and technical knowledge and coordinating a response. For
example, the Canada-United States Air Quality Agreement commits
both countries to reducing emissions and protecting visibility.
 Radioactive pollution
Radioactive pollution is the release of radioactive substances into the
environment, which can cause irreversible damage to the environment and
public health. Radioactive pollution can occur in the air, water, and soil.

Radioactive pollution can be caused by:

• Nuclear weapons testing
• Nuclear power plant accidents
• Mining radioactive ores
• Spillage of radioactive chemicals
• Radiation tests
• Dumping of nuclear waste into the ocean

Radioactive pollution can have a range of harmful effects on human health

and the environment, including:
 Radioactive pollution
Health effects
• Exposure to radioactive pollution can cause cancer, genetic
mutations, birth defects, anemia, leukemia, hemorrhages, and
cardiovascular diseases. The severity of these effects depends on
the level and duration of exposure. At high doses, radiation can
cause acute effects such as nausea, vomiting, skin redness, hair
loss, and even death.

Environmental effects
• Radioactive pollution can contaminate surface water and
groundwater, and radioactive dust can be blown into populated
areas by the wind. Radioactive pollution can also damage plant
cells, which can inhibit seedling growth, reduce photosynthetic
efficiency, and even cause cell death.
• Radioactive waste should be disposed of properly and stored in
double-walled tanks until it reaches its natural level of radioactivity.
 Measures to reduce radioactive pollution
• Avoid ordering radioactive materials in quantities that exceed your
intended usage
• Don't mix non-radioactive wastes with radioactive wastes
• Use short-lived radionuclides where feasible
• Reduce the activity and volumes of materials used in the experiment
• Radioactive waste is managed by controlling and reducing the
radioactive releases to tolerable levels.
• One way to dispose of radioactive waste is to drill a borehole into
basement rock and place the waste canisters in the lower part of the
borehole.
 Arsenic pollution
Arsenic pollution is a serious health and environmental
concern caused by the presence of arsenic in the soil, water,
and food:

Sources
• Arsenic can be found in the environment due to natural
processes like weathering and mineral dissolution, as well as
human activities like mining, the use of pesticides, and
industrial effluent.
Health effects
• Long-term exposure to arsenic can cause cancer, skin
lesions, cardiovascular disease, and diabetes. It can also
negatively impact cognitive development in children and
increase the risk of stillbirth.
 Arsenic pollution
Contaminated water
Arsenic is often found in groundwater, which is used for drinking, food
preparation, and irrigation. Arsenic contamination is invisible, tasteless, and
odorless, so it's hard to detect.

Foods
Arsenic can also be found in some foods, like rice and certain fish, due to its
presence in the soil or water.

Regions affected
Arsenic contamination is a problem in many countries, but it's especially
prevalent in Asia. India and Bangladesh are among the most affected
countries in the region.

Mitigation
Rainwater harvesting and watershed management can help reduce arsenic
exposure and ensure a safe water supply.
 Wastes from power generating industries
Nuclear power plants and other industries that use radioactive
materials generate radioactive waste. This waste is classified
into three types based on its level of radioactivity: low,
intermediate, and high:

• Low-level waste: This waste is mostly made up of lightly

contaminated items like tools and work clothing, and
accounts for 90% of the total volume of waste.
• Intermediate-level waste: There are permanent disposal
facilities for this type of waste.
• High-level waste: This waste is mostly made up of used
nuclear fuel, and accounts for 3% of the total volume of
waste. High-level waste remains highly radioactive for tens
of thousands of years
 Wastes from power generating industries
Radioactive waste must be managed safely and effectively. This includes:

Reducing the volume of waste

This can be done through administrative measures, like using reusable
protective clothing, or by improving operational implementation.

Storing and disposing of waste in accordance with its risk

For example, uranium mill tailings are covered with a sealing barrier to
prevent radon from escaping into the atmosphere.

Using cementation to immobilize radioactive material

This process involves mixing a specially formulated grout with the waste to
create a monolithic block that can be stored and disposed of.

Containment and isolation

Radioactive waste must be kept away from humans and the living
environment for a long period of time.
 Environmental damage from extraction, transport
and use of fossil fuels
The extraction, transport, and use of fossil fuels can cause significant
environmental damage, including:

Air pollution
The burning of fossil fuels releases harmful pollutants into the air, including:
• Sulfur dioxide
• Nitrogen oxides
• Particulate matter
• Carbon monoxide
• Mercury
• Volatile organic compounds (VOCs)

Water pollution
Fossil fuels can pollute water through:
• Oil spills
• Hydraulic fracturing fluids
• Wastewater from refineries
 Environmental damage from extraction, transport
and use of fossil fuels
Greenhouse gas emissions
• The burning of fossil fuels releases carbon dioxide (CO2) and other
greenhouse gases into the atmosphere.

Land and soil contamination

• Accidental spills, leaks, or improper disposal of oil and its byproducts can
contaminate land and soil

Habitat destruction and biodiversity loss

• Oil extraction can lead to habitat destruction and fragmentation

Deforestation and land use change

• Oil extraction projects can contribute to deforestation and land use change

Sea level rise

• Climate change driven by fossil fuels will expose more than 1,600 critical
buildings and services to disruptive flooding at least twice per year by
2050
 Measures to reduce fossil fuels emissions
There are many ways to reduce fossil fuel emissions, including:

• Reduce energy use: Reduce your energy consumption and switch to

renewable energy sources.
• Use energy-efficient appliances: Use energy-saving light bulbs, install
solar lights, and look for the Energy Star Label.
• Use renewable energy: Use renewable energy sources like solar, wind,
hydro, and geothermal.
• Reduce driving: Take public transportation, carpool, ride a bicycle, or walk.
• Reduce food waste: Compost leftover fruits, vegetables, and yard waste.
• Use a heat pump: Replace your furnace or gas water heater with a heat
pump.
• Use an induction stove: Replace your gas stove with an induction stove.
• Use an electric fireplace: Replace your gas fireplace with an electric one.
• Use a manual or electric lawnmower: Save on gas and put less pollution
in the air.
• Buy local products: Reduce fuel use from transporting goods.
• Recycle: Recycle as much as possible.
• Buy used products: If you must buy new, be sure it can be recycled or
reused.
 Environmental damage from greenhouse effect
The greenhouse effect is a natural process that keeps the Earth warm
enough for life, but human activities are increasing the amount of
greenhouse gases in the atmosphere, which contribute to environmental
damage in many ways, including:

Climate change: The greenhouse effect traps heat in the atmosphere,

which causes the Earth to warm and the climate to change. This leads to
extreme weather events, such as more devastating hurricanes, and can
disrupt food supplies.
Sea level rise: As the Earth warms, glaciers melt and coastal cities and
islands flood.
Species migration: Climate change causes species to migrate.
Desertification: Fertile areas can become deserts.
Air pollution: Greenhouse gases contribute to smog and air pollution,
which can cause respiratory disease.
Wildfires: Climate change increases the number of wildfires.

The main greenhouse gases are carbon dioxide, methane, water vapor,
nitrous oxide, ozone, and chlorofluorocarbons (CFCs). Carbon dioxide is the
most important greenhouse gas related to human activities.
 Ozone depletion and acid rain
Air pollution from the burning of fossil fuels can cause both acid rain and ozone
depletion:

Acid rain
• Sulfur and nitrogen emissions from burning fossil fuels react with water, oxygen,
and other chemicals in the atmosphere to form acids. These acids fall to the earth
as rain, snow, or dry deposition, damaging soil, killing plants, and harming aquatic
organisms.

Ozone depletion
Synthetic chemicals accelerate the destruction of ozone in the ozone layer, which
protects the earth by filtering ultraviolet (UV) radiation from the sun. This allows more
harmful UV to reach the earth, leading to:
• Increased skin cancers
• Disruption of ocean food webs
• Eye cancer in animals

To reduce acid rain and ozone depletion, individuals can: Conserve energy, Reduce
emissions by turning off lights and electrical appliances when not using them, Use
public transport, Use energy efficient electrical appliances, and Use clean fuel.
 Fuel wood use and deforestation
The use of fuel wood, or firewood, is a major contributor to deforestation, especially in
developing countries:

Deforestation
• The purposeful clearing of forests for various reasons, including to obtain wood for
fuel. Fuel wood is responsible for 54% of deforestation in developing countries.

Environmental impact
• Deforestation is a leading cause of increased greenhouse gas emissions
(GHG). Burning wood for fuel also creates indoor pollution, as firewood and
charcoal produce smoke.

Other impacts
• The use of fuel wood can also have social, economic, and public health issues.

Other uses for forests include:

• Timber: Forests are used to supply furniture, flooring, lumber, and other building
materials.

• Agriculture and animal grazing: Forests are razed to make space for these
activities.
 Environmental effects of nuclear and
electromagnetic radiation from industries

Nuclear and electromagnetic radiation can have a number of environmental

effects, including:

Nuclear radiation
• Radioactive waste: Nuclear power plants create radioactive waste, such
as spent reactor fuel and uranium mill tailings, that can remain
dangerous for thousands of years.
• Soil contamination: Radioactive substances can contaminate soil,
especially in the upper layers. This can make soil infertile for decades.
• Water contamination: Radioactive precipitation can directly contaminate
surface waters, such as lakes, rivers, and oceans.
• Genetic mutations: Nuclear pollution can cause genetic mutations in
living organisms and their offspring.
• Potential accidents: Nuclear accidents can occur.
• Habitat destruction: Uranium mining for fuel can destroy habitats.
 Environmental effects of nuclear and
electromagnetic radiation from industries

Electromagnetic radiation
• Effects on plants and animals: Electromagnetic
radiation can affect plants and animals, including:
o Reduced radial growth of pine trees
o Lowered density of bird species and mammals
o Effects on bees
o Effects on magnetic-based homing mechanisms of
birds
• Disruption to magnetic compass orientation: Weak
broadband electromagnetic fields can disrupt magnetic
compass orientation in night-migratory songbirds
Effect of climate change on machinery use and
land degradation
Climate change can affect land degradation and machinery use in a number
of ways, including:

Intensified rainfall
• Rising global temperatures increase the hydrological cycle, which can
lead to more intense rainfall. This can cause soil erosion, which can
make it difficult for farm machinery to move across the land.

Extreme events
• Climate change can lead to extreme events like drought, fire, and
changes in precipitation, which can amplify local effects and introduce
new degradation.

Agricultural mechanization
• In the long term, agricultural mechanization and rainfall can increase
agricultural carbon emissions (ACE).
Effect of climate change on machinery use and
land degradation
Land-use change
• Clearing forests for cropland and rangeland, and cultivating peat
soils, can emit greenhouse gases (GHGs) from both soils and
biomass.

• Other factors that can contribute to land degradation

include: Unsustainable management of agriculture, High levels of
consumption in a globalized economy, and Multiple interacting
causes.

• To reduce the impact of climate change, desertification, and land

degradation, the international community can help developing
countries diversify their economies. This can include encouraging
households to adopt livelihood systems that are less dependent
on traditional land uses.
 Effect of post-harvest operations on the
environment
Post-harvest operations can have a significant impact on the
environment, including:
• Resource use: The production of food that is never consumed
results in the use of many resources, such as water, energy, and
land.
• Greenhouse gas emissions: The transportation, cooling, and
disposal of food after harvest requires a lot of energy, which
contributes to greenhouse gas emissions.
• Deforestation: Widespread agricultural production can lead to
deforestation.
• Soil degradation: Agricultural production can lead to soil
depletion and degradation.
• Pesticide residue: Pesticide residue can contaminate
underground water.
• Reducing post-harvest loss (PHL) can help with food security,
resource efficiency, and sustainable resource use.
 Effect of post-harvest operations on the
environment

Some ways to reduce the environmental impact of post-harvest

operations include:

• Using reusable packaging materials

• Reducing the distance food is transported
• Using vehicles that run on natural gas or hybrid technologies
• Using renewable energy in the processing factory
• Using organic residues for higher value applications, such as
animal feeding
• Teaching farmers climate-smart agricultural practices and
food loss reduction skills
 Environmental impact of hydro-construction
Hydropower construction can have a number of environmental
impacts, including:

Altered water flow

• Dams can change the natural flow of rivers, which can impact
water quality, sediment distribution, and habitat areas.
Blocked migration routes
• Dams can block the migration of native fish, which can lead to
population decline.
Created favorable conditions for invasive species
• Dams can create conditions that are better for invasive species
that are adapted to lakes than rivers.
Changed water temperature and chemistry
• Dams can change the natural temperature and chemistry of the
water, which can negatively impact native plants and animals.
Created reservoirs that are sources of methane
• Reservoirs can be sources of methane, a greenhouse gas, due to
decaying organic matter in the stagnant water.
Environmental impact of hydro-construction
Used concrete, a carbon-intensive material
• The construction of large dams requires massive amounts of concrete, which
is carbon-intensive to produce.
Quarrying sand and gravel
• Quarrying sand and gravel for dam construction can destroy habitats.
Increased methylmercury in the food chain
• Filling a reservoir can create conditions that transform mercury into
methylmercury, which can be harmful to human health if ingested in large
quantities.
Changing the landscape
• Reservoirs can drastically change the landscape and rivers they are built on.
Degrading water quality
• Dams and reservoirs can reduce river flows, raise water temperature, and degrade
water quality.
Impacting wildlife
• These changes can negatively impact fish, birds, and other wildlife.
Vulnerability to geological hazards
• Hydropower infrastructure is vulnerable to geological hazards like landslides,
earthquakes, and volcanic eruptions.
 Ways to reduce the environmental impact of
hydro-construction
Here are some ways to reduce the environmental impact of hydro-construction:

Use inflatable water dams

• These dams are reusable, easy to install, and environmentally friendly because
they use existing water on the worksite. They can help with erosion, water runoff,
and sedimentation.
Use sustainable materials
• Recycled materials like wood and metal can limit environmental impacts and save
money.
• Hydropower can have environmental and social impacts, including:
Use microalgae
• Microalgae can be used to treat water, prevent pollution, and reduce salt in dams.
Consider the carbon footprint
• Some hydropower reservoirs are carbon sinks, but others have carbon footprints that
are equal to or greater than fossil fuels.
Be aware of geological hazards
• Hydropower infrastructure can be damaged by geological hazards like earthquakes,
landslides, and volcanic eruptions.
Consider the impact on wildlife
• Dams and reservoirs can reduce river flows, raise water temperatures, and degrade
water quality, which can negatively impact fish, birds, and other wildlife.
 Renewable Energy Sources (RES)
• Renewable energy is energy that comes from a natural resource that is not
depleted when used. Renewable energy sources are considered vital in the fight
against climate change because they are natural, self-replenishing, and have a low
or zero-carbon footprint.
• Renewable energy can be used for many purposes, including: Generating
electricity, Heating and cooling water and spaces, and Transportation.

Renewable energy resources can be classified into several types, including:

Solar:
• Uses photovoltaic cells to capture sunlight and convert it into electricity. Solar
power can also be used for heating, cooking, lighting, and hot water.
Wind:
• One of the cleanest alternative energy sources, with a low environmental
impact. Using wind energy reduces the need for energy sources that create
pollution and carbon emissions.
Geothermal:
• Uses the heat trapped in the Earth's core, which is created by the decay of
radioactive particles. This heat can be used to generate electricity, heat buildings,
and bathe.
Biomass:
• Also known as bioenergy. Uses waste from agriculture, homes, and
industry to generate electricity. For example, corn and sugarcane can be
used to create ethanol, a type of biofuel. This process is more cost-
effective and environmentally friendly than thermal energy.

Hydroelectric:
• Uses the energy of running water to produce electricity without
reducing the amount of water.

Hydropower
• The largest and most mature source of renewable
power. Hydropower plants use turbines to convert the energy in
flowing water into electricity. Dams are a common type of
hydropower plant, where water from a large reservoir is released
through turbines.
Hydrogen
• Burns cleanly and can be stored in fuel cells, which work like
batteries to create electricity. However, hydrogen can only be
considered a renewable energy source if the electricity used to
produce it also comes from renewable sources.
Ocean energy sources
• Ocean energy is a renewable energy source that comes from the
ocean's natural movement and temperature differences. The
three main types of ocean energy are:

• Wave energy: Uses the energy of ocean waves to generate

electricity. Wave energy devices can use buoys to capture the
ocean's horizontal and vertical movement, or they can use
pressure fluctuations below the surface.
• Tidal energy: Uses the energy of the ocean's tides to generate
electricity. Tidal barrages are built on estuaries to hold back water
when the tides rise and fall. When the water is released, it drives
turbines to generate electricity. Tidal flow is predictable, even though
it isn't constant.
• Ocean thermal energy: Uses the temperature differences
between warm surface water and cold deep water to generate
electricity. Ocean thermal energy conversion (OTEC) plants use a
thermal gradient to create power. They pump hot surface water
and cold deep water into the plant to vaporize and condense a
fluid, which spins turbines to generate electricity.
 Limitations of RES
Renewable energy sources have several limitations, including:

Geographic limitations
• Different renewable energy technologies are best suited for specific
locations. For example, solar panels are more efficient in sunny areas,
while wind farms work better in areas with consistent wind.
Intermittent supply
• Renewable energy sources are dependent on weather conditions, so
they're not available 24/7. For example, storms, clouds, and flooding can
damage infrastructure or block sunlight.
High upfront costs
• The initial cost of renewable energy technologies can be high and
unaffordable. This is due to the cost of manufacturing and installing the
devices.
Efficiency limitations
• The efficiency of renewable energy technologies can be low. For
example, commercially available solar panels are only about 15% to 20%
efficient.
Land use
• Large-scale renewable energy farms can cover a lot of land, which can
harm ecosystems and wildlife habitats.
 Limitations of RES
Storage capabilities
• Alternative energy storage technologies are still in development and may
not be efficient or affordable enough.
Scarce elements
• Solar panels and batteries depend on lithium and cobalt, which can be
environmentally damaging to mine and process.
Transmission and distribution
• The infrastructure needed to transfer power to populated regions can be
expensive
 Comparison of RES with non-RES
Replenishment
• Renewable energy sources can be replenished naturally, while non-
renewable energy sources cannot.
Environmental impact
• Renewable energy sources are considered to be cleaner and more
environmentally friendly than non-renewable energy sources.
Cost
• The upfront cost of renewable energy is high, while non-renewable
energy has a comparatively lower upfront cost.
Accessibility
• At least one type of renewable energy is accessible in every region, while
non-renewable resources are location-specific.
Examples
• Renewable energy sources include wind, water, geothermal, and
biomass. Non-renewable energy sources include coal, oil, and natural
gas.
 Comparison of RES with non-RES
Availability
• Renewable energy sources are easy to access because the sun
shines continuously and water is available depending on the water
cycle.
Carbon emissions
• Renewable energy sources have low carbon emissions, while non-
renewable energy sources have a comparatively higher carbon
footprint.
Infrastructure
• Infrastructure for harvesting renewable energy is prohibitively
expensive and not easily accessible in most countries.
Formation
• Fossil fuels take millions of years to form.
 Solar energy
• Solar energy is energy that comes from the sun in the form of light, heat,
and ultraviolet rays. It can be used to generate electricity or heat air,
water, and other substances. Solar energy is a renewable energy source
that can be harnessed directly or indirectly.

Here are some ways solar energy is used:

o Solar electricity: Solar panels use the photovoltaic effect to convert light
from the sun into an electric current.
o Solar water heating: Solar energy can be used to heat water.
o Solar heating: Solar energy can be used to heat air.
o Solar ventilation: Solar energy can be used for ventilation.
o Solar lighting: Solar energy can be used for lighting.
 Solar energy
Some benefits of solar energy include:
• Cost savings: Solar panels can help save money on electricity bills.
• Home value: Solar panels can increase the value of a home.
• Climate adaptability: Solar systems can work in a variety of climates.
• Grid independence: Solar panels can keep the lights on during a grid
outage.

Some disadvantages of solar energy include:

• Cost: Solar energy storage can be expensive.
• Weather dependency: Solar energy is dependent on the weather.
• Space: Solar energy can use a lot of space.

Some types of solar energy include: Photovoltaic (PV) Solar Energy, Solar
Thermal Energy (STE), Concentrated Solar Power (CSP), Passive Solar
Energy, and Building-integrated Photovoltaics (BIPV).
 Solar energy conversion into heat
Solar energy can be converted into heat through flat-plate and concentrating
solar collectors, which are both types of solar collectors:

Flat-plate collectors
• These collectors are the most common and cheapest way to produce
thermal heat from solar energy. They are used for low-temperature
applications, such as heating water and spaces.

Fig. 1 Flat-plate solar collector

 Solar energy conversion into heat

Concentrating collectors
• These collectors are made up of a concentrator and a receiver, and can
reach very high temperatures. They can be used to generate electricity.

Fig. 2 Concentrating collectors arranged in tilt

 Solar thermal devices
• Solar thermal systems capture solar heat for space heating or water heating,
while solar PV systems convert sunlight directly into electricity. The choice
between the two technologies depends on the specific energy needs and
objectives of the application.

There are many different types of solar thermal devices, including:

Concentrating solar thermal power systems

• These systems use mirrors, lenses, and tracking devices to focus the sun's
energy. The three main types of concentrating solar thermal power systems are
linear Fresnel reflectors, parabolic troughs, and solar power towers.
Solar thermal chimneys
• These are passive solar ventilation systems that use convective cooling
principles.
Solar water heaters
• These systems use a collector and a storage tank to capture heat from the sun
and transfer it to water.
Evacuated tube collectors
• These collectors are lined with glass tubes that contain copper, which is a good
conductor of heat.
Hybrid solar panels
• These panels can convert sunlight into heat and electricity. They can also be
combined with other renewable energies, such as wind power.
 The principle of a solar drying system
The principle of a solar drying system is to use solar energy to heat air and circulate it over the
items being dried. The main difference between natural and forced convection solar drying
systems is how the air is moved:

Natural convection
• The air moves due to natural processes, such as buoyancy, which causes warmer air to rise
and cooler air to fall. This mode is used for crops with lower moisture content.
Forced convection
• The air is forced to move by an external source, such as a fan or pump. This mode is used
for crops with higher moisture content and offers more control over the drying conditions.

Here are some other principles of solar drying systems:

Closed system
• The drying chamber is kept closed to prevent contamination from the environment.
Indirect solar radiation
• The items being dried are not directly exposed to the sun.
Hot air
• The hot air from the solar collector is circulated through the drying chamber.
Decreased relative humidity
• Increasing the temperature of the air decreases its relative humidity, which increases its
ability to absorb water.
Removal of moisture
• The dry air absorbs moisture from the product, and the air movement carries it away.
Solar photovoltaic: Basics and applications
Solar photovoltaic (PV) is the process of converting sunlight into
electricity. Here are some basics and applications of solar PV:

How it works
• Solar cells, also known as photovoltaic cells, absorb photons from
sunlight and transfer the energy to electrons in the cell. The electrons
then flow through the cell as an electrical current. The efficiency of a PV
cell is the amount of electrical power it produces compared to the amount
of light energy it receives.
Applications
Solar PV has many applications, including:
• Powering homes and businesses: Consumers can install small PV
systems on their homes or businesses to generate clean, renewable
electricity.
• Selling excess energy back to the grid: Consumers can earn extra
income by selling excess energy back to the grid.
 Solar photovoltaic: Basics and applications
• Alleviating grid instability: PV systems can provide a renewable source
of energy if the main grid goes down.
• Space satellites: Solar cells were first used to power space satellites in
the 1950s.
• Smaller items: Solar cells were also used to power smaller items such as
calculators and watches.

Components
• A solar PV module is made up of a number of solar cells connected in series. The
primary component of a solar cell is silicon, a semiconductor material.

Types of PV systems
• There are grid-connected and off-grid systems. Off-grid systems are used
for remote buildings or vacation homes that don't have access to the
public grid.

Benefits
• Solar energy is non-contaminating, doesn't generate waste, and doesn't
pollute water.
 The P-N Junction ( The Diode )
If a block of silicon is doped with a trivalent impurity and the
other part with a pentavalent impurity, a boundary called the p-n
junction is formed between the resulting p-type and n-type
portions. The p-n junction is the basis for diodes, certain
transistors, solar cells, and other devices.
A diode is a device that conducts current in only one direction.
The p-n junction is the feature that allows the diode, certain
transistor, and other devices to work.
If a piece of intrinsic silicon is doped so that part is n-type and
the other part is p-type, a p-n junction forms at the boundary
between the two regions and a diode is created, as indicated in
Figure 3 below:

1
 pn junction
p region n region

Figure 3: The basic diode structure at the instant of junction formation showing only the
majority and minority carriers.

Formation of the Depletion Region

The free electrons in the n region are randomly drifting in all
directions. At the instant of the p-n junction formation, the free
electrons near the junction in the n region begin to diffuse across
the junction into the p region where they combine with holes
near the junction, as shown in Figure 4.
 pn junction

Figure 4: At the instant of junction formation, free electrons in the n region near the p-n
junction begin to diffuse across the junction and fall into holes near the junction in the p
region.

When the p-n junction is formed, the n region loses free

electrons as they diffuse across the junction. This creates a layer
of positive charges (pentavalent ions) near the junction. As the
electrons move across the junction, the p region loses holes as
the electrons and
these two layers of positive and negative charges form the
depletion region, as shown in Figure 5 below:
Depletion region
p region n region

Barrier
potential

Figure 5: For every electron that diffuses across the junction and combines with a hole, a
positive charge is left in the n region and a negative charge is created in the p region,
forming a barrier potential. This action continues until the voltage of the barrier repels
further diffusion. The blue arrows between the positive and negative charges in the
depletion region represent
the electric field.
Barrier Potential
Any time there is a positive charge and a negative charge near each other, there is a
force acting on the charges as described by Coulomb’s law. In the depletion region
there are many positive charges and many negative charges on opposite sides of the
pn
junction. The forces between the opposite charges form an electric field, as
illustrated in Figure 12 by the blue arrows between the positive charges and the
negative charges. This electric field is a barrier to the free electrons in the n region,
and energy must be expended to move an electron through the electric field. That is,
external energy must be applied to get the electrons to move across the barrier of the
electric field in the depletion region.
The potential difference of the electric field across the depletion region
is the amount of voltage required to move electrons through the
electric field. This
difference is called the barrier potential and is expressed in
volts.
The barrier potential of a pn junction depends on several factors,
including the type of semiconductive material, the amount of
doping, and the temperature. The typical barrier potential is
approximately 0.7 V for silicon and 0.3 V for germanium at 25°C
Review Questions:
1. What is a pn junction?
2. Explain diffusion.
3. Describe the depletion region.
4. Explain what the barrier potential is and how it is created.
5. What is the typical value of the barrier potential for a silicon
diode?
 Calculation of energy through PV power
generation
• Output energy is vital for PV solar systems. The output energy of a
photovoltaic solar system greatly impacts user benefits.

• Therefore, in the early stage of PV solar systems construction, we will

make a theoretical prediction of the output energy of the photovoltaic
power station.

• This is used to analyze the return on investment and then decide whether
the project is worth building.

• This process is usually calculated and analyzed based on various factors

such as the local annual solar radiation and power generation
efficiency!
 Factors affecting photovoltaic output energy
• The factors that affect the output energy of photovoltaic solar energy systems
mainly include capacity, efficiency, and solar radiation.

Installed capacity of photovoltaic system

• A solar power system’s installed capacity is the sum of its rated power. Thus,
the installed capacity is crucial to photovoltaic power station power
generation.

• Under the same other conditions, the larger the solar panel, the more output
energy.
Solar energy system efficiency
• Two factors determine the efficiency of solar power: the conversion efficiency
of the solar array and the energy efficiency ratio (PR)

• PR refers to the ratio of the power output of the photovoltaic power generation
system to the solar energy received by the solar array.

• It has nothing to do with the capacity of the solar system, the solar radiation at
the installation site, the inclination and orientation of the array, and other
conditions.
 Factors affecting photovoltaic output energy
Solar radiation

• The same power solar panel array, installed in different regions, will have
different output energy.

• The electrical energy generated by the solar system depends on the

amount of solar radiation it receives.

• Since solar radiation is random, it is impossible to accurately measure the

solar radiation of the solar power station every day. Generally, the average
value of the local solar radiation data for many years is used
 How to calculate the output energy of the solar system?
• According to the factors that affect the output energy of photovoltaics
mentioned above.

• We can use theoretical calculations, actual measurements, empirical

estimates, software simulations, and radiation calculations to count the output
energy of the solar system.

1. Calculating PV solar system output energy theoretically

• The theoretical output energy (E) of a solar power station can be calculated
by the following formula:

• 𝐸 = 𝑃𝑟 ∗ 𝐻 ∗ 𝑃𝑅𝐸 = 𝑃𝑟 ∗ 𝐻 ∗ 𝑃𝑅

Where E: Output energy (kWh); Pr: Rated power of the solar energy system
(kW), that is, the total power of all photovoltaic modules under standard test
conditions (STC); H: Annual average solar radiation (kWh/㎡), usually expressed
as daily radiation multiplied by 365 days; PR: Performance ratio, which
represents the overall efficiency of the system, including photovoltaic module
efficiency, inverter efficiency, line loss, etc.
1. Calculating PV solar system output energy theoretically
Calculation steps:

• Solar modules are rated according to their power under standard test
conditions (1000 W/m2 of irradiance at 25°C).

• If a photovoltaic power station is equipped with 1000 modules with a rated

power of 300W, the total rated power is Pr=1000×0.3kW=300kW.

• Obtaining the annual average solar radiation (H) The annual average solar
radiation can be obtained through meteorological data in kWh/㎡. For
example, the average annual solar radiation in a certain place is 1500 kWh/
㎡.

• When you calculate the performance ratio, it’s usually between 0.75 and
0.85. The calculation of PR takes into account the following factors: Assume
that PR is 0.8

o PV module efficiency: about 15% to 20%

o Inverter efficiency: about 95% to 98%
o Line loss, dust shielding, temperature effects, and other losses
 1. Calculating PV solar system output energy theoretically

For example:

• Assume that the parameters of a photovoltaic power station are as

follows:

o PV system rated power (P_{r}): 300 kW

o Annual average solar radiation (H): 1500 kWh/㎡
o Performance ratio (PR): 0.8

• Then the annual output energy (E) is: E=300kW×1500kWh/m²×0.8

=360,000kWh
2. Calculating PV solar system output energy by actual
measurements
• Using the actual measurement method to calculate the power generation
of the photovoltaic power station is an accurate way to ensure system
performance.

• This method can evaluate the impact of various factors on power

generation in actual operation. The following data are usually collected:

o Electricity meter: measures total power consumption.

o Solar radiometer: used to measure actual solar radiation.
o Environmental monitoring equipment: including temperature, humidity,
wind speed, and other sensors.

The calculation formula is as follows:

• P(t)——Instantaneous power (kW) at time point P(t)
• △t——Time interval (hours)
 3. Calculating PV solar system output energy by empirical
estimation

• This method analyzes the historical power generation data of other

photovoltaic power stations in the same region or under similar
conditions.

• Combined with local sunshine conditions, climate characteristics, and

other factors, the possible power generation of new photovoltaic power
stations is estimated.
4. Using software to simulate solar power stations
• The calculation of photovoltaic power station power generation can be carried
out by software simulation method.

• This is a common method in the design and analysis of modern photovoltaic

systems.

• This method can simulate solar radiation, system component characteristics,

and other environmental factors through professional software to predict the
power generation of photovoltaic systems.

The general steps are as follows:

• PV module parameters: including module type, power, efficiency,
temperature coefficient, etc.
• Inverter parameters: including efficiency, power, input voltage range, etc.
• System layout: including module arrangement, inclination, azimuth, etc.
• Enter meteorological data: Use local meteorological data, including annual
average solar radiation, temperature, humidity, wind speed, etc.
• In most cases, these data can be found in meteorological databases.
4. Using software to simulate solar power stations
The general steps continued:

• Set system losses: System losses include cable losses, dust shielding,
shading effects, temperature effects, etc. These losses can be adjusted
by default values in the software, or manually set according to actual
conditions.

• Run simulation: Use the software to run the simulation and calculate the
annual power generation of the system under given conditions. The
software will generate a detailed power generation report and
performance analysis by simulating the operation of one day and one
year.

• Analyze results: Analyze the simulation results and view detailed data
such as power generation, performance ratio, system loss, etc.

• Optimize the system design based on the results, adjust the arrangement
of components, select a more efficient inverter, etc.
4. Using software to simulate solar power stations
Example:

• Suppose we use PVSyst. software to simulate a 1 MW photovoltaic power

station. The steps are as follows:

o Enter the parameters of photovoltaic modules and inverters: module

power: 300 W, module efficiency: 18%, inverter efficiency: 97%

o Enter meteorological data: annual average solar radiation: 1600 kWh/㎡,

annual average temperature: 25℃

o Set system losses: cable loss: 2%, dust shielding: 3%

o Run simulation: The software calculates the annual power generation and
performance ratio.

o Analysis results: Check the annual power generation report and assume
that the annual power generation is 1,280,000 kWh
 5. Calculate the output energy of solar panels by
radiation

Formula:
• 𝐸𝑝 = 𝐻𝐴 ∗ 𝑆 ∗ 𝐾1 ∗ 𝐾2

• Where: HA—Total solar radiation on the inclined surface (kW.h/m²); S—

Total area of solar panels (m²); K1—Conversion rate of solar panels; K2—
System overall efficiency
• The overall efficiency coefficient K2 is a correction coefficient after
considering the influence of various factors, including:
a) Energy reduction of factory power, line loss, etc: The loss of AC and
DC distribution rooms and transmission lines accounts for about 3% of the
total power generation, and the corresponding reduction correction coefficient
is taken as 97%.
b) Inverter reduction: The inverter efficiency is 95%~98%.
c) Operating temperature loss reduction: The efficiency of photovoltaic
cells will change with the temperature during operation. When their
temperature rises, the power generation efficiency of photovoltaic modules
will tend to decrease. Generally speaking, the average operating temperature
loss is around 2.5%.
d) Other factors reduction

• In addition to the above factors, the output energy of solar power

stations is also affected by unusable solar radiation loss and maximum
power point tracking accuracy, as well as other uncertain factors such
as grid absorption.

• The corresponding reduction correction coefficient is taken as 95%.

• This calculation method is a variation of the first method and is suitable

for projects with tilt installation.

• In the case of tilt surface irradiance (or horizontal irradiance, it is tilt

surface irradiance that is needed), then more accurate data can be
calculated.
 Cost economics of photovoltaic (PV) power
• The cost economics of photovoltaic (PV) power includes the cost of the
modules, the balance of system (BOS), and the life cycle cost (LCC):

o Module costs: Typically make up 40–60% of the total cost of a PV

system.
o BOS costs: Include the inverter, PV array support structures, electrical
cabling, equipment, and installation.
o LCC: Includes the cost of site preparation, system design and
engineering, installation labor, permits, and operation and maintenance.

• Here are some other factors that affect the cost of PV power:
o Location: The choice of location can significantly affect the results due to
differences in environmental conditions, economic parameters, and
government policies.
o System size: The average cost per watt for a PV system can vary
depending on the system size.
o Economic feasibility study: This study can help identify logistical or
business problems that the project may face, as well as solutions.