ENV1800 Chap 9 Renewable energy

World energy consumption data (2018)

Fossil fuel 85%

• oil - 34%

• coal - 27%

• natural gas - 24%

• nuclear energy - 4%

Total energy from renewable sources 11% (hydropower: 7%; other renewables 4%)

Fossil fuels

Definition: Fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing organic molecules originating in ancient photosynthesis that release energy in combustion

• The majority of our energy: coal, oil, and natural gas

• energy form too slowly to be renewed —> non-renewable energy

• cannot be replenished on a human time scale

Coal

• From ancient forests and swamps that existed 300 million years ago

What did coal power? When and Why?

Coal powered the Industrial Revolution in the 19th century and is widely used today in power generation and heavy industry because it is abundant and inexpensive

• global coal supplies 10x larger than oil and gas combined

How does coal form

1. Begins with peat (partially decomposed plant material found in wetlands)

2. Buried and compressed —> lignite (brown coal)

3. High pressure and temperature as soil layers build up on top of lignite —> bituminous coal —> anthracite

What is coal mainly composed of?

• carbon

• hydrogen

• sulfur

• oxygen

• nitrogen

• sometimes mercury

Depending on its type coal is used for different purposes:

Anthracite (hard coal) —> high heating value

• for steel making

Sub bituminous and lignite (brown coal)

• used for electricity generation

Why does coal remain a widely used energy source in especially in developing countries? (HAL)

• High energy density

• low cost per unit of energy

• abundant reserves

Coal in malaysian context

Share of coal in electricity: 45% of total energy generation

Share of coal in emission: 39% of total co2 emissions from fuel combustion

Why does burning coal result in air pollution?

Releases more co2 per unit of heat energy produced than other fossil fuels —> major contributor to global warming

When coal is burnt

• releases small particles of burnt material (particulate matter e.g PM0.5, PM2.5 and PM10) —> hazy air and impact on human health

How does burning coal result in acid rain?

• Release sulfur dioxide (SO2) and nitrogen oxide (NO and NO2) which dissolve in rainwater —> acid rain

• Release toxic metals (arsenic, mercury, etc.) into the atmosphere

Impacts

• Damage to plants caused by leaching of nutrients from soil as these dissolve more easily in acidic water

• Loss of calcium makes the plant have low cold tolerance

• Damage to aquatic habitats esp. lakes due to acidic water and increase solubility of aluminium ions which are harmful to aquatic animals (fish eggs, mollusks)

How is Co2 emission reduced for coal power plants? and concerns

Coal - carbon capture and storage.

• A technology for removing CO2 emissions before they enter the atmosphere (at a coal power station) and trapping them underground (coal mines or oil wells that are no longer being used)
  
  

• A method for reducing Co2 emissions from coal (and other) power stations, but concerns remain about
  - high costs
  - risk of leakage in the future - CO2 would need to be stored permanently.

How does the carbon capture and storage work?

Natural gas production

1. Gas containing CO2 is produced from natural gas reservoir at wellhead platforms

Capture and Compress

2. CO2 concentration >95% is captured from produced gas by Membrane technology and compressed for transport

Transport of CO2

3. CO2 is transported from the capture-compress facility to the wellhead platform for injection

Geological Storage

4. CO2 compressed up to 150 bar pressure is injected back into the specified saline aquifers and depleted reservoirs for permanent storage

Oil (petroleum)

Oil forms when marine algae and animals die and are buried by mud (anaerobic conditions), slowing down decomposition

• buried under layers of mud and rock —> increasing heat and pressure

• Hydrocarbons in the mud are transformed —> oil and natural gas (often found close together)

• Oil based fuels power millions of automobiles but burning oil is one of the leading source of CO2 emissions

What is crude oil?

A mixture of hydrocarbons of different molecular weights plus small amounts of sulfur, oxygen and nitrogen

• refined into oil products —> gasoline, diesel, kerosene and heavy fuel oil to fuel automobiles (airplanes, ships)

How is crude oil refined for different purposes?

Heated in refineries; different fractions used for different purposes

• this process releases CO2

• most oil used for transport (65-70%) combustion —> adds more CO2

What are other petroleum products made from oil that have non-energy uses

asphalt, engine lubricants, and raw materials for making plastics

Oil (Malaysian context)

The share of oil in emissions is 30% of the total CO2 emissions from fuel combustion

• increased by 20% from 2000-2022

Oil impacts

Similar to coal but lower emissions per unit of heat energy generated:

• releases CO2 —> GHG

• releases some SO2 —> acid rain

• releases particulates —> hazy air and impacts on human health

MAJOR air pollutant released by burning petroleum

nitrogen oxide (NO) and nitrogen dioxide (NO2)

• irritates airways

• react with other molecules in the atmosphere to form ground level ozone (O3) —> harmful to human health

• contribute to acid rain (not as much as sulfur dioxide so not as serious as coal)

• Diesel vehicles emit more NO2 than petrol vehicles

Environmental impacts of drilling for oil

Seismic waves are used to find new reservoirs on the seabed —> underwater sound waves that can travel 1000s of km

1.impact marine mammals (dolphin, dugong, whales)

• distrupt their behaviour (increased stress)

• masking of communication and navigation sounds

• physical injury including hearing loss

2.Drilling for oil creates waste (mud and contaminated waters) that smothers seabed communities

3. Accidental release of petroleum (small and regular to large spills)

• direct pollution by oil —> toxic when eaten or absorbed by aquatic animals, damages feathers and mammal fur which affects flight, insulation and buoyancy

• oil remains in the environment for years —> long term habitat degradation

• chemicals applied to disperse oil spills can also be toxic to wildflife

Another form of oil extraction

Tar sands: Unconventional petroleum deposits

A mixture of clay, sand, water, and thick crude oil (bitumen) with high sulfur content

• naturally found in borreal forests in canada, high abundance

• typically uses surface (open pit) mining in canadian borreal forest —> large forest deforestation

• Increased co2 emissions compared to conventional oil

• Large amounts of water used to separate oil from tar sands —> water polluted with heavy metals, sulfur, other harmful chemicals

What is bitumen?

a thick, tar-like form of hydrocarbons that must be heavily processed before it can be used for energy

Electric cars. Pros and Cons

Pros

• decrease local air pollution, especially in cities (reduce particulates, NO2)

• reduce CO2 ONLY if the electricity used to charge the cars in generated with renewable energy

Cons

• use small amounts of rare earth metals (neodymium) mining and processing generates toxic and radioactive water which is difficult to dispose of

• expensive compared to conventional vehicles

• require infrastructure development —> more recharging points dependant on battery storage capacity

• May increase global CO2 emissions if cars charged by electricity from coal-powered stations

Natural gas

Mostly methane plus smaller amounts of ethane, propane and butane and other trace gases

• widely used for heating, cooking, production of fertilizers, and electricity production (24% of global electricity production)

• typically found together with deposits of oil, extracted by drilling

What is the major limitations of natural gas?

Transport

• can be transported via pipelines (within continents) or as liquified natural gas (LNG) by sea for global distribution

• LNG: gas is cooled and pressurized —> liquid for transport on container ships (expensive and energy intensive process as it requires maintaining low temps)

• Leakage of ch4 called fugitive emissions during drilling and transport —> climate change

Natural gas malaysian context

• 34.9% of total electricity generation -2023

• 31% of total electricity generation -2022

• 74.378 Mt CO2 produced from NG in 2022

Impacts of natural gas

Hydraulic fracturing (‘fracking’)

• Method for extracting petroleum and natural gas

• use fracking liquid (water, sand, and other chemicals) injected at high pressures into underground shale rocks to fracture the rocks to release natural gas and or petroleum

• typically caried out on land close to people

Environmental impacts of natural gas

• Use large amounts of water

• Fracking chemicals are potentially carcinogenic and injecting them deep into the ground may contaminate groundwater

• High pressure fluid injection into rocks —> noise pollution and potential to trigger minor earthquakes

• Some methane is released during fracking

Conflict of non-renewable energy sources

• Fracking has the opportunity to increase the availability of natural gas

• Burning natural gas releases fewer GHG emissions than coal —> according to the fossil fuel industry, fracking can potentially help address climate change

Not truly sustainable in the long run

Non-renewable energy - Nuclear energy

Powered by nuclear fission

reaction where the nucleus of an atom splits into 2 or more smaller nuclei, releasing energy

• Neutron collided with Uranium-235 (radioactive)

• Uranium-235 splits apart, releasing heat and light energy plus neutrons

• extra neutrons released by the nuclear fission reaction cause more uranium-235 to split —> chain reaction

• slow/controlled splitting —> heat energy —> electricity

How does a nuclear power plant work? (Pressurized water reactor)

1. Nuclear fuel (uranium-235) is placed inside the nuclear reactor

2. inside the reactor, nuclear fission occurs - uranium atoms split, releasing a large amount of heat

3. Heat is absorbed by a coolant (water) which heats up

4. Hot water turns into steam which spins the turbines connected to a generator

5. Generator produces electricity

No fossil fuels are burned, considered low carbon (significant lower GHG emissions than fossil fuels)

Nuclear energy global context

Not common - only in 31 countries

• 10% of world total energy

• China, Mongolia, South Korea, US

• France has most energy generated by nuclear energy

• SEA does not have

Nuclear energy impacts

• Mining

• Radioactive waste

• Release of radioactive materials

Nuclear mining

Types of mining

• open-cast mining

• underground mining

Radon (radioactive gas produced by uranium decay) and radioactive dust —> Lung cancer, air pollution, water pollution

Open-cast mining is damaging to overlying habitat (as with coal mining)

Most commonly used fuel in nuclear energy

most commonly used fuel is an isotope of uranium (uranium-235)

What is “in situ leaching”?

Mining method that involves that extracts underground minerals without physical excavation.

Nowadays, uranium mines can use ‘in situ leaching’: water or other oxidizing solutions are circulated through the uranium ore to extracting the uranium —> less ground disturbance

Impacts of open cast and underground mining

Both methods release radon (a radioactive gas) is produced by uranium decay + radioactive dust can lead to lung cancer, air and water pollution

Dangers of nuclear energy

Radioactive waste

• nuclear waste has a half life of 10s to 100s thousands of years —> must be stored until its radioactivity decays to safe levels

• surface storage for 40-50 yrs is first required so that heat and radioactive can decay to levels which make handling and storage easier

• after surface storage, buried deep underground. Waterproof and tightly sealed to avoid leakage of any waste during subsequent 10000+ yrs

• storage typically in stable geological formation such as deeo rock layers to avoid groundwater contamination

Release of radioactive materials

• leakage of radioactive fuel or waste or explosion of the reactor e.g chernobyl 1986 case

• similar technology for nuclear bomb is used to enrich uranium ore to make fuel

• regulate international regulations on nuclear weapons

Renewable energy sources

• Solar

• Hydro

• Wind

• Biomass

• Tidal

Why is renewable energy becoming increasingly popular?

• renewable and sustainable on a human timesclae

• more diverse than the traditional 3 energy sources —> increase energy security

• fewer negative environmental impacts

What is the global average for energy generated using renewable sources 2022

29%

Malaysia average - 19%

Solar energy

Photovoltaic panels convert sunlight energy into electrical energy

• mirrors and lenses are used to focus heat energy from the sun into a small area

• NORMALLY heat generates steam —> spin turbine —> energy NOT THE ENERGY WE ARE TALKING ABT

Solar thermal energy

BUT photovoltaic cells are made from semiconductors materials (silicon)

• alternate between negative (N-type) and positive (P-type) due to mixing with other elements

• sunlight energy/photons excite the electrons which flow through the cell as an electrical current (-ve —> +ve)

Difference between solar panel vs solar thermal energy

Solar panel —> sunlight into electrical energy

Solar thermal energy —> heat into energy

Pros and cons of solar energy

Pros

• no fossil fuel (renewable)

• decentralized energy generation (vs centralized) - remote areas and reduces energy loss, increasing reliability

• domestic energy source - reduce reliance on imported fuels

• generating systems made out of modules, independant and can reach rural areas

Cons

• Expensive installation costs

• Storage of the electricity generate requires further development

• Land use for large scale PV energy displace forests etc…

Hydroenergy

Electricity generated by the movement of water, downstream —> turbine —> energy

• relatively cheap

• generates a large amount of electricity

• favoured in places controlling river flows

Two most common types

1. Conventional - high area to low reservoir

2. Pumped storage - actively pumps water uphill to upper reservoir when electricity supply e.g sunlight is abundant

How does hydroenergy power plants work?

1. Renewable energy is stored - excess energy generated through solar or wind power is used to power the pump

2. Water is pumped uphill - during times of low electricity demand excess electricity is used to pump water from a lower reservoir to an upper reservoir

3. Water is stored - The water stays in the upper reservoir storing potential energy

4. Water flows downhill - when electricity demand is high the stored water is released from the upper reservoir, flowing back down to the lower reservoir

Pros and cons of hydro energy

Wind energy and how it works?

Through wind turbines 2nd most used energy behind hydro power

1. KE causes the large blades of a wind turbine to rotate

2. The rotational movement spins the shaft connected to a generator. Converting mechanical into electrical energy

3. Grid connection the generated electricity is channeled to the electrical grid, supplying power to homes and businesses

Wind energy pros and cons

Tidal energy

The rise and fall of sea levels are caused by the combined effects of the gravitational forces exerted by the moon and a bittt of the sun

• capture rise and fall of tides using tidal barrages and underwater turbines to convert waters KE into electrical E

• areas around island or coast where currents are fast

• more predictable —> reliable

Tidal energy pros and cons

Biomass

All organic matter is biomass - derived from recently living (or still living) organisms, primarily plants and animals, that can be used as a renewable energy source either

• directly (burning wood)

• indirectly (converted into biofuels)

Can be solid, liquid or gas and are predominantly plant based

1. Solid biofuels - wood, straw for electricity

2. Liquid biofuels - palm oil, sunflower oil or ethanol fuel vehicles

3. Biogas - gaseous product of organic material decomposition (anaerobic digestion)

Generations of biofuels

4 generations

1. 1st generation - high carbon content (edible items)

2. 2nd generation - GHG less than 1st gen leftover from food crops

3. 3rd gen - carbon neutral (carbon emitted = co2 sequestrated) using microorganisms

4. 4th gen - made from GMO they are carbon negative reduce GHG

Biomass energy

• Biofuel is produced relatively quick from biomass (organic material derived from recently living organisms

• Biofuel produced from plants or from agricultural, domestic or industrial bio waste

• Mostly used for transportation but can also be used for heating and electricity

First generation of biofuels

• well developed technologies such as fermentation or distillation to produce liquid fuels potentially replacing petroleum —> biodiesel

• support rural livelihood (increase crop demand)

• reduce emission of particulates and CO but may produce smaller size particulate air pollution. More harmful to human health

• Potential for increased food prices

Second generation biofuels

• from lignin or cellulose of leftover food crops

• requires more processing (enzyme hydrolysis) to extract fuel from the plant tissues - more expensive than 1st gen

• some plants for 2nd gen compete w food crops for land —> deforestation for crops

Third generation

• from algae, oils can be extracted —> fuel

• less competition for land

• high water requirements but can be grown in wastewater

• tech limited in scale, does not produce enough energy to compete with other energy sources

4th generation

Producing ultra-clean, carbon-negative biofuel while enabling carbon sequestration

• Genetically modified algae to enhance biofuel production

• carbon negative in raw material and process technology

• still in development phase

Theoratical concepts of fourth gen biofuels:

• developing genetically modified plants that absorb more Co2 from the atmosphere

• combining oilseed crops w alagae to create high yield, cross genetic species for improved biofuel production

Methane as a biogas

Released by decomposition of organic waste in landfill or palm oil processing mills can be burned —> energy for electricity or heat buildings

• burning methane release co2 but reduce methane

• methane is a stronger GHG than co2 overall better

Biomass energy in malaysia

Using biogas produced from decomposition of waste products (oil palm fruit husks) for electricity

Pros and cons of biomass