AOS 4 - Enviro - Energy + Renewables

What are the different forms of energy?

• Mechanical

• Heat

• Electrical

• Nuclear

• Light

• Chemical energy

What is kinetic energy?

The object’s speed (motion)

What is potential energy?

An object’s position (height) stored energy that can be released to perform work

What is mechanical energy?

Movement of objects and conversion of potential energy into other forms of energy

Define temperature

Is a measure of the average kinetic energy of molecules within a material. In solids, such as ice, the molecules vibrate around basically fixed positions

• High temps: higher speeds and higher average molecular kinetic energy

• Low temps: speeds of vibrations are lower

What is heat energy?

• Heat is the transfer of energy

• When two objects are of different temps and are in contact, thermal energy will transfer from the hotter one to the cooler one, until they are at the same temp

• Reactions that release heat = exothermic

• Reactions that take up heat = endothermic

What are energy sources?

Energy sources are naturally occuring fuels or energy sources that can be converted into forms of energy useful to society

• Fuels are substances that contain chemical energy (potential) that is released when oxidised, usually by combustion.

What is renewable energy?

Are those that can last indefinitely without any reduction in their supply

What are the main types of fossil fuels?

• Coal

• Petroleum (crude oil)

• Natural gas

What are fossil fuels, and how are they formed?

FF are formed overtime, where plant material and dead decaying organisms been pushed down in layers, buried under sediment and rocks. With increasing temperatures and pressure causing the material to fossilize, compressing it until it is converted into ff to be harvested

What conditions are needed for coal to form?

• Coal has commonly been found to form in locations such as swamps.

• Swamps offer a unique combination of factors, including abundant plant growth, waterlogged conditions that inhibit decay, and the subsequent burial and compression of plant debris

• The increased temperatures of these locations also aids in the creation of coal

What is the process of creating coal?

• First peat is created, then as temps and pressure rises soft coal is created (brown coal), then with more compression black coal is created

• Black coal (or anthracite) and brown coal (lignite) differ due to anthracite containing less oxygen and moisture and more carbon, creating more heat when burnt.

• Therefore the older the coal, the more heat it creates when burnt, and the more energy created.

What is petroleum?

Petroleum is simply oil extracted from rock.

How is petroleum extracted?

Petroleum extraction primarily involves drilling into the earth to reach underground reservoirs of crude oil and then bringing it to the surface. This process often utilizes oil rigs or platforms, depending on whether the extraction is on land or offshore. After drilling, natural pressure or pumps are used to extract the oil, which is then transported to refineries for processing into various products.

What is petroleum/crude oil converted into?

Diesel oils, petrol, kerosene and gas

How efficient is petroleum as a energy source?

• Oil is more convenient than coal, due to easier transportation

• It has a higher energy content, burns more cleanly and produces less smoke

• But combustion engines that use petroleum are only 25-30% efficient - so 75% of the oil is used in transportation is lost as heat.

What is natural gas?

• A mixture of hydrocarbon gases, mostly methane but also ethane, propane and butane

• The combustion of methane releases energy and forms carbon dioxide and water; other hydrocarbon gases burn in the same way

• Found in reservoirs trapped underground in rock formations

How is natural gas as an energy source compared to the other options?

• The combustion of natural gas is quite a clean process, compared to other ff which produce pollutants such as sulphur dioxide and nitrous oxide

• Approximate overall efficiency of 30% for electricity production

  90% for heating

What is coal seam gas?

Natural gas that collects in underground coal seams and bonds to the surface of coal particles

The coal seams are generally filled with water, and it is the pressure of water that keeps the gas as a thin film on the surface

What are the methods used to extract CSG?

Hydraulic fracturing (fracking)

• Involves high pressure injections of sand, water and chemicals into the coal seam gas wells, allowing gas to flow to the surface of the well

• This method causes concern due to the potential for fugitive gases to contaminate water sources, possible seismic activity and tremors associated within the drilling process

What is uranium?

• Not a fossil fuel, but another non-renewable energy source

• Is used in nuclear reactors to produce heat, which is used to generate electricity

• Nuclear reactions use nuclear fission chain reactions to release energy

• Uranium is a naturally occurring, radioactive, heavy metal

What are the different methods of nuclear reactions to extract uranium?

Nuclear Fission (forced apart)

• Is initiated by a neutron striking the nucleus of an atom with a larger mass number, splitting the nucleus into smaller nuclei

• Each reaction liberates energy and additional neutrons, which can continue the reaction (chain)

• In these reactions, a small amount of mass from each nucleus is converted into energy

• Uranium 235 is an isotope of uranium and can be taken apart via this method

Nuclear Fusion (forced together)

• Occurs when two atoms are forced together

• This source is more attractive because its clean, sustainable.

• It uses hydrogen isotopes deuterium and tritium - which are so abundant that they could meet the world’s electricity needs for millions of years - despite not being renewable

• The likelihood of a full sized reactor is low

How efficient as an energy source is uranium?

Nuclear energy is highly efficient, with a total efficiency of 90%

What are the different types of solar energy sources/methods

• Heat collectors

  Heat from the sun is absorbed by black tubing, often on roofs, this heats up water moving through it warming swimming pools. When there is insufficient sunlight, electricity kicks in as an energy supply.

• Photovoltaic cells

  These cells are mainly made of silicon, which is a semiconductor so light energy is immediately converted into electricity. They have a direct current type, but can be converted to alternating currents.

• Solar thermal

  Use mirrors to concentrate heat to target locations, the heat is captured in fluid which heats water to produce steam that is used to produce electricity → solar panels are now more economically viable, so these are in less use

How do wind patterns develop?

Sunlight falls unevely on Earth, heating the air unevenly. The warm air rises and cooler air moves in to replace it. The circulation from cool areas to warm areas produces wind. Wind patterns are influenced by Earth’s rotation, ocean currents and different land masses.

How is wind energy generated?

Made with a propeller that spins when wind is caught by the blades. The spinning blades drive a shaft connected to the mechanical device such as a wind pump, or to an electrical generator. Electricity generation needs unobstructed steady flow - high elevation land or ocean off the coast.

What is hydroelectric power?

• Produced using water stored in dams. The stored water flows through a turbine that spins a shaft connected to an electric generator to produce electricity

• Depends on the volume of water flowing through the turbine and vertical distance that water falls

• The gravitational potential energy of the water stored in the dam is converted to kinetic energy upon release, then to electrical energy via a generator.

Benefits and disadvantages of hydroelectric

+

• clean and emits no pollution

-

• displace humans when initial dam is built

• disrupts habitats - the storage, diversion and release of water disrupts natural flow

• release dam water is usually cold and at the bottom disrupts aquatic species downstream

How is tidal power generated?

• A dam wall is built across the entrance to a bay or inlet, moving water passes through turbines to produce electricity

• can use incoming and outgoing water to generate power

• large volumes are required to generate energy

• Cons include the fact that few sites are suitable for this energy source, being expensive to built and causing harm to aquatic ecosystems.

What is geothermal energy?

• heat energy found deep beneath the earth, where high pressures and temperatures escape to the surface

• In these areas, cracks and faults in the outermost layer of earth allow heat from within Earth to come close to the surface

• water finding its way down is heated and re-emerges as steam, this can drive turbines to generate electricity

• CONS: local depletion of resource, damage to environment, high grade sources of geothermal are low - high cost

Where is geothermal energy most abundant?

Areas of the surface where the crust is thin have high geothermal energy - volcanic areas

What is biomass energy?

• Is derived from material produced by living things

• some can be used directly - burning woods for heating

• others are used to produce fuels (biofuels) for transport or gas for heating

• biomass is produced from the breakdown of plant/animal waste material in the absence of oxygen

What are some examples of biomass energy?

wood

• used all around the world for heating/cooking

• CONS: low energy transfer, 90% is lost as heat production, smoke is produced leading to air pollution, unsustainable in terms of deforestation

ethanol

• a biofuel made from materials that contain sugars, starch and cellulose - via fermentation and distillation

• CONS: productio nmethds can lead to photochemcal smog, less tropospheric ozone formed, costly, can conflict with food production

biodiesel

• manufactured from vegetable oils and animal fats

• safer to use, has low toxicity compared to fossil diesel fuel, biodegradable, low exhaust emission rate, no diesel engine modification needed

• CONS: may displace food crops

What is hydrogen power?

• very little hydrogen exists as hydrogen gas

• the combustion of hydrogen is an exothermic reaction

• when bydrogen gas burns in air in combines with oxygen and forms water - removing air pollution issues

• sources of hydrogen power is from the breakdown of water by eletrolysis to release hydrogen and oxygen

• can involve electrolysis of water using electricity generated from ff - generation is the issues (expensive, needs ff)

How do greenhouse gases impact carbon sinks?

• changes in carbon cycle impact each reservoir

• excess carbon in the atmosphere warms the planet and helps more plants grow

• excess carbon in the ocean makes it more acidic

How do fossil fuels impact the CC and the atmosphere?

• CO2 is the most important gas for controlling earth’s temp

• CO2 causes 20% of the earth’s gh effect, water vapour accounts for 50% and clouds 25%

• water vapour concentrations are controlled by earth’s temps. as water temps evaporate more water from the oceans, air masses expand, causing higher humidity. cooling causes water vapour to condense and fall out as rain, sleet or snow. -

• so while CO2 doesnt contribute much directly to the gg effect, it does set the temperature which controls the amount of water vapour in the atmosphere and thus the size of the gg effect.

How does the combustion of ff impact the oceans?

• CO2 dissolves in seawater to form carbonic acid → ocean acidification → too acidic, harming corals, mussels and plankton.

• The ocean’s ability to take up CO2 is decreasing, as the water chemistry is being altered. Cool oceans are more effective in absorbing CO2, than warm.

How does the combustion of ff impact phytoplankton

• warmer oceans als odecrease the abundance of phytoplankton, which grow better in cool, nutrient rich environments

• this could limit the ocean’s ability to take up carbon

• CO2 is essential for plant growth, an increase in it could increase growth by fertilizing those few species of phytoplankton that take CO2 directly from the water. however, most species are not helped by the increased abundance

How does the combustion of ff impact land?

• increased carbon fertilization (more carbon in the atmosphere, so more photosynthesis and more growth)

• extension of growing seasons, with increased humidity, but this heat can also stress out plants

• with increased growth due to longer growing seasons, plants need more water, but this is in reduced supply

• dry, water-stressed plants are more suseptible to fire - burning releases CO2

• tropical forests are impact simularily

• soil is ‘baking’, accelerating the rate at which carbon seeps out of the soil - permafrost is thawing releasing rich deposits of carbon once stored in plant matter

what is peak oil?

is the concept that the rate of oil extraction will reach a peak and then decline. this time of max should not be confused with the time of oil depletion

define energy efficiency and the formula to determine it

• is the ratio of energy input to a system to the useful energy output

• useful energy output/total energy output x 100

• the chain energy conversions can be calculated by multuplying the individual frequencies together

how can increased energy efficiency be achieved?

• carrying out particular operation, such as heating a house to a comfortable temperature, using less energy

• eg: using a more efficient fuel or reducing heat loss via double glazing, insulation

what is energy efficiency affected by?

The energy efficiency for different fuels is affected by the number of energy conversions in the sequence between the original source of energy and the final use. The energy available is reduced with each step, with energy commonly being lost as heat

when can energy transformations be detected?

energy cna usually only be detected when it changes from one form to another, for example from electricity into heat and light energy

State the first law of thermodynamics

Energy is neither created or destroyed. It is merely changed from one form to another

State the second law of thermodynamics

When energy is converted from one form to another, some of it become degraded to a lower quality of energy. The degraded energy is less able to do work and in most conversions is released as heat

what do the laws of thermodynamics tell us?

• the first law tells use that you can get no more energy out of a process than you put it

• the second law tells use that the amount of useful energy is reduced by conversions and that any high-grade energy source cannot be used again

Define the following:

• Precision and accuracy

• Reproducibility and repeatability

• Validity

• Precision is the closeness between results, and accuracy is the closeness to the ‘true value’

• Both assess the consistency of the results, but repeatability is the closeness of agreement between results obtained with the same method on identical test items and reproducibility is the closeness of agreement between results obtained with the same method on identical test items, but by different operators.

• How well a study or experiment measures what it is intended to measure. It's about the accuracy of a measurement or the appropriateness of a method in addressing the research question

Define the difference between renewable and non-renewable energy sources

Nonrenewable and renewable energy sources differ primarily in their rate of replenishment. Renewable sources, like solar and wind, are naturally replenished at a rate comparable to or faster than their consumption, while nonrenewable sources, like fossil fuels, take millions of years to form and are finite

Outline one advantage and disadvantage for each non-renewable energy source:

• Oil

• Coal

• Natural gas

• Coal seam gas

OIL: high energy density, easy to transport + oil spill risk/harm

COAL: reliable, large-scale energy + high CO2 emissions

NG: burns cleanly + methane leaks during extraction

CSG: lower emission energy + fracking risks contaminating ground water

Outline one advantage and disadvantage for each renewable energy source:

• biomass

• biofuels

• solar

• hydro-electric

• wind

• tidal

• geothermal

BIOMASS: uses organic matter + releases CO2 when burnt

BIOFUELS: replace petrol/disel + competes with food crops

SOLAR: clean, abundant in sunny regions + requires storage backup

HYDRO-ELECTRIC: provide large-scale electricity + damming rivers

WIND: low costs + needs backcups/can’t meet high demand

TIDAL: predictable energy source + limited locations

GEOTHERMAL: reliable, low emission power + only viable in suitable locations, high upfront costs

Carbon cycle steps

Photosynthesis, respiration, decomposition, carbon sequestration (in oceans and as fossil fuels), and combustion of fossil fuels

What is land rehabilitation?

the process of returning land to its former state after mining (such as for coal) has resulted in damage. Eg: open cut mines can span vast areas destroying ecosystems and habitats, displacing species

What is mechanical rehabilitation?

Involves physically moving components of a site to, from or within the site. This could be removing contaminated soils through excavation or replacing soil lost to the mining process

What is chemical rehabilitation?

Involves ensuring the chemical properties of the mine site are returned to normal + safe levels equivalent to that of pre-mine site. This may be applying fertilizer to newly deposited top soil or requiring the elimination of harmful chemicals that were deposited during the mining process

What is biological rehabilitation?

Often involves replating and reintroducing life to the mine site. Can include biological processes (biogeochemical processes by bacteria) to rehabilitate the site