Fuel choices Flashcards
Define fuel
a fuel is a substance that can be reacted with other substances (often oxygen) leading to the release of energy (usually chemical) that can be harnessed for a specific purpose
Define renewablility
A renewable fuel is one that can be replenished or replaced by natural processes within a related short period of time renewable feels like considered a substantial source of fuel, since we can continually replenish the fuel.
Define fossil fuel
Fossil fuels are chemicals that are produced by fossilization of dead plants and animals
Fossilisation process in the formation of fuels
Occurs over millions of years, the preserved dead organism is subject to high pressures in the multiple layers of rock and sentiment that formed over it, and the chemicals are comprise the organism are broken down into a mixture of hydrocarbons and other organic substances. This leads to the formation of a mixture of solid coal, liquid crude oil and natural gases
Fossil fuels are considered…
a non renewable source of energy this is because the rate of which fossil fuel production by fossilisation occurs is extremely slow
Define biofuels
Are fuels that are derived from matter from living or recently deceased plants
Process of biofuels
Photosynthesis is the process by which plants produce glucose from C2O and H2O using sunlight as a source of energy. The glucose is converted into other organic molecules such as oils protein and complex carbohydrates, these organic molecules including glucose and oils can be extracted and the plant and chemically modified to form biofuels such as bioethanol and biodiesel
When is biogas produced
Biogas is produced when plants die and start to decompose, bacteria breaks down these large molecules into smaller molecules including methane gas, these fuels are renewable.
How are biofuels carbon neutral (no net production of CO2)
CO2 released during the burning of fuel is approximately equal to the CO2 consumed during the production of the fuel example growing of the crops (via photosynthesis)
Biofuel
Burning of fuels
Fuels that burn in oxygen are combustion reactions. Combustion reactions are exothermic reactions (ie ΔH<0) Where there is a net loss release of chemical energy throughout the reaction. Chemical energy is converted into other forms of energy such as thermal energy light energy and in some cases mechanical energy
Biofuel
Burning of fuels
1 MJ = ____ kJ and 1 tonne = _____ kg
1000, 1000
Biofuel
Define complete combustion
Complete combustion occurs when a fuel is burnt in excessive oxygen to form CO2 and H2O
Biofuel
Define incomplete combustion
Incomplete combustion occurs when a fuel is burnt in limited amount of oxygen this produces CO
Biofuel
The enthalpy of incomplete combustion of a fuel is always ____ negative than the enthalpy of complete combustion of a fuel
Less
Biofuel
Greenhouse gases
The thing about fuels is that when you combust them, you produce greenhouse gases which are gases that can absorb infrared radiation which warms up the planet. Greenhouse gases include CO2 and Ch4 as well as water vapour H2O. Excess production of greenhouse gases is problematic because they can cause global warming also known as climate change
Fossil fuel choices
Define coal
a black rock, is a fossil fuel that is composed of a variety of very long hydrocarbon molecules that, like any other hydrocarbon, can be combusted to release energy to generate electricity. The energy content of coal is approximately 30 MJ / kg. -Non renewable
Fossil fuel choices
-
-
- Wildlife habitat is destroyed
- contamination of water within underground water disposits
- Coal miners who breathe coal dust can end up getting black lung disease
Fossil fuel choices
-
-
-Combustion of coal leads to the production of greenhouse gas CO2, which to contributes to global warming
- Coal is a mixture of N and S atoms (+ others) therefore the production leads to NO and NO2.
Therefore the Nitrogen and sulphur oxides, being acidic acid can react with and dissolve in water to form acid rain
-The burning coal also leads to release of particular matter in air which is basically unburnt bits of coal this contributes to air pollution and smog and when inhaled can cause serious health effects
Fossil fuel choices
Define crude oil
a black tarry liquid that is composed of a series of large hydrocarbon molecules and other organic molecules containing some N and S atoms
Fossil fuel choices
Crude oils The products of fractional distillation are -L -P -K -D -F
- Liquidfied petroleum gas (LPG): a mixture of propane and butane
- Petrol: liquids containing about 8-10 carbons
- Kerosene: slightly more viscous liquids, used as jet fuel
- Diesel: more viscous liquid containing (15 carbon atoms)
- Fuel oil: mixture of large hydrocarbon atoms, a black tarry liquid
Fossil fuel choices
Process of crude oil
Crude oil is very rarely used in its raw form as a fuel. It is first refined (the different compound of crude oil are separated by fractional diffusion (The components are separated by boiling point and therefore by molecular size)
Fossil fuel choices
Crude oil has a ____ energy content than coal
greater
Fossil fuel choices
-🚱
-🛢
- habitat destruction
- Fracking, is used where the oil is hidden within a layer of Rock deep in the ground called shale. The issue is water contamination
- Oil spill during extraction of oil from below seabed
Fossil fuel choices
Crude oil
How is it extracted
By drilling a hole through the bottom of a seabed or landmass.
Fossil fuel choices
-🌧
-☁
-Produce greenhouse gases
Acidic nitrogen oxides and sulphur oxides can also be emitted, leading to
-acid rain, and
-photochemical smog (high level of ozone)
Fossil fuel choice
Define Petroleum gas (LPG)
natural gases -Dry natural gas
-Wet natural gas
Usually sold in liquid form as LPG, is composed primarily of propane and butane. Is generally used as vechial fuel and for cooking
- Primary methane, used for cooking and electrical generation
- Wet natural gas is best compost of very small hydrocarbons also formed from fossilisation as well as from crude oil.
(non renewable)
The energy content of dry natural gas is the ____ of all the fossil fuels
highest
Fossil fuel choices
-
- Habitat destruction
- gas leaks (leakage of methane into the atmosphere) methane is a very powerful greenhouse gas more than carbon dioxide
Fossil fuel choices
Process of petroleum gas and natural gas
A hole is drilled unto the ground to extract wet natural gas. The wet natural gas is refined, separating the methane from the heavier hydrocarbons, as well as pollutants such as sulphur compounds. The heavier hydrocarbons are collected and packaged as petroleum gas whereas the methane is packaged as dry natural gas.
Fossil fuel choices
-
- The production of CO2, greenhouse gas
- as well as the production of nitrogen and sulphur oxides with associated acid rain and smog
Fossil fuels choices
Petroleum gas and natural gas
Burning natural gas to generate electricity releases ____ greenhouse gas per unit of energy generated from coal and oil
less
Fossil fuels
Coal steam gas
Coal seam gas is primarily methane, just like wet natural gas. Is found mixed within deposits of wet coal underground known as coal steam (non renewable)
Fossil fuel choices
Environmental impacts of coal steam gas (sourcing) - - - -
- Habitat destruction
- Gas leak of methane
- Fracking
- Sources of groundwater may be depleted
Fossil fuel choices
Environmental impacts of coal steam gas (combustion)
Same as natural gas
Biofuel choices (renewable)
Bioethanol
Bioethanol is produced from….
the fermentation of glucose by yeast cells
Biofuel choices
Bioethanol
-
Sugarcane- the sugar is extracted from sugarcane directly
Wheat, corn, wood- The cellulose (a polymer of glucose molecules) is broken down into glucose in a process known as saccharification, and then the glucose is fermented.
Biofuel choices
Bioethanol
The energy content of buy ethanol is ____ than petrol
lower
Biofuel choices
Bioethanol
Environmental impacts of bio ethanol (sourcing)
Natural habitat has to be cleared to grow crops leading to changes in the ecosystem disadvantage for wildlife. Although source bio ethanol from existing crop plantations minus in the amount of land that needs to be cleared
Biofuel choices
Bioethanol
Environmental impacts of bio ethanol (combustion)
Usually there is more CO2 that is produced in the production of crops because processing the crops requires electrical power which is generated usually via coal which itself produce CO2
Biofuel choices
Biodiesel
Biodiesel is a mixture of…
Fatty acid methyl esters (frames). These frames are produced from modifications of triglycerides
Biofuel choices
Biodiesel
Where do we get the triglycerides from?
We get them from vegetable oil crops are grown and vegetable oil is extracted from these crops and converted to frames
Biofuel choices
Biodiesel
How are they converted to frames though?
By a process called transesterifiedation, Whereby the triglycerides are mixed with a mixture of potassium hydroxide (KOH) dissolved in methanol. KOH is a catalyst whereas methanol is a reactant.
Biofuel choices
Biodiesel
Environmental impacts of biodiesel (sourcing and combustion)
Same as bio ethanol
Biofuel choices
Biogas
is a mixture of gases compose primary of methane with a significant amount of CO2 that is produced from anaerobic metabolism of recently living plant material
Biofuel choices
Biogas is sourced in Australia from :
- 🏭
- 🏕
- 💀
- Sewage treatment plants; Were the organic matter in sewage decomposes anaerobically to produce methane into the atmosphere
- Landfill; The organic matter in Lancefield decomposes anaerobically to reduce methane in the atmosphere
- Biomass; Organic matter from organism that have recently died can be anaerobically digested by bacteria to form methane
Biofuel choices
Biogas has ____ energy content of coal steam gas and natural gas
the same
Biofuel choices
-
- If sourced from biomass and we experience the same issue related to land clearance
- If soured from landfill and sewage treatment plants there is the relatively little negative environmental impact
Biofuel choices
-
- If sourced from recently dead plant material as biomass this is considered carbon neutral
- If biogas is sourced from sewage treatment plants or landfill this will decrease the impact of greenhouse gases admission. This is because if the methane has not been extracted from the sewage treatment plant or landfill it would have just escaped into the atmosphere anyway
Methane itself is in extremely powerful greenhouse gas, _____ pollutant than carbon dioxide
much more
Petrodiesel and biodiesel fuel choices
-
- Petrol diesel is composed of a mixture of Lots of different hydrocarbons
- Petrodiesel is source primary from fractional diffusion of crude oil as a fossil fuel
Comparing biodiesel and petrodiesel
biodiesel and petrol diesel (combustion products)
Compared to petrodiesel, biodiesel produces less carbon monoxide and more nitrogen oxides.
Biodiesel is considered to contain less sulphur than petrodiesel
Comparing biodiesel and petrodiesel
-
-
- Increased viscosity makes it difficult to pump fluid through the narrow pipes and through the fuel pump and fuel filter
- Biodiesel is more viscous than petrodiesel likely because the presence of additional dipole dipole interaction between the C=O group
- The viscosity of fluids increases as the temperature decrease
- Once the temperature is cool enough (below what is called the pour Point ), the fuel becomes so viscous that it is practically unable to flow. The pour point is significantly higher in biodiesel then it is in petrol diesel
Comparing biodiesel and petrodiesel
-
- Hygroscopicity, The ability of the fuel to absorb water from the atmosphere
- Biodiesel has a significantly higher hygroscopicity than petrodiesel because it can form hydrogen Bonds with water molecules.
Comparing biodiesel and petrodiesel
Biodiesel and petrodiesel (environmental impacts) - - - -
Combustion of biodiesel leads to :
- Lower production of carbon monoxide
- Lower emission of particulate matter
- Lower emission of unburned hydrocarbons
- Higher emission of nitrogen oxides
