Fuel and Energy Flashcards
what is the difference between hydrogen and hydrocarbons
oils are all large ____
hydrocarbons
UK only has ___ years of natural gas left
6.
what is “fracking”
cracking underground rocks with high pressure liquid. used to extract oil and natural gas from deep underground.
what is a downside of fracking?
uses a lot of water between 5 and 13 million litres.
it can also encourage earthquakes.
what’s the first step in processing natural gas
reforming, this is heating with a small amount of steam which forms synthesis gas. (mix of H2 and CO2.)
is coal or oil more common
coal
what are some waste products of burning coal
SO, NO and other heavy metals
what are examples of biofuels
ethanol and methanol
what are negatives of biomass
deforestation, burning the plants and wood produces CO2, can compete with food production.
what are positives of biomass
made from renewable sources such as plants and burn cleaner than petroleum fuels.
what are negatives of hydrogen as a fuel
colourless and odorless . can be bad if catches on fire.
not easy to move and hard to pump.
Hydrogen reacts with the atmosphere to increase the concentration of greenhouse gases like methane or ozone.
negatives of ammonia as a fuel
its toxic
emits lots of pollutants.
what is combustion
exothermic reaction between a fuel and oxygen
what is complete combustion
only produces CO2 and H2O
what is incomplete combustion
occurs when there is not enough oxygen to fully burn the fuel.
produces CO + C(soot) + water
it also produces much less energy than complete combustion.
what is a thermal power generation?
using steam power created by burning oil, liquid natural gas (LNG), coal, and other substances to rotate generators and create electricity.
examples of non-thermal energy sources
hydro
tidal
wind
wave
examples of direct energy
photovoltaic cells - conversion of light into electricity. (solar panels)
fuels cells - 2 electrodes , similar to a battery.
what is Carnots theorem ?
no heat engine can be more efficient than a Carnot engine when operating between the same two heat reservoirs.
it sets a thermodynamic limit on efficiency of heat engine.
what is the symbol for carnots theorem
n
what is the equation for carnots theorem ?
n = max work (energy out) / heat in
= Th - Tc /Th
Th is hot reservoir temp in K
Tc is col reservoir temp in K
how is hydrogen fuel produced
splitting up water
H20 -> 2H+ + 2e-
2H+ + 2e- -> H2
what example is used for the negatives of hydrogen
hindenburg disaster.
- an electrostatic discharge (spark) ignited the hydrogen and created an explosion.
- it killed 35 people.
