Environmental problems Flashcards
what are the main burners of fossil fuels?
power stations and cars
what happens during combustion of crude oil and coal?
the carbon and hydrogen are oxidised so that carbon dioxide and water vapour are released into the atmosphere (and energy)
what happens if the fuel contains sulfur impurities?
the sulfur will released as sulfur dioxide when the fuel is burnt
if the fuel is burned at a high temperature, what will also be produced?
oxides of nitrogen
what is complete combustion?
when there is plenty of oxygen and all the fuel burns `
what is partial combustion?
when there is not enough oxygen and some of the fuel doesn’t burn, particulates of soot (carbon) and unburnt fuel are released. carbon monoxide is also released
what is the gas that causes acid rain?
sulfur dioxide
how is acid rain formed?
the sulfur dioxide released mixes with the clouds and forms sulfuric acid, which forms as acid rain
what effects can acid rain have?
causes lakes to become acidic and many plants and animals die as a result, kills trees and damages limestone buildings and stone statues
disadvantages of removing sulfur from fuels before they are burnt
costs more to do it, takes more energy which comes from burning more fuel releasing more of the greenhouse gas carbon dioxide
how do power stations take out the harmful gases before releasing their fumes into the atmosphere?
they have acid gas scrubbers
what is happening to the level of carbon dioxide in the atmosphere and why?
it is increasing because of the large amounts of fossil fuels humans burn
what is carbon dioxide causing?
global warming-the average temperature of the earth has increased
what types of climate change can global warming cause?
changing rainfall patterns and severe flooding due to the polar ice caps melting
what is global dimming?
in some areas nearly 25% less sunlight has been reaching the surface of the earth compared to 50 years ago.
what is global dimming caused by?
particles of soot and ash that are produced when fossil fuels are burnt reflect sunlight back into space, or they can help to produce more clouds that reflect the sunlight back into space
alternative fuels to fossil fuels
ethanol, biodiesel and hydrogen gas
how is ethanol produced?
from plant material (so known as a biofuel), made by fermentation of plants and is used to power cars, often mixed with petrol to make a better fuel
pros of ethanol
it’s carbon neutral- the CO2 released when it’s burnt was taken in by the plant as it grew
only other product is water
cons of ethanol
engines need to be converted before they’ll work with ethanol fuels.
ethanol fuel not widely available
worries that as demand for it increases farmers will switch from growing food crops to growing crops to make ethanol, so food prices will increase
how is biodiesel produced?
from vegetable oils such as rapeseed oil and soybean oil, can be mixed with ordinary diesel fuel and used to run a diesel engine
pros of biodiesel
‘carbon neutral’
engines don’t need to be converted
produces much less sulfur dioxide and ‘particulates’ than ordinary diesel or petrol
cons of biodiesel
can’t make enough to completely replace diesel
expensive to make
could increase food prices if farmers switch from growing food crops to growing crops to make biodiesel (due to increase in demand)
how is hydrogen gas produced?
from the electrolysis of water, electrical energy needed to split water up which can come from a renewable source e.g solar
pros of hydrogen
combines with oxygen in the air to form just water-very clean
cons of hydrogen
need a special, expensive engine
hydrogen isn’t widely available
still need to use energy from another source to make it
hard to store
