Hydrocarbon Fuel Problems Noadswood Science, 2011

Hydrocarbon Fuel Problems To understand the concerns with burning hydrocarbons Monday, May 04, 2015

Combustion Combustion is the chemical reaction which takes place when a substance burns – it is an exothermic reaction The substance reacts with oxygen, releasing energy (heat and light) Combustion is extremely important (>90% of the world’s energy comes from combustion reactions (e.g. fossil fuels such as coal, natural gas and petrol) During combustion the hydrogen and carbon are oxidised

Fuels Many fuels are hydrocarbons - made up of hydrogen and carbon – when they burn they produce carbon dioxide and water Methane + Oxygen  Carbon Dioxide + Water Petrol is a complex mix of hydrocarbons, with an important component being 2,2,4-Trimethylpentane (isooctane) However as it is a hydrocarbon the equation above still applies, resulting in carbon dioxide and water being produced during the combustion (along with a few other products such as nitrogen oxides, sulfur, some un-combusted hydrocarbons and soot (particulate matter))

Environmental Concerns Levels of carbon dioxide in the atmosphere are increasing – in no small part due to the increased burning of fossil fuels As carbon dioxide levels in the atmosphere increase so the reaction between carbon dioxide and seawater increases – producing insoluble carbonates and soluble hydrogen-carbonates In this way the sea acts as a buffer – however this buffering system is put under increasing strain as we burn more fossil fuels…

Greenhouse Effect Normally the Earth absorbs heat and emits heat at the same rate, causing the temperature to remain constant Certain gases, like CO 2 and methane, act like a greenhouse – they let heat in but do not let it out meaning the more CO 2 and methane there is, the hotter planet will become… Earth Heat from sun Heat loss Earth Heat from sun Heat loss hotter And hotter More CO 2 = hotter! Balanced = same temp

Acid Rain Acid rain has a higher than normal acid level (a low pH) Acid rain may contain weak solutions of carbonic, sulfuric acid, and nitric acids Where it falls over a prolonged period it can cause damage to the environment…

Acid Rain The vast majority of these chemicals are pollutants, produced from cars and power stations When these dissolve in rainwater they produce strong acids (sulfuric acid and nitric acid) forming acid rain

Acid Rain

Global Dimming Global dimming is also a major concern due to the burning of hydrocarbons - tiny particles that are released when fuels are burned cause global dimming (like global warming, this process may change rainfall patterns around the world) The amount of sunlight reaching the Earth’s surface has decreased by about 2% every ten years, because more sunlight is being reflected back into space – the particles from burning fuels reflect sunlight, and they also cause more water droplets to form in the clouds This makes the clouds better at reflecting sunlight back into space

Global Dimming It is likely that global dimming has hidden some of the effects of global warming, by stopping some of the Sun’s energy reaching the Earth’s surface in the first place Governments around the world are introducing controls on pollution There is the possibility that as the air becomes less polluted by smoke and soot, global dimming will decrease, causing the effects of global warming to become more obvious…

Release Or Consume?