Combustion

Fossil Fuels

There are three primary ways we generate this power for our modern world:

Burning Fossil Fuels is most common, burning oil, gas, or coal to make a turbine spin and generate electricity.
Green Energy comes from hydroelectric dams turning turbines, solar panels converting sunlight into electricity, wind turbines, and the like.
Nuclear Power comes from nuclear reactors heating steam to turn a turbine.

The most common energy source we use in the modern world are Fossil Fuels; things like coal, oil, and natural gas. To use these fuels we burn them, converting the heat they produce into electricity. These fuels are used and found worldwide with industries that are already well developed and efficient, making them the go to for easy energy. In addition the amount of energy within them is dense for their size, making them easy to ship where energy is needed.

Fossil fuels also come with downsides, specifically the high amount of carbon dioxide produced when burned. They are all extracted from the earth, non-renewable, and highly flammable. Each of them also have additional concerns:

Coal: Coal is considered the most dangerous fuel to use. Coal mines require a lot of land, create lots of noise and pollution, and injury is more frequent than other forms of energy.
Oil: Oil contains many different types of molecules that make it require refining before use. Oil is extracted from the ground via drilling and extraction. Some oil may be found in hard minerals, making it more difficult to extract and requiring additional processes that can cause more pollution and instability to the ground and any water nearby as the harder minerals are broken up.
Natural Gas: While the cleanest fossil fuel, natural gas is the most difficult to transport since it either requires specialized cooling to transport as a liquid or a lot of space as a gas. It's also difficult to store, being a gas.

Green Energy

Green Energy is relatively new but is gaining a lot of traction as we work on reducing our dependency on fossil fuels. While it's cleaner it requires specific locations for maximum efficiency - not every location can use wind, solar, or hydroelectric power. On top of that, it's difficult to store green energy. Each of these types of energy also come with their own issues:

Wind: Wind energy has several downsides. It has high startup costs, can cause problems to flying wildlife, and requires a lot of land to generate enough electricity to provide energy for a city.
Solar: Solar requires mining of rare earth metals, has relatively low energy efficiency, and is the newest technology that we often use. Solar panels are also expensive to repair, need special disposal when broken, and are completely weather dependent.
Hydroelectric: Hydroelectric power is usually made by making a dam. These dams can disrupt water flow, flooding new areas and causing problems for people and wildlife alike if not done carefully. They're expensive to make, can only be done at ideal locations on a river, and can cause major problems if they ever break.

As technology advances we have more potential options as to where we get our energy from. This list contains some of the new technologies that have promise but aren't as widespread as the others yet:

Geothermal: Energy from the heat given off from the Earth's Core.
Hydrogen: Energy from burning hydrogen gas.
Biomass: Energy from burning plant matter.
Tidal: Energy from tidal forces in the ocean.

Humans and Energy Use

In the past individuals were forced to harness power that humans or animals created from the energy stored in food, however now energy is widespread and varied. Today our focus is generally on efficient, clean, and accessible energy use. An energy system can even include multiple energy sources that can be combined to convert energy into useful forms, such as in hybrid cars or other machines. We also know that many sources of energy won’t last forever and that they can have negative consequences on the environment. There's always tradeoffs in selecting the right energy source.

The United States uses many different energy sources for power. Keep in mind that biomass also releases CO2 into the atmosphere so our "green" renewable energy is about 6%. This green energy also requires products that use fossil fuels to be produced and shipped worldwide.

We use stored energy in different ways for our lives. Commercially this generally happens through combustion inside of some form of turbine, burning of fossil fuels to produce electricity. Combustion can also be used in a smaller scale for objects such as portable generators, vehicles, grills, and more, burning fossil fuels similar to its large scale counterparts.

Carbon Emissions

While it has many potential dangers associated with it, fossil fuels are still the most abundantly used source of energy in the world by far. They can be found in one form or another in most countries and we have the infrastructure necessary to continue using them efficiently and effectively for the time being, unlike green energy. Fossil fuels are also used to make products of all kinds - both directly in things such as plastics and clothing and indirectly in the production of glass, concrete, and much more.

The United States produces a lot of greenhouse gases, especially CO2. A further breakdown of these emissions can be found here.

Many countries are responsible for the high levels of CO2 emissions, not just the United States. Even so, global shipping and transportation cause the highest amount of emissions throughout the world, more than any one country.

This link contains a partial list of other products made from crude oil. There's many things we'll need to find alternatives to or modify on this list if we try and go green.

The current CO2 jump in the atmosphere is happening very quickly compared to the usual cycles, the highest concentration since times before the ice age.

Our current CO2 is nothing (percentage-wise) compared to how much there was in the past billions of years ago; life will ultimately go on no matter what the heating of the planet means for mankind.

The Science of Fire (PSA)

Fire is made by combustion reactions and requires 3 things in total:

A fuel source: This fuel source can be anything flammable, the most common of which are organic molecules (so compounds primarily made of Carbon and Hydrogen). Organic molecules are found everywhere, be it clothing, food, gasoline, or furniture!
Oxygen gas: The air around us is 21% oxygen gas, allowing fire to easily spread under normal conditions. Fires can run out of oxygen in the air by smothering them or filling the air with some contaminant (such as other gasses or flame suppressing vapors/gasses).
Heat: If heat is allowed to build up near a fuel source it can cause that fuel to ignite (depending on how flammable it is). To prevent this we try to have ways of venting heat out of locations where its buildup would be bad, ways to reflect heat, or ways to insulate fuel sources. Once the combustion reaction begins the heat given off from the reaction is usually enough to continue sustaining it.

When looking at a fire we try to primarily find the origin of the fire (where did it start?) and the cause of fire (ignition source, the first fuel source, how did these two things come together). The types of causes are the following:

Accidental. The fire was either spread on accident or started on accident.
Natural. The fire was created from a natural source, such as lightning or wind.
Incendiary. The fire was deliberately made.
Undetermined. The cause is hard to figure out or under investigation. Suspicious activity can be found through specific burn patterns, specific chemicals, tampering with buildings or utilities, and more.

How fires spread is also based on a triangle! Topography's elevation and slope change how the fire can move, wind spreads the fire different directions and dries out vegetation, and the availability of fuel can change how quickly it spreads from one source of fuel to another.

In combustion reactions, oxygen gas reacts with something organic, releasing energy as both heat and light. The general reaction for combustion is the following:

CxHy + O2 -> CO2 + H2O + Heat

Incomplete combustion is also a possibility in cases where there's not enough oxygen, making extra chemicals in the air (such as carbon monoxide or carbon):

CxHy + O2 -> CO2 + CO + H2O + Heat

Complete combustion produces more energy than incomplete combustion but in both cases the amount of matter doesn't change - it's just rearranged.

Most things don't burn clean. Combustion often makes many contaminants, causing the other chemicals in the reaction to leave residue. This is true for wildfires, gunshots, and explosives!

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