TheLittlestGuy

The carbon emission factor for a particular fuel is the amount of carbon released per amount of energy produced. Fuels are combusted to release their energy. In general, a fuel source, oxygen, and some initial energy (often heat or a spark) are required to start a combustion reaction. Currently, most of our fuels are some sort of hydrocarbon (a molecule that is made of hydrogen and carbon atoms). The bonds of these molecules must be broken (which is why the heat or spark is required) and then these hydrogen and carbon atoms react with oxygen to form CO₂ and H₂0. The formation of these new bonds releases energy that we can capture and use to do work (like move a car from one place to another or to heat and light our home).

The carbon emission factor of a fuel simply tells us how much carbon will be released per unit energy. The less carbon that is released when we produce a certain amount of energy the less CO₂ we produce and the less greenhouse gases there are to cause global warming and climate change. Since reducing greenhouse gases is important, carbon emission factors are important too.

Below are the carbon emission factors for several common fossil fuels. The lower the number the less carbon is released per unit of energy released.

Natural Gas: 0.46 kgC/watt-year
Oil: 0.60
Coal: 0.77
Wood: 0.89
(Watts, Robert, Innovative Energy Strategies for CO₂ Stabilization, 32)

math & science warning

Lets take a brief look at how this number is calculated. I’ve chosen to use coal as an example. One popular type of coal, gas coal, produces about 35,000 Joules per gram according to Wikipedia (http://en.wikipedia.org/wiki/Coal). 85% of this type of coal is made of carbon.

0.85 carbon	1 gram coal	1 kilogram	1 Joule	31,536,000 sec
1 coal	35,000 Joule	1,000 grams	1 Watt-sec	1 year

= 0.766 kilograms Carbon/Watt-year (compared to 0.77 kilograms Carbon/Watt-year above)

I hope I didn’t lose you there…that’s about as scientific as I’ll get in this article. If that didn’t make sense then you can decide whether you want to believe me or you can take the time to prove that coal’s carbon emission factor is 0.77 for yourself.

Whether you desire to prove this to yourself or not, what this means is that over the course of a year, coal can produce 1 Joule of energy per second for an entire year and produce 0.77 kg of Carbon over that year. 0.77 kg of carbon is equivalent to 1.425 m² of CO₂ gas.

That’s not a very easy fact to visualize so let me work with a more concrete example. The very bright halogen light that I’m using as a desk lamp currently has a 50 Watt light bulb in it.

50 W * 1hr	1 Joule/s	60 mins	60 sec	1 g coal	0.85 g carbon	44.01 g CO2
	1W	1 hr	1 min	35,000 Joule	1 g coal	12.01 g carbon

W = Watt

g = gram

= 16.02 gram CO₂ is produced by my 50 Watt lamp every hour. This number is not quite accurate because it doesn’t account for the energy lost when combusting coal. Efficient coal plants run at 36-38% efficiency (http://en.wikipedia.org/wiki/Fossil_fuel_power_plant). New designs may allow coal plants to operate with efficiencies between 40-48%. What this means for our 50 Watt light bulb example is that three times as much coal may be required to power the light bulb than calculated above.

back to basics

So let’s say that 45 grams of CO₂ are produced for every hour a 50 Watt lamp is on. This is kind of difficult to imagine so let me put it in more concrete terms. One US nickel has a mass of about 5 grams. So take about nine nickels and that is the approximate mass of CO₂ produced by having my light on for one hour. In order for this CO₂ to be removed from the atmosphere, a plant (or some other kind of phototroph) must use photosynthesis to convert the sun’s energy into chemical energy. Photosynthesis uses light, CO₂, and water (CO₂ and water are products of a combustion reaction) to make glucose, a sugar which is often converted to a carbohydrate like starch or cellulose (for energy storage/transport or structural reasons).

In another article I do the math and figure out how many trees it would take to get this CO₂ I just produced out of the atmosphere (carbon offsetting). The short answer is that if I plant one tree I could run my 50 watt lamp for 500 hours a year without having a net increase on the CO₂ in the atmosphere. But there are two problems: I didn’t plant a tree and I have a lot more stuff consuming power than this one lamp right now.

conclusion

So before I get too far off the topic of carbon emission factors, let me wrap things up so you can read about carbon offsetting. Carbon emission factors are important because they tell us how much carbon we’re releasing when we combust fossil fuels to get energy. The shorter the hydrocarbon (link), the less carbon is released per unit energy produced. [I may explain the fairly complex chemistry of why this is in another article.] So natural gas (methane primarily) releases less carbon per joule of energy than oil, which releases less carbon than coal, which releases less carbon than burning wood. Most of the United States power comes from coal, of which the US has vast amounts. Coal has a fairly high carbon emission factor, which means that if we were to combust natural gas instead of coal we could release less CO₂ and still produce the same amount of energy. This is important for developing countries like Chine, which is currently building huge infrastructure of coal plants. China could help out the climate change situation a great deal by using fuels that have lower carbon emission factors.

Oh yeah, I forgot to mention that most renewable energy sources have carbon emission factors of 0. That’s because they don’t release any CO₂ into the atmosphere or because they release the same amount of CO₂ that they consumed when they were created. Ethanol is made from plants which consume CO₂. Then the ethanol is combusted and releases CO₂ back into the atmosphere and more plants are grown.

Global warming (which is a misnomer for the weather phenomena called Climate Change) is no longer up for debate. It is no longer deniable that humans are having an effect on the environment. Think about the climate the last few years. Increased hurricane activity, warmer summers, and shorter but often harsher winters are signs that we are changing the face of the planet. The question is how much damage have we already done and what are we going to do about it? Only we have the power to stop climate change; you and I, the littlest guy.

proof

The proof is all around us. The average temperature of the earth is rising. The composition of the atmosphere is changing to include more greenhouse gases like CO₂, CH₄, SO₂, N₂O and CFCs. Atmospheric levels of these gases are rising at an unprecedented rate. The cause is an increased combustion of fossil fuels to meet our rising energy needs.

CO₂ and the other greenhouse gases raise the temperature of the earth’s surface by not allowing the earth to reflect as much of the sun’s energy back out into space. In 2004, CO₂ levels were measured to be 377.6 ppm (parts per million). Pre-industrial revolution CO₂ levels were 280 ppm +- 10 ppm for 1000 years (1, Recent Greenhouse Gas Concentrations & 2, Historical CO₂ Records). Is it any coincidence that atmospheric CO₂ levels have been raising ever since CO₂ producing fossil fuels have become our primary source of energy? No, it is not. Fossil fuels like gasoline and coal provide energy for us but produce earth harming CO₂.

future

We will continue to experience the effects of climate change. The severity of damage and the time until the earth recovers are outcomes that we have the power to adjust. But until we decide to change things we will continue to damage the planet and feel the effects of our negligent behavior. Ecosystems are already adapting by reducing biological diversity. Fresh water runoff will be reduced affecting crop irrigation, hydroelectric power sources, water transportation, and the availability of water for industrial uses. Severe drought will make some areas of the world uninhabitable desert. Rainfall will increase in other areas, contaminating drinking water with the runoff from fertilizers, pesticides, hazardous and human waste in the soil.

A decrease in agricultural production in the tropics and subtropics may cause famine and hunger in areas where people are already very poor and cannot afford the resulting increase in the cost of food. The cost of meat will increase as grain for cattle becomes scarce. Sea levels will continue to rise about 50 cm (roughly 20 inches) in the next 100 years as melting snow and ice pour into our oceans from glaciers and the polar ice caps (3, IPCC). As water levels rise, increased flooding, billions of dollars in property damage, coastal erosion, surging during inclement weather, saltwater contamination of freshwater sources, and damage to coastal and shallow-water habitats are likely to follow.

Heat waves, disease (spread by higher population densities and better breeding conditions), and insufficient food production will all affect the quality of life for humans. Social and economic collapse may follow which could unravel the fabric of our global society. The physical sacrifices may be very great but the psychological effects may be even more scarring. Change will occur – whether we like it or not. The sooner we recognize the need for change, the easier the change will be.

hope

Climate change is here to stay until we decide to make it a serious priority. The time for debate over global warming and climate change has come and gone. The facts show that humans are changing the earth. If we make serious changes soon we may be able to avoid a terrible future and survive through the next few decades with minimal disruption to our standard of living – but the choice is in your hands.