The Science of Global Warming

The Case for Biodiesel

Sources of C O ₂

One of the easiest things that the world can do to help alleviate the problems of global warming is to cut down CO ₂ emissions. In America there are two main sources of emissions. The first is the transportation industry. Most Americans of age own a car and drive it polluting the environment. The two things that make this worse in America than most other countries is the fact that we drive cars by ourselves instead of car-pooling or taking public transit and the ridiculously low mileage we get in our vehicles. Foreign cars get 50% more mileage per gallon than American cars. Knowing this the American public has started buying fewer and fewer American cars, yet the American auto industry is trying to keep the required MPG at the lowest in the world. And that's just the cars; SUV's are not considered cars.(5) GM has successfully lobbied the government to get SUV's classified as trucks, meaning they can get even fewer miles to the gallon. We are wasting fuel at a ridiculous rate. A few months ago the Secretary of Energy for Bush gave a speech on energy conservation. He flew on a private jet to California, then took an SUV to a speech he gave from said SUV without turning off the engine, then flew back on another private jet flight. In giving his speech on energy conservation he wasted more energy than most people in the world consume in 3 years. Despite this, the transportation industry is not the biggest consumer of fossil fuels. Fully 70% of the United States energy is put into the power grid from the burning of fossil fuels, primarily petroleum and coal. The energy industry is a huge polluter, having in the past 5 years successfully gotten the government to change laws so the energy industry can pollute more than they could at any time since 1970. There are other sources of gaseous emissions, but these are the two largest. Additionally jets and other fuels that are now primarily petroleum could possibly be modified with Hydrogen Peroxide, but the emissions from that might not be any better and safety concerns with using rocket fuel for planes is beyond the scope of this unit. If we cut down our emissions our ecosystem would have a chance of recovering.

But what can we do? Americans use a lot of energy and want to be able to drive places without carpooling. Is there a way to cut emissions without cutting our energy consumption? Yes.

Why Biodiesel

Biodiesel could be a key ingredient to helping save our environment. It is not a panacea, but it will definitely help. Biodiesel cuts CO ₂ emissions by over half compared to the emissions of gasoline. It still emits carbon dioxide making it only a band-aid, but it is a stop-gap measure until alternative energy sources can be better harvested. I think biodiesel is a viable source of energy because there are little or no alterations that need to be made to our cars and power plants for it to be used. The consumer does not need to make major changes, just the suppliers. Biodiesel is diesel that is produced (process to be discussed in experimental section) from vegetable oil instead of petroleum oil. Biodiesel is not the final solution to our energy/environment conflict, but it is a good first step to wean ourselves off of petroleum based fuels.

Throughout this unit there will be reference to theoretical and actual values. Wherever possible actual values (either collected from industry or experiments) will be used, although mention of theoretical values may be made because as we start doing things in larger scale processes become more efficient, but sometimes there is not enough data so theoretical calculations must be made. This is especially true when talking about calculations of capacities in foreign countries, for example how efficient is the drilling for oil in the Middle East? We do not know for sure, but we can compare it to what the numbers were in similar climates in America when the oil was similarly plentiful. Is this exact? No, but it is very close and will be a decent ball park figure. Since some of the data is not exact there will need to be a very large difference between biodiesel and petroleum oils to be sure, so the calculations made are using the numbers that are the least favorable to biodiesel although reference to the other calculations is made. So if the most petroleum friendly numbers are used, and there are shown to be marked environmental and economic advantages to biodiesel, we can be sure that biodiesel is preferable to petroleum oils.

Energy Balance

In order to figure out how much Biodiesel helps the environment we need to look at energy balances. The first thing to consider is how much energy it takes to produce fuel. The oil in the ground does not end up in your car (or heater or other use of oil) without any effort. Many things must be taken into account.

Let's first look at gasoline. Gasoline must be pumped from the ground, refined, transported, and then finally it can be burned to release energy. Depending on where the oil is gotten from sometimes things like sand and water must be filtered out. And if the oil is in sand pumping it out is much more difficult. If the oil is gotten from frozen areas it must be transported (see permafrost melting section for discussion of transportation) to areas where it will be refined and used. All of these things take energy. The technical name for this calculation is Energy Returned on Energy Invested (EROEI). It is estimated that back in the 1930's we had to put one joule of energy into producing enough gasoline to release 100 joules of energy (EROEI of 100). By 1960 that same one joule would only produce enough gasoline to release 50 joules of energy (EROEI of 50). That reduction is mainly due to the fact that we were using oil that is harder to pump, all the oil we could easily get to was used. By 1998 the average EROEI of oil consumed in America was 10, and it is calculated that the average EROEI in 2004 was 5. We are using all the oil that is easy to get to, and that ratio is going to get worse and worse as it gets harder to pump oil. Some estimates have that ratio going down to 2 or lower in the next decade. In addition to the lighter oil and non-sandy oil being consumed, the oil in the colder areas will be harder to get. Currently most of the roads in Alaska and the pipelines depend on the soil being frozen. They are placed on permafrost and as that soil unfreezes the roads become undrivable and the pipelines crack from sinking. Entire pipelines and roads will have to be re-laid. Diesel does not have the same EROEI as gasoline, but it is similar. Diesel has more energy per gallon than gasoline and the engines are more efficient. The increased efficiency of the engines (gasoline engines require 4 strokes to propel the car while diesel engines require 2 strokes) was not taken into account because while this is an advantage to Biodiesel over gasoline, it is not an advantage to Biodiesel over petroleum diesel.

Calculating the EROEI of Biodiesel is a little bit trickier. The main thing that affects this is where you get your vegetable oil. The main sources of vegetable oil that are being used are soy, corn, and used cooking oil. Used cooking oil (called yellow grease) is the best to be used by far, with soy and corn oil virtually the same but behind yellow grease. Yellow grease has a theoretical EROEI of 35.7 since the expense of turning the vegetables into oil is ignored because that oil was produced and used for its initial purpose, but realistically has an EROEI of 6.34. Unfortunately there is a limited supply of yellow grease; only about 2 billion gallons of yellow grease and the like per year are produced in America today. This is helpful, but not enough considering the US consumes about 150 billion gallons of petroleum a year. We must look at other sources for Biodiesel.

The EROEI of Biodiesel from soy and corn is variable; it depends mostly on where the crop is grown and how much fertilizer must be used. I will focus mostly on soy Biodiesel because soy is a crop that is less exhaustive on the soil than corn. The EROEI of soy Biodiesel could range anywhere from 1.2 to 7, but 3.4 seems to be the most accepted low estimate.

Materials Balance

Now that we have figured out the energy balance, let's look at a materials balance. More specifically, what are the CO ₂ emissions of the fuels? Theoretically 3.96 Liters of gasoline produces 8.8 Kg of CO ₂, that same amount of diesel produces 10.1 Kg, and that same amount of Biodiesel produces 2.6 Kg! Experimental data is skewed even more towards Biodiesel, with gasoline emissions being 12.6 Kg of CO ₂ and Biodiesel emissions being 2.7Kg and other experiments showing an even bigger differential. Even using the conservative estimates though, Carbon Dioxide is reduced by 54% (calculations in Appendix) using Biodiesel (experimental data from the Department of Energy and United States Department of Agriculture showing reductions 78% or more). Also, remember that the plant used to make the biodiesel is soaking CO ₂ from the air, the CO ₂ that is released, making biodiesel virtually carbon neutral and that one Liter of biodiesel gets you further than one Liter of gasoline.

Other molecules like carbon monoxide, soot, methane, and others are reduced substantially, anywhere from 37% to 84% Sulfur oxides (SO _X) are theoretically reduced by 100% (experimentally reduced 99.9997%). SO _X are particularly dangerous pollutants. Not only are they one of the main molecules that lead to acid rain, but they have also been shown to cause bronchitis, emphysema, heart disease, and are occasionally carcinogenic. Cutting out SO _X could help mitigate the lowering pH of our water supplies. There is one down-side to biodiesel…there is an increase in nitrous oxides (NO _X) emissions. There can be as much as a 10% increase in NO _X emissions, but 8% is more common. NO _X is also a precursor to acid rain. The decrease in SOx emissions more than makes up for the increase in NO _X emissions, but that doesn't even have to be taken into account. Knowing the release of NO _X and SO _X gases is bad for the environment catalytic converters were put into cars and power plants to take out those gases. They currently are designed to take out a high percentage of both, but if they were changed to effect only NO _X gases they would become even more efficient and cheaper. They also would last longer, meaning you would have to replace the catalytic converter in your car even less often than you do now.(14)

Waste of Petroleum vs. By-Product of Biodiesel

Another difference between biodiesel and petroleum oils is the amount of solid waste in their production. The production of biodiesel causes twice as much solid waste; however this is a good thing. The solid waste of biodiesel production is almost entirely fertilizer. It is biodegradable and can actually be used to make soil more fertile, increasing the EROEI of biodiesel even further, or it can be used to produce other alternative fuels like celluloid ethanol which cuts greenhouse gases by 85% (also there is currently enough farm waste to reportedly make enough celluloid ethanol for 25% of American transportation). There is some hazardous waste from biodiesel, but it is 96% less than petroleum oils. Disposal of waste from petroleum refineries is a major problem, quite often the waste is carcinogenic, and it is always harmful and must be stored similar to nuclear waste. This is not to say that the petroleum waste is as bad as nuclear waste, it doesn't need to be stored as long; but when you're talking about billions of Kg's instead of a few Kg's, there is a major issue. Biodiesel does not have this problem, almost all of its waste could actually be considered a useful by-product that can be sold itself or turned into more fuel.(14)

Economic/Geopolitical Safety

An additional advantage is that if we switch to biodiesel the US could be completely self sufficient as far as fuel is concerned. We will not have to worry about the whims of other countries that might want to make more money at the cost of the American consumer. Since all of our oil is produced domestically we would not have to import any oil. Also, when we are gouged at the pumps at least the money will be reinvested into our economy more broadly to farmers instead of into the few pockets of the oil magnates. This would also create many jobs for Americans, even further helping our economy. Since we would not be as concerned economically with other countries we could possibly become even more insular, but a cost benefit analysis (in my mind) would say that we're better off ignoring a world than not having a world. This is a tough sell though, because a lot of fortunes would be at risk, many people with power in America have a lot to earn from instability and petroleum.

Possibly more important than the direct economic issues is the fact that we would be self sufficient as far as energy is concerned. We would not have to depend on the good will of other countries to keep our energy supply and the ability to trade. At $70 a barrel, domestically supplying oil would decrease our trade deficit 448 billion dollars, 61.7% (calculation in Appendix).

Is There Enough Land

But is this practical, how difficult is it to make biodiesel and is there enough land to grow the stuff to make biodiesel? The United States consumes about 20.6 million barrels of gasoline a day, and each barrel makes approximately 19.5 gallons (leaving 22.5 gallons of waste and other by-products) meaning that the US consumes nearly 150 billion gallons of petroleum fuels a year (calculation in appendix). Each acre of land devoted to making biodiesel can produce enough crops for 55 to 200 gallons of fuel depending on how arable the land is and the crop chosen. This means that we would need 3 billion to approximately 750 million acres of land (or less if optimum figures are used) devoted to making biodiesel. This is a lot, but not an impossible amount. Currently the United States government pays people to not plant crops on their land in order for the prices of crops to be higher, there is enough land in that situation or is otherwise lying fallow to develop about 60% of the biodiesel needed. Other land could be converted or used for dual purposes (we're losing about 100 million acres of farm land to urban sprawl a decade), and also soy can be grown on parcels of land in places like New Mexico and other areas that normally are not thought of as arable. Additionally, there is more than enough land in Mexico that is not being used on which soy could be grown. This of course loses the possibility of America becoming completely independent of foreign governments as far as our fuel is concerned, but would you rather depend on the Middle East for fuel or a country with whom we share a border?(2)