It was probably my limited view, that when I started studying biofuels, I was only concerned about the transformation of one form of substance into another. It was not about the environment or the climate then. Biodiesel was my first exposure to biofuels. My goal then was the synthesis of fatty acid methyl ester (FAME) from some seed oil. FAME is biodiesel. This is done by the esterification of triacyl glycerol (TAG). During that time, the carbon dioxide was only a combustion product. It was just called a flue gas. Had I done some due diligence, I could have known that CO2 is also a greenhouse gas.
When I was a grade-schooler, CFC was the worst of the greenhouse gases. As a student trying to complete a requirement for graduation, CO2 was but a part of the equation that express the complete combustion of FAME. Growing up observing the understandable antipathy to unstable fuel prices, the biofuels provided a glimmer of hope. We are an agricultural country; thus, we have the renewable feedstock.
The fuel prices made the biodiesel research meaningful. It was also the thrill of doing something for the first time, which was the prospect of running a compression – ignition engine with something extracted and synthesized from plants.
I remember hoarding literatures about Rudolf Diesel that I can find. It was a real challenging work skimming through catalog cards and the bookshelves. The Internet then was a 56k dialup that can’t give reliable results thus the library is the only hope. Rudolf Diesel fueled his engine by FAME he synthesized from peanut oil. It was technically the first biodiesel. Rudolf Diesel was like an Übermensch, an engine inventor who also synthesize his own fuel and from a biomass too.
Some people believe that CO2 and global warming are related. If it was suggested by Svante Arrhenius, then it must be true. Who am I to not believe the father of Acid-Base theory? Arrhenius & Diesel lived after the first industrial revolution in Europe and as far as my memory can supply, I didn’t recall encountering phrases like “green fuel” and “carbon neutrality” while reading about them. Perhaps I was just nervous with the third-party lab testing which was no less than our DOE that I didn’t notice.
When I was working on my thesis, I was concerned that the acrolein might be produced if I fail to rid my biodiesel product of glycerol (or sometimes glycerin). Acrolein is a poisonous gas that are unintentionally synthesized by burning glycerol at the combustion chamber. I’m glad I avoided the transesterification route and heeded advice to perform the mundane fat splitting method, in which the fatty acids were cleaved from the TAG. The fatty acids are then esterified. This process ensured the glycerol is already removed during neutralization and washing. Glycerol is miscible with water; thus, it will not stay with the fatty acid. Acrolein in a biodiesel lab result is an automatic failure and it was non-negotiable.
Years after I graduated, when CO2 has long outdone the CFCs in the greenhouse totem pole, I began catching on the buzzword “green fuel.” I assumed that "green" is something related to plant chlorophyl. I was ecstatic because there's a grapevine that biodiesels give less CO2 emissions too. It was all my projection. Something I encouraged myself to believe while looking at the posters of green fuel pumps that dispense some leaf-shaped droplets.
Even if we're no longer seeing biofuels in rose-tinted glasses, it would be nice to know if the amount CO2 produced during biodiesel combustion, is really less than that of fossil fuels per volume. The answer to this question will be a sure challenge because biodiesels are mixtures of fatty acid esters. There are three fatty acids in TAG and the combination differs from batch to batch. If biodiesel is synthesized from a specific fatty acid, then it would be easier to write a balanced equation and determine the CO2 emitted assuming complete combustion. With this, a true comparison can be performed. Maybe I'm just unaware, but the tests associated with biodiesel, even if it is the ASTM, are only to qualify the consistency of the product to the FAME molecule. Extra information such as amount of methyl ester in a batch, number of glycerides, amount of glycerol, and trace metals are also tested for other reasons. In other words, it is only about ensuring the quality. Not about the CO2 produced upon burning the biodiesel.
The flue gas analysis for combustion is mostly done in blends with fossil fuels, and needless to say, this is a pointless activity. Perhaps there's a study that would authoritatively and quantitatively present the CO2 emission of pure 100% biodiesel. If there are, they will truly shed light to the CO2 emission comparison. Then again, we seem to be leading into an Orwellian future where anything CO2 will not be tolerated wherever you are in the planet. Even if biodiesel or biofuels for that matter, prove to be carbon negative. It might not be deemed as good as technologies that would require punching large holes in the planet to extract the raw materials to make better batteries and better electric current conductors or better catalysis. And not to mention, an operation that might start with the use of fossil fuel products and highly polluting chemicals.
I want to believe that biodiesel is carbon neutral. In the Philippines we have CME or the coconut methyl ester. This is defined in “The Biofuels Act of 2006” or the RA 9367. Is CME carbon neutral? In my humble opinion, the fact that the coconut tree sucks up CO2 in its entire lifetime could mean that it is. The use of coconut oil as a feedstock for the biodiesel might already be carbon neutral if not carbon negative even. Perhaps, a separate study is needed, but the process of harvesting coconuts, husk removing and copra making will surely produce CO2. How does it compare to the CO2 already sucked up and are still being sucked up by coconut trees then? And the husk and coconut shell, will it be turned into coco fiber and activated carbon respectively? How much CO2 will it produce in the process? Or, if they are left in the field to rot, for sure the detritivores will attack them and will produce CO2 during cellular respiration. Let alone, when the coconut tree dies, it will also release the CO2. Will the CO2 sucked up by the tree in its lifetime and the biodiesel burning with less CO2 emission, compared to fossil fuels, compensate for the entire biodiesel footprint and actual usage? Even they are carbon neutral or even carbon negative, will biofuels stand the test of time?
I am only limited to the biodiesel making. I am not lucky enough to study the entire manufacturing footprint. Thus, it is hard to tell objectively whether the biodiesel production and use is really carbon neutral or not.
The ethanol though is a different story. The cellulosic ethanol making can be miniaturized enough to gain an insight to raw material conversion which leads to ease of costing to determine the scale up plausibility. For the environmental part, the CO2 production in ethanol production footprint is established as ethanol is a pure substance, unlike biodiesel that is a mixture. Being a pure substance means possible stoichiometry for combustion testing which makes CO2 production quantitatively calculable. Then we can say if it is carbon neutral or not.
Personally, I find the ethanol processing to be a lot easier than biodiesel making. For once, the feedstock is easier to come by. The Republic Act 9367 will not ease on the biodiesel feedstock anytime soon: it is currently coconut oil and I think it will be forever. But for ethanol, much as the Philippines law suggested the use of sugarcane and sweet sorghum, it is open to the development of other feedstock, provided that the ethanol product passes the reasonable parameters of the Philippine National Standard (PNS) for fuel grade.
I also think that ethanol production is carbon neutral if not carbon negative. This is especially when the feedstock for ethanol making is farm waste. Some have misgivings in the use of farm waste because of the innate difficulty of rendering the cellulose from the biomass. However, there are available chemical means that can easily render the cellulose from the biomass feedstock.
The cellulose conversion to a fermentable glucose, the fermentation and distillation are all straight forward processes. If the energy needed for optimum heating during the enzymatic conversion, fermentation and distillation is supplied by the ethanol produced from farm waste, then perhaps this is a carbon neutral endeavor. Ethanol can be fed into a generator run by a spark-ignited engine. If the supply is sufficient, there is no doubt that it can power the heating requirements for the ethanol making processes. And hopefully there is surplus electricity too.
Biodiesel is to diesel engines as ethanol is to spark-ignited engines. Nicolaus Otto used ethanol when he introduced his spark-ignited engine for the first time. Otto invented an engine compatible to ethanol as fuel. No doubt, another “Übermensch.”
Biofuels could be fed into existing technologies that does not require modifications. Biofuels has an established use in the transportation industry.
This is opinionated. This was not academically reviewed. Kindly do your own research before believing anything I wrote here. Thanks.
By: AJ Martirez
Edited & Proofread by: Kristine Paraiso
Comments