From FOG To Fuel
“Whoever is number 44,” meaning the next president, “will transfer $2 trillion to $3 trillion out of the economy - the amount America will spend on foreign oil in his first term.” - Shai Agassi, an Israeli entrepreneur seeking to establish electric cars and necessary support infrastructure as a major segment of land transport worldwide.
Alternate energy. One hears the term every day, everywhere, usually followed by the phrase, “energy independence.” While researching this article, I learned at least two fundamental, probably obvious to many, scientific facts about energy. First, there is no such thing as alternate energy. Second, energy independence is not possible. The terms are not proper science, not even technically accurate. Rather, they are social terms akin to, “ask your father for the money,” and “I need a job,” respectively.
(Photo) Solid biomass (wood) chips can be converted to a dark brown viscous liquid by a process known as pyrolysis. In this process, heat is applied to the biomass very rapidly in the total absence of oxygen. This is typically carried out in fluidized beds with an inert gas used as the fluidizing medium. Liquid yields of up to 70wt% have been demonstrated under optimum process conditions. The bio-oil liquid can be used in fuel applications in addition to extracting useful chemical compounds. Source: National Renewable Energy Laboratory
U.S. Energy Sources and Uses: Currently, 28.70% of the entire U.S. energy
source flow is comprised of petroleum imports, and the transportation sector
comprises 29.0% of energy use. Without further refinement of the data relative
to other sources and uses of petroleum products, one might conclude we are
importing virtually all of our transportation fuel.
Where We Are Now
There is a serious economic, and strategic, imbalance in the U.S. energy structure. The imbalance centers on liquid fuels and is, therefore, directly impacting on every citizen in gasoline and diesel prices. The impact also affects everyday prices of virtually everything we wear, eat and ride.
The liquid fuel imbalance is strategic because expenditures for liquid fuel are leaving our economy and largely not returning via equally offsetting purchases of goods and services by the fuel importers - resulting in an ever-cumulative and increasing drain on our economy.
The media repeatedly refers to big oil companies in the context of high energy prices, implying responsibility. In fact, if big (domestic) oil companies were directly responsible for high and variable carbonaceous transportation fuel [CTF] prices, the strategic impact could be lessened by taxation. The largest portion of the cost of a gallon of gas or diesel is crude oil.
Most of that crude oil is not produced by U.S. companies. Crude oil imports, refined products imports, and other liquid imports are more than double production (domestic) quantities. We frequently hear and, I think generally believe, most of these imports come from the Middle East and from countries that hate us. This is not the case.
The majority [94%] of U.S. oil purchases are from reserves owned outright by nations or by nationalized monopolies, which constitute approximately 73% of all known reserves. U.S. big oil must purchase crude oil (to supplement domestic production until domestic refining capacity is reached) and finished products to satisfy domestic demand. They purchase products at the world spot price. Any addition to that cost is directly reflected in the selling price.
Alternate Sources May Mean Alternate UsesAny significant reduction in foreign CTF purchase may, by necessity of finite supplies of alternate source, or process complexity, require a concurrent usage change. The scope of change is determined by the necessary depth of change, which is, in turn, determined by the quantity and type of imports eliminated.
What quantity of CTF currently being purchased abroad would have to be replaced with domestic sources -conventional or alternate to be import independent? Most sources put the near future figure at 15 million barrels per day. Department of Energy figures for 2007 put the figure somewhat lower.
So where do we go to acquire these 15 million barrels per day to eliminate import fuel dependence? Here. How do we do it? As quickly and inexpensively as possible. That means comparatively minor short term infrastructure and engine modification and even less behavior modification.
It makes little economic sense to undertake immediate major infrastructure abandonment and rebuilding necessary for most advanced CTF alternatives like hydrogen, electric, or exotic liquids such as biodiesel or compressed natural gas [CNG] on a complete replacement scale. Much of the money for such an undertaking would have to be borrowed abroad, thereby nullifying most economic strategic benefit from import fuel independence efforts. The cost of infrastructure change has to be amortized through fuel purchase (or tariffs on imports). Major infrastructure cost equates to proportionally less consumer relief either way.
Therefore, the most useful short term CTF alternate source must literally drop into a pipeline, preferably downstream of existing refineries or, at most, supplementary to existing refineries while refining capacity is increased and modified to accept a broader input grade range.
CNG holds significant potential as a component in a CTF matrix and a context of existing infrastructure – in some areas. However, while the U.S. possesses by far, the largest reserves of natural gas, the production, distribution and utilization as a transportation fuel is not as ubiquitous as TV commercials might imply.
For example, Montana comprises an area of more than 147,000 sq. mi. and has abundant natural gas reserves. Yet, Montana has few distribution pipelines of sufficient capacity to absorb additional demand and just one CNG outlet in Billings where CNG sells for $ 0.99 per gallon. Many other states have similar infrastructure challenges facing conversion to CNG as a transportation fuel.
Additionally, conversion to CNG would also require the expense of individual vehicle conversion on existing vehicles and tooling and production costs on new vehicles. Conversion of diesel-powered over-the-road fleets to CNG requires significant vehicle modification to enable burning CNG or duel fuel. Fleet operations modifications would be required as well to accommodate range and power reduction as a result of the lower btu yield per unit of fuel.
Alternate Energy Sources and Uses: We know where we are - importing approximately
15 million barrels of petroleum products per day and -exporting more than $100
for each barrel. Or, to put it another way, approximately $1.5 billion per day
flying out of our economy; dollars we are borrowing from energy projects,
infrastructure repair, advancement of domestic science and technology
education...the wish list could go on forever. The situation cannot.
Where We Should Be Headed
The solution is simple: Stop buying that foreign oil. But implementation of a domestic replacement so we can stop buying foreign oil is not so simple.
We are in a survival situation. If you think survival is too strong a word, think of this: Everything in the supermarket arrived there on a truck fueled by diesel, and no diesel equals no food. The first step is to take inventory of resources available, starting with the most beneficial, and things we can do that require the least energy and risk to maximize benefit.
ConservationOur first resource multiplier is conservation of CTF. Conservation has an immediate and a net one-to-one benefit ratio. I won’t digress into detail about all the ways we can consume less diesel and gasoline; the various ways all fall under one word: purchase. Everything is hauled by truck and or train so purchase locally produced products and purchase in season.
Driving less during the first and second oil embargoes resulted in a 21% decrease in gallons per vehicle consumption. If you must replace a car or truck, purchase one that uses less fuel without unacceptably diminishing utility. You get the idea. The less CTF demand, the less CTF import. Conservation is immediate, 100% effective, and...green.
Reallocation of FuelApproximately six million barrels of petroleum per day are used by mainly stationary sectors: residential, commercial, industrial and electric generation. To the extent feasible, every effort (aka incentive) should be made to allocate non-petroleum domestic energy sources to those uses.
If 75% of the non-transportation uses of petroleum could be replaced with other domestic energy sources, that reallocation alone would emasculate the OPEC effect on our economy and politics.
OPEC imports are just slightly more than six million barrels per day, but the amount is increasing daily. I am certain switching is not just a simple matter of making a different selection. However, directed research, innovation and invention in that area with that goal can only benefit us. Residential and commercial heating consumes more than one million barrels per day, inviting super efficient system and alternate fuel innovation.
Fuel consumption by fleet trucks consumes the greatest portion of CTF per vehicle. However, that is due mostly to miles driven per truck rather than fuel inefficiency. Truck mpg is relatively unchanged over the last three decades. Allocation of more long distance freight to rail, encouraged by rate incentives, would have a dramatic effect on the total diesel fuel consumed. Increased emphasis on alternate diesel fuel sources would likely not have a great effect on per vehicle/mile consumption given the current state of high-efficiency, clean-burn diesel engines.
Success in finding viable alternate sources from which to manufacture composite diesel and gasoline, combined with onset of CNG conversion, will reduce total petroleum imports faster than all other transportation-related innovations currently being developed. The two fuels consume approximately 13 million barrels of petroleum per day. In fact, 50% success reallocating alternate fuels to stationary petroleum consumers and composite diesel-gasoline supplements would eliminate approximately 10 million barrels of imported oil per day. That reallocation alone would take us two-thirds of the way to our goal of imported petroleum independence without yet considering the effect of gasoline to CNG conversion.
Reallocation of WasteI believe reallocation of waste is the area where the greatest cost-benefit gains can be made per effort after conservation and fuel reallocation.
Technologies that produce distribution-ready fuels are of more immediate value than longer-term petroleum substitutes requiring distribution infrastructure and vehicle alteration. Not to say those efforts should be abandoned; they should just not be rushed into another ethanol situation.
I have not included food-crop-based ethanol production in the examples of resource multipliers because emerging data indicates the product may be net energy negative in its production and use, and the effect on food prices is quite evident; though a likely uncounted value is substitution of foreign oil. I do discuss ethanol, methanol and butanol production from cellulosic sources such as cost and energy consumptive waste, and from harvestable non-food biomass.
Another resource multiplier in our survival kit is carbonaceous waste that we are currently using fuel for to haul to a disposal area. Many older landfills are being capped to capture escaping methane, generated from anaerobic decomposition of organic waste. Most new landfills are designed to generate and capture methane. Landfill capping, along with animal waste conversion to methane, is important to the climate (methane as a greenhouse gas is 20 times more insulating than Co2), and generated methane (or bio-gas) figures significantly in our total energy production future as an alternate source of CNG.
Several examples of promising and rapidly developing waste to liquid and gas fuel innovations are in the scientific literature. I have included those that focus on producing a drop in fuel I described earlier. That is, they do not require extensive infrastructure alteration or expansion or vehicle alteration. The selected technologies also include those that provide beneficial use opportunities for FOG and food waste, providing additional incentive to re-capture drain discarded grease and food waste. I am not speaking of bio-diesel produced from spent frying oil; I am referring to new methods of synfuel production. Synfuel production is considered the next generation of fuel production from non-mineral and mineral sources and is typically not as restrictive to source as either ethanol or bio-diesel and has a greater energy-to-volume ratio.
Food Waste Cost. The cost associated with collection system grease blockages resulting in sanitary sewer overflows (SSO) is estimated at $24 billion annually. FOG and food wastes are released to drainage systems in alarming and harmful amounts simply because it is easier and less expensive for food-service establishments to flush them than to maintain proper retention and disposal equipment and practices. Local and federal pretreatment regulations are somewhat effective in reducing improper disposal – where the regulations are up to date and enforced. However, as currently practiced, FOG and food waste disposal is viewed as a costly and odious duty by every responsible sector and generally not seen as a valuable energy resource.
Food Waste Value. In a study sponsored by the Dept. of Energy in 1998 of 30 metropolitan areas selected scientifically to represent a cross section of the country, the investigators established the annual interceptor grease per person amount as 13 lbs. and yellow grease as 9 lbs. for a total per person of 22 lbs. If one considers interceptor grease only, since most yellow grease market prices far exceed cost of collection and processing, the total FOG available for conversion to energy is more than 4 billion pounds annually factored by population. The interceptor grease number was derived only from gravity interceptor pumping manifests. Widespread use of modern, more efficient grease removal devices would likely increase the total measurably.
FOG weighs approximately 7.6 lbs. per gallon. Based on 4 billion pounds, the U.S. is producing approximately 526 million gallons of interceptor FOG annually. Current interceptor grease disposal costs vary widely ($0.11 - $0.80/gal.) with distance, location and disposal options. For purposes of this illustration, I have chosen an average of 0.45/gal., which would mean the restaurant industry is paying approximately $236 million annually to dispose of interceptor grease.
I have not added the SSO figure to this cost estimation because the benefit of reduced SSOs as a result of increased attention to interceptor efficiency cannot be known until the event occurs. However, I think it reasonable to suppose converting interceptor grease to a salable product would result in less FOG reaching the collection system and causing fewer SSOs.
Food waste in the form of solid food particles amounted to more than 25 million tons, representing 10.9% of 230 million tons of municipal solid waste generated nationally in 1999. The increase in total waste tonnage from 1996 to 1999 was 21 million tons. If it is assumed the growth and proportions remained constant, the projected 2008 food waste tonnage portion would approximate 32 million tons. Tipping fees average $36.91 per ton nationally. Therefore, national food waste disposal cost is more than $1 billion annually.
FOG energy content is somewhat more difficult to quantify because of widely varying water and free fatty acid content. Samples reveal variances from less than 1,000btu/lb. to 15,000btu/lb. An averaged comparison can be obtained by referencing gas production to volume of feed over time. Plant digesters reportedly produce approximately 20 cu. ft. of digester gas per gallon of FOG.
Using the FOG generation figures above, annual FOG waste generation can produce 10.5 billion cu. ft. of digester gas, which may have a methane content varying between 60% and 95%. Using an average of 77.5% methane, 10.5 billion cu. ft. of digester gas equates to approximately 8 billion cu. ft. of high heat value natural gas, resulting in a barrel-of-oil equivalent approximating 1.5 million barrels (using a ratio of 5487 cubic feet of natural gas per one barrel of crude oil). Total combined barrel-of-oil equivalent is somewhere around 22.5 million barrels, costing approximately $1.23 billion [$54 per barrel] for disposal!
Depolymerization. Several companies have developed technologies to convert waste to liquid fuel gasoline and diesel equivalents having equal or greater energy yield per unit and advanced fuel such as hydrogen. I included only those technologies which produce an infrastructure-compatible, distribution-ready fuel from the currently net negative food wastes. If other solid waste can be utilized as well, so much the better.
Hydrothermal depolymerization is a process that breaks long chain carbon molecules into short chain molecules (oil) capable of being burned as diesel or further refined into gasoline or steam stripped into hydrogen. Basically, there are five steps in the process:
- 1. Pulping and slurrying the organic feed with water.
2. Heating the slurry under pressure to the desired temperature.
3. Flashing the slurry to a lower pressure to separate the mixture.
4. Heating the slurry again (coking) to drive off water and produce light hydrocarbons.
5. Separating the end products.
Generic terms for the process include: thermal depolymerization, hydrous pyrolysis, hydrothermal liquefaction and hydrothermal upgrading. The process emulates the geological processes of heat and pressure to break the molecular structure of carbon compounds into shorter chains resulting in light oil and gas. The process can convert plastics, wood, sewage sludge, food waste, meat processing residue, etc.; basically anything with a long chain carbon structure.
The process of high heat, high pressure in water to produce oil was originally patented in 1939 and has undergone several improvements and advancements utilizing calcium hydroxide, carbon monoxide and other catalysts (depending on desired product), resulting in a process that produces oil from virtually all carbonaceous material.
Short chain molecules occurring in the biomass such as methane cannot be broken by this method. However, they can be captured and burned in gas turbines to power the process.
Why hasn’t this process taken the neo-fuel greenfield by storm? Ironically, the oil produced does not meet the current legal definition of bio-diesel because it does not contain alcohol and is, therefore, not eligible for tax credits, bio-diesel grants and other federal subsidies. Though, chemically, the product is superior to bio-diesel as fuel stock.
Proponents were able to get a Congressionally Directed study conducted at the Department of Energy’s National Renewable Energy Laboratory where work continues on several applications of the technology in a User Sponsored program but not with the vigor government-sponsored processes like ethanol and bio-diesel enjoy.
Lower intensity plasma conversion systems are used for more than high temperature waste disposal. They are used to generate syngas from municipal waste as well as reclaimed water, construction aggregate, industrial salts, electricity and fertilizer.
Plasco Energy Group, Ottawa, Canada, say they are harvesting, per ton of municipal waste, 12MWh electricity, 300L potable water, 5-10kg commercial salts, 150kg aggregate, 5kg sulfur fertilizer, as well as syngas and metals. Startech Environmental Corp., Bristol, CT, in conjunction with the U.S. Department of Energy, has explored the feasibility of producing ethanol and other liquid hydrocarbon fuels through the application of the plasma conversion process to junk tires to produce syngas rich in hydrogen. The syngas can be varied with the different types of feedstocks, their moisture content, the type of gasifier used, the gasification agent, and the temperature and pressure in the gasifier.
Drawn-off syngas undergo clean-up and conditioning to create a contaminant-free gas having the product-suitable hydrogen-carbon monoxide ratio prior to a catalytic conversion step. Among the contaminants removed during clean-up are tars, acid gas, ammonia, alkali metals, and other particulates. Syngas is then conditioned: Hydrogen sulfide levels are reduced by sulfur polishing, and the hydrogen-carbon monoxide ratio is adjusted using water-gas shift. Syngas can be burned directly to produce electricity or converted into hydrocarbons (such as gasoline and diesel), alcohols, ethers, or chemical products.
Several characteristics favor plasma carbonaceous conversion processes:
- 1. Versatility of feedstock. Virtually anything from old computers to
sewage sludge can be profitably utilized;
2. The process is self-contained, all products are useable;
3. Versatility of application. Custom composition synthesis gas can be produced to more efficiently produce the finished product, whether gasoline, ethanol, diesel, butanol (a much better gasoline additive or substitute than ethanol) or direct to hydrogen-fuel cell for mobile or stationary application.
ConclusionFour general energy suppositions are reasonably believable, at least in the short to mid-term:
 Consumer energy sources will continue to consist of, in order of quantity consumed, electricity, natural gas and liquid carbonaceous fuel.
 A shift in methods of production (sources) of each is required for economic and strategic security of our country.
 Individual consumption patterns will change more as a function of financial impact than social consciousness.
 Engineers, through innovation and invention, will drive these changes, not policy makers, and it will be up to the engineering community to educate the policy makers, lest inflexible policy becomes one more infrastructure obstacle.
Alternate energy sources? Yes, they are here now. Advanced industrial processes such as depolymerization and plasma conversion are available to produce a variety of fuels that will substitute easily and quickly, without major infrastructure replacement. Both processes are used more extensively abroad than in the U.S. and, there’s a bonus point - they both convert dollar negative wastes to valuable resources simply by redirecting them. Imported oil independence is achievable, exciting and it doesn’t have to be in the far off future.
Most of the information in this article came from the Department of Energy website and other online sources you should be able to locate easily. I invite you to browse them - and invite your senators and representatives to do so also.
In closing, I invite inquiries for further discussion, especially if you have an idea of how to make butanol directly from FOG!