From FOG To Fuel
by Max Weiss
October 1, 2008
“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: Where We Are Now
|
|
| Figure 1. U.S. Primary Energy Consumption by Source and Sector, 2007 (Quadrillion Btu) |
|
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.
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 Uses
Any 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: Where We Should Be Headed
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.
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.
Conservation
Our 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 Fuel
Approximately 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 Waste
I 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.
|
|
| Technically Recoverable Crude Oil |
|
Plasma Conversion. Plasma conversion is the
application of high voltage electricity between two electrodes creating an
electric arc. Inert gas under pressure is directed between the electrodes
through the arc, creating a superheated gas -plasma. Temperatures in the plasma
column can be more than 25,000°F and more than 7,000°F in a sealed container
containing waste material. The reactor vessel operates at a negative pressure,
allowing produced gas (called synthesis gas) to be drawn off for further
processing to various fuels, including hydrogen.
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.
Conclusion
Four general energy suppositions are reasonably
believable, at least in the short to mid-term:
[1] Consumer energy sources will continue to consist of, in order of quantity
consumed, electricity, natural gas and liquid carbonaceous
fuel.
[2] A shift in methods of production (sources) of each is required for economic
and strategic security of our country.
[3] Individual consumption patterns
will change more as a function of financial impact than social
consciousness.
[4] 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!
|