April 2009 Archives
When it comes to transportation, no battery technology comes close to
the energy density of liquid hydrocarbon fuels. Whether they be derived
from ancient or recent biomass, the energy density of hydrocarbon fuels
is many times that of even the most advanced battery technology. And
energy density is one of the most important metrics when it comes to
transportation energy, because you have to carry the energy with you. For the sake of this article, I am only focusing on mass energy
density, not volumetric energy density. Volumetric energy density
doesn't usually come into energy discussions until the topic of
hydrogen comes up, which has terrific mass energy density, but
extremely poor volumetric energy density. But that's a completely
different topic that I won't get into here. There are some who may
like to point out that not all transportation modes require carrying
fuel onboard, such as electric trains and subway systems that pick up
their power from overhead cables or tracks. However, these forms of
transportation are typically only suitable for high population density
environments like large cities. And we've run this experiment in many
cities before and when given the choice, people generally choose
flexible, personal transportation over public transportation. To those
who would seek to proselytize, incentivize, or cajole the general
populace in demanding more and better public transportation, well, good
luck with that.
Energy density is important because the weight of a vehicle determines its fuel economy. Aerodynamic drag plays a role too, of course, but not until you get to highway speeds. Rolling resistance, which is proportional to vehicle weight, still has the largest influence on a vehicle's overall energy requirements.
A typical passenger car holds approximately 15 to 20 gallons of fuel weighing between 90 to 120 lbs, making it account for less than 4% of a vehicle's overall weight. And, unlike batteries, the fuel weight declines as the tank empties making its average weight contribution even less than 4%. In the case of electric cars, the battery weight is a substantial portion of a vehicle's weight at all times. Even in the Tesla Roadster, which uses the most advanced battery technology available, the battery weighs over 900 lbs., making it responsible for more than a third of the 2550 lb. weight of the vehicle. It seems incredible but this 900+ lb. battery only gives the Roadster as much range as the equivalent of about 4 gallons (24 lbs.) of gasoline. You don't have to be a math whiz to see that the energy density of even the most advanced battery technology is only about 3% that of gasoline. If you go with the most economical battery chemistry, namely lead-acid, which has been around for 150 years, the energy density is 4 times worse than lithium-ion, or less than 1% that of gasoline. To store the equivalent energy of 24 lbs. of gasoline, you'd be looking at a battery that weighed nearly 2 tons!
The reason I even bring up lead-acid batteries is because they are still the workhorses of the electric energy storage industry, despite their low energy density compared to the much more modern lithium-ion technology. A major advantage lead acid batteries have over their competition is that their materials are relatively low cost and very recyclable. In fact, about 98% of lead acid battery materials can be recycled. They actually have enough value after they've worn out that someone will pay you to take it off your hands, which is rare in the world of recycling where there are usually drop off fees associated with getting products recycled because it's cheaper to bury them in a landfill than it is to recycle them. In the case of lithium-ion batteries, their materials and construction makes them difficult and costly to recycle. For the sake of worker safety, lithium battery recycling needs to be done in cryogenic temperatures. To complicate matters, there is a finite supply of lithium in the world. In fact, if all vehicle production were to switch to lithium-ion technology, there are some who say we'd completely exhaust all known reserves of lithium in the world in less than a decade. The topic of how much lithium we have available is a subject of debate, but no one is in disagreement that about 80% of the world lithium reserves are in politically unstable regions in South America like Bolivia and Chile. The last thing any manufacturer wants is a material whose primary supply is located in politically unstable regions.
Lithium batteries are also quite expensive relative to other battery types. They cost about 5 times as much per unit of energy stored as lead acid batteries, which helps explain why lead acid batteries are still used even in some mobility applications today, where keeping weight to a minimum is critical. Unlike semiconductors whose cost has effectively dropped by half every 18 months, lithium-ion battery cost has remained relatively flat for the past decade. The demand for lithium-ion batteries has been substantial during that time, since they power nearly all portable electronics today. This means we are not at the beginning of some nascent learning curve that will inevitably allow us to reduce manufacturing costs as we begin to understand the technology better. If one were to extrapolate the previous 10 years of progress curve into the future, it's likely that lithium ion battery cost will remain flat or even increase. In other words, we should not expect some manufacturing breakthrough to cause lithium batteries to go into a downward price spiral. Downward cost spirals usually occur when a technology is new and has a steep learning curve and a material cost that comprises just a small portion of its overall cost. In the case of a lithium battery, the majority of its costs can be traced back to the commodity pricing of its raw materials. After all, this isn't an integrated circuit with just a few grams of materials. It requires hundreds of pounds of materials, some of which are exotic and expensive, to make a lithium-ion battery large enough to power a car.
Another advantage of internal combustion engines is that they have value even after they are worn out. The majority of an engine's materials are made of metal, which is highly recyclable. In some cases, for example, the light aircraft reciprocating engine, it's very common to just replace the wear items such as the engine's rings and bearings, allowing an engine to last for decades since the non-wear items, which comprise the majority of the materials that make up the engine, can be used indefinitely. In fact, the wear items account for just a few percent of a typical 300 lb. aircraft engine. Although the internal combustion engine is often thought to be an environmental menace, it has many features related to recyclability that EV propulsion systems cannot easily match.
As enthused as everyone is about seeing EVs in every garage, when you combine the internal combustion engine with biofuels, you have a winning combination in nearly every transportation category, including economy, range, existing infrastructure compatibility, and sustainability.
Energy density is important because the weight of a vehicle determines its fuel economy. Aerodynamic drag plays a role too, of course, but not until you get to highway speeds. Rolling resistance, which is proportional to vehicle weight, still has the largest influence on a vehicle's overall energy requirements.
A typical passenger car holds approximately 15 to 20 gallons of fuel weighing between 90 to 120 lbs, making it account for less than 4% of a vehicle's overall weight. And, unlike batteries, the fuel weight declines as the tank empties making its average weight contribution even less than 4%. In the case of electric cars, the battery weight is a substantial portion of a vehicle's weight at all times. Even in the Tesla Roadster, which uses the most advanced battery technology available, the battery weighs over 900 lbs., making it responsible for more than a third of the 2550 lb. weight of the vehicle. It seems incredible but this 900+ lb. battery only gives the Roadster as much range as the equivalent of about 4 gallons (24 lbs.) of gasoline. You don't have to be a math whiz to see that the energy density of even the most advanced battery technology is only about 3% that of gasoline. If you go with the most economical battery chemistry, namely lead-acid, which has been around for 150 years, the energy density is 4 times worse than lithium-ion, or less than 1% that of gasoline. To store the equivalent energy of 24 lbs. of gasoline, you'd be looking at a battery that weighed nearly 2 tons!
The reason I even bring up lead-acid batteries is because they are still the workhorses of the electric energy storage industry, despite their low energy density compared to the much more modern lithium-ion technology. A major advantage lead acid batteries have over their competition is that their materials are relatively low cost and very recyclable. In fact, about 98% of lead acid battery materials can be recycled. They actually have enough value after they've worn out that someone will pay you to take it off your hands, which is rare in the world of recycling where there are usually drop off fees associated with getting products recycled because it's cheaper to bury them in a landfill than it is to recycle them. In the case of lithium-ion batteries, their materials and construction makes them difficult and costly to recycle. For the sake of worker safety, lithium battery recycling needs to be done in cryogenic temperatures. To complicate matters, there is a finite supply of lithium in the world. In fact, if all vehicle production were to switch to lithium-ion technology, there are some who say we'd completely exhaust all known reserves of lithium in the world in less than a decade. The topic of how much lithium we have available is a subject of debate, but no one is in disagreement that about 80% of the world lithium reserves are in politically unstable regions in South America like Bolivia and Chile. The last thing any manufacturer wants is a material whose primary supply is located in politically unstable regions.
Lithium batteries are also quite expensive relative to other battery types. They cost about 5 times as much per unit of energy stored as lead acid batteries, which helps explain why lead acid batteries are still used even in some mobility applications today, where keeping weight to a minimum is critical. Unlike semiconductors whose cost has effectively dropped by half every 18 months, lithium-ion battery cost has remained relatively flat for the past decade. The demand for lithium-ion batteries has been substantial during that time, since they power nearly all portable electronics today. This means we are not at the beginning of some nascent learning curve that will inevitably allow us to reduce manufacturing costs as we begin to understand the technology better. If one were to extrapolate the previous 10 years of progress curve into the future, it's likely that lithium ion battery cost will remain flat or even increase. In other words, we should not expect some manufacturing breakthrough to cause lithium batteries to go into a downward price spiral. Downward cost spirals usually occur when a technology is new and has a steep learning curve and a material cost that comprises just a small portion of its overall cost. In the case of a lithium battery, the majority of its costs can be traced back to the commodity pricing of its raw materials. After all, this isn't an integrated circuit with just a few grams of materials. It requires hundreds of pounds of materials, some of which are exotic and expensive, to make a lithium-ion battery large enough to power a car.
Another advantage of internal combustion engines is that they have value even after they are worn out. The majority of an engine's materials are made of metal, which is highly recyclable. In some cases, for example, the light aircraft reciprocating engine, it's very common to just replace the wear items such as the engine's rings and bearings, allowing an engine to last for decades since the non-wear items, which comprise the majority of the materials that make up the engine, can be used indefinitely. In fact, the wear items account for just a few percent of a typical 300 lb. aircraft engine. Although the internal combustion engine is often thought to be an environmental menace, it has many features related to recyclability that EV propulsion systems cannot easily match.
As enthused as everyone is about seeing EVs in every garage, when you combine the internal combustion engine with biofuels, you have a winning combination in nearly every transportation category, including economy, range, existing infrastructure compatibility, and sustainability.
The other day while pondering the effectiveness and durability of different "clean car" options available on the market, specifically flexfuel cars vs. veggie oil vs. EV, I began considering which fuel type would be the most convenient if the grid went down and suddenly gasoline became unavailable. I've heard that up here in Northern California when the power has gone out in the past, nobody can pump gas because the pumps run on electricity and furthermore, nobody can accept credit cards. This would mean an EV couldn't be charged unless you had solar panels at your house. Veggie oil might be available at a few select locations but probably would not very convenient if there was a state of panic. What if this happened and I needed to drive somewhere with my car immediately? What if I had a flex fuel car that could run off of E85 ethanol or gasoline, could I use a bottle of Scotch or Vodka to power my flex fuel vehicle?
It troubles me to have to answer this question, almost making me want
to sip a fine single malt before I write my response, but for the sake
of coherency, I will resist the temptation. Although there are a lot
of products found in a typical liquor store that would be better off
burned than drunk, it's not a good idea to pour any of them into your
vehicle's tank, even if your vehicle is flex fuel capable. The reason is
that even the strongest substances, for example 100 proof whiskey,
still contain 50% water and that mixture will not burn properly in an
automobile's engine and is likely to damage it.
To get the percentage concentration of ethanol in a bottle of spirits you need to divide the proof in half. Ideally, to run a flex fuel car, you should have something that is 200 proof or 100% ethyl alcohol. However, you won't find this concentration of alcohol in anything you can buy at a liquor store. The reason is because removing all of the water from alcohol requires a secondary step since distillation can only get to a maximum concentration of 95% alcohol. To dry the alcohol, you need to pass it through a material like zeolite, which will absorb the remaining water, allowing just the alcohol to pass and then presto - you will have pure ethyl alcohol capable of running a flex fuel vehicle.
However, zeolite isn't something most of us have laying around, and a 95% alcohol concentration would most likely allow you to power a car in a pinch without risking damage to it. That said WARNING, I am not recommending this as a long term solution and do not want to be liable when your brand new flex fuel car throws a rod. Okay, now that we've covered liability... Many liquor stores carry a substance college students use to make up a rather potent form of alcoholic punch. The brand name most commonly used for this drink is Everclear and it is 190 proof ethyl alcohol, also sometimes called grain alcohol. However, it's likely to be costly compared to E85 fuel. Not that I've been pricing it lately, but I expect that a gallon of Everclear could set you back as much as $80. That's still a much better price than the equivalent alcohol you'd get from further distilling and then drying the alcohol in a fine bottle of Scotch, and if you really needed to drive somewhere then it might be worth it.
It troubles me to have to answer this question, almost making me want
to sip a fine single malt before I write my response, but for the sake
of coherency, I will resist the temptation. Although there are a lot
of products found in a typical liquor store that would be better off
burned than drunk, it's not a good idea to pour any of them into your
vehicle's tank, even if your vehicle is flex fuel capable. The reason is
that even the strongest substances, for example 100 proof whiskey,
still contain 50% water and that mixture will not burn properly in an
automobile's engine and is likely to damage it.To get the percentage concentration of ethanol in a bottle of spirits you need to divide the proof in half. Ideally, to run a flex fuel car, you should have something that is 200 proof or 100% ethyl alcohol. However, you won't find this concentration of alcohol in anything you can buy at a liquor store. The reason is because removing all of the water from alcohol requires a secondary step since distillation can only get to a maximum concentration of 95% alcohol. To dry the alcohol, you need to pass it through a material like zeolite, which will absorb the remaining water, allowing just the alcohol to pass and then presto - you will have pure ethyl alcohol capable of running a flex fuel vehicle.
However, zeolite isn't something most of us have laying around, and a 95% alcohol concentration would most likely allow you to power a car in a pinch without risking damage to it. That said WARNING, I am not recommending this as a long term solution and do not want to be liable when your brand new flex fuel car throws a rod. Okay, now that we've covered liability... Many liquor stores carry a substance college students use to make up a rather potent form of alcoholic punch. The brand name most commonly used for this drink is Everclear and it is 190 proof ethyl alcohol, also sometimes called grain alcohol. However, it's likely to be costly compared to E85 fuel. Not that I've been pricing it lately, but I expect that a gallon of Everclear could set you back as much as $80. That's still a much better price than the equivalent alcohol you'd get from further distilling and then drying the alcohol in a fine bottle of Scotch, and if you really needed to drive somewhere then it might be worth it.
One of our readers recently submitted the following question: After reading Robert Zubrin's book Energy Victory I have two questions. Can ethanol production facilities make or be converted to make methanol and are sugar beets being used to any significant degree in Colorado to produce ethanol as a substitute for corn?
These are great questions. The sugarbeet industry in Colorado produces refined sugar, a commodity that has seen large price fluctuations over the years, making it a difficult business in which to achieve consistent profits. The Great Western Sugar company once had more than a dozen sugar beet processing plants in Colorado but now has only one plant left in Fort Morgan. There are no plants I'm aware of that use refined sugar as feedstock to produce ethanol because refined sugar is more valuable than the ethanol that can be derived from it. Similarly, I know of no alcohol plants in the U.S. that use sugar beets as an input.
Sugarbeets are not as flexible a feedstock as corn for a continuous
process like large-scale alcohol production. Beets are harder to
handle than grain crops because of their lower energy density and must
be harvested and processed quickly, so that their sugar content does
not chemically degrade. Corn can be dried and stored for months or
years, which allows the processing plants that use corn as a feedstock
to run all year round thereby making better use of their capital
expense. You'll also note from Zubrin's book that that amount of
maximum ethanol yield that could be produced per acre is nearly the
same when comparing corn to sugar beets (i.e. about 400-450
gallons/acre/yr).
The processing plants that make corn ethanol are highly tuned to produce ethanol from corn grain only. The processing equipment contains automated feeding and processing mechanisms all the way from the rail cars that deliver the grain to the tanker cars that take away the ethanol. It would not be practical to convert a plant constructed to make alcohol from corn to another feedstock. This is typical of many processing plants. All of the equipment inside fits together like a giant puzzle.
If you can get ethanol from a feedstock, it wouldn't be advantageous to settle for methanol. Methanol's lower cost today is likely due to the fact that most of it is derived from non-renewable sources such as natural gas which is still inexpensive and abundant. Methanol has lower energy content than ethanol and is much more corrosive and toxic. I believe Zubrin's enthusiasm for methanol is related to the fact that it's easier to convert cellulosic and other non-food sources of biomass into methanol. Converting food products into motor fuel is a source of a lot of controversy and presumably methanol won't be similarly stigmatized. Having said that, there are initiatives by several companies to convert cellulosic materials directly into ethanol.
I agree with Zubrin that all cars manufactured today should be able to run on any form of alcohol fuel or gasoline. At one time, this was costly, but now that all fuel systems need to handle ethanol in gasoline anyway, and engine computers can adjust the air-fuel ratios accordingly based on feedback from sensors, there's really no reason not to make all vehicles flex-fuel capable.
These are great questions. The sugarbeet industry in Colorado produces refined sugar, a commodity that has seen large price fluctuations over the years, making it a difficult business in which to achieve consistent profits. The Great Western Sugar company once had more than a dozen sugar beet processing plants in Colorado but now has only one plant left in Fort Morgan. There are no plants I'm aware of that use refined sugar as feedstock to produce ethanol because refined sugar is more valuable than the ethanol that can be derived from it. Similarly, I know of no alcohol plants in the U.S. that use sugar beets as an input.
Sugarbeets are not as flexible a feedstock as corn for a continuous
process like large-scale alcohol production. Beets are harder to
handle than grain crops because of their lower energy density and must
be harvested and processed quickly, so that their sugar content does
not chemically degrade. Corn can be dried and stored for months or
years, which allows the processing plants that use corn as a feedstock
to run all year round thereby making better use of their capital
expense. You'll also note from Zubrin's book that that amount of
maximum ethanol yield that could be produced per acre is nearly the
same when comparing corn to sugar beets (i.e. about 400-450
gallons/acre/yr).The processing plants that make corn ethanol are highly tuned to produce ethanol from corn grain only. The processing equipment contains automated feeding and processing mechanisms all the way from the rail cars that deliver the grain to the tanker cars that take away the ethanol. It would not be practical to convert a plant constructed to make alcohol from corn to another feedstock. This is typical of many processing plants. All of the equipment inside fits together like a giant puzzle.
If you can get ethanol from a feedstock, it wouldn't be advantageous to settle for methanol. Methanol's lower cost today is likely due to the fact that most of it is derived from non-renewable sources such as natural gas which is still inexpensive and abundant. Methanol has lower energy content than ethanol and is much more corrosive and toxic. I believe Zubrin's enthusiasm for methanol is related to the fact that it's easier to convert cellulosic and other non-food sources of biomass into methanol. Converting food products into motor fuel is a source of a lot of controversy and presumably methanol won't be similarly stigmatized. Having said that, there are initiatives by several companies to convert cellulosic materials directly into ethanol.
I agree with Zubrin that all cars manufactured today should be able to run on any form of alcohol fuel or gasoline. At one time, this was costly, but now that all fuel systems need to handle ethanol in gasoline anyway, and engine computers can adjust the air-fuel ratios accordingly based on feedback from sensors, there's really no reason not to make all vehicles flex-fuel capable.
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