Hybrids Cars, LNG, and Alternative Fuels: The Move to Reduce Cost and CO2 Impact
Interest is keen in electric cars, alternative fuels, increased mileage, and CO2 footprint. Gasoline and diesel vehicles have served us well, but change is approaching. We’ve gone pretty far since the days of the gas guzzlers at 10-12 mpg: a good sedan gets 30 mpg on the highway. Now, for gasoline engine cars, the next improvement yields small advantage in fuel cost or CO2 impact, and we hear of all-electric, hybrids, and LNG. LNG is relatively new in the usual discussions and is perceived by the public at large ambiguously or as just abstruse, so a valid comparison to alternatives would point out the driver’s cost, safety, and the supply chain.Personal vehicles consume two-thirds of transportation fuel and the public interest, but context is important about concomitant applications in trucking, marine, rail, and power; the supply chain is necessary to feasibility, as well as the nature of LNG and its implications in safety and CO2 footprint. This is about cars and feasible alternatives to gasoline and diesel vehicles.
CO2 Impact
First, a word about CO2 impact. These discussions are mostly highly polarized, from talk shows to Congress, often entailing hyperbole and polemic bordering on hysteria. It is true, however, that a lot of people believe that the CO2 emissions into the atmosphere by human activity is important and should be reduced. It’s a good assumption that this is important to society.
All-Electric Cars
All-electric cars save substantial money in fuel compared to a gasoline car. Elon Musk famously, and other manufacturers, are now providing all-electric cars with reasonable acceleration and range. It costs at least $10 for 250 miles. In comparison, an all-gasoline car at 25 mpg average costs about $25. A standard gasoline car driving 12,000 miles per year at $2.50 per gallon and 25 mpg will cost $1200 for fuel. An all-electric will cost $480, saving $720.
They charge at home with special circuits in about 10 hours at 240 V/30 amp and at a filling station with specialized equipment in 45 minutes. In comparison, a typical clothes dryer also needs a special socket for 240 V, however, it uses only 13 amps, whereas 30+ amps for a car will require special wiring. The 10 hour charge time above is not acceptable to enough people. Besides that it takes too long, you can’t charge it in the street where so many people park. At filling stations, it’s possible to charge in faster using DC power, about 45 minutes for cars and more for trucks, unacceptable to people on the road and impossible for trucks.
But there’s a bigger problem: the amount of energy consumption is on the order of 25% of existing electrical consumption. The United States consumes 12,000 kWh per year per person; the car uses about 3700 kWh per year. In cities it would be near impossible to get that much electricity in: the land area for the transmission lines alone is prohibitive, to say nothing of transformer stations. The electrical infrastructure does not exist and cannot be easily created.
Worse yet, the generation of electricity is not CO2 footprint-free; it still takes a lot of hydrocarbons.
These cars cost several thousand dollars more than a comparable gasoline car. The savings in fuel does justify the cost of a car, marginally, but not the electrical supply infrastructure. If the CO2 footprint savings were so substantial that society could justify the investment in infrastructure, that would be terrific, but it’s not. That investment in infrastructure has its own impact on CO2 footprint: the metal, materials, and labor for the electrical power plants, the transmission lines, and the transformer stations, all require heat, hydrocarbons, and CO2 emissions. Work requires man-hours: more workers and their personal activity in their homes and society consuming hydrocarbon generated energy. The installation of that much electrical infrastructure would be extremely disruptive to society.
There is a certain logic train that if the CO2 impact is dire and urgent, then we should invest in electrical generation, infrastructure, and electric cars. Alternately, there is another logic train that innovation will generate technical solutions and that prosperity enables innovation. Prosperity is stifled by add-on costs, such as any tax-funded energy initiatives. In any case, it is not at all given that the CO2 impact is dire and urgent, and there might be an alternative that will solve both the cost and the CO2 issues.
Hybrid Electric-Gasoline Cars
Hybrid electric-gasoline cars are another matter. The electrical part is only about 20% of the power, much easier and quicker to charge. Like an all-electric, braking charges the batteries and provides extra mileage (efficiency), but the gasoline engine can also charge, while, for example, sitting still at a stoplight, so the engine runs more evenly, more efficiently.
LNG
LNG is a good replacement for gasoline or diesel. The fuel price is about an equivalent $1.50 per gallon and not likely to rise even if gasoline does. Fuel for a standard gasoline car is about $1200 per year, whereas for an LNG car it would be $720 per year, and for a hybrid electric-LNG it would be $360 per year.
The CO2 footprint of LNG is very different from gasoline and diesel, about 18% less. Other pollutants from gasoline and diesel engines are near zero for LNG. This is perhaps the most easily achievable reduction in CO2 footprint and pollution available.
Although there are thousands of trucks running on LNG right now, and all the technology for filling stations and distribution is proven, there aren’t enough LNG filling stations and cars the kick off the supply chain. Taxpayer funding is not needed, but National organization is.
LNG is made from NG, natural gas. The supply of NG in North America is practically unlimited. LNG plants already exist: large ones on the coasts and many smaller ones spread throughout the hinterland. Sufficient expansion is easy; the technology for small plant expansion and distribution by road tanker is already in place. LNG liquefaction plants are small and clean compared to diesel and gasoline refineries. Because the supply chain up to the filling stations saves money net to the consumer, the economic activity of creating the supply and distribution infrastructure is profitable, and will generate significant prosperity in the United States.
It costs several thousand dollars to convert a gasoline or diesel engine, and the conversion kits are readily available. Many drivers would be hard-pressed to come up several thousand cash, even though it does save substantial fuel money, and the return is marginal. Tax funded initiatives, tax credits for example, don’t provide sure and balanced funding. In the current political climate, it is more likely that the gasoline and diesel suppliers and owners of the filling stations could be organized to convert both the filling stations and the cars. It’s reasonable to balance the investment and profit from converting to LNG between the supply chain and the consumers, to extend the forthcoming gains in sales to find or streamline the conversions. There’s money in it, for everyone, because NG in North America is cheap.
Trucks, trains, planes, automobiles, and barges
LNG is being used in trucks, barges, and the first ships: things that can run between fixed filling stations, since there are not enough of these for general use. Planes wouldn’t have a problem with boil-off, but they would need more storage than is currently available. Trains have been designed and will be implemented soon. Because cars haven’t started in widespread use yet, the number filling stations is limited.
The electrical power provides necessary acceleration, therefore the gasoline engine is smaller. There are numerous ins and outs, such as that the electric engine in a hybrid or an all-electric produces good torque at low speeds where the gasoline engine is least efficient and needs more gearing. All in all, a hybrid electric-gasoline car gets about 50 mpg both in-town and on the road, costing about $600 per year full fuel compared to $1200 for the standard gasoline engine.
The hybrid conveniently is able to use 110 V, but better 220 V, and a kit can be put on a shelf or floor of the garage. Charging takes a lot less time, but still it’s impractical for many people, and yet impractical for trucks.
The Electrical Supply Problem
Hybrid electric-LNG or electric-gasoline cars don’t really require charging with electrical supply sockets but do provide the efficiencies that get a vehicle from 30 mpg to 50 mpg. All-electric cars do require charging, and as stated before, they require about 25% more electrical power generation and distribution than currently in place.
The problem of getting that much power into the cities would cause a lot of disruption to society, however, generating requires hydrocarbons. Wind or solar can never generate that much; there isn’t the amount of wind, sunlight, and the problem of electrical transmission is still great, especially offshore; and worse, it’s debatable if vast arrays of War-of-the-Worlds aspect on the horizons is aesthetically compatible with our envisioned future society, neither vast arrays of solar panels. It could be done with nuclear if anyone wanted to go that route.
It’s still debatable whether nuclear power is safe. Advocates rightly maintain that the accidents all had shortcomings that are today easily avoidable. For example, the Chernobyl design was inherently unstable in that an incident tended to gain momentum by the structure of the system; Fukushimi was on a fault line in the simplified-almost-beyond-recognition version; and 3-Mile Island was installed before modern Safety Integrated Function or Quantitative Risk Assessment methodology was formulated for either hydrocarbon or nuclear plants to say nothing of possible future accident-tolerant fuels, and it was an operational screw-up. Yet, however unlikely, the consequences of an unmitigated nuclear accident are horrific. If somehow it were made safe, if fusion were realized safely, we could imagine extending the electrical infrastructure. It’s still not easy.
It doesn’t really come down to the realization of fusion, thorium, or safe fission. Liquid hydrocarbons are easily transportable energy, and would be just perfect if we could engineer them to not explode except in the engine; we can produce them in the right places and quickly and safely get them into vehicles. After all, we’ve been doing this already for a long time. Besides, batteries have their own issues.
If we had cheap, abundant energy, we might yet opt to pull CO2 out of the air and react it to hydrocarbon so that we can transport it and fill vehicle fuel tanks. The day that batteries can be charged quickly is probably the day that we achieve fusion. Prosperity and necessity engender innovation, and if we can reduce cost and CO2 footprint together, then we can provide the prosperity and focus necessary to accelerate to the next great innovation; the optimal path is a series of stepwise innovations into an unknown technological future: each step yields resources and enlightenment for the next. Leapfrogging technologies is like going straight over the mountain rather than around.
At this time, our technology requires hydrocarbons to generate electricity. We will achieve cheap, abundant energy and optimum atmospheric CO2, just as change in our society is ever engendered and manifested by man’s struggled to adapt to his environment, to technology.
A Survey of Alternative Fuels
LNG, CNG, Gasoline, and Diesel
NG is like the gas that comes piped into a house, town gas or natural gas. It burns blue and clean like the flame on a gas stove, in the hot water heater, or some house space heaters. LNG is a liquid because it is as cold as liquid air (oxygen or nitrogen), closer to absolute zero than to room temperature. The only difference between the gas coming into the house and vaporized LNG is the removal of things that would freeze: CO2, H2O, and a tail of heavy hydrocarbons, nothing noticeable to the consumer.
The liquid is stored in the vehicle in a heavily insulated container, transferred as a liquid to a vaporizer, which uses heat from the exhaust gas, and then to the injectors and the combustion piston. It burns like any hydrocarbon, but much cleaner.
CNG is also just the same as the gas that comes into the house, but it remains a gas and is under a lot of pressure in order to get it dense enough to store practicably. LNG, as a liquid, is already dense enough and can be stored at low pressure. LNG is stored at 20 bar or 280 psig, and CNG is stored at 3200 psig, the same as scuba tanks. The high-pressure poses a safety consideration. The weight and volume of the storage tank to hold the pressure is limiting, and CNG will never have much range, but it’s okay for buses and vehicles that can refill frequently.
LNG is more difficult to ignite, vaporizes quickly being so cold, and it is much lighter than air, thinning quickly into the atmosphere. As cold as it is, a slug of liquid would instantly freeze anything it hits, and it would vaporize as fast as an explosion.
Comparatively, gasoline and diesel, more or less safe though they have been in practice, are yet again not as safe as LNG. Both spread along the ground and persist in liquid form, gasoline will mostly vaporize in a few minutes, diesel requires cleanup. Gasoline will ignite on any spark, but fortunately diesel will not, though it will feed a fire.
Hydrogen Cars
This absurdity is easily debunked. Hydrogen is only produced by stripping hydrocarbons or splitting water. Short of massive nuclear power, hydrocarbons are required either way, and not very efficiently.
Storage and transport of hydrogen is near impossible. It leaks through almost any seal, ignites easily with static electricity, and the thin blue flame is nearly invisible. It explodes. It can’t be stored in any quantity.
Ethanol
Ethanol is corrosive, so in gasoline it is limited to 10%. Compared to gasoline, it adds nothing to efficiency or storage. It mixes easily with water, so protection must be added or seepage from a corroded tank or pipe might get into groundwater or surface water where it’s very difficult to separate. It takes a huge amount of land, equipment, time, and fuel to farm and process, with attendant significant CO2 emissions. Now that it’s been implemented in farming and a complete supply chain, it would be terrifically disruptive to dismantle. It was a really bad idea, very poorly thought out, a good example of a cross between attributional psychology and politics. A good plan would be to slowly and methodically phase out the industry.
LPG
LPG is being used in cars, especially taxis in many places around the world; it’s cheaper. It doesn’t have much range and is used where it can be refilled often, like taxis. It burns cleaner than gasoline or diesel but not as clean as LNG or CNG. It can be stored at about the same pressure as LNG, 245 psig, at ambient temperatures which is good. However, there are two problems with LPG: safety and availability. If LPG loses containment, spills to the atmosphere in a crash, it is both highly flammable and, being heavier than air, rolls along the ground, spreading dangerously. It’s produced in association with natural gas, and there will never be enough to fuel the majority of cars.
Duel-Fuel Vehicles
Dual-fuel gasoline-LNG vehicles and also diesel-LNG vehicles are feasible and extant. Dual-fuel might make some sense in the conversion of an existing car but is probably too expensive in a new car.
Balancing the Supply Chain
In a fixed, intermingled network of a multi-entity supply chain encompassing a society that is both a part of the supply chain at all levels as well as the ultimate benefactors and consumers, the motive to participate is only exceeded by the compensation from having participated.
The gas is produced dirt cheap in the US and is practically limitless. It can be liquefied almost anywhere, though most of the liquefaction facilities already exist in large, coastal liquefaction plants as well as many peak shaving plants spread throughout the hinterland. If that isn’t enough, yet still, the US is very good at supplying liquefaction plants from small portable to large.
The LNG cryogenic distribution trucks are commonly available. Most or nearly all filling stations can have LNG tanks and pumps installed.
The driver, the ultimate consumer, would prefer to have a conversion financed to time his savings in fuel, or perhaps buy fuel at a higher price until he paid for the conversion. It’d still be cheaper than gasoline.
The producers of all the equipment and steel for the plants, trucks, filling stations and conversion kits would do very well to have their existing and future capacity flush. It would also still save money and tend to reconcile society on hydrocarbons and CO2.
Summary
All-electric cars, an all-electric transportation society, would require about 25% more electrical production and we now have, and, worse, 25% more infrastructure: transmission lines, substations, distribution lines, and the real estate, as well as hydrocarbons to generate the extra electricity. Society won’t tolerate that much fission, and the day we have cheap, safe energy is probably the day we have fast charging batteries. The amount of solar and wind would obliterate landscapes.
LNG and LNG-electric hybrid vehicles, would save money and slash CO2 emissions. There is enough added value in the entire supply chain from the ground to the fuel tank to provide financial balance and motivation for conversion. National organization is all that’s needed to kick off the supply chain conversion.
LNG, being currently achievable, will provide the resources and enlightenment for the next technically advanced toward cheap and safe energy.
Of all the hydrocarbons, LNG is the safest we’ve come. We may yet come to a fuel that uses cheap power to pull CO2 from the atmosphere, a fuel engineered to burn only in the engine, or we could make our LNG this way.
Boil-Off Gas
Lots of people might know that LNG, being cryogenic, will tend to heat or pressure up while sitting still. For trucks on a loop between LNG supplies, that isn’t a problem. For cars that might be left in people’s garages, it’s something people might want to understand.
A full fuel tank, not being used at all, will be fine for 9 days. Let’s consider new, LNG designed, electric hybrid cars. At the end of 9 days, the car can turn on automatically, run for a few minutes, charge the batteries, and reset the tank for another 9 days.
If that seems too easy, rest assured, it is just that simple. Let’s consider the worst case. The driver filled the car on the way home, drove it into the garage, plugged the batteries in the wall charger, and went on vacation. It may seem odd, but that’s probably exactly what will happen, and why not?
After 9 days, the car will turn on automatically and run, but in this case the batteries are full. It can, however, still run and reduce the pressure, it just takes a few minutes longer. This can repeat indefinitely. Like a ventless fireplace, the exhaust gas is not dangerous with a reasonably vented space, like most any normal garage, specially vented slightly at the floor and ceiling.
Eventually, the tank would run empty, but not for a long, long time. The heat leak on a full tank is about 0.7% per day. On half a tank it’s half that, etc. Zeno is not going to get to the wall. A half tank takes several times the 9 days to pressure up. No methane ever needs to be released to the environment; the driver can be delayed for several months and still get to the filling station easily.
Boil-Off Gas
Lots of people might know that LNG, being cryogenic, will tend to heat or pressure up while sitting still. For trucks on a loop between LNG supplies, that isn’t a problem. For cars that might be left in people’s garages, it’s something people might want to understand.
A full fuel tank, not being used at all, will be fine for 9 days. Let’s consider new, LNG designed, electric hybrid cars. At the end of 9 days, the car can turn on automatically, run for a few minutes, charge the batteries, and reset the tank for another 9 days.
If that seems too easy, rest assured, it is just that simple. Let’s consider the worst case. The driver filled the car on the way home, drove it into the garage, plugged the batteries in the wall charger, and went on vacation. It may seem odd, but that’s probably exactly what will happen, and why not?
After 9 days, the car will turn on automatically and run, but in this case the batteries are full. It can, however, still run and reduce the pressure, it just takes a few minutes longer. This can repeat indefinitely. Like a ventless fireplace, the exhaust gas is not dangerous with a reasonably vented space, like most any normal garage, specially vented slightly at the floor and ceiling.
Eventually, the tank would run empty, but not for a long, long time. The heat leak on a full tank is about 0.7% per day. On half a tank it’s half that, etc. Zeno is not going to get to the wall. A half tank takes several times the 9 days to pressure up. No methane ever needs to be released to the environment; the driver can be delayed for several months and still get to the filling station easily.
Boil-Off Gas For The Technically Curious
Let’s take a good look at this phenomena. The material is practically as cold as liquid oxygen, closer to absolute zero than room temperature. It’s going to pick up heat no matter how good the insulation, and the insulation in currently available car LNG fuel tanks is not going to improve much because of cost and space, although all costs will come down with mass production. So it remains at 0.7% per day, but only for a full tank because the heat leak occurs in the liquid, and is much less in the vapor space. I.e., as the tank depletes, the heat leak falls off nearly proportionately, and the pressure build-up rate slows rapidly.
The heat leak vaporizes the LNG. The vaporized LNG goes into the vapor space above the liquid. As vapor is added to the vapor space, the pressure increases. A tiny vapor space would result in a very quick pressure buildup, so the tank has enough to begin with to last 9 days.
Those readers with some thermodynamic background might be aware of a few complications. As the pressure builds so does the temperature (unavoidable as pressure and temperature are inextricable, one being related to the momentum of particles and the other to the kinetic energy of particles). Various ineluctable changes compete to both slow and speed the progression.
Slowing the Progression
- The liquid, as it warms, absorbs some of the heat
- The vapor space increases from the evaporating liquid
- The heat leak slows with higher temperature
- The vapor space density increases
Speeding the Progression
- The heat required to vaporize any amount decreases
- The liquid expands slightly, squeezing the vapor space
If anyone wanted to be exact, it’s not hard to calculate all these competing factors with a simulator, pretty much standard chemical engineering, but I promise you that the overall result is that the progression decreases so that at the end of 9 days, the rate of pressure increase is about 80% of what was in the beginning.
However, it doesn’t really matter to the practical man, because the tank would be designed to give you the 9 days. A comparison of actual tanks available now with the preferred characteristics of a new, hybrid car tank bear out this result; there are some specifications below.
So, at the end of 9 days, in a car not being used at all, the engine runs a few minutes and resets the tank pressure, with the level being about 6% less. The vapor space was about 10% and is now about 16%, so it takes about 15 days until the engine has to run again. The next time it’ll take about 20 days.
Meanwhile, if the car is ever used, the tank pressure resets. The pressure only builds when the car sits without running.
In these scenarios, no methane is ever released to the atmosphere, nor should ever be allowed. It’s not necessary, and, although it is not dangerous in these quantities, it defeats the purpose of reducing pollution by using LNG instead of gasoline and diesel.
Ultimate Safety
A gasoline tank subject to an adjacent fire or an impact can burst and, if it hit a heat source, explode. An LNG tank is less likely to burst or explode. If the engine doesn’t run and the car is sitting, a simple backup burn chamber through the exhaust would relieve the tank pressure.
LNG Fuel Tanks Currently Available from Cryo Diffusion
Here’s what’s on the market for example.
| LNG TANK SPECIFICATION | TAXI | BUS | TRUCK |
| External diameter (mm) | 410 | 440 | 670 |
| Length (mm) | 1044 | 2100 | 1720 |
| Gross capacity (L) | 75 | 216 | 430 |
| Net capacity (L) | 70 | 205 | 408 |
| Empty weight (Kg) | 97 | 180 | 260 |
| Full weight (Kg) | 126 | 271 | 431 |
| Max working pressure (b) | 20 | 20 | 15 |
| Norm | EN 1251 | EN 1251 | EN 1251 |
The taxi has a 70 L tank, 18.5 gallons.
A hybrid car that normally takes a 9 gallon gasoline tank would need a 15 gallon LNG tank, which includes the vapor space for boil-off gas. This still provides the relatively large touted range of a hybrid, but a hybrid needs this range, because on an extended road trip, the batteries don’t charge so much as they do around town.
Filling Up, Filling Stations
There is a lot that goes into the subject of what to do about a filling station. Technically, there is no bar. The tanks can be installed as well as the pumps, if there is space. In a station that has diesel as well as gasoline already, adding the LNG may or may not present a simple logistical problem, but in the larger stations on the road, it shouldn’t be very difficult.
Boil-off gas is an issue. Some sources say the off-gas is compressed to CNG, but now we have a fourth fuel, and CNG is never going to be preferred to LNG because of its limited range. However, the solution is not too difficult: a small package re-condenser or a small electric generator would consume the off-gas.
In a filling station with occasional low consumption, it would help if the electrical generator could feed the grid, cost-credited back to the station, which is anyway a needed political mandate for solar and wind generator.
In order to put enough filling stations in an extended area, like the United States entire, a comprehensive organization is required. Incentives like tax credits will not guarantee a result and could be counterproductive, as well as not in keeping with the foreseeable political climate. However, it seems more likely than ever that the federal government would assist in organizing the oil companies’ distribution system, which is pretty much in keeping with developments in other industries like manufacturing.
LNG Supply
LNG is available in more than sufficient quantities. Gas is available throughout the United States. Large LNG liquefaction plants are located on the coasts in order to export by ship, and there are about 150 or so small peak shaving liquefaction plants scattered throughout the hinterland. It’s easy to install truck filling stations at these for distribution to the filling stations. In fact, this is already being done in some. LNG transport trucks are readily available.
Incidentally, T Boone Pickens, to his credit, tried to set up a lot of filling stations from LA to Boston, but it was a bit too soon perhaps.
Perhaps needless to say, the economic activity would generate more prosperity throughout the populace, in fact, quite a boom, thrusting the United States or Europe into the forefront of reducing ongoing fuel costs taking a massive swipe at global warming and pollution.
