In the debate over cleaner energy and reducing CO2 emissions and given the options of having an electric car or a natural gas-fuelled car, why would someone choose a natural gas fueled car? In the “Great Degeneration” by Niall Ferguson, he does not mention electric cars as an option to reducing CO 2 emissions. I don’t think it was an oversight. So what could be the reasoning?
davidmich
That electricity comes from somewhere and more and more commonly that is a natural gas powered electrical plant although it could be an older coal fired plant (other electrical power sources in the U.S. besides hydro are minor and will remain so for the foreseeable future for lots of reasons). From a physics and environmental standpoint, you are better off just cutting out the middleman and the thermodynamic waste if you power your vehicle directly from natural gas rather than have an electrical plant use natural gas to produce electricity and then you use that to charge a battery. You are losing efficiency during every step of the process.
The practical advantage is also very important. Natural gas also offers near instant refueling just like gasoline and indefinite range whereas electric cars do not. The primary early-adopters of natural gas powered vehicles are not consumer cars right now. They are fleet vehicles and that is because natural gas offers both a huge cost advantage over gasoline or diesel fuel and because they can also build their own filling stations for their fleet.
The main reason natural gas powered vehicles are not common at all for consumer vehicles today is simply because there are very few filling stations and even those tend to be clustered in just a few areas but this may change rapidly in the next few years. All major car companies already build natural gas powered vehicles mainly for select overseas markets so there is no engineering challenge. It is simply a logistics problem to build up the infrastructure to support wide-scale adoption in the U.S.
Thank you Shagnasty. A very helpful answer.
davidmich
I think Shagnasty answered it all but will give you a user perspective. I have had a LPG car in Australia and for all intents it was no different to a petrol powered car. Every petrol station has LPG and it is really simple to fill up.
Very common in Australia to convert petrol to LPG, costs about $3,000 and takes about 3 years to get your money back on average, this is why the majority of taxis run LPG.
We even had government subsidies a while ago to help drive the uptake, I know when my dad retired he converted his Nissan Maxima to gas sorry LPG so he could save money.
Nitpick-
Is 19.2% minor? That’s U.S. nuclear power, and hydroelectric is 6.2% in the U.S., both according to Wikipedia.
Point taken but the overall point stands. Nuclear power would have been a good way to get lots of electricity to power electrical powered vehicles if we built that infrastructure up decades ago but we didn’t and now we can’t in any reasonable time-frame. It takes 25 - 30 years to get new nuclear powerplants online even if we started today and there is still remarkably little will to do that. You can’t power any significant part of the U.S. transportation fleet with nuclear power without building new nuclear power plants.
The major players are coal and natural gas fired electrical plants. Natural gas is about as environmentally friendly as a fossil fuel can get and we have found out in the past 10 years that the U.S. alone has much more of that resource (a huge understatement) than previously believed.
If you are limited to realistic choices over the next few decades, natural gas powered electrical plants are much better than coal so that is why there is a large-scale push to use them there and exploit that resource for those purposes. However, it is still better to power vehicles directly from natural gas rather than have it go through the efficiency losses and disadvantages of producing the same power in an electrical plant and then transferring that power to vehicle batteries.
There is another shift to get fleet vehicle natural gas filling stations online as well. That is already happening but it takes time. Those shifts will eventually flow down to consumer vehicles in the U.S. because of the obvious cost savings but nobody knows when. It is a logistical chicken and egg problem. What is known is that natural gas is much cheaper than gasoline and will not rely on foreign imports at all to make it work.
Electrical energy beyond normal household and industrial demand (which widescale transportation energy would be) generally comes from natural gas and coal plants designed for variable or intermittant load, as Shagnasty indicates. We haven’t constructed new nuclear power plants in almost four decades, and even with the need for more sources of non-carbon dioxide producing energy pushing nuclear in the post-Fukushima environment is an uphill battle even with reactors that are technically much safer and more securely sited.
Aside from the range and fueling rate limitations of electric cars, there is the expense of the energy storage system which may comprise a significant portion of the cost of the car. (The Li-ion cell pack for the Tesla S runs at US$30k, plus a US$3k labor cost.)
There is also the issue that battery performance degrades considerably with ambient temperature. The power being delivered comes from chemical reactions in the cells, the reaction rate of which is proportional to temperature; for reactions occuring at terrestrial temperatures, a rule of thumb is that the rate increases or decreases by a factor of 2 per every 10 °C, so a battery that could provide 1500 kW (around 200 hp) at 30 °C would only deliver 325 kW (50 hp) at 0 °C or a paltry 163 kW (25 hp) at -10 °C. This isn’t a head to head comparison with an internal combustion engine as an eletric motor provides peak torque at zero rotation speed, but still you get the idea. Plus, there is a threshold level below which the battery will not produce a useful level of current and/or the motors cannot overcome internal resistance. Internal combustion engines, on the other hand, operate at the combustion temperature of the fuel and provide sufficent excess heat that the problem is usually dumping all of the excess heat, and for all but the smallest automotive engines there is an entire complex system designed to transfer excess heat to the environment. (Although it is called a radiator, most of the heat transfer is actually via convection, hence why it is mounted where the air flow passes over it.)
As sisu notes, the technology of internal combustion engines is very mature and we can come close to extracting maximal available energy from such engines notwithstanding the fundamental thermodynamic limitations and losses through the powertrain. Although gasoline, kerosene, and diesel are the fuels which are typically used, the same basic principles and even many of the same compoents and engines can be run using other hydrocarbon fuels. LPG can essentially be used in spark combustion engines as a replacement for gasoline with some modest design modifications. LNG can be used in diesel compression ignition engines with almost no modifications other than pressurized fuel system.
However, both of these fuels are significant carbon emitters, and LNG–which is mostly methane–is a far more potent greenhouse gas than CO[SUB]2[/SUB] by about a factor of 60. Better choices for sustaintable fuels are actually fuels which can be synthesized from natural organic sources or from excess natural gas beds, such as methanol or dimethyl ether (DME), which can be used as essentially a direct replacement in conventional gasoline and diesel engines respectively with only very minor modifications. This means that you don’t have to stand up and entirely new distribution infrastructure or go through the design and manufacturing learning curve of developing an entirely new type of engine system; you can leverage off of over a century of history with internal combustion engines while moving to a carbon-reduced or even carbon-neutral (if you can draw the carbon constituants from sequestered atmosopheric CO[SUB]2[/SUB]) synthetic fuel without having to limit usage, and such fuels are also potentially viable replacements or supplements to general transportation, marine, and aviation fuels as well as cars.
Electric vehicles may well be suitable for some applications, like moderate range daily commuting where they can be readily recharged during scheduled down periods, but they are not a panacea for either the dwindling supply of natural petrocarbon fuels or to reduce carbon emissions. The viability of electric vehicles for general transportation is dependent upon substantial improvements on electrochemical battery technology which is just not on the horizon, and will likely never be suitable for marine or aviation applications except in very limited contexts.
Stranger
Forbes (no fan of EVs in general) has these points to make:
If you need long range NG is the only real alternative to petroleum and diesel. (Albeit diesel is for the foreseeable future the more reasonable option.) If you do not then EVs win handily. Not even a contest.
While it is true that the thermodynamic efficiency of fixed large scale stations using heat regeneration and other methods to improve efficiency, you have to consider the total end-to-end efficiency, including that of the power grid, losses during non-use, et cetera. Depending on usage load and power generation system, I’d be surprised if it isn’t close to a wash
Not if you consider the time value of money; a CNG filling station can fill one vehicle to full range in minutes. Even a high voltage DC station is going to take on the order of an hour to pump a battery from, say 10% to 90% of charge
Hardly. For a vehicle with comparable range to a CNG or petrocarbon fuel vehicle, the only thing truly comparable is the Tesla S (and even that with significant restrictions on how and where it is operated). The base Tesla S, after the $7500 federal tax rebate, runs over $60k. A well-equipped family sedan capable of running on CNG is a fraction of that. (Admittedly, it doesn’t have the phenomenal performance of the Tesla S, but from a functional standpoint it will have more range and be faster to refuel.)
Although true, not by as much as you’d think, and the way electricity prices are rising the gap is narrowing. The real advantage of electric vehicles is the fungability of the root energy source; you can convert from natural gas and coal to nuclear, solar, or electric, and the vehicle doesn’t care. But the same is true for synthetic fuels such as DME produced form renewable resources…
Electic vehicles definitely have a place in the realm of daily commuters who know they will have hours of dwell time to recharge. They are not so fantastical as a general transportation energy solution.
Stranger
I would request a cite for this statement or back of the envelope calculations. While I believe your premise and the reasoning, this may or may not be true because transporting natural gas as CNG or LNG has its own inefficiencies and the leaks that occur during transportation are methane (more greenhouse effect than CO2). Moreover a natural gas combined cycle plant is more efficient than cars. So from a physics and environmental standpoint, using the natural gas to make power near the natural gas well may make more sense - however the economics and environmental impacts of producing a lot of electric cars may not make sense.
Spark ignition internal combustion engines are really mind bogglingly ineffecient, though. These days most have a peak efficiency of around 25%, but that’s only at the power peak, which car engines rarely run at. Newer natural gas turbines are up to around 60% efficient and do run at peak efficiency all the time. Compared to an ICE car that’s realistically running at maybe 10-15% efficiency in day to day driving, that’s going to be hard to overcome.
I think you are confusing the greenhouse effect of a gaseous fuel when leaked versus when combusted. Burning Propane and Natural gas for the same amount of heat release, will result in lesser CO2 emission for propane than natural gas.
Cite please ? I have worked on several large Methanol and DME plants and am very familiar with the technologies in this space. Anything can be synthesized from “natural organic sources” including Diesel and Gasoline (and it has been done before - see Sasol in South Africa and other Fisher Tropsch application). The point is that there are NOT many “natural organic sources” available - if you are thinking using biomass, not even a small fraction of the energy needs can be met. Methanol and DME are better utilized for the Chemical Industry currently as feedstock.
Assuming you will be making Methanol and DME from coal (China already does this ) , you will have to setup massive new plants (expensive and time consuming) and infrastructure to mine, move and convert coal to Methanol and DME and incur associated enviornmetal impacts.
Cite please ? This is blatantly false and an Utopian dream. The amount of renewable carbon (biomass etc.) and renewable energy available on earth - even if harnessed to the fullest will only be a small fraction of what the world’s energy profile is.
First off, let’s be clear. What you are quoting is not what I have claimed but what Forbes stated and provided citations for.
“You’d be surprised …” is a nice statement but does not stand up to actual cited studies. Let’s go to the Argonne National Laboratories GREET analysis of well-to-wheel end-to-end efficiency (pdf): EVs US mix total greenhouse gases significantly lower than for natural gas vehicles.
How about the Rocky Mountain Institute’s take?
So yes, reality may surprise you.
The claim that it is “better to power vehicles directly from natural gas rather than have it go through the efficiency losses and disadvantages of producing the same power in an electrical plant and then transferring that power to vehicle batteries” is simply false.
Whether it is a significant point or not your claimed fact about DC fast chargers is also wrong. Under 30 minutes to full charge and significantly less to 80%. The Tesla “supercharger” can give 3 hours of additional drive time in 20 minutes. Nevertheless there is no debate that EVs are not the best choice for someone who routinely needs to travel long distances. Diesels are.
Comparing a “well-equipped family sedan capable of running on CNG” to a Tesla is disingenuous at best; compare the one NG vehicle in America, the NG Civic, to the Nissan Leaf perhaps. The Leaf can be had for as low as $21,300 and leased for $199 a month. The Honda Civic Natural Gas starts at $26,305 (although they throw in a $3K fuel card).
100% agreed that pure EVs are not a one size fits all solution for all. I’ve compromised myself. My plug-in EV hybrid goes on all-electric for my typical daily commute charging up at night and some days needs to run a bit on gas (during which time I typically have been getting 42 to 46 mpg, but YMMV). It has also managed to take me and my college bound with his stuff, bikes on the back, and roof top carrier, from Chicago to the Jersey shore to Maine and then back getting nearly 500 miles between stops for gas. (Mpg was down to upper 30’s fully loaded with that rooftop carrier travelling 70.) And several other road trips.
For kicks I went on fueleconomy.gov and did the total GHG calculation for the Civic CNG and the Nissan Leaf. The Civic runs 127 g/m of upstream CO2 and 218 tailpipe for a total well-to-wheel of 345. The Leaf’s varies depending on electical generation mix in the region but is total of 190 for the US average.
He’s a historian and doesn’t know anything about the energy industry?
The other big thing about burning natural gas at a power plant vs. in a car is the ease of combining it with other energy sources. As the technology for things like wind and solar (and the political environment for nuclear) change, it might start making sense to use a mixture of these non-fossil sources and fossil fuels. If you’re using electric cars, then it’s just a matter of building a new wind farm or whatever and hooking it to the same grid as the gas turbine. When the wind is calm, you continue using the power from the natural gas, just like you were before, but when the wind is blowing, you can turn off the natural gas plant and save a bunch of fuel. It’s much harder to do something like that on the level of individual cars, if you’re putting the gas engines in the cars.
“The amount of renewable energy available if harnessed to the fullest” is a much bigger amount than you think it is. The Sun delivers a bit more than a kilowatt per square meter, at the distance of the Earth. The Earth’s cross-sectional area is over 10[sup]14[/sup] square meters. That means that, even without touching geothermal, nuclear, or tides, the available renewable energy is over 10[sup]17[/sup] watts. The world’s power consumption is 150 petawatt hours/year, or less than 2*10[sup]13[/sup] watts, nearly four orders of magnitude smaller. That leaves a lot of room for inefficiency, while still providing far more power than we consume.
Related to that point is the fact that while current production of NG is ample, no energy expert is able to predict with any confidence how long those stores will produce, especially in the context of increased demand. Investing in a new infrastructure, NG filling stations across the country, when NG may reach a point of rapid price increase, due to demand outpacing supply, within a decade or so, seems like a poor idea.
No, I’m referring to the actual effects of methane released into the environment, where it rises and persists in the stratosphere, contributing to the formation of water vapor which traps infrared heat. Using methane as a source of transportation fuel would inevitably result in a significant amount escaping due to spillage and leaks, and this combined with natural sources of methane increase the climate warming trend.
Coal and oil shale are about the worst sources of feedstock for the production of methanol or DME. About the best non-renewable sources is natural gas, which is otherwise difficult to store and transport in large volumes as it requires liquification and cryogenic storage (which is why so many oil production facilities just flare off the natural gas released during oil extraction) but of which there are enormous known reserves suitable for many decades of use at projected demand. Renewable sources include biomass (including otherwise unusable biomass such as wood pulp) but it can also be synthesized from CO[SUB]2[/SUB] and water provided you have a source of energy.
As Chronos has already demonstrated this just isn’t true. Sequestering CO[SUB]2[/SUB] from the atmosphere is certainly a technical challenge beyond the existing capabilities, but it is conceivable that it could be a genuinely renewable source of carbon for DME or another hydrocarbon energy carrier suitable as a transportation fuel. For instance, automated mid-ocean floating platforms using wave and wind power could extract CO[SUB]2[/SUB] from the ocean (where it is in equilibrium with the atmosphere and easier to extract) and use this to synthesize DME and/or methanol. Both of these substances have some drawbacks as fuels, but they also have some considerable advantages over many other conventional options such as biodiesel, LNG, gaseous/liquid hydrogen, and possible even gasoline.
George Olah, who is one of the leading researchers in the production and use of methanol and DME for fuel applications published Beyond Oil and Gas: The Methanol Economy, which is a semi-technical explanation of the production methanol and DME from various sources and comparisons with other natural and renewable transportation fuels. It is neither “blatantly false” nor a “Utopian dream”. He is honest about the limitations of the fuels, particularly the low energy density of DME compared to diesel and propane, but he also points out many of the advantages of these fuels which could be used in the existing transportation infrastructure and with current automotive internal combustion engine technology with only very modest modifications.
I have personally done some research and simulation on using DME as a renewable propellant for liquid propellant rocket engines. While the low energy density makes it unsuitable for conventional combustion rocket engines, the high cetane rating and favorable thermodynamics may possibly make it a superior fuel for pulse detonation and continuous wave detonation engines, providing better output and specific thrust than the best conventional combustion propellants. The same may apply to the use in compression detonation engines given the higher cetane rating of DME in comparison to #2 diesel. The biggest downside, other than the fact that it does have to be stored under light pressure (around 6 bar) to remain liquid, is that it provides poor lubrication, requiring a separate lubrication system or self-lubricating seals.
Stranger