Posted on 06/08/2007 1:08:55 PM PDT by Red Badger
Comparing life cycle CO2 emissions from plug-in hybrids, coal-to-liquids gasoline, and conventional gasoline.
A study from the Carnegie Mellon Electricity Industry Center (CEIC) concludes that while enacting policies to subsidize the production of coal-to-liquids transportation fuel would enhance national security by lowering oil imports, encouraging plug-in hybrids powered by coal-generated electricity is a less costly policy that also reduces oil imports and does more to lower greenhouse gas (GHG) emissions.
CEIC produced the paper in the context of the current work by the US House Committee on Energy and Commerce on transportation energy legislation, the current draft of which includes significant support for CTL. (Earlier post.) The CEIC paper compares GHG emissions of CTL gasoline to the emissions of plug-in hybrid vehicles powered with electricity generated from coal on a full life cycle basis.
Although CTL conventionally produces more diesel than gasoline, the process can be altered with catalysts to upgrade some of the diesel and waxes produced in the standard F-T process to gasoline, with an overall efficiency of around 52% (HHV).
The CEIC team used CTL inputs and outputs derived by Bechtel in 1993, and allocated the total emissions factor among the various CTL co-products using the method in the GREET model (by energy content of the co-products).
The allocated worst-case well-to-plant emission factor (no carbon capture and sequestration, current electricity generation mix) is 190 pounds CO2 equivalent per MMBtu of CTL gasoline, and 50 pounds CO2 equivalent per MMBtu of CTL diesel. With 80% CCS and zero-carbon electricity, the allocated factors drop to 50 pounds CO2 equivalent for gasoline and 15 pounds for diesel.
Adding in the other complete lifecycle factors (transportation for distribution, combustion in the engine) resulted in complete well-to-wheel CTL lifecycle emissions of 360 pounds CO2 equivalent per MMBtu of gasoline in the worst-case scenario and 220 pounds CO2 equivalent per MMBtu of gasoline in the best-case scenario.
CEIC then used a fuel consumption figure of 34 mpg and an annual driving distance of 12,000 miles to calculate the annual CTL gasoline emissions: 1.18 lbs/mile (536.7 g/mi) in the worst case; 0.72 lbs/mile (325 g/mi) in the best case.
For plug-ins, the CEIC researchers calculated the impact of both electricity and gasoline. For electricity generation, they used two scenarios: bituminous coal in a pulverized coal power plant and bituminous coal in an integrated gasification combined cycle power plant with carbon capture and sequestration (IGCC w/ CCS).
For a vehicle, they assumed a plug-in hybrid built on a Toyota Prius platform in a parallel configuration with an all-electric range of 60 miles. To determine the fraction of vehicle travel powered by electricity or gasoline, they used the percentages resulting from the cumulative distribution function of daily vehicle miles traveled constructed in another paper from CMU (Samaras and Meisterling, “Decarbonized Electricity Needed for Plug-in Hybrids” 2007). The CEIC distribution estimates electricity would power about 85% of average annual vehicle travel for a plug-in hybrid with a 60-mile electric range, assuming vehicles are charged once per day.
The results: total well-to-wheel emissions of 264.6 g/mi for the conventional coal-generated scenario; 105.8 g/mi for the scenario with advanced IGCC with CCS). The conventional gasoline baseline in the study was 344 g/mi.
It can be seen that gasoline derived from CTL plants with no CCS could increase GHG emissions from vehicles by almost 60%. If CCS is available, then a reduction of less than 6% could be obtained. It is important to note, once again, that in this best-case CTL scenario, not only is there CCS at the CTL plant, but also a low-carbon electricity source is used for CTL production. This might not be a very realistic assumption, but is presented here to show that at best we could only obtain a very small reduction in GHG emissions following a path of increased CTL production.
Plug-in hybrids look more promising as a pathway for reduction of GHG emissions. Even if coal electricity without CCS is used, plug-in hybrids could lead to a GHG emissions reduction of almost 25%. This demonstrates the worst case for plug-in hybrids, as GHGs would be further reduced with a low-carbon electricity portfolio. It is important to note however, that this analysis does not include the emissions from manufacturing the storage battery used in plug-in hybrids. If GHG emissions from lithium-ion batteries for plug-in hybrids are included, total annual GHGs from plug-ins would increase by about 800-1,500 pounds of CO2 equivalents, depending if a twelve or eight-year vehicle life is assumed (Samaras and Meisterling 2007). Battery technologies are difficult to predict, but even when emissions from current battery production are included, plug-in hybrids result in substantially lower emissions than CTL pathways.
The Carnegie Mellon Electricity Industry Center (CEIC) was established in August 2001 as one of 20 centers of excellence in different industries that the Alfred P. Sloan Foundation has established at 13 universities. CEIC’s core funding comes jointly from Sloan and from the Electric Power Research Institute (EPRI).
Resources:
“For energy security and greenhouse gas reductions, plug-in hybrids a more sensible pathway than coal-to-liquids gasoline”; Paulina Jaramillo and Constantine Samaras; CEIC Working Paper CEIC 07-04 – June 2007
Most of what I have seen for sale is B20, or 20% biodiesel, 80% petroleum diesel. There is also B100 (100% biodiesel) for sale some places, but I’ve never seen it. I don’t know if they change the blend in the winter time like they do with ethanol. E85 is 85% ethanol, except that in the winter time they make a “winter blend” that is a good bit less than 85% ethanol because really high concentrations of ethanol in in your fuel makes it hard for you to start your engine in the winter time. Biodiesel will gel when it gets too cold.
From what I have heard, the farther north you go the lower the blend. I don’t think it is changed even in the summer. Down here, B80 is good enough for winter. I don’t know of anything running B100 except for maybe a few peaking generators.
I think the real problem is we are trying to figure out how to fuel machines that have been designed around petroleum fuel.
The trick is finding an abundant fuel and designing fuel around them.
Creating a replacement for gasoline and diesel will be very dificult. They have great fuel properties including high heat value, reasonably long shelf life and still reasonable price. They also work perfectly in the engines designed to burn them.
Luckily, in the next few years, there are products coming which will allow creation of engines that are much less picky about the fuel they will consume.
It is said that we have 500 times more coal energy than saudi arabia has in oil energy. Whatever the actual number, COAL is the hydrocarbon fuel we should be concentrating on, not ethanol, nor bio-diesel, nor even fission-nuclear. MHD is anywhere from 60% to 90% efficient, depending on who you’re talking to.
The PROBLEM with coal-MHD is that coal slag quickly coats the throat walls, gumming it up. So they’ve been shooting the coal plasma thru the throat at mach 2 to get around that problem. But that in turn creates still further problems/inefficiencies in the system.
Years ago this inventor thought of an easier solution : 4 film-belts, as endless loops, that slide thru on the throat walls. They get coated with the coal crud/particle damage and are then cleaned off on the outside, recoated with fast setting gel/paint, and fed back thru the throat again. They also help COOL the cryogenic MHD unit.
With (former) Sen. Conrad Burns help, got the idea to the DOE where it got the one-soldier-at-attention finger salute, as I knew it would. The DOE is the LAST place you go for innovative thinking.
Why not just use TEFLON COATED our SILVERSTONE process?......
Teflon/silverstone? What’s that? In coal burning MagnetoHydroDynamics you have a superconducting field of E vector on say the y axis and M field on the x axis. It’s usually rectangular in cross section. The coal plasma comes thru on the z axis. The z axis plasma has to do WORK against the intense EM field lines, and just like some people you know, will do almost anything to avoid WORK.
Here that means coal slag slides sideways and piles up as gunk/slag on the throat walls, quickly gumming up the process. Also there is some radiation damage to the delicate, highly machined walls, actually a grid of nested buttons.
Yes, you could place 4 pads on the throat walls, but how fast would you have to replace them? But at least you’ve got the basic idea : protect the MHD walls from coal slag and radiation damage.
In thinking of the continuous 4 film-belts solution on waikiki beach 5 years ago, this solves the slag/radiation problem as well as keeping the walls cooler. The remaining problem, the CO2 coming out, could possibly be solved by shooting it thru a CaO(lime dust)chamber and thus getting CaCO3(limestone), nature’s way of storing CO2.
Anyway, as I envisioned it, the whole MHD package would fit inside a semitruck trailer and be moved around the coal field with mobile electric lines following along. A sort of muhammed coming to the mountain instead of transporting whole mountains of coal to muhammed.
Be as it may, imagine what it would mean to export electricity at 60%+ efficiency directly from the coal fields, and leaving only limestone blocks behind?
That's not gunk, that's DIAMOND COATING............
That’s why I said “currently made from food crops”.
Yes, algae is promising as a bio-diesel source. I wouldn’t go the whale route. I like whales.
You would think that since power lines already run alongside most roadways, that an inductive pickup would be a no-brainer. Maybe it is, or maybe the difficulty in metering the usage per vehicle would be very expensive. Or maybe allowing inductive taps would allow too high a bleed loss even when there is no vehicle around. It isn’t really necessary in the cities, anyway, since battery tech is already good enough for short distances. Where you really need it is on the long stretches between cities, but the traffic density on those stretches may not justify the cost in infrastructure.
I like the idea of cars tailgating with their braking and acceleration coordinated by computer to form “Trains” on the road. It would fit more traffic on the same highway and use less energy because wind resistance would be less. Can’t be done until a significant numbers of vehicles are designed to take advantage of it, though. Vehicles joining and separating from the “Trains” becomes a problem, especially when there is an entire train of vehicles in the lane you need to move into. Instead of finding a space between two 20ft long vehicles, now you have to look for spaces between 200ft long trains of ten vehicles each.
Be careful if you decide to use cooking oil as a motor fuel, you could get arrrested!
http://www.freerepublic.com/focus/f-news/1847746/posts
It seems to me that the conclusions are stilted toward the plug in hybrids by the fact that they are assuming an efficiency of 120 miles per gallon equivalent (3.5 mi/kWh) vs. 34 MPG for a gasoline powered sedan. Further, the assumed electric car only has a range of only 60 miles. If these huge differences in vehicle types were normalized, I'd wager that CTL would come out significantly better than the electric option.
The whole report is just skewed for some reason. They don’t even mention diesel fuel being made from coal, nor do the bring up the subject of a diesel-hybrid combo.........
IMHO, the impact of liquid fuel type is far less significant than the wiggle room allowed by comparing IC to electric powered vehicles. I think they’re comparing a suped up commuter golf cart to a real car.
You know, after re-reading this from another viewpoint, maybe it was designed to be anti-gasoline and pro-diesel, in the first place.............
And what do you propose to run such a plant on?
Solar Towers ?
http://www.time.com/time/2002/inventions/rob_tower.html
That is pretty cool. Be interesting to see if it will work.
You mean the coal GUNK that piles up on MHD walls is DIAMONDS? Please demonstrate said diamond production....
We are talking about different things. The walls of the MHD throat have to be kept as clean and clear as possible. Thus the film-belt has to interfere with the E and M fields as little as possible, and yet remove the gunk that gets blown sideways onto the walls, as well as remove some of the heat from the throat.
This is sort of what my body is going thru now : ulcers(erosians in esophagus)and congestive heart failure(fluid in lungs) : a week in the hospital.
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