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Interesting article. Excerpt: Since the glass electrolyte is not reduced by the anode, no anode-electrolyte interphase (SEI) is formed, and since the electrolyte is wet by the anode, no anode or cathode dendrites are formed. Moreover, wetting of the electrolyte by the alkali metal anode allows volume changes at both the anode and the cathode during cycling to be accommodated by pressure from a spring at the back of one of the current collectors since the volume change of the electrodes is constrained to be perpendicular to the electrode electrolyte interface. The absence of an SEI on both electrodes and elimination of a large 3D insertion particle volume change and/or small active electrode particles that limit volumetric capacity provide a simplified, low-cost structure in which the principal sources of capacity fade on cycling are not present. The result is a cheaper cell with a large volumetric capacity and a long cycle life. The cell voltages and rates are acceptable.
350kW isn't that difficult, but it helps to bump up the voltage to 750V or higher to lower the amperage. We're doing 650kW with buses for some time now, and 350kW is becoming quite common in the bus charging industry. Of course we don't use hand held plugs which helps a lot.
Sounds like this is will become a whole new branch of materials science, and they haven't even scratched the surface of what is possible.
Past time to fix this. What with the entrenched EU OEMs colluding to fix prices and delay emissions, and little progress in making existing trucks more efficient, let's boot them out and embrace a new paradigm - driverless, electric trucks.
Interesting to see the Foton Daimler Cummins "China Internet Super Truck" alliance http://www.greencarcongress.com/2016/06/20160623-foton.html . Will they adopt the Pony Express model and go electric? Or is the influence of Cummins too strong, and they stay with diesel. Driverless electric trucks from China to Europe across Siberia...
This is the ticket. Autonomous electric trucks traveling from Asia to Europe, or to NA over a land bridge or tunnel from Siberia.
Energy storage increased, charging time reduced, I wonder about cycle life?
Roger Pham, since I'm trying to approach this from an economic rather than environmental view, the Supertrucks are worthy adversaries, and relatively equal in economic benefit/cost. This begs the question; why aren't Supertrucks taking over the market if they are so much cheaper to run? An answer to this would help me decide whether the Pony Express (or EHighway for that matter) is worthwhile pursuing. Perhaps it is because as Mr. Wilder mentions, natural gas is the most economic alternative at the moment?
Brian, another thought to consider. From a purely economic standpoint, the difference in fuel cost between electric and diesel is best exploited in transport modes where fuel is a large component of overall costs. From what I've seen, heavy trucks have the highest percentage of operating costs due to fuel, therefore they are the best candidate for finding an economic reason for switching to electricity. I've been involved with urban buses for years, and electrification always becomes a political decision, not an economic one, and it always ends up with the bean counters winning - very frustrating. Electric cars are even worse economic candidates, where fuel costs are a practically insignificant part of actual TCO, and electric car ownership is purely a status symbol or political statement.
Hi Brian, Certainly in the USA, the electric vs. diesel cost savings is maybe 50%. In the EU, it is more like 20-25% because of the much higher price of fuel. Even in the US, if fuel cost is 39% per mile (see http://www.thetruckersreport.com/infographics/cost-of-trucking/ ), then the savings per mile will "only" be 50% of 39%, or 19%. Add in the chargers and extra tractors, and you may only end up with a 10 or 15% advantage. This still confers a significant financial advantage over the competition in corridors with tight profit margins. In the EU, this advantage is likely more like 20 to 25%, a huge competitive advantage. Indeed, much of this comes at the expense of taxes, and if electric trucks gain much market share, the governments will have to add taxes or fees to make this up. But in the meantime, there is big money to be made!
This scheme can also be termed the "Pony Express" solution - the driver changes tractors (ponies) every so often to keep going. Certainly it is not ideal, but with current battery technology, it is a practical interim solution. The real impetus here is not convenience of the driver, or for environmental reasons, but simple economics. Electricity costs 20% of diesel. Diesel is 30 to 40% of trucking costs. Profit margins are very tight in the trucking industry. These facts show a huge profit potential in converting from diesel to electric. Any one who cracks the electrification nut gets a huge payout. Of course, driverless trucks will lower costs even further, and this scheme is perfectly compatible.
There is an easy way around connecting these big chargers to the grid - use some grid storage batteries to even out the grid draw, plus the batteries also provide a powerful energy source to push power fast into the EV. You have a relatively low power AC to DC converter to the grid storage, and then a high power DC to DC converter out to the EV. Here is a paper that discusses this: http://www.hpe.ee.ethz.ch/uploads/tx_ethpublications/06397481_01.pdf
Hi Jim, I think that especially for buses, the additional level of safety provided by galvanic isolation may be important, since people may be getting on and off the bus during the charging process. Also, for fast charging (>300kW), an automated overhead connection like the Opbrid Busbaar would be more difficult to provide the 6 contacts needed for AC charging. The 4 contact CCS DC connection is already hard enough! And since we are getting close to a standardized DC overhead connection (Opbrid/Siemens/ABB/Volvo/Novabus/others), AC charging like you describe may always be cable and plug only. Getting all-day bus operation including AC and heat is difficult - even a BYD bus will likely need a fast charge topup during the day, and 300 to 650kW is tough to do using an AC plug.
I'd like to see this analysis for different types of electric buses. My guess would be that the use phase is considerably higher since buses can run over 1 million km in a lifetime, with rather poor l/100km (typically around 50 l/100km).
I think Mr. Wang should look at the cost of burning diesel. Not just the pump price, but the cost of air pollution to the health of his citizens. However, I'd like to know more about these failures. A BYD bus shouldn't need its batteries changed until about 8 years unless something is very wrong. (3000 cycles LFP, one cycle per day). Indeed, Volvo's execution of the plug in hybrid is excellent. Based on their well tested hybrid, it will be a solid workhorse, and very flexible since it can revert to normal hybrid when charging isn't available. Certainly 100% grid electricity is the goal, but 80% grid power isn't bad, since previously it was 0% for their normal hybrid! Go Volvo!
Buses are particularly good candidates for ultra fast opportunity charging because they run the same route over and over. This is really a no-brainer. What about long distance trucks and buses? Any hope there? In the EU, long haul drivers have to stop for 45 minutes every 4.5 hours (this can be split into a 15 minute stop and 30 minute stop). In the US, it is now 30 minutes within an 8 hour period. Perhaps these rest stops could be used to add some grid power to long haul heavy vehicles? Let's do some light math: From a chart from VTT Finland, shows an energy output of the engine of a 60 ton tractor+trailer, full payload freeway at 80km/h is 168kW, including going up and down hills. Say an electric motor/battery is 90% efficient. We would consume about 190kW. As a sanity check, this corresponds to 190kW/h / 80 km/h = 2.4kWh per km, this seems about right for 60 tonnes. So, in 4.5 hours, you would consume 855kWh out of the battery - rather a large battery! To refill this in 45 minutes, you would have to charge at 1.2MW - a large amount, but not out of the realm of possibility, since this is only about 2C of that large battery. The battery is just too big. Does it make any sense to do this partially - using a plug-in hybrid? You will get some savings from reducing the hysteresis losses of going up and down hills, plus displacing diesel with as much power as you can charge during the stops. Example: 300kWh of batteries Gets you maybe 1.5 hours of runtime electric only, but the other 3 hours is on diesel. A reduction of about 40% in diesel usage if you add in the hysteresis reduction. To charge 300kW in 45 minutes, you only need a 400kW charger, well within current technology. Not too bad, but not too wonderful either. Probably a non-starter until batteries get better, or diesel gets really expensive. Delivery trucks, port trucks, trash trucks are likely a better business case, especially if a city has a zero emission or zero noise CBD, like is starting to occur in Europe. Medium haul buses might be a good candidate, since they are much lighter than the above 60T truck, probably around 12T. In that case, a 300kWh battery might be sufficient.
I have been working on this project for two years, so know it intimately. The batteries on the bus are 28kWh, slightly larger than a Leaf. They use maybe only 8kWh on the run. The only reason it isn't 100% electric is that there are some steep hills on the route. This is a parallel hybrid, so the diesel turns on to help the electric motor up the hills. This is an extremely flexible and robust solution to bus transport. Any combination of diesel and electricity can be used, depending on the route. And if there is a blackout or charger malfunction, then the bus keeps going. It also has a high passenger carrying capacity. These buses are based on their high-volume 7900 hybrid bus, so prices should be quite reasonable. Expect to see this being a big sales winner for Volvo.
One of the ABB engineers mentioned LTO batteries, which makes sense. The video doesn't show the rather massive charger house which contains both a charger and a bank of super-caps. The super caps are what are used to do the 15 second flash charge of 1.7kWh. I can't imagine that this would be economic, to install one of these every km or two, but I could be wrong. I still think end station charging of 5-8 minutes is the most cost effective. If you think about it, a bus charger will be used at close to 80% duty cycle. A bus leaves the charger, another pulls up. This is an efficient use of the work needed to connect the charger and amortize the charger itself. Car chargers would rarely reach this level of utilization. The TOSA "hammer" charge mechanism is pretty cool to watch however!
So, if we put these two sources together, Tar sands and oil palm plantations, we get how much compared to the coal power plants in China?
Actually, it really isn't clear, and likely depends on the route and the preferences of the bus operator. I personally think that a plug-in hybrid bus is a very good choice in most situations. You can size the battery to a normal run, not over-sized like an all-electric bus has to have. If you run out of battery power due to a traffic jam or other situation, you just revert to hybrid mode and keep going on diesel. Normally you run 100% electrically and just use the diesel for backup. Since all the engineering for hybrid buses has already been done, it is "simply" a matter of adding a bigger battery and a fast charging system. This is what Volvo is doing with their 7900 hybrid. It will be very reliable in all situations, yet act as an electric bus most of the time - very cool if you think about it.
The visual impact of the Opbrid Busbaar station has been markedly reduced in the latest version, a single pole and an largish box that contains the charger. Not much more than a streetlight really, and can be combined with a bus shelter. An inductive charger also has a largish charger box - you have to put the charger electronics somewhere! In either case, you don't have overhead lines like a trolley bus or tram strung throughout the city. Shorter charge times can translate into fewer buses. If a bus is out of service for 10 minutes each hour charging, this adds up to 180 minutes over 18 hours, perhaps requiring an additional bus to be purchased.
If you do the math, this is a pretty easy route to cover. I mapped this from the Milton Keynes public transport site in to Google Maps and arrived at a distance of 10km, very flat terrain. Here is the map: http://goo.gl/maps/sZu0Z . Given this short route of 10km, and a power draw of about 1.5 kWh/km, this gives a power requirement of 15kWh per charge. They are charging only 2/3 of the required charge, for 10kWh in 10 minutes. This translates into a charger of 60kW, about average for an inductive charger. Hybricon in Umea is using AltairNano LTO batteries, an Opbrid conductive charging station, and charging at 300kW. This means a 100% charge (15kWh) in only 3 minutes.
This kind of thing makes me angry. It is done just for the image of being green, but is inefficient and an illusion. Electricity has the advantage of being able to be transported reasonably efficiently from far away by high voltage transmission lines. This means that electricity can be generated by large solar arrays, or large wind generators situated in areas with good wind, not next to the charger! I recently read that very large wind turbines are much more efficient than small ones, rendering this idea worse than useless, simply green-washing. Let's make the grid green with BIG projects like offshore wind farms, and then put EV chargers wherever they make sense where people live. (likely not offshore!)
This could be what I've been looking for. I don't really want an electric bike, too expensive for a good one, and you are always hauling around all that battery and motor. This way my wife and I can share, but keep on using our normal bikes. It should even fit on the elevator to charge in the office (and keep it safe). Anyone tried it?
We went with conductive charging to provide for very fast charging (200-300kW) just at the end of the route. If you charge inductively at intermediate stops, the passengers have to wait. As a bus rider, I much prefer faster journey times! The buses here in Granada, Spain only stop 5-10 seconds to let people off and on most of the time. This is not enough time to get any meaningful charge. Charging at the end of the route doesn't impact the journey time, since only the driver is in the vehicle. Also, typically there is some wait time at the route ends to keep the buses on schedule. You might have noticed how buses tend to "bunch up" - the one in front gets slower and slower as it picks up more people, and the one in back goes faster because there are less people to pick up. The wait time at the ends evens this out. It is called "Layover time", and is typically 4-10 minutes depending on the route. This also give the driver some time to use the facilities and have a smoke (in Spain at least), before continuing on. A PHEV bus also has the advantage of being able to continue even if it doesn't have time to charge, since it can revert to hybrid mode in a pinch. This can really come in handy at times! The range extender can be a fairly light and cheap automotive diesel engine since it isn't used much, just there for backup.