Tuesday, February 5, 2013

The Future Of Electric Vehicles

This is an article speculating upon advanced cars of the future, looking at the near-future (5 years), mid-future (10 years), and longer-future (15-20 years) future. I say “advanced” cars because of course not all features appear everywhere instantly: typically, there are some vehicles that are early adopters of new technology, and conventional vehicles may continue to be made well after the advent of new technology (consider a comparison of the technologies in my four-wheel vehicles: a Nissan Leaf and a Dodge Caravan). The speculation is my own, and while I try to stay abreast of interesting technology, I may mistake optimism for probability.

I believe the main drivers in vehicle development are consumer market pressure, competitive pressure, and technological advances, in that order. But, even if pure technological improvement is not the main driver, I think we are moving toward a period where consumer expectation, competitive manufacturers, and greater opportunity for funded research is moving the automotive industry toward faster implementation of new technologies.

Generally speaking, there are 5 leading factors in vehicle purchases: 1. Purchase-price bang for the buck in that price bracket; 2. Style / status / brand perception; 3. Efficiency; 4. Performance; 5. Safety (and of course, the order varies with the purchaser). However, as car prices continue to increase, as the length of car ownership continues to increase, and the influence of informational sources like Consumer Reports and internet reviews continue to increase, I believe that as we go forward it is likely that consumers will become more concerned with long-term bang for the buck, often referred to as “total cost of ownership.” I trust that this shift will be good for technological improvement, which provides greater efficiency, safety, and lower long-term costs.

Here is a critical truth: the average car sold today costs about $30,000, will burn about 500 gallons of gas a year, and will be on the road for at least 10 years, and so in its lifetime it will burn at least 5000 gallons of gas. Historically, over the past couple of decades gas has gone up about 12% a year. Therefore, using a rough conservative average value of $7.00/gallon over its lifetime, fueling the average car will cost about $35,000 – more than the car’s purchase price. Clearly, buyers should understand the significance of efficiency and total cost of ownership.

An electric vehicle (“EV”) can be either a pure battery–powered electric vehicle like the Nissan Leaf, or one that carries an engine as a generator to make it an Electric Vehicle with Extended Range (“EV-ER”) like the Chevy Volt. EVs are far more efficient than any gas or hybrid vehicle measured by any metric, including miles per gallon (or “miles per gallon equivalent” (“MPGe”) for EVs), carbon dioxide pollution per mile, or total cost of ownership. While there are interesting potential developments regarding engines, there are far more potential developments regarding EVs, and therefore I will be focusing my technology speculation primarily on EVs. (If you would like to review an earlier article I’ve written speculating on EV-ER engines / generators, please read the following: http://jungreislaw.blogspot.com/2011/05/best-ev-er-electric-vehicle-with.html.)

EVs will benefit from advancements primarily in the following areas: batteries; motors; construction; electronic management; and charging (particularly involving public charging stations, the equivalent of public gas stations). I have no doubt that as these areas improve – especially battery technology – EVs will become more and more common, and will eventually become the most common vehicles on the road. This also dovetails nicely with the advent of more renewable electricity generation, so that these EVs will be able to drive without producing any pollution (on a limited basis, the future is already here: I have solar modules on my home, and so my EV drives pollution-free – and, as the solar system will soon be paid off in savings, cost free!).

In the near future (in approximately 5 years), we may see the following advancements:

1. Batteries: Lithium batteries with silicon-based cathodes, which can absorb many lithium ions and therefore would provide the battery with dramatically more energy storage. There are many “flavors” of lithium battery chemistry: today, relatively common lithium chemistry can contain around 133 watt hours/kilogram (wh/kg). This is about enough energy to drive an EV half a mile. With silicon cathodes, the energy density would likely be around 400 wh/kg – three times better than today’s common batteries. With a 400wh/kg battery, a 150 mile range battery pack will only weigh about 220 pounds. (It would actually weigh more due to necessary battery reserve, pack containment, thermal management, etc., but I want to try to keep this simple.)

In order to build silicon-based cathodes, it is likely that nano-sized silicon will be contained in porous ceramics or other materials that allow for sufficient surface area and yet keep the silicon from physically crushing itself as it expands when absorbing the lithium ions. Also interesting is that such a cathode, with a lot of usable surface area, will enable greater power-release and power-acceptance. This means that even a small battery pack, such as that found in EV-ERs, could provide adequate power to accelerate quickly, and allow a maximum amount of regenerated (braking) electricity to be put back into the battery.

Lastly, it is likely that a non-flammable version of lithium electrolyte will become common, and thereby enable greater efficiency at the temperature extremes of vehicle operations, as well as potentially lighten and simplify battery pack cooling systems.

2. Motors: Non-precious-metal motors are smaller and cheaper. While some EV motors in production are already using non-precious-metals, such as Tesla’s AC Induction motor, many still use precious metals. It is likely that the industry will move entirely away from precious metal designs. While this may entail some small tradeoffs in size, weight, and efficiency, it has the advantage of broader powerbands, ensuring that no transmissions will be needed.

3. Construction: More of the vehicle’s components will be made from aluminum and high-strength steel construction. This will serve to lighten the vehicle, and low weight is the key to efficiency and performance. Vehicles basically use energy to accelerate, to push through the air, and to overcome friction. Friction is the least concern, and in any event friction technologies are already good and will continue to make some headway (ex: lower friction tires). As for pushing through the air, this is a concern when driving at highway speeds.

But the lower the weight, the less energy it takes to accelerate, and acceleration is when a vehicle uses the highest amount of power. Obviously, though, you don’t want to make a car out of balsa wood, as it would not protect its passengers (and flexing would make it handle badly). Therefore, building a vehicle from strong but light components is critical. Here, there are numerous interesting developments in improved metal alloys, such as better aluminum and better steel, and improved construction techniques such as welding steel and aluminum together and employing powerful bonding agents, that will allow lighter and more rigid chassis, suspension elements, and body parts.

4. Electronic Management: There are numerous developing advances in plotting directions, maximizing safety through electronic controls of vehicle dynamics, and driver and user interfaces that will make driving easier, safer, and more convenient. Many of these advances are probably going to be common to both EVs and conventional cars, but as EVs are necessarily computers on wheels, the advances will integrate more fully and seamlessly in EVs.

5. Charging: There will be development of real-time information for plotting, locating, and reserving charging station used to recharge EVs. We will see continued charging station expansion, hopefully accompanied by cross-platform user-interface standardization. These advances, in additional to standardization of charging system protocols and vehicle-to-internet networking, will encourage EV owner confidence that their EVs will be able to successfully charge in more and more places across the country.

Looking ahead to the mid-future (in approximately 10 years), we may see the following advancements:

1. Batteries: Lithium sulfur, lithium salt-water, or possibly lithium air batteries. It is as yet unclear which of these batteries will develop into the most accepted technology, but it is hoped that one of these chemistries, or perhaps another form of lithium-based battery chemistry, will leave the laboratories and become a commercial product. These batteries promise over 1000 wh/kg, which would enable 600 mile trips with a battery weighing around 350 pounds. (Lithium, the lightest of metals, has a theoretical capacity of about 10,000 wh/kg, and while that theoretical limit cannot be approached these appear to be the best of several avenues for taking maximum practical advantage of that capacity).

2. Motors: It is possible that switched reluctance motors, which may even be built with iron-embedded plastic manufacturing, will enable very inexpensive, light, powerful motors from common materials. The key to the development of such motors will be tremendously accurate and powerful controllers that can transition electrical energy through the motor with precise timing and amounts. An additional advantage is that these motors should be able to operate at lower temperatures, potentially simplifying the cooling system.

3. Construction: The use of carbon fiber, slowly moving into high-end vehicles right now, should be widespread for many vehicle parts (possibly including even engine parts). Because the material is much lighter than equivalent metal parts, it will be a great advantage for all vehicles, enabling the drivetrain to be smaller and/or to accelerate the vehicle faster. Also, carbon fiber works fantastically for passenger protection (modern race cars are made of carbon fiber and provide excellent driver protection).

4. Electronic Management: There will be, for both EVs and conventional cars, increased ability to engage semi-autonomous driving – that is, the car can drive itself to some degree. There are already cars that park themselves, and that warn the driver of blind-spot traffic and when slipping out of a lane on the highway. However, EVs are more readily capable to more deeply use autonomous driving, as they all have telemetrics that enable the vehicles to communicate in real time with the internet. Therefore, EVs are candidates to be able to connect with one another and move in concert. This would be quite valuable on highways: it is well known that 25% or more of the energy of highway travel can be saved by driving vehicles closely nose-to-tail. Of course, for humans to drive just a few feet from the vehicle in front of it at highway speeds would be unacceptably dangerous. However, when all the vehicles are in constant communication, they can run in very close formation and act as a single unit for purposes of braking and accelerating, and allow individual vehicles to enter into and drop out of the “train.”

5. Charging: With improved batteries that accept electricity quickly, charging will take less time – if the charging station is up to the task of pumping all that electricity in quickly. It may be hoped that there will be a fast-charging standard of at least 100KW. Using such a charging station, for every minute that the EV is plugged in it can drive about 6 miles – this means that in an hour, the car would receive enough electricity to drive 360 miles.

Also, induction mats, already starting to come on the market now, will be designed into garages and parking structures in the future, so that EVs will be able to charge without the driver ever having to touch anything. The induction mats allow the vehicle to wirelessly receive power when parking over them, freeing the driver from ever having to even have to think about charging unless they are taking long trips or park on the street.

Lastly, it will likely be the case that EVs will share their battery’s storage of electricity with utilities (known as “vehicle to grid” integration). In this way, homes can be powered by the EV during the hours of the day when electricity it most expensive and hardest for the utilities to produce, and EV batteries will store electricity at night when it is plentiful and inexpensive. Utilities will also be able to buy back electricity stored in the EVs, and in that way the EV may partially pay for itself (as well as enable the cleanest possible electrical grid).

Looking ahead to the longer-future (in approximately 15-20 years), we may see the following advancements:

1. Batteries: While it is still quite early to know what will be its ultimate uses, the wonder material of the 21st century appears to be graphene. It is a single sheet of carbon atoms, and it is being investigated for several electricity-based applications, as the basis for ultra-strong materials construction, even as a scaffold for growing organ tissue, and more. For purposes of storing electricity, graphene seems to be able to quickly absorb tremendous amounts of electrons, hold them without significant loss, and then release them just as quickly. In this way, graphene seems most like a superdupercapacitor. Capacitors generally differ from batteries in their ability to efficiently hold an electrical charge and then quickly release it: they have high power density, however they generally cannot hold as much energy as a battery and thus have lower energy density. But, at some point, the line between energy density and power density blurs, and so whether graphene might ultimately be seen as a battery or as a capacitor is irrelevant.

There are a number of government, government-funded, and private laboratories that have only recently begun serious investigation of graphene, and so we are still far from seeing the final form that it might take, let alone a commercial production mechanism. Still, graphene looks to be the most interesting possibility for truly dense electricity storage. One calculation holds that graphene batteries could have an energy density of over 7000 wh/kg. If this were proved true, then a mere 110 pound battery would enable a car to travel over 1300 miles.

2. Motors: For many years we’ve heard promise of possible superconducting materials, which would have nearly no resistance and consequently would allow for very small, very light, and very powerful motors. Unfortunately, the superconductors that exist require significant efforts to keep them at very cold temperatures. However, as technology marches along, we may be starting to approach the era when high temperature superconductors could become real, as research is now focusing on non-metal high temperature superconductors. And, it is also possible that wires and motor parts may be made from our new hero, graphene, which has been demonstrated to have very low resistance to electrical transmission. And, with superconductors we’d see small, light motors that could be mounted in the wheels, thereby allowing for much more flexible vehicle chassis design without compromising ride dynamics.

3. Construction: Given the progress that has been made into commercialization of carbon fiber materials, it is possible that the logical extension of this development will result in (you guessed it) graphene-based construction materials. Such materials would be remarkably light and strong. And, as pure carbon atoms, they would also be perfectly recyclable.

And while we’re still talking about graphene, let’s look at some other properties it has that might help tomorrow’s cars. It has no band gap, and so it might make an ideal thin photovoltaic cell to absorb solar energy. These solar cells could power the vehicle by covering all surfaces, including the windows. Why would you be able to put it on the windows? Because as a single sheet, it is functional, flexible, and also nearly transparent. Remarkable.

4. Electronic Management: It is likely that, in a couple of decades, the concept of networked equipment will be so ubiquitous that you can assume that all vehicles will be fully autonomous. Tell it where to go, and it will take you there, all the while talking to other vehicles on the road to drive with the greatest efficiency and assure your safe arrival. It will park itself, interact with the grid in whatever way the grid computer thinks is best, and come get you wherever you wander. This will be very convenient. And so ridiculously complex that only the controlling computers will understand how it is all being managed.

5. Charging: With batteries capable of holding large charges, charging will become much easier, as there will be less of a need to charge at any specific place or time. Therefore, when the vehicle thinks it should charge, perhaps with its autonomous control if it is not parked where it can charge it will know to drive itself over to the charge station and be back before you could miss it. In other words, the need to charge will no longer be your concern.

It is a bright and efficient future. I look forward to its arrival, so that we can put all this carbon-based energy behind us in favor of clean renewable energy. Then, we will be putting this endlessly cycle-able carbon where it belongs: not in the air, but into the vehicle itself.

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