Last week, I had the pleasure of attending a meeting of the Power & Energy Society of the IEEE Boston Section. The topic was plug-in hybrid electric vehicles (PHEVs) and the speaker was Alan Millner, of MIT Lincoln Laboratory, whose areas of interest include energy and hybrid vehicles.
He noted these hybrids potential to reduce fossil fuel use and emissions, along with introducing more renewable resources for transportation—but likewise touched on the cost of their lithium-ion batteries, which are currently "too expensive," exacting a large price penalty (with a similarly long "payback" period) that will deter many from buying a PHEV.
However, in presenting study results, Millner showed PHEV operation can be enhanced in three ways to improve their economics. First, the incorporation of GPS information into the car’s energy management algorithm would allow predictive control through prior knowledge of the route and energy required—so that fuel consumption is optimized and reduced.
Second, the use of the vehicle battery while parked (vehicle to grid, or V2G) can provide additional revenue to the owner to offset the expense of the battery. A specific version of V2G, called vehicle to building (V2B), offsets the short peaks in commercial-scale facility electrical demand (such as where the driver recharges his vehicle at work during the day) to reduce his/her employer's electricity charges. Revenue provided the driver from V2B can pay for most of the battery cost (say $100/month) over the vehicle life. And reducing facility demand, if widespread, also lowers need to build new power generation capacity.
Third, battery-cycle life must be maximized to avoid high replacement costs. Millner presented a model of battery wear out for lithium-ion batteries, and how lifetime can be extended with good practices (cooling/heating and charge level control).
The enhanced PHEV is then seen to have improved economics, helping bootstrap the technology into wider acceptance and economies of scale.
For the Lab Note that was the basis of Millner's presentation, click here. The note also includes a discussion of non-plug-in (Prius) and "conventional" plug-in (Chevy Volt) hybrid battery-use algorithms.
Alan Millner was a principal in a pioneering photovoltaic systems firm. He has developed switch mode power electronics for medical MRI and ultrasound systems, propulsion motors for marine applications, and power electronics for industrial applications up to 30 kW. He has authored 11 patents.
@antiquus and @msd1107 -- I think you may have the wrong idea. V2B is aimed at short (15-30 minute) peaks associated with things like HVAC. This adds to the DEMAND charge associated with large scale facilities, which can be 10's of dollars / kW, assessed on a monthly basis.
If V2B can return $100/mo., that means you give up nearly 70kWh in an 80 hour month -- approaching 1kW continuously (time out for dr. appointments, forgetting to plug in, low demand, etc.).
And when you get home, you return that 70kWh to the battery at the "night rate", but that would cost over $70 in my neighborhood.
To clear $100 _profit_, you would have to deliver 3x, or about 3kW continuously. At http://en.wikipedia.org/wiki/Electric_vehicle_battery it says that a typical car will carry 25kWh, so 3kW times 8 hours pretty well drains the tank, so to speak, and you'd be a-walkin' home.
I'm not buying your math, but instead will vote with msd1107.
Using the PHEV or EV battery to supply energy to the grid during the day while at work and then recharging during the night at home has fatal flaws.
A down loadable spreadsheet at http://bit.ly/b5xI64 discusses this with examples.
As "Work to Ride, Ride to Work" says, if this could be done, the power companies would be doing it already.
Scheme is right on the money. I'm sorry to say that if you could make money buying batteries, charging them during off-peak hours and then selling back the electricity during peak hours, the utilities would already be doing it. In a big way. There are plenty of energy storage ponds around various places. I have yet to see any meaningful peak shaving battery systems. Millner has a dog in the fight so I'm not surprised by his rosy assessment.
In Millner's presentation, he had numbers that showed the "cost" of extra charge/recharge cycles of supplying power to the grid on battery life of about $3/month versus a benefit to the owner of selling power of $100/month.
New technologies, such as carbon-nanotube-based batteries and power generators such as fuel cells and the (shock)Wave Disk Generator recently funded at Michigan State (http://arpa-e.energy.gov/LinkClick.aspx?fileticket=0O_uoJdrclc%3d&tabid=225) will have a much larger impacts on the value of PHEVs than some pie-in-the-sky ideas about the side-benefits of plugging in your car. For one, who expects the cost-benefit of using your car to decrease power needs during peak hours is really going to help? Not only will that require the use of (currently) expensive fuel to recharge the battery, but it increases the number of charge/discharge cycles and shortens the life of the (currently) expensive batteries. The only part of Millner's findings I agree with are that making the car "smarter" will allow it to be more efficient in its power use.
Check out that Wave Disk Generator, by the way. It's a pretty cool concept, and we could actually see it in use within a few years. Combine that with high-torque/high-efficiency electric motors on the horizon, and I can imagine a hybrid that can beat a super-car off the line and drive cross-country on a tank of (insert fuel) in the relatively near future.
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