A rapid charging electric motorcycle

Over the last few months we've been working on a rapid charging electric motorcycle. Here's a picture of the full setup:

We made our own custom battery packs, charger, etc. It's using a battery-to-battery charging scheme.

We wrote up our full design, cell cycling results, etc. and have submitted it for journal publication. Hopefully we can release all of this information soon - very exciting!

Batteries in Transportation and upcoming events

Today, MIT Energy Club hosted discussion series on Batteries in Transportation. It was very well attended by professionals in the industry, MIT students, from engineering and business school, Harvard Kennedy School of Government, Boston University, Northeastern University and Tufts . The main topics were the history of batteries, the advantages of Lithium-Ion batteries over other battery chemistries, and the limitations of the current generation of Li-Ion batteries, such as energy density and cost. Several potential solutions were proposed.

This discussion will be followed up by a related discussion on the stationary grid storage devices later this year.

We will have a busy weekend attending Lexington Energy Fair on Sunday and Altwheels 2009 on Monday. 56 vehicles of different sizes and applications, including MIT Porsche 914-EV,are expected at Altwheels.

2009 MIT Community Fall Break

Yesterday, we attended the MIT Community Fall Break 2009. The event was designed to familiarize MIT community with GreeningMIT, an institute-wide initiative to encourage sustainable practices. It was a wonderful zero waste event with delicious food and compostable cups made from corn.

In early fall, we always try to engage MIT community in our outreach efforts. We had a superb turnout of incoming undergraduate and graduate students. If you are interested in joining the team, please see this page.




If you are looking to make immediate impact, check out the MIT Facilities Transportation page. It lists multiple options available to MIT students and employees. Students can take advantage of Zipcar heavily discounted membership and of subsidized T passes. Employees also qualify for Alternative Transit Subsidy and Bicycle Commuter Benefit Program.

Greenhouse Gas Emissions from One Gallon Challenge

Just to complete the previous post, here a map of the United States describing the fuel mix used for electricity generation. Source: EPA eGrid page.



Emissions from tailpipe.

Gasoline and hybrid-electric cars emit through their tailpipes. They produce emissions and reduce air quality in the urban centers where population density is high. An electric car does not have a tailpipe. Here is a chart of CO₂ directly emitted by the cars during the One Gallon Challenge. [Based on DOE data, more info at Carbon Dioxide FAQ]


Emissions from well to wheels.

Even though an electric car does not have a tailpipe, an electric car produces greenhouse gas emissions where electricity is generated. These emissions are usually counted as "well to wheel" emissions, that is, a full life cycle of fossil fuels from their extraction to actual process of burning. They are differentiated from "tank to wheel" (or "plug to wheel" for electricity) emissions from the tailpipe.

Gasoline-powered cars, both conventional and hybrids, also produce upstream emissions. Most significant ones are emissions from the oil refineries that convert barrels of oil in gallons of gasoline. [Based on Argonne National Lab GREET]


A few comments:

1. Since we kept track of when we charged the car, we know that natural gas was used as a fuel to produce electricity for our drive. In general, you do not know which fuel was used to produce electricity for your air conditioner or flat screen TV. A common approach is to take US average grid fuel mix with 50% coal, which is almost twice as polluting as New England grid.
2. The 75 MPGe well-to-wheel number quoted in the AutoBlog was based on the US average grid. Had we taken New England numbers, we'd get above 100 MPGe. Had we charged our car with wind or solar power -- no fossil fuels used -- we would have infinite MPGe!!!

As you can see, an electric car is two and a half times cleaner than a gasoline-powered Prius with its strong 52.9 MPG. The main difference is the fuel. Our Porsche effectively used natural gas while Prius used gasoline. Had Prius used compressed natural gas (CNG), its greenhouse gas emissions would be probably about the same or even slightly lower than those from an electric car.

A conventional engine CNG vehicle, for example, the only mass-produced available in the states Honda Civic GX would not be able to rival an electric car because it lacks a hybrid option. There have been prototypes of CNG Hybrids, for example, Toyota Camry CNG Hybrid and Opel/(Saturn) Astra Caravan CNG Hybrid, demonstrated in the past year.

CNG Hybrids or Electric Cars?
As a society, should we focus on electric cars or CNG Hybrids?

Advantages of CNG Hybrids.

1. Price. Electric cars are quite expensive due to the cost of batteries. When our Porsche was built a few years ago, the battery cost for ~100 miles range was $36,000. If the car were mass produced today by a major automotive manufacturer, the battery cost would be closer to $15,000. It is still much more expensive than a hybrid powertrain.

Disadvantages of CNG Hybrids.

1. Leakage. Natural gas leaked from the refueling stations and from the car itself due to leaky hoses is a potent greenhouse gas, four times as damaging as CO₂. Because of that, developing a complex infrastructure for natural gas refueling may end up producing just as much harm to the climate as today's gasoline cars.
2. Renewable energy. Electric grid in the US will become greener with time. Emissions from the grid are already tightly controlled and budgeted (see RGGI, an initiative by ten Northeast and mid-Atlantic states). Addition of renewable sources, such as wind energy or solar power, to the fossil fuel powered grid will inevitably reduce well-to-wheel emissions from electric cars.
   An average car in the US lives for about 15-17 years. An electric car sold TODAY emits as much greenhouse gases as TODAY's CNG Hybrid car. In ten years, an aging CNG Hybrid car will emit the same amount of CO₂ per mile or even more, due to leaky hoses. In ten years, the same electric car will emit less CO₂ per mile because its electricity will be cleaner. Electric cars are future-proof. That is one of the reasons our team is the Electric Vehicle team.

Gallons in an electric car?

MPGe and gallons equivalent is a convenient metric to compare electric and conventional cars, but it's pretty evident that an electric vehicle does not burn gasoline. What does an electric car really use?

We monitored the charging behavior of the car closely and matched this information with the hourly data from ISO New England (wikipedia: about).
Here is a plot of electricity demand in New England with the profile of car charging overlayed. Both axes are in the units of power, MW stands for a megawatt (1 million Watts), and kW is 1000 Watts. An average incandescent light bulb is 60 Watts, an average compact fluorescent bulb is 20 Watts, and an average car has about 160 horsepower, equal to 120 kW. That makes 6,000 CFL bulbs in an average car.


The electricity demand follows a fairly typical summer profile. We use much more electricity in the afternoon (peak demand) than at night. The main use during the day is air conditioning.

The car charges whenever it is plugged in. Most electric cars will be charged at night in garages, on driveways, or on public charging spots. Just like we charged at our friendly hosts, Ford of Greenfield. We also charged during the day, in fact, during peak demand. Did it matter for the utility company? We'll see shortly.

United States fuel mix for electricity generation

United States electricity grid consumes about 50% of coal. Electricity produced with coal is particularly "dirty". Yet all states are quite different. Here is a fuel mix used in the New England: coal is only 11%, and renewables (including hydro) is greater than that. As you can see, the electricity demand on August 19th and August 20th were less than maximum capacity, so we did not run the dirty diesel generators.


The car charges "on top" of the demand bar, so we used capacity from a combined cycle natural gas plant. For this race, our Porsche was actually powered by the natural gas. It is a fossil fuel, yet its source is all domestic.

We were concerned whether our electric car mattered for the utility since it was being charged at peak. For the comparison, we looked at the difference between two consecutive days, Wednesday and Thursday. Wednesday was slightly hotter, so consumers used a bit more electricity. A difference between Wednesday peak and Thursday peak is 871 MW sufficient to recharge 414,762 electric cars like our Porsche

We will continue with the summary of CO₂ emissions from the race.

One Gallon Challenge: 164 MPGe

Last week, the Porsche participated in the One Gallon Challenge, part of Boston Greenfest 2009. We traveled from Greenfield, MA to Boston City Plaza using 23 kWh of battery power, equivalent energy to 0.65 gallons of regular ethanol-containing gasoline. That translated to 164 miles per gallon equivalent (MPGe). Here is a link to our path. We also got lost on the way which added a detour, so the total length of the trip was 118 miles.

View Larger Map

Both in Greenfield and in Boston, we had a tent for the car and a lot of visitors. Outreach and public education is an important part of our effort. For everyone who stopped by to see our car last week, thank you.




A day before the race, we drove from Cambridge, MA to Greenfield, MA. We completed this drive on a single charge during the prior night. In Greenfield, MA we charged using 240V AC at Ford of Greenfield which generously let us park there at night.


However, we were not able to fully charge during night due to logistical difficulties, so we started the race with 80% full batteries. We had to recharge on the way. Luckily, Colonial Dodge of Hudson, MA let us park next to their service bays during the day and fill up our battery.

Charging at Colonial Dodge

We also had two cars, a hybrid-electric Toyota Prius and conventional Pontiac Grand Prix which drove with the Porsche. We took the chance to compare the vehicles against each other considering all three cars drove together along the same route.


Toyota Prius ran the race at very respectable 52.9 mpg, while the Pontiac Grand Prix did 22.8 mpg, fairly typical for a midsize sedan. We observed that fuel economy measured in mpg is not as telling as fuel consumption, usually measured in gallons per 100 miles or in liters per 100 kilometers, a European metric. You can readily see a difference between equivalent fuel consumption of an electric, a hybrid and a conventional car on this plot.

More updates are coming about our recharging experience and about our greenhouse gas footprint.

Update: There was quite a bit of press coverage for this event.
One Gallon Challenge: alt-fuel "race" cars get up to 164 MPGe

The feasibility of rapidly charging EV's

Below is a poster I put together describing the feasibility of rapidly charging EVs.

There are three main things to consider: (1) Cell chemistry (2) Power source (3) Chargers and (4) Battery pack design.

The good news is that it's all totally feasible - though research & development is obviously required! A123 has already developed the cells necessary.

Remember that drivers would not rapid recharge all of the time. Most of the time they would charge EVs for the lowest cost - slowly - over night in their garage. But in the event they need the extra range, rapid charging should be an option.

Included is a chart Shane and I (with help from professional electrical engineer Dave Rodgers) put together. It shows how you could rapid recharge a motorcycle at home, while a sedan would require higher power - which is already available in most industrial buildings (think Home Depot, Best Buy, etc.).

Thus our vision is that the rapid recharge stations would not be at home - but rather at fueling stations like Hope Depot, Shell Gas Stations, etc. This is totally feasible - and the power already exists in many of these buildings.

(click to enlarge)