FCV vs BEV

In this week’s installment of the Bollinger Motors Blog, we’ll dispel some rumors, dismiss some misconceptions, and drop some basic facts related to cars, propulsion types, and energy flow.

Coming from the hydrogen fuel cell industry, I’ve had the opportunity to directly compare and contrast some of the major challenges that building and operating both an FCV and BEV present. First, let’s set some clear definitions as to what these acronyms we throw around mean.

FCV (Fuel Cell Vehicle) – Usually fueled by highly compressed hydrogen gas (at 700 bar or 10,000psi), these vehicles use a delicate sandwich of exotic materials such as PTFE membrane, porous carbon, stainless steel, and platinum (known as the fuel cell stack) to produce electricity real-time to drive the wheels and propel the vehicle. Although the high voltage battery pack is much smaller than that of a BEV, these vehicles have all the drivetrain components of a pure electric system in addition to the fuel cell system, which leads to a significantly higher overall cost. The major advantage of an FCV, in addition to those of a traditional electric vehicle, is the rapid refueling rate, which is comparable to the time to fill a gasoline tank – that is, of course, if you are lucky enough to live in one of the few areas with a hydrogen fueling station.

BEV (battery electric vehicle) – All energy is stored on-board in a high-voltage battery pack. Generally consisting of anywhere from 100 to 7,000 individual lithium ion battery cells, these packs contain enough energy to propel a vehicle between 90 to 350 miles on a single charge. Depending on the infrastructure available, this battery pack may be recharged overnight from a standard 120VAC outlet in your garage, or in as little as 30 minutes from a high-current DC source such as a CHAdeMO charge point. Although the “refuel” time is longer with this arrangement, the infrastructure (at least for Level 1 charging) already exists in practically every residential and commercial building.

Both FCVs and BEVs enjoy most of the benefits of an electric vehicle – near silent operation, zero local emissions, and loads of torque at low motor RPM. Aside from initial investment and refueling time, some of the more fundamental differences arise before the energy ever gets to your vehicle’s battery or storage tank. A concept known as Well-To-Wheel efficiency allows us to compare the effectiveness of converting these energy sources from raw materials or renewable phenomena into motive torque turning the wheels of the vehicle.

A Well-To-Wheel energy flow diagram for both an FCV and a BEV looks like the following:

 

At each stage of energy conversion, there are various unavoidable losses governed by the laws of physics. As you can see, the flow of energy from well to wheels of an FCV (indicated by the blue arrows) incurs many conversion losses. The flow of energy of a BEV, such as the Bollinger B1 truck, when operated in a region with high renewable energy content such as New York State, closely resembles the orange path. It is apparent that few conversions take places, resulting in high overall efficiency with energy harnessed from mostly renewable and clean sources.

Although the metrics associated with the losses at each conversion stage are beyond the scope of this post, consider the following: a BEV of similar mass and drag area can travel 2-3 times the distance than an FCV with the same initial energy investment (before conversion losses). For greater detail on this example, check out the following link:

http://insideevs.com/hydrogen-fuel-cell-toyota-mirai-energy-efficiency-compared-to-bevs/

Understanding where the energy to sustain your transportation needs comes from is an important step in deciding which type of vehicle to buy, whether it be ICE (internal combustion engine), BEV, FCV, or some hybrid combination. We at Bollinger Motors believe that the pure battery electric power in our B1 truck provides class-leading performance, while retaining the simplicity and sustainability required for an economic and pleasurable ownership experience.

-John Hutchison