Grantee Research Project Results

Final Report: "H2 v. BE": A Case Study of the Reliability, Cost, and Environmental Sustainability of Hydrogen Fuel Cell Hybrids vs. Battery Electrics for Near Urban Personal Transportation

EPA Grant Number: SU834698
Title: "H2 v. BE": A Case Study of the Reliability, Cost, and Environmental Sustainability of Hydrogen Fuel Cell Hybrids vs. Battery Electrics for Near Urban Personal Transportation
Investigators: Frymier, Paul , Counce, Robert , Irick, David , Tolbert, Leon , Cherry, Christopher , Ansink, Theodore , Atchley, Matthew , Browning, Virginia , Cao, Yue , Everett, Michelle , Hall Jr., James , Henson, Ray , Ng, Eugene , Pickelsimer, Michael , Ridenour, Justin , Teeters, Scott , Wilson, James
Institution: University of Tennessee
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2010 through August 14, 2011
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2010) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities

Objective:

The goal of this P3 project was to test three hypotheses:  1) there exists a vehicle or class of vehicles that can be effectively used to replace a car for near-urban commuting and short range transportation in cities of similar population, topology and traffic volume as Knoxville, TN with significantly less environmental impact than a typical automobile,  2) this vehicle has the appropriate capacity, convenience, and comfort such that people who are not likely to use other forms of alternate transportation will adopt it, and  3) between a fuel cell hybrid and fully battery electric, one of the two designs will prove to be more effective at satisfying our criteria for low environmental impact with appropriate capacity, convenience, and comfort.

 A three-wheeled plug-in battery electric vehicle (BEV) was constructed and comprehensively road tested.   The fuel cell hybrid equivalent was designed and is currently awaiting installation of an appropriate fuel cell. The overall sustainability of these two vehicles (BugE^® BEV and BugE^® H₂) is compared to that of the best selling passenger car, the Toyota Camry, and a smart fortwo^® (intentional non-capitalization).  This study analyzes the environmental, social, and economic sustainability of the four vehicles, and was conducted to examine the sustainability of the typical commuting options used for individuals currently commuting in near-urban environments as single passengers in an average passenger car.  A public survey of consumer vehicle preferences was created and distributed.  We defined “nearurban” as a driving distance of less than 15 miles, one way.  Also, these near-urban commuters must have available to them an appropriate route that does not require interstate travel (meaning: a route exists with posted speeds 45 mph or less) although the commuter may currently use the interstate to commute.

Summary/Accomplishments (Outputs/Outcomes):

Construction: There proved to be difficulties in purchasing the fuel cell.  Once those details were ironed out, Heliocentris had problems with quality control in a vendor-supplied part and the team’s order was delayed by months.  Due to this, only the BugE^® BEV was completed before the time of the competition.  The first change made to the original plan was the motor.  The diameter of the 7 hp motor that was initially chosen was too large and a 36V brushed motor was chosen.  The ME team ran stress simulations on the motor mount, and found that a gusset was needed to limit flexing of the motor mount.  A chain tensioning device for the rear wheel was also added.  These were fabricated and welded to the frame.  Some students found that the transition from modeling and planning to construction was difficult, and in fact felt so out of place they chose not to continue with hands-on work.  Other students found that the hands-on work brought all the fundamentals together and gave them a sense of confidence in their engineering abilities.

Results: The construction phase ended as the car rolled out of the garage on February 8 for its first test run, which was highly successful.  The students took turns driving the car every morning and every evening for two weeks.  The goal was to drive it from 10 – 15 miles oneway, each morning and evening, as if it were being used in a daily commute and to record data containing various information on distance, current, and voltage. There were two courses used; one had little elevation change, where the other had a sizeable grade.  A Grin Cyclery (Vancouver, B.C.) Cycle Analyst^® and Analogger^® were used to record real-time data on the energy system and car performance and a Watts Up meter was used to find the power pulled from the wall to recharge the battery. With this information the exact power needs of the car were determined.

In order to address the second goal of capacity, convenience, and comfort, the drivers were polled.  All agreed that the capacity was sufficient for a quick trip past the grocery on an average commuting day.  There is a small trunk in the front of the BugE^® appropriate for two average size grocery bags.  It was also suggested that there is room behind the driver to add motorcycle type saddlebags for more storage.  The BugE^® convenience was rated higher than that of both bicycles and motorcycles based on inclement weather gear required for the later.  The windshield offers protection from the wind and rain.  In the cold weather, it was noticed that only the hands need significant extra protection.  The driver’s felt they didn’t need to wear any more layers on their bodies than they already did for winter.  As for comfort, the same can be said; a BugE^® is more comfortable, due to weather protection, than a bicycle or motorcycle.  The average passenger car was considered more convenient, capable, and comfortable, but the goal aimed for appropriate levels of these, which all drivers agreed were met by the BugE^®.  The BugE was driven in temperatures from 22°F to 66°F, and all conditions including rain and dark.

Sustainability Analysis: After the actual driving data was gathered, the following comparisons could be made.  Each of the following sections ranks the cars from most to least sustainable. The emissions reported are from the full life of the energy source.  The yearly numbers are based on 7800 miles traveled per year (30 miles/day, 5 days/week, 52 weeks/year).  The gas price used for the Camry is $3.23 per gallon (Knoxville average of regular at time of report).  The smart car requires premium, which is $3.54 per gallon.  The cost for electricity in Knoxville is $0.087 per kW and the mix is 62% coal, 28% nuclear, and 10% hydroelectric.  The miles per gallon equivalent (MPGe) for BugE^® BEV and BugE^® H₂ are based on 33.7 kWh per gallon of gasoline, which is the number used by the US EPA.  The average price for H₂ is based on $2.47 per MPGe from Holston Gases in Knoxville.  The survey data mentioned in the write up comes from 310 respondents. 

Environmental Sustainability: The four vehicles were compared based on air emissions (including the production of the fuel) and natural resource use.  The BugE^® H₂ has the advantage since fuel cells generate zero tailpipe emissions.  Even though hydrogen is produced by steam reformation of methane, the BugE^® H₂ requires little energy compared to the average car.  For the same miles traveled the Camry, smart fortwo^®, BugE^® BEV, and BugE^® H₂ attribute 7.2, 5.2, 0.309, and 0.287 tons of CO₂ emissions per year. In Knoxville, based on 113,520 commuters totals for each vehicle of 817 kton, 590 kton, 35 kton, 33 kton a year are emitted.  By switching from a Camry to the BugE^® H₂ 784 kton of CO₂ reduction would occur.  Switching to BugE^® BEV, would save 782 kton of CO₂.  Likewise a switch to the BugE^® H₂ from the Camry would reduce NO_x by 1.4 kton per year.  This is a very important number because it is directly related to smog, and currently Knoxville is in nonattainment for 8 hour ozone.  Emissions for electric vehicles fall short for methane.  In this study the BugE^® BEV produces 2600 times more than the gasoline car, although the total emission of methane is relatively low in either case.  For overall air emissions from best to worst, the cars rank BugE^® H_2, BugE^® BEV, smart fortwo^®, and Camry.

For a primary energy source, the Camry and smart fortwo^® use gasoline, the BugE^® BEV uses some coal, and the BugE^® H₂ uses hydrogen, none of which are renewable resources (at this point).  Both oil and coal are produced by millions of years of organic decay differing in result by pressure and temperature conditions.  It will never be replaced faster than the rate at which it is being used.  Hydrogen is currently manufactured industrially through steam reformation of hydrocarbons, primarily methane.  There is, however, a lot of research taking place that could make renewable hydrogen cost effective.  The impetus for this would increase with market demand for hydrogen.  The standard used thus far in this reporting has been based on current prices and technologies.  Due to that, the efficiency of the motors and MPG ratings put the BugE^® BEV on top for the least amount of natural resources used.  The cars rank, in order from least to most natural resource usage, BugE^® BEV_, BugE^® H₂, smart fortwo^®, and Camry.

It is not the intent of this report to imply that coal is a cleaner burning fuel than gasoline.  The intent is to show that a reduction in vehicle weight saves energy, and the 64% efficiency of an electric car (grid to wheels) helps to better utilize energy, therefore using less than the 34% efficient (service station to wheels) ICE powered car.  However, it should be noted that electricity is becoming greener and the EPA has time sensitive goals for power plants to meet.  As sources for renewable energy become more cost effective, and standards for flue gas emissions become more stringent, electricity will become cleaner.  Further, based on the Sanyo residential solar panel technology, the BugE^® BEV could be charged completely grid free from six 1.2 m² panels.  This would easily fit on less than 10% of the southern facing half of an average US home.

Economic Sustainability: The vehicles were compared based on purchase price, annual maintenance, and fuel cost.  The BugE^® BEV saves $1080 per year in fuel costs over the Camry, but this will likely increase.  Gasoline prices have steadily increased from $1.19/gal to $3.57/gal from 1990 to 2011.  The savings in fuel and annual maintenance is $1175 per year. 

The team sees this vehicle as a secondary vehicle.  In this capacity, the BugE^® BEV would pay for itself in 6 years.  It could also take the place of one car in a two-car household, saving additional costs of around $13,000.  In the survey conducted by the sustainability team, 45% of respondents ranked initial purchase price as the #1 most important factor when buying a commuting car, and 68% ranked daily cost to operate in the top three.  The smart fortwo^® claims to be the most affordable car on the market right now, and that appears to be the case.  When ranking the cars from lowest to highest direct cost, they rank BugE^® BEV, smart fortwo^®, BugE^® H₂, and Camry. 

Social Sustainability: A study conducted in San José, CA concluded that low-income families have to actively and strategically manage their transportation costs concerning small changes in their income.  Often better transportation options open up more job opportunities, which could help to stabilize such incomes.  Some interviewees said they were willing to pay higher transport cost with the hope of improved income.  The BugE^® BEV offers this.  The upfront cost is less than buying a car, and the annual maintenance and fuel costs are 5 times less.  This type of low weight, low energy vehicle would promote social equity.

One concern of many in purchasing a lightweight vehicle is safety.  The 2011 Camry comes equipped with 7 air bags, vehicle stability control, traction control, and electronic brake force distribution.  None of which is offered in BugE^® BEV or H₂. Important to note, though, the Insurance Institute for Highway Safety (IIHS) has given the Camry the best rating, “Good,” in the ability to keep the passenger cabin intact in the event of a roll over. The smart fortwo^® has a tridion safety cell, which is the silver C-shape that can be seen on the exterior design. It is designed to distribute the impact of a crash around the whole car's body, and therefore protects the passengers. The rear-mounted engine breaks away and slides underneath the passenger compartment in the event of a rear impact. This dissipates the collision energy and reduces rebound shock.  The IIHS also rated smart fortwo^® a “Good” for impact safety.  It has four airbags and traction stability measures. These impact ratings cannot be directly compared, since neither the BugE^® BEV nor H₂ has been tested in that way.  What can be said is the cabin does not offer protection from side impact or roll over. However, the low speeds of city driving do not offer much opportunity for roll over accidents. We note that for the BugE^® H2, there is also the added negative public perception of driving with compressed H₂ cylinders.  

As for the perception of safety, there is not a metric that can be directly derived from personal opinion.  In our own survey, only 20% ranked safety #1 for importance on purchase, but 62% ranked it in the top three.  The Camry received an average 2.3 (1 was very safe; 7 was very unsafe), and 29% scored it as a 1.  The smart fortwo^® received an average of 4.4, and 2% scored it as a 1.  The BugE^® received an average of 4.6, and 5% scored it as a 1.  The ranking for safety measures and perception, from most safe to least, is Camry, smart fortwo^®, BugE^® BEV, BugE^® H₂. 

The two previously mentioned high rankings of the BugE^® BEV and H₂ in economic and environmental impacts also apply to the social dimension. There is more coal domestically than oil; in fact the US reserves have more total energy content than all of the world’s recoverable oil.  The governmental push to electrify the US fleet can arguably be directly related to this fact.  Reducing oil consumption directly reduces the US dependence on resources from politically unstable foreign countries.  This is a significant improvement in the socio-political impact of these vehicles with 17% of oil imports coming from the Persian Gulf and 10.7% coming from Venezuela.  Likewise, reducing emissions by such a large margin improves the health of the nation.  In a London, UK study, it was predicted that reducing CO₂ emissions from urban transport by 35% would save 160 disability-adjusted life years (DALYs) and 17 premature deaths per million population per year.  In Knoxville, that would equate to saving 32 DALYs and 3.4 premature deaths per year.

Conclusions:

Of the four cars compared, the BugE^® BEV appears to have the best balance of reducing emissions and saving money while still getting people to work.  The team realizes that there are a number of weighted variable models that can be employed to determine a best option from the sustainability analysis.  Since sustainability metrics are still an active area of development and study, a significant amount of speculation and justification must go into these models.  At this time the team has chosen to assess the findings with their best objectivity in order to declare the best choice.  The important thing to note is that all goals of the project were met, and the team successfully completed undertaking this challenging task in such a short amount of time.

Supplemental Keywords:

Hydrogen, battery electric vehicles, fuel cell hybrid, emissions