IEEE Energy2030 Atlanta, GA USA 17-18 November, 2008

Green Fleet of Fuel Cell Powered Light Utility Vehicles: An Energy Analysis

William A. Hornfeck Shailesh Shrestha ECE Department ECE Department Lafayette College Lafayette College Easton, PA 18042 Easton, PA 18042 hornfecw@lafayette.edu shresths@lafayette.edu

Abstract – This paper provides insights into the feasibility of clean energy sources for Light Utility Vehicles (LUV’s). First, energy analysis for the fleet of LUV’s for a small college are presented. Secondly, the energy implications for a larger (>100) fleet of LUV’s, and finally for the whole of the United States are presented. The technologies discussed include producing pure hydrogen, leaving no carbon footprint and replacing the internal combustion engine or the battery powered drive system with fuel-cell engines. Except for the clean production of usable amounts of hydrogen, all other processes are developing, but proven technologies. The possibilities of the transition from fossil fuel to hydrogen powered LUV’s is limited by hydrogen production technology and fuel cell costs. These limitations will be addressed. The paper will conclude by analyzing the fossil fuel savings associated with a transition to hydrogen fuel for small, intermediate and large scale fleets of LUV’s.

I. INTRODUCTION

It is well to begin any consideration of the use of fuel cell technology with a comparative energy budget, and the energy budget must consider costs from a number of standpoints. These costs include the presently high cost of fuel cell engines, the comparative costs of fuels, and the cost to the environment.

This paper will begin by developing a detailed energy analysis of the feasibility of converting the Light Utility Vehicle fleet of a small college (Lafayette College) to fuel cell driven systems. There are twelve gasoline-powered light utility vehicles in the Lafayette College fleet and, unless there is a retrofit strategy for vehicle conversion, an unreasonable cost penalty will likely be the result. However, this analysis will serve as the baseline for further analyses.

As a second and more realistic case, the transition of the United States’ golf cart fleet from gasoline/electric-drive vehicles to fuel cell driven systems will be considered. On such a scale, energy savings and environmental benefits could likely outweigh consideration of vehicle costs. This analysis will consider all Light Utility Vehicles at a typical golf facility and the energy implications associated with their conversion to fuel cell drives.

In the final section of the main body of this paper, transitioning the United States fleet of Light Utility Vehicles to Fuel Cell Vehicles will be considered, especially from the standpoint of fossil fuel savings and the subsequent atmospheric advantages. This analysis will take into account

the green production of hydrogen through solar or wind generated power for the electrolysis of water.

II. MOTIVATION

News headlines are dominated by energy issues. It’s telling that energy stories are invariably linked to financial developments, and then to two current prices: yellow gold and black gold – or, oil! The public, worldwide, is being alerted to the competition for petroleum and the need for its derivatives. At the same time, any reasonable alternatives to oil are heralded as (at least part of) the answer to the world’s (and particularly the United States’) dependence on oil. In this climate it’s fair to focus on the ways that we might squander what remains of an extraordinarily useful resource, i.e., the combustion of oil for recreational purposes.

The motivational core of this paper is the author’s interest in energy studies combined with early experience as a golf caddy – put “out of work” by the technical innovation known as the golf cart. In addition to taking away part-time employment opportunities for young workers, these were transportation conveniences used for sporting purposes, and burning fossil fuels for propulsion (either internal combustion engines, or batteries deriving their charge from mostly-coal-based energy off the grid).

If we accept the inevitability of the nearly universal preference to ride rather than walk as a game is played, a rational strategy is to minimize the deleterious effects of the use of vehicular assistance. That is, the depletion of an increasingly scarce resource for nonessential purposes. It was a natural extension of this vehicle type to the general class of light utility vehicles. This opens the way to include somewhat essential vehicles in the target group.

III. ANALYSIS CONSTRAINTS

Predictions of the near-term emergence of a hydrogen

economy in the United States, it is generally acknowledged, have been overstated[1]. Fuel cell applications to stationary power supplies, transportation, and portable power are the three principal areas of research and development in hydrogen technologies. This paper will focus on transportation, and in particular, the application of the Proton-Exchange Membrane Fuel Cell (PEMFC) to light utility vehicles, more commonly referred to as golf carts. The

conclusions drawn in this study could be extended to the class of vehicles known as low speed vehicles (LSV’s). This would include not only golf carts but any motor vehicle other than a motorcycle whose speed attainable in one mile is more than 20 miles per hour but not more than 25 miles per hour. The consideration of the golf cart used for two applications—playing the game of golf or as a neighborhood electric vehicle (NEV)—will allow the analysis to be reasonably bounded and accurate. It should also be noted that the NEV is considered to be an off-road vehicle used primarily in gated communities, an increasingly popular trend[2].

By considering the development of fuel cell powered vehicles for light utility vehicles, or golf carts, this represents a logical stepping stone to more widespread application to standard motor vehicles, or even heavy-duty vehicles. Most analysts agree that significant numbers of standard cars fueled by hydrogen is a prospect for year 2030 and beyond. It seems realistic to concentrate on smaller vehicles as fuel cell technologies and hydrogen infrastructure mature.

The principal roadblocks to a transition to a hydrogen economy are (i) the cost-efficient and clean generation of hydrogen, (ii) the development of a hydrogen storage and distribution infrastructure, and (iii) the cost of fuel cell engines. The paragraphs that follow consider how these three obstacles are addressed in looking at the system aspects of a fuel cell powered fleet of golf carts.

This study has the additional motivation that the elimination of fossil fuel combustion for purposes of recreational or nonessential transportation should be given highest priority when considering the conservation of fossil resources and the reduction of greenhouse gases.

IV. SYSTEM CONFIGURATION

This study will be based on several assumptions regarding

the system aspects of a fuel cell powered fleet of light utility vehicles. Most importantly, an environmentally green fleet of vehicles is the overall objective. This leads to the need to produce hydrogen using a renewable, clean source for power, and electrolysis of water as the source of pure hydrogen. Wind turbine generators, a reasonably mature and fast growing technology, will be assumed for the power source.

A critical assumption for hydrogen generation is that the fuel will be locally produced. This implies that hydrogen distribution costs and associated efficiency penalties are not incurred. This assumption also considers the increasing tendency away from central coal-powered electric generating stations toward localized renewable energy sources. This analysis assumes wind generation of electrical power, although different regions of the country would be better served through either a wind-solar generation system or totally solar generation.

Proton Exchange Membrane (PEM) fuel cells are a reasonable choice for transportation applications and this fuel cell type uses pure hydrogen in the fuel cell reactor. Air is a suitable oxidant. The system architecture includes a wind

turbine, electrolysis facility, hydrogen storage, fuel cell engine, and electric drive train.

The PEM fuel cells have the advantages of quiet operation, low emissions, high efficiency, and synergy with automotive research and development. Principal disadvantages are high cost, limited field testing, and limited cogeneration potential. Throughout the world, there are more than forty companies involved in the development of PEM fuel cell systems.

V. SMALL COLLEGE ANALYSIS

The energy analysis begins with an enterprise having

fewer than twenty light utility vehicles. Lafayette College in Easton, Pennsylvania, is a Liberal Arts College with Engineering with roughly 2,250 students, 190 faculty, and 300 additional employees. The college makes use of twelve gasoline-powered light utility vehicles. Each of these vehicles weighs approximately 600 lbs. and is rated at an average peak power of 12 horsepower. This represents roughly one-fifth the weight of a small car and one-twentieth the horsepower. Energy requirements will be correspondingly lower than for a standard size car. For a gasoline-powered vehicle model that is capable of delivering 100KW of peak power (135 hp) and driving approximately 300 miles, 60KWhr total energy is delivered to the wheels[3]. Scaling these numbers to light utility vehicles, it is estimated that 6KWhr is delivered to the golf cart wheels for approximately 100 miles distance. Using 36KWhr per gallon of gasoline, 6 gallons of gasoline would be required for every three-hundred miles of operation. If one cart requires twenty-six refills in a year (one refill per six week period), each cart would require 52 gallons of gasoline. For a fleet of twelve utility carts, 624 gallons of gasoline would be required in one year. If the energy for these twelve units were to be generated by means of wind energy, then 36 * 624KWhr = 22,464KWhr/yr of energy is needed at the wheels of the fleet. Considering the following efficiencies,

Electrolysis of water = 72% efficient Hydrogen storage and Fuel Cell = 54% efficient Electric drive train = 89% efficient Total = 35% efficient,

The wind energy renewable source would need to generate approximately 64,000KWhr per year. This energy could be produced by a 10KW wind turbine. The cost would be approximately $40K for an 80 ft. wind turbine. The payback time for the wind turbine would be 16-20 years. This payback time would not include the higher cost of a fuel-cell-powered cart, which would be approximately $20,000. Except for experimental or educational applications, the cost of converting a Lafayette College-sized enterprise to fuel-cell-powered utility vehicles would be prohibitive. However, the assumption of a hydrogen delivery infrastructure providing fuel at a price competitive with gasoline, could prove feasible when savings in carbon emissions are also considered.

VI. LARGER ENTERPRISE ANALYSIS

When a larger facility, such as a golf course having 3hp

electric golf carts numbering approximately one-hundred is considered, the following analysis applies. Golf carts are charged daily for four hours using the electric grid. Chargers operate at 48 volts and 17 amps, or 0.816KW, yielding 3.26KWhr/charge. Daily charge cycles would require 3.26 * 365 * 100 equals approximately 120,000KWhr/yr for charging of the fleet.

Using 36 KWhr/gallon of gasoline, this would be the energy equivalent of approximately 3,300 gallons of gasoline. At $3-$4 per gallon, the cost of this energy is approximately $12K. At $0.07 per KWhr, the cost of the electrical energy is approximately $8.4K.

Now considering the generation of hydrogen for this fleet, each golf cart traveling 300 miles and using approximately one Kilogram of hydrogen would require 33KWhr to generate hydrogen. The average golf cart may travel an average of approximately 2,500 miles per year. A fleet of 100 carts would then require 1KgH2 * 2,500/300 * 33KWhr/KgH2 * 100 = 27,500 KWhr/yr. At an efficiency of 35% for the fuel-cell system, approximately 80,000 KWhr per year of wind energy production would be required. This energy could be produced by a 10KW wind turbine. The cost of $40K for a 10KW wind turbine now begins to realize a 5-6 year payback time for energy costs. The cost of the fuel-cell-powered carts would of course be critical to feasibility.

VII. NATIONWIDE ANALYSIS

There are approximately 16,000 18-hole-equivalent golf

courses in the United States. These are categorized as public, private, semi-private, resort and military courses. In order to estimate the energy requirements of all golf courses, it will be helpful to consider that courses employ exclusively gasoline-powered carts, then exclusively electric carts, and finally a fleet of fuel-cell-powered carts.

Each 18-hole golf course has an inventory of approximately 75 golf carts. The United States population of golf carts is therefore approximately 1.2 x 106 carts. From our earlier analysis, each cart requires approximately 52 gallons of gasoline per year. Nationwide, the 1.2 million carts would burn 62.4 million gallons of gasoline in one year. Because each gallon of gasoline burned produces 19 lbs of carbon dioxide, the 62.4 million gallons of gasoline weighs 374.4 million lbs and would produce approximately 1.2 billion lbs of carbon dioxide which acts as a greenhouse gas.

Now consider that the 1.2 x 106 carts are electric-powered carts. Our previous analysis indicated that one-hundred golf carts require 120,000KWhr of electrical energy per year for charging the fleet. Therefore the nationwide fleet of 1.2 x 106 carts would require 1.44 billion KWhr/yr.

Because electricity from coal produces carbon dioxide at a rate of about 2 lb/KWhr, the charging of the nation’s

exclusively electric golf cart fleet would produce 2.88 billion lbs of carbon dioxide, from the burning of 1.58 billion lbs of coal.

It was pointed out earlier that a fleet of 100 fuel-cell-powered golf carts would require 27,500KWhr/yr of hydrogen energy and approximately 80,000KWhr per year of wind energy. A nationwide fleet of 1.2 million golf carts would therefore require approximately 960 million KWhr/yr of wind energy.

This energy could be generated by 1100 100-KW windmills. Considering the varying levels of wind intensity across the USA, each 100KW windmill (or equivalent solar-wind, or solar) installation could service approximately ten golf courses with hydrogen to operate their fleet of fuel-cell-powered golf carts.

VIII. CONCLUSION

It appears feasible that the nation could benefit from the

use of renewable resources for generating hydrogen to power the country’s fleet of light utility vehicles that are used at golf courses. Although the economics would indicate further investigation of a green fleet of light utility vehicles, the critical cost component is the cost of the fuel cell engine in such a fleet. The cost of a fuel-cell-powered golf cart could be as much as 15-20 times the cost of an electric cart. If, over the next decade, this cost could be reduced to 4-5 times the cost of an electric cart (with accompanying reductions in wind energy cost), a widespread conversion to hydrogen for this class of vehicles could be possible by 2030.

The analysis in this paper could be extended to other light vehicles, e.g., utility carts, forklifts, personal watercraft, and other conveyances. It has been assumed for this paper that no large-scale hydrogen distribution grid is necessarily essential to the realization of the hydrogen-based green fleet of utility vehicles. It should be pointed out, however, that costs of hydrogen storage and distribution would be significant.

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[10] B. S. Ferretti, Director/Physical Planning, Plant Operations, conversation, Lafayette College, Easton, PA, March, 2008.