Final Report: Mass Production Cost Estimation of Direct H2 PEM Fuel Cell Systems for Transportation Applications (2012-2016)

456

367

This study provides an analysis of the technological barriers for all-electric vehicles, either based on batteries (BEVs) or on H 2 -powered proton exchange membrane (PEM) fuel cells (FCEVs). After an initial comparison of the two technologies, we examine the likely limits for lithium ion batteries for BEV applications, and compare the projected cell-and system-level energy densities with those which could be expected from lithium-air and lithium-sulfur batteries. Subsequently, we will review the current development status of H 2 PEM fuel cells, with particular attention to their viability with regards to the required amount of platinum and the resulting cost and availability constraints. It is widely accepted that global warming is caused by CO 2 emissions and that they must be substantially reduced in order to prevent climate change. Since ≈23% of the world-wide CO 2 emissions are due to transportation, ≈75% of which are contributed by the road sector (numbers from 2012 1 ), a reduction of CO 2 emissions from vehicles is imperative to combat global warming. Towards this goal, many countries have passed legislature to lower passenger vehicle emissions over the long term like, e.g., the European Union mandate for 95 g CO2 /km fleet average emissions by 2020.2 The analysis by Eberle et al. 3 in Figure 1 suggests that this rather ambitious goal can only be met by means of extended range electric vehicles or all-electric vehicles in combination with the integration of renewable energy (e.g., wind and solar). Without increased integration of renewable energy sources and basing the calculations on the current European electricity generation mix, the only vehicle concept which could meet the 95 g CO2 /km target are pure battery electric vehicles (BEV100 in Fig. 1). However, for electricity produced entirely by renewable energy sources, the 95 g CO2 /km target could also be met by extended range electric vehicles with 40 miles all-electric range (E-REV40 in Fig. 1), if 50% of driving is powered by the battery (i.e., the average driving range would have to be below 80 miles), or by fuel cell electric vehicles (FECVs), with hydrogen produced by water electrolysis. While these propulsion concepts look promising, their contribution to CO 2 emission savings in the transportation sector would only be meaningful if their market penetration were substantial. In the absence of government regulations, the latter largely hinges on consumer acceptance, which in turn strongly depends on cost. In addition, in the case of BEVs, recent studies clearly showed that BEV driving range (closely followed by cost) are the predominant variables determining consumer acceptance. 4 In the following we will thus focus on the two vehicle types, which would be capable to meet and exceed the CO 2 emission targets of 95 g CO2 /km on the long-term, viz., pure BEVs and hydrogen powered FCEVs. For both vehicle types, but particularly for the latter, meaningful CO 2 emission reductions require the predominant use of renewable energy, which in turn necess...

Section: Hydrogen Fuel Cells -Materials Requirements and Durabilitymentioning

confidence: 99%

Section: Hydrogen Fuel Cells -Materials Requirements and Durabilitymentioning

confidence: 99%

Review—Electromobility: Batteries or Fuel Cells?

Gröger

Gasteiger

Suchsland³

2015

456

367

“…Equation 13 can be used to link ex-situ diffusion measurements to in-situ crossover, thereby negating the need to execute a series of experiments to study the effect of current density on crossover. An all-vanadium flow battery provides a concrete example of how to apply this criterion.…”

Section: Journal Of the Electrochemical Society 163 (1) A5029-a5040 mentioning

confidence: 99%

“…11 Techno-economic modeling for PEFCs projects that a substantial increase in production would result in an order-of-magnitude reduction in price. [12][13][14] Thus, reliance on membranes like Nafion should not present an insurmountable barrier to achieving future cost goals. However, moderate-to-high specific cost will be required in the mid-term to cover costs associated with scaling production if market demand rises.…”

mentioning

confidence: 99%

Transport Property Requirements for Flow Battery Separators

Darling

Gallagher

Xie

et al. 2015

127

152

Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been reported in a general manner that enables quantitative evaluation of new systems such as nonaqueous flow batteries. This gap is addressed by deriving specifications for transport properties that are chemistry agnostic and align with aggressive capital cost targets. Three key transport characteristics are identified: area-specific resistance R , crossover current density i x , and the coupling between crossover and capacity loss . Suggested maximum area-specific resistances are 0.29 and 2.3 · cm 2 for aqueous and nonaqueous batteries, respectively. Allowable crossover rates are derived by considering the possible fates of active molecules that cross the separator and the coupling between Coulombic efficiency (CE) and capacity decline. The CE must exceed 99.992% when active species are unstable at the opposing electrode, while a CE of 97% can be tolerated when active molecules can be recovered from the opposing electrode. The contributions of diffusion, migration, and convection are discussed, quantified, and related to the physical properties of the separator and the active materials. Energy storage can mitigate electrical transmission bottlenecks and provide ancillary services in addition to supplying stable and continuous power when coupled to inherently variable renewable energy sources or placed in remote regions or districts with unreliable grids.1-4 Redox flow batteries (RFBs) are a class of electrochemical devices that are suitable for storing energy for multiple hours as described in several recent review articles.3,5-8 In a flow battery, the reactants or active materials are stored in external tanks separate from the reactor, enabling independent scaling of energy and power. This segregation permits cost effective implementation of electrochemical couples with low energy density. The reactants are commonly ions dissolved in an electrolyte at concentrations near 1 mol/L. A conventional battery like lead acid or lithium ion utilizing active materials with such low volumetric capacity would incur tremendous cost, mass, and volume penalties because the amount of inactive material, principally current collectors and separators, scales with volumetric capacity in enclosed architectures.9 Appropriately designed flow batteries optimize the power density of the reactor, consequently minimizing the contributions of separators and current collectors to total system cost.The primary functions of a separator are to prevent shorting of the electrodes while allowing ionic charge carriers to move freely. 10Any material that fulfills these basic functions is referred to as a separator in this work. The term membrane is reserved for a separator that selectively favors transport of a desired charge carrier, like protons, and thwart...

“…[1][2][3][4][5][6][7][8][9][10][11][12] Present-day requirements for durability limit the performance loss to 80 mV over required lifetimes of 5000 hours. Since potential cycling, start/stop, and idling conditions contribute to these performance losses, 11,[13][14][15] the tolerance for losses due to contamination is much smaller than 80 mV.…”

mentioning

confidence: 99%

Understanding the Effects of PEMFC Contamination from Balance of Plant Assembly Aids Materials: In Situ Studies

Opu

Bender

Macomber

et al. 2015

In situ performance data were measured to assess the degree of contamination from leachates of five families of balance of plant (BOP) materials (i.e., 2-part adhesive, grease, thread lock/seal, silicone adhesive/seal and urethane adhesive/seal) broadly classified as assembly aids that may be used as adhesives and lubricants in polymer electrolyte membrane fuel cell (PEMFC) systems. Leachate solutions, derived from soaking the materials in deionized (DI) water at elevated temperature, were infused into the fuel cell to determine the effect of the leachates on fuel cell performance. During the contamination phase of the experiments, leachate solution was introduced through a nebulizer into the cathode feed stream of a 50 cm 2 PEMFC operating at 0.2 A/cm 2 at 80 • C and 32%RH. Voltage loss and high frequency resistance (HFR) were measured as a function of time and electrochemical surface area (ECA) before and after contamination were compared. Two procedures of recovery, one self-induced recovery with DI water and one driven recovery through cyclic voltammetry (CV) were investigated. Performance results measured before and after contamination and after CV recovery are compared and discussed. While the energy conversion efficiency of proton exchange membrane fuel cell (PEMFC) systems is relatively high, economical applications have been limited due to initial stack costs and the degradation of performance over time which can be affected by contaminants that enter the system with the air or fuel feed stream, or component materials of construction leaching into the gas/water stream.1-12 Present-day requirements for durability limit the performance loss to 80 mV over required lifetimes of 5000 hours. Since potential cycling, start/stop, and idling conditions contribute to these performance losses, 11,[13][14][15] the tolerance for losses due to contamination is much smaller than 80 mV. In addition, with the recent reduction in cost related to the fuel cell stack, the relative cost of balance of plant has risen. This presents the opportunity to further reduce overall system cost by choosing functional, low cost BOP materials for PEMFC systems. Educated selection of BOP materials requires a level of understanding of potential contaminants from system components that does not currently exist in the literature. Chemically inert and low cost materials with low amounts of total and non-reactive leachates would be the most desirable materials for fuel cell applications.16 This paper focuses on the effect of leachates from system components on fuel cell performance and seeks to add to the limited knowledge base discussing PEMFC contaminants from system components. 2,3,5,[7][8][9]12,[17][18][19][20][21][22][23][24] Here we describe (1) a protocol to create leachate solutions from BOP materials, (2) ex situ quantification and speciation of the components present in the BOP leachate solutions, (3) in situ quantification of performance effect due to the leachate solutions and, (4) an attempt to correlate ex situ with in situ resu...