The Case for Natural Gas Fueled Solid Oxide Fuel Cell Power Systems for Distributed Generation

Abstract

Natural‐gas‐fueled solid oxide fuel cell (NGSOFC) power systems yield electrical conversion efficiencies exceeding 55% and may become a viable alternative for distributed generation (DG) if stack life and manufacturing economies of scale can be realized. Currently, stacks last approximately 2 years and few systems are produced each year because of the relatively high cost of electricity from the systems. PNNL has performed cost modeling for production of 270 kW (DC) NGSOFC power systems, sized for light industry or large box stores. If mass manufacturing (10.000 units per year) and a stack life of 15 years can be reached, the cost of electricity from an NGSOFC system is estimated to be about 8,2 ¢/kWh, well within the range of commercial and residential retail prices at the national level (9,9–10 ¢/kWh and 11–12 ¢/kWh, respectively). With 5 ¢/kWh in estimated additional benefits from DG, NGSOFC could be well positioned to replace the forecasted 59–77 gigawatts of capacity loss resulting from coal plant closures due to stricter emissions regulations and low natural gas prices.

Cost Study for Manufacturing of Solid Oxide Fuel Cell Power Systems

“…Clearly when annual production is small and stack life is short, the stack replacement costs make NGSOFC infeasible even for distributed generation because even with the potential benefits of distributed generation, the net cost of power is greater than the national average retail price of electricity for commercial and residential level customers, 9.9-10¢/kWh and 11-12 ¢/kWh, respectively [EIA 2013] (see Figure 13). The LCOE at 250 units per year and stack life of 6-8 years is in the range where the net costs of the NGSOFC including the benefits of distributed generation might make the system economically feasible (see Chick et al 2013. ).…”

On governing equations and closure relations for the multiscale modeling of concentration polarization in solid-oxide fuel cells: mass transfer and concentration-induced voltage losses.

“…This is especially true when SOFC systems rely on CHP (i.e., bottoming-cycle with conventional thermal engines). In the foreseeable future, SOFCs might find particular application in the niche market of stationary, distributed power generation [ 10] , and perhaps also as a promising energy storage technology through use of the so-called reversible SOFCs [ 11] , when they are applied as solidoxide electrolyzer cells (SOECs) to produce hydrogen gas. However, thus far there are still significant technical challenges inhibiting the full commercialization and wide-scale rollout of SOFC technology.…”

“…All these tubes must be sealed hermetically against the PEN disc before the assembly is positioned within the furnace. Reducing and oxidizing gases are supplied to either side (anode and cathode sides, respectively) of the PEN via much thinner inner feeding tubes 10 . For example, in Fig.…”

“…Finally, to end this section, attention is driven to one of the more commonly implied As noted in § §2.3.2, in typical high-temperature SOFCs the electrolyte-phase conductivity is several orders of magnitude lower than the electrode-phase conductivity 10 .…”

“…This pressure rise results in a pressure gradient in the -direction which causes the spreading of the flow in the -direction at the anode edges. 10 Darcy equation cannot handle correctly situations in which Stefan velocities at wall are (substantially) different from those existing in the "bulk" of the homogenized porous medium. The same is true if "diffusion slip" phenomenon occurs in a significant way [ 197,196,195] .…”