The following describes the results of the Base Case analysis, which uses all of the assumptions noted in Section 1. All input and output sheets from the base case analysis are included in Appendix A.
Per Bus Costs:
The base case analysis shows that first-year annual operating costs for Diesel buses will range from $167,000 to $190,000 per bus, with an average of $178,988. Costs for Diesel Hybrid buses will be marginally lower (-3%), and costs for CNG buses will be marginally higher (+9%). The analysis shows that annual costs for Fuel Cell buses will average $269,832/bus (+62% compared to diesel) and annual costs for Fuel Cell Hybrid buses will average $227,601 (+36%).
Increased fuel costs account for the majority of the increase in annual costs with Fuel Cell buses compared to Diesel buses. Fuel Cell Hybrid buses have much lower annual operating costs than Fuel Cell buses due to a significant savings in fuel use and fuel costs. The Base Case results for first year annual costs are summarized in Table 12.
The base case analysis shows that first-year technology-specific annual operating costs for a 100-bus depot housing Diesel buses will be $14,000. Costs will increase to $24,250 if Diesel Hybrid buses will be assigned there, due to an increase in annual training costs. CNG buses will incur additional training costs as well as additional costs for fuel station O&M and incremental depot systems O&M, so that total costs will be $136,750. Depot costs for Fuel Cell buses will total $330,500 and for Fuel Cell Hybrid buses 211,500, due to even higher fuel station and incremental depot systems O&M costs. Costs are lower for Fuel Cell Hybrid buses due to fact that the required hydrogen fuel station will be smaller and less expensive, and will therefore have lower annual O&M costs.
The Base Case results for first year annual depot costs are summarized in Table 13.
The base case analysis shows that capital costs to purchase a 100-bus Diesel fleet and make technology-specific infrastructure investments total $32.93 million. With an 80% federal cost share this will require $6.59 million in local capital funds. Capital costs for the purchase of 100 CNG buses and necessary infrastructure total $40 million (+21%), while they total $50.5 million (+51%) for Diesel Hybrid buses.
The purchase of 100 Fuel Cell buses and necessary infrastructure will cost $326.2 million, almost ten times more than the purchase of Diesel buses, and will require over $65 million in local capital funding. The purchase of 100 Fuel Cell Hybrid buses and necessary infrastructure will cost several million dollars less because the required hydrogen fuel station can be smaller and therefore less expensive.
The equivalent annualized cost for this amount of capital spending is $3.71 million for Diesel buses, $4.44 million for CNG buses, $5.69 million for Diesel Hybrid buses, $36.61 million for Fuel Cell buses and $36.41 million for Fuel Cell Hybrid buses. This figure takes into account the fact that infrastructure investments have a longer useful life (20 years) than buses (12 years).
The Base Case results for total life-time overhaul costs are summarized in Table 16. Overhauls for diesel and CNG buses include one base bus and one engine overhaul (in years seven and eight, respectively) and three transmission overhauls (in years four, seven, and ten). Hybrid bus overhauls include a base bus overhaul, drive system overhaul, and battery replacement in year seven and an engine overhaul in year nine. Both Fuel Cell and Fuel Cell Hybrid overhauls include fuel cell stack replacement in years four and eight, and a base bus and drive system overhaul in year seven. Fuel Cell Hybrid also includes a hybrid battery replacement in year seven.
As shown in Table 16 total overhaul costs are marginally higher for Hybrid and CNG buses than for Diesel buses. Overhaul costs for Fuel Cell and Fuel Cell Hybrid buses are approximately three times higher than for diesel buses.
The total life cycle costs of the various bus/technology types analyzed are summarized in Figures 1 5. Figure 1 shows total life cycle costs per bus (net present value) for each bus/technology type, while Figure 2 shows the local life cycle costs per bus. The difference between these two figures is that local costs in Figure 2 do not include the portion of capital costs paid by the federal government.
Figure 3 shows the average total annual costs per bus (in current dollars). Figure 4 shows average total life cycle costs per mile (in current dollars) and Figure 5 shows the average local life cycle costs per mile (in current dollars). Figures 4 and 5 also includes error bars' showing the range of costs projected by the life cycle cost model based on the high and low values input for each cost assumption.
As shown in Figure 1 Diesel, Diesel Hybrid, and CNG buses have similar total life cycle costs of $2.2 million, $2.3 million, and $2.3 million per bus, respectively. Life time Fuel Cell bus costs are almost three times higher at $6.2 million per bus. Life time Fuel Cell Hybrid bus costs are slightly lower at $5.8 million per bus.
As shown, the single biggest contributor to the increased life cycle costs for Fuel Cell and Fuel Cell Hybrid buses is the increased capital cost to purchase buses and install necessary infrastructure. However, all cost elements other than operator labor costs are significantly higher for fuel cell buses than for the other bus types, including life time overhaul costs (~3x higher), annual maintenance costs (~2 x higher), and fuel costs (~3x higher for Fuel Cell and ~2x higher for Fuel Cell Hybrid).
As shown in Figure 2, if only locally paid costs are included (not including the portion of capital costs paid with federal funds), life cycle costs per bus fall to $1.9 million for Diesel and Diesel Hybrid buses, $2.0 million for CNG buses, $3.6 million for Fuel Cell buses, $3.2 million for Fuel Cell Hybrid buses.
As shown in Figure 3 average annual costs for Diesel, CNG, and Diesel Hybrid buses are approximately $200,000 per bus, while they are approximately $514,000 per bus for Fuel Cell buses and $479,000 for Fuel Cell Hybrid buses.
As shown in Figure 4 total per mile costs for Diesel buses range from $5.28 to $5.89, with an average of $5.58 per mile. CNG bus costs average $5.87/mile (+5%) and Diesel Hybrid costs average $5.90/mile (+5%). Fuel Cell bus costs range from $14.97 to $16.59/mile, with an average of $15.78/mile. Fuel Cell Hybrid bus costs are slightly lower, averaging $14.70/mile, with a range of $14.09 to $15.31/mile
As shown in Figure 5, if only locally paid costs are included, per mile life cycle costs fall to $4.91 for Diesel buses, $4.86 for Diesel Hybrid Buses, $5.06 for CNG buses, $9.15 for Fuel Cell Buses, and $8.10 for Fuel Cell Hybrid buses.
Figure 6 and Figure 7 show the percentage distribution of total lifecycle costs and local life cycle costs, respectively, for Diesel and Fuel Cell buses. As shown in Figure 6 operator costs make up 60% of total life cycle costs for Diesel buses; the second largest cost element is amortization of capital costs, at 15%. The distribution of costs is similar for both Diesel Hybrid and CNG buses.
With Fuel Cell buses amortization of capital costs accounts for over 50% of total life cycle costs, pushing operator costs down to only 21% of the total. Though higher in total for Fuel Cell buses, the other cost categories (overhaul costs, maintenance costs, fuel costs, and depot costs) comprise a similar percentage of the total for both Diesel and Fuel Cell buses.
As shown in Figure 7, if only locally paid costs are included operator costs account for over 68% of total costs for Diesel buses; the second highest cost category is fuel costs at 14.4%, and capital costs only account for 3.4% of local costs. By contrast, operator costs only account for 36.5% of local costs for fuel cell buses. Capital costs still account for almost 18% of local costs and fuel accounts for over 25% of local costs.