Civil Engineering Reference
In-Depth Information
How Do Electricity Prices Change My Project Economics?
Not much. Increasing electricity prices 50% increased the payback period
a maximum of 0.7 years (for a 100-bus school fleet) or 0.5 years (for a 20-
truck refuse fleet).
How Do Station Maintenance Costs Change My Project Economics?
Maintenance costs affect project economics more than electricity prices,
but they are still not very influential. Increasing maintenance costs 50%
increased payback time for a 100-school bus fleet by 2.7 years and a 300-
school bus fleet by 0.7 years. The same cost increase resulted in one additional
year to pay back for a 30-truck refuse fleet and only 0.1 additional years to pay
back a refuse fleet of 125 or more trucks.
C
ONCLUSION
As with all fleet projects, predicting whether a project is financially sound
is challenging but critically important. Decisions made on equipment
purchases, capital upgrades, and fuel contracts have long-term impacts on the
operational success of the fleet. NREL has modeled the impact of these
decisions and other fleet parameters with its VICE model and analyzed fleet
projects. When these parameters are compiled as a fleet, the fleet can be
classified as "Resilient," "Marginal," or "No-CNG." Resilient fleets tend to use
a lot of fuel and are profitable enough to be resilient to multiple changes in
fleet parameters. Marginal fleets are profitable but can quickly become
unprofitable if parameters change. No-CNG fleets are ones for which CNG
would be an unprofitable proposition.
Larger transit and refuse fleets (75+ vehicles) tend to be profitable and
resilient to variations in project parameters. This is because the miles driven
by the fleet overall use enough fuel to magnify the benefits of the lower-price
CNG to offset the entry costs of CNG (vehicle incremental costs and
infrastructure costs). Their payback period only rises above 5 years when
diesel drops below $2.25/gallon, vehicle incremental costs are doubled, CNG
vehicle maintenance costs increase 50%, VMT drops below 26,000 miles/year
(transit) or 14,000 miles a year (refuse), vehicle incremental costs are doubled,
or when these factors combine.
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