How Much $ For Lower Emissions?

Emission, Cost and Range Trade Offs

When I started managing projects I learned most projects made compromises with timing, costs or quality.  More time and/or money were typically required to deliver higher quality outcomes.   I found a similar trade off comparison with alternative fuel vehicles recently attending the Advanced Clean Transportation Expo in California.

On the first day I attended a session on hydrogen fueling.  There was strong attendance and interest because when measuring tailpipe emissions, hydrogen provides California lawmakers' desirable zero emissions.

At additional sessions I collected information on options for alternative fuel transit buses because there are market ready options for hydrogen, electric and natural gas.  It is clear that the technology exists and works for each option.  Fleet bus managers in California shared their experiences on the pros and cons of each option.  My understanding and summary of the sessions are shared below.

Near Zero Emissions, $50K, Lower Average Fuel Cost & Full Range

Natural Gas Transit Buses have been successful in many cities around the world but they are especially prevalent in California cities with strict emission regulations.  California transit fleets including San Diego, Los Angeles and Santa Monica have years of experience and data associated to their natural gas fleets.  They have higher upfront costs but lower average fuel costs.  Fueling and maintenance is similar in timing and process. Incremental costs are $50,000 per bus which has been recovered with lower average fuel costs.  The problem with natural gas buses is meeting zero emission regulations.  The newest natural gas engines are labeled "near zero" emissions but they will not meet California's new "zero" emission requirements. For more on natural gas near zero emissions read Gladstein, Neandross & Associate's Technical White Paper or Executive Summary. 

Zero Emissions, $500K, Significantly Lower Fuel Cost & 1/3 Range

Electric Battery Transit Buses will meet zero emission requirements based on tailpipe emissions.  Battery emissions are not considered in the equation.  Electric buses can provide a cleaner and quieter option but the incremental costs per bus are $500,000 per bus, 10 times the incremental costs for a natural gas bus.  Charging the bus batteries is very inexpensive compared to diesel or natural gas. The biggest challenges for electric buses are that they require long charging times and only go about one third of the range of a diesel or natural gas bus. The lower range is the obstacle most bus fleets cannot accept. For more on battery electric buses read NREL's 2016 Demonstration Results. 

Zero Emissions, $1.2M, Significantly Higher Fuel Costs & Full Range

Hydrogen Transit Buses combine batteries with fuel cells and have the same range as diesel or natural gas buses.  They also meet zero tailpipe emission standards.  The challenge with hydrogen powered buses is the price tag with $1.2 million in incremental costs per bus and hydrogen fuel for $5-14 a gallon. The hydrogen will most likely come from methane - using the four molecules of hydrogen in CH4. The least expensive methane will be conventional natural gas though prices for renewable natural gas are becoming more competitive. With increased adoption the higher bus prices should trend down as they did with natural gas buses.  I support the idea of using hydrogen but expect tax payers to resist picking up the bill at current prices.  As research and development moves this option forward it may become a more feasible option.  Near term projects will have a hard time showing a return on investment.  For more on these buses see NREL's 2016 evaluation.

We can strive for progress and perfection by using the affordable market ready products that reduce tons of emissions today and support those who are bringing new alternatives to the market.