Gas stations are ubiquitous across the world, many with diesel pumps as well, to fuel the more than 1 billion vehicles now roaming the surface of our planet.
As regulators get increasingly serious about reducing carbon emissions from transportation, we'll see competing sites for refueling or recharging zero-emission vehicles emerge--the first serious competition to hydrocarbon fuels in a century.
So it's worth looking at "throughput," or the number of vehicles that can be refueled or recharged at these different locations.
A modern gas station and convenience store, with 12 pumps in three or four single or double ranks, can serve as many as 12 vehicles simultaneously and costs roughly $2 million to construct.
Even adding in bathroom breaks and the purchase of sugary sodas, salty snack foods, cigarettes, and lottery tickets--the main profit drivers for these enterprises--the average stop is no more than 10 or 12 minutes.
Assuming each pump serves three vehicles an hour (for 20 minutes each) over 24 hours a day, the maximum throughput is more than 850 vehicles in a 24-hour day.
Cut the average dwell time to just 10 minutes a car--entirely possible, as any driver knows--and you're up to 1,700 vehicles fueled each day as a theoretical maximum.
Petro-Canada gas station, Crossfields, Alberta, with electric-car charging station
But the vast majority of gas stations actually run at no more than 5 percent of their theoretical maximum throughput--or fewer than 100 cars a day.
Hydrogen station throughput lower
So how many vehicles can the latest hydrogen fueling stations and DC quick-charging sites (like the growing Tesla Supercharger network) serve in comparison?
Our reader Rik has commented at length on the topic, and we've taken the liberty of adapting those comments into this article.
California is now building dozens of hydrogen fueling stations, which receive more than $1.6 million apiece in construction funding from the state.
The balance of the cost of $2 million each is made up by local government agencies and for-profit companies that include carmakers and companies like First Element Fuel that hope to make money selling hydrogen over time.
The hydrogen fueling stations that California is currently building are receiving an average of more than $1.6 million each from the California state taxpayers for construction.
Additional funds are received from local government agencies and corporate investors because the cost per station is about $2 million each.
2016 Toyota Mirai hydrogen fuel-cell car, Newport Beach, CA, Nov 2014
How many hydrogen cars can fuel?
According to the California Air Resources Board, those stations will have a maximum fueling capacity of 180 kilograms of hydrogen per day.
That's enough to fill 36 Toyota Mirai vehicles completely each day; the Mirai has a stated fuel capacity of 5 kg.
In other words, while the refueling process itself will likely take less than 10 minutes--or a total of six hours for those 36 Mirais--the other 18 hours is required for the necessary hydrogen to be generated and compressed.
That works out to $11,100 for each kilogram-per-day capacity provided--or $55,500 per daily maximum Mirai refueling session.
That's about 25 times the capital cost of an average gasoline or diesel car refueling session in our gas-station example above.
Busiest Supercharger site
In contrast, the most heavily-used Tesla Supercharger site is in Amsterdam. It has 10 stalls, meaning five Superchargers delivering up to 135 kilowatts each. (Delivery rate has been successfully raised from 90 to 120 and now 135 kW.)
That works out to a theoretical maximum of 16,200 kilowatt-hours over a 24-hour day. So what's the actual utilization factor for a Supercharger site?
Tesla Supercharger site in Dorno, Italy, photo by problemidiricarica.wordpress.com/
Despite occasional waiting periods on Friday evenings as hordes of Tesla owners migrate from San Francisco to Los Angeles and vice versa, a Supercharger site operates at well below its theoretical maximum as well.
For the busy Amsterdam site, actual Supercharger usage data for the location shows it delivered about 4,000 kWh.
If every car was an 85-kWh Model S taking up 60 kWh, that would be about 70 actual cars--but it's probably more than 100, assuming some partial charging.
MORE: Tesla Supercharger Network Growth Surges Over Last 14 Months (Mar 2015)
So the busiest Supercharger had a utilization factor is of 25 percent.
Again, that's high compared to the average gas station, which runs at about 5 percent of its theoretical maximum capacity factor.
Cost of DC quick-charging site?
Tesla CEO Elon Musk said a few years ago that Supercharger sites cost $150,000 to build when connected to grid power, and $300,000 when photovoltaic solar panels were included to provide renewable electricity.
2016 Toyota Mirai hydrogen fuel-cell car, Newport Beach, CA, Nov 2014
In its most recent SEC filing, the company stated:
As of June 30, 2015 and December 31, 2014, the net book value of our Supercharger network was $139.8 million and $107.8 million and currently includes 480 locations globally. We plan to continue investing in our Supercharger network for the foreseeable future, including in North America,
Europe and Asia and expect such spending to be approximately 5 percent of total capital spending over the next 12 months. During 2015, this investment will grow our Supercharger network by about 50 percent. We allocate Supercharger related expenses to cost of automotive revenues and selling, general, and administrative expenses. These costs were immaterial for all periods presented.
That works out to about $290,000 per Supercharger station--each of which can serve two Tesla vehicles.
Tesla Supercharger site with photovoltaic solar panels, Rocklin, California, Feb 2015
Expanding its Supercharger network from 480 stations to 720 will consume less than 5 percent of the company's total expenditures, which the company calls "immaterial" compared to the huge cost of actually developing the vehicles themselves.
Hydrogen throughput: the open question
So if each of the new hydrogen stations, at a total cost of $2 million each, can presently service a theoretical maximum of 36 Toyota Mirais per day, what is a likely throughput?
Some hydrogen modeling has assumed throughputs as high as 70 percent, which might be possible if drivers were willing to make appointments to refuel (and at least some of them were willing to do so at 3 am).
But In the real world, the heaviest usage for fueling stations is before and after work. To achieve 70 percent utilization without a scheduled appointment process, drivers of hydrogen vehicles would likely find themselves waiting in a long line to fuel up at either end of their workday.
Which brings us back to the question of whether selling hydrogen fuel will be viewed as a profit-making opportunity for private industry in the years and decades to come.
Clearly the first round of stations are quite expensive, and they can serve far fewer vehicles than their gasoline/diesel or DC fast-charging equivalents.
Whether gas station operators en masse will be willing to add hydrogen fueling stations to their pump ranks depends on how quickly they feel they can make back their capital investment.
A capital expenditure payback period of three to five years is usually required for such expenses--and at the current costs, it seems unlikely that such a payback can be achieved without massive subsidies from governments or automakers.
Overall, today's modern gasoline stations clearly have by far the highest throughput for the lowest cost.
Beyond that, however, it appears that DC fast-charging stations for electric cars may be cheaper to build than many analysts have assumed--and that they already provide a far better throughput than the latest hydrogen stations.
Which means the question becomes whether hydrogen stations can increase throughput by a factor of 10 or more to become worthwhile for private industry to install.
Within two or three years, California's experience in building and operating dozens of the latest hydrogen fueling stations will likely point the way toward answers to that question.