Electric vs Hydrogen: Which is the cleaner alternative fuel?

—Thumbnail by Two-bit da Vinci

In recent years, there has been a large discussion surrounding alternative fuel sources for automobiles. The two most common that come to mind are hydrogen and electric. Whereas electric is proven to be a viable, scalable alternative fuel—simply look to Tesla—hydrogen is still the subject of much debate and criticism. Proponents of hydrogen fuel cell vehicles include Honda and Toyota which are seeking to further their research and production of hydrogen fuel cell vehicles (FCV). Opponents include, most notably, Elon Musk—co-founder and CEO of Tesla Motors—who believes that hydrogen fuel is far too inefficient.

Economics and company politics aside, we wanted to explore which alternative fuel source was truly cleaner. That is, which resulted in lower pollution both directly and indirectly?

To answer this question, we have to first define our metric of comparison. When looking at the environmental impact of electric vehicles (EVs) and hydrogen FCVs, we decided on miles per unit of pollution generated. In other words, how many miles does one have to drive in order to produce 1 unit of pollution?

For electric, the answer was fairly simple. As per Statistica, the average battery capacity in EVs worldwide was estimated to be 43 kWh. A typical efficient electric vehicle can travel 4 miles per kWh. The US Energy Information Administration reports an average byproduct of 0.92 lbs of CO2 for each kWh generated. With some simple calculations, we find that your average EV indirectly generates 1 lb of CO2 pollution for every 4.35 miles driven.

For hydrogen FCVs, our numbers were a little less precise. Current hydrogen-powered vehicles have a capacity of around 5-6 kg. To produce hydrogen fuel, the most common and effective water electrolysis processes have an electric efficiency of 70-80%, which would mean 50-55 kWh of electricity is required to produce 1 kg of hydrogen fuel. The range of most hydrogen cars also varies greatly, ranging from 312 - 380 miles on a full tank. With these numbers, we found that an average hydrogen FCV can travel 6.24 - 6.90 miles per kWh. Using the same statistic for CO2 byproduct from electricity generation, we find that—for hydrogen—1 lb of CO2 pollution is generated for every 6.78 - 7.50 miles driven.

In terms of CO2 pollution, we can see that hydrogen is a cleaner alternative fuel compared to electric. Hydrogen FCVs, for the same amount of pollution generated, drive a longer distance. Although the environmental impact of hydrogen FCVs vary, its least environmentally-friendly types are still significantly cleaner than your average EV.