If you've been paying a glimmer of attention to the discussion surrounding sustainable transportation, you'll have assuredly heard the term hydrogen fuel cell (HFC) bandied about. Many in the transportation industry claim HFC technology will become the primary replacement for conventional gas and diesel-powered engines in cars, trucks, buses, trains and marine transportation. That's quite an intriguing pronouncement!
So, what is a hydrogen fuel cell anyhow? My Wikipedia source neatly defines it as "an electrochemical cell that converts the chemical energy of a fuel (hydrogen) and an oxidizing agent (oxygen) into electricity through a pair of reduction and oxidation reactions."
More simply stated:
Hydrogen (H2) + Oxygen (O2) => Electricity + Water Vapour (H2O) + Heat
Wow – it doesn't take a rocket scientist to picture the immediate benefits of this power source!
The HFC is not a new technology. Indeed, the first fuel cells were created in 1838. However, it wasn't until NASA used HFCs in its space program in the 1960s that their use became practical. Today, all types of primary and backup power situations use HFC technology, particularly in remote locations where power is otherwise not readily available. And increasingly, they power cars, trucks, trains, buses and ships. This video offers some interesting insights into HFC technology for vehicles.
Let's narrow our focus to modes of transportation most of us use every day. Why is there so much excitement around HFC-powered cars and trucks? And what are the drawbacks?
On the plus side:
The most obvious benefit we noticed in the equation above – HFC vehicles emit only water vapour and a bit of heat from their tailpipes. That's it. No smog. No toxic fumes. It's estimated that replacing an average fossil-fuel-powered vehicle with an HFC-powered version will reduce CO2 emissions by five metric tonnes each year. Consider the fact that well over one billion gas and diesel vehicles operate globally today. It's clear when we do the math – if we're serious about reducing greenhouse gas (GHG) emissions to the atmosphere to offset the effects of climate change, HFC transportation is a great place to focus.
HFC vehicles get roughly twice the range out of a tank of (hydrogen) fuel than their fossil-fueled counterparts. OK – adding this statistic to the point made above and you produce a double-fisted whammy of positive impact to reduce the environmental impact.
HFC vehicles are inherently safer to operate. We're all familiar with handling gasoline and diesel every time we stop to fill up our vehicle. But what about hydrogen? How safe can that be? For a great response to that question, check out this excellent article. Spoiler alert – if you're comfortable fueling your car with gas or diesel, you'll find fueling your HFC vehicle a reassuring process.
So far, so good. What's the flip side to all this rosy news? Here are some of the challenges:
Hydrogen is the most abundant element in the universe. The hitch is, it doesn't exist as pure hydrogen in its natural state – it demonstrates an overwhelming tendency to combine with other elements to form compounds such as water (H2O) and hydrocarbons (fossil fuels), to name two common examples. So, we need to expend energy to extract hydrogen from such compounds.
The least expensive way is to strip hydrogen from hydrocarbons (most commonly, natural gas) in a process known as reforming. However that process produces GHGs, and that's what we're trying to avoid. The silver lining to this bad news? Despite generating GHGs to produce hydrogen fuel, HFCs considerably reduce net GHG loading to the atmosphere over their operating lifetime.
Another way to create hydrogen is to electrolyze water (effectively zapping water with electric current), stripping it to its hydrogen and oxygen constituents. This method is generally more costly than reforming and can emit substantial amounts of GHGs if the source used to generate electricity (like coal-burning) is "dirty." Using solar and wind or hydro-generated power are sustainable methods to reduce both the cost of electricity and GHG emissions, thereby producing what is known as "green hydrogen."
Storing hydrogen, whether in liquid form or as a highly compressed gas, is challenging. It takes energy to produce, store and transport hydrogen in these forms, roughly doubling its price compared to fossil fuels.
The cost of HFC vehicles is presently higher than for conventional vehicles. Also, the fueling infrastructure for hydrogen is not yet well developed.
The value of hydrogen as a fuel source for vehicles is not a cure-all. No one method is. However, the benefits of HFC technology are driving its adoption worldwide – offering an increasingly practical way to reduce global warming meaningfully while serving our growing demands for safe transportation.