Energy can be used to do different things. Electricity is useful for lighting and computers. Heat is useful for cooking and warming your house. And gasoline is useful for transportation. However, we need to stop using fossil fuels.
Solar and wind and nuclear can provide electricity with relatively low carbon emissions. However, electricity isn’t that useful for transportation. Some proposed solutions include batteries, biofuels, and hydrogen (usually as a fuel cell). There are some big hurdles to all three; today I talk about the issues with hydrogen.
It’s a tempting solution because when hydrogen is burned as a fuel (or recombined with oxygen in fuel cells), the only byproduct is water. Technically the heat can cause chemical dissociation and other pollutants to form (like NOx), but let’s ignore that for the sake of this argument.
Hydrogen doesn’t just happen; it has to be produced. Most of the hydrogen produced today is made from natural gas. This is because it is cheaper to rearrange natural gas molecules than to make hydrogen from water. Nevertheless, proponents of wind and solar energy expect that these technologies can produce all our electricity and contribute hydrogen for transport and heating. But hydrogen might not be the way to go.
As it stands now, the energy consumption to produce hydrogen outweighs the benefit. Hydrogen vehicles can use 80% to 220% more energy than fossil fuel vehicles. Hydrogen also isn’t very energy dense. That means to use it in a personal vehicle, you need to compress it, liquify it, or use a fuel cell. All of these processes are energy-intensive and make transportation much more expensive.
Then you actually have to build the network of fuel stations. But think also, how does the hydrogen get to a fuel station? It can’t really be produced on-site without the increased costs of many inefficient machines. It can’t really be piped there, because hydrogen molecules are much smaller than hydrocarbons and escape the piping network relatively easily while also altering the pipeline’s material properties.
Neglecting the land footprint required to produce the extra electricity, we still need to build more solar panels or turbines. The US produces a lot of electricity, but only 4.4% comes from wind or solar. If all of the US’ transportation energy needs were also met by electricity, we would need 64% more energy coming from electricity (Note: this could be less if we use the electricity directly). That means solar and wind are covering 2.7% of our current need.
Furthermore remember that the US should have stopped burning fossil fuels yesterday. No new fossil fuel infrastructure should be built anywhere in the world after 2017, so the US as a wealthy (and exploitative) nation should have stopped years ago. Bottom line, hydrogen will not play a role in transportation unless huge technological advancements are made.
Ultimately we need to change the way we use energy. In transportation, personal vehicles are not ever going to be eco-friendly. We need cities that are walkable and bike-able and have good electric public transit. Freight and passenger transport between cities should be transitioned to electric trains. They won’t need batteries or blacktop or fuel stations and won’t emit pollution. These changes are necessary, but they will only happen if we recognize the opportunities and make them happen.