The potential is tremendous. But, when it comes to solving climate change, we also need to reckon with an inconvenient truth: There are more than 1.2 billion gas-powered vehicles on the world's roads right now, and we can't realistically replace enough of them with solar-fed Teslas in time to keep global temperatures in a safe range.
Even when the price of electric cars declines dramatically and solar and wind come to dominate the electricity production, we'll still have plenty of gas-powered cars left on the roads for decades to come. Trucks, airplanes and ships — which can't be easily electrified — also contribute a growing share of transportation emissions.
To solve climate change, we need to deal with the global emissions that come from transportation, which is roughly one-quarter of all emissions, according to the Environmental Protection Agency. This requires a bigger strategy than electric vehicles alone. We also need to think about how to replace what's filling the tanks of the vehicles that currently occupy our roads, skies, and waterways.
As Bill Gates pointed out recently, the dream of converting solar energy into liquid fuel to power cars is now surprisingly close to reality. Over the past decade, there's been a quiet march of progress on a range of technologies like engineered photosynthesis (the conversion of carbon dioxide from industrial waste into fuel using help from micro-organisms like algae), power-to-gas or P2G (methods that can transform renewable-produced electricity into liquid fuels by separating water molecules into hydrogen and oxygen), and new waste-based alternative fuels (that reduce emissions relative to fossil fuels without impacting the food system).
When it comes to greening the transportation sector, these innovations could present some exciting possibilities. They can rely on all the existing infrastructure from car engines to gas-station pumps. They open the door to emissions reductions in otherwise-difficult sectors like aviation. Crucially, they can cut emissions while creating diverse new employment opportunities in fields from biotech and agriculture to local refineries.
Still, looking to the often-disappointing history of biofuels, the world should proceed with caution. While some biofuels were sold as panaceas just a decade ago, their emissions impacts have been roundly questioned, and they have presented other challenges in areas from biodiversity to food prices.
With new low-carbon fuels, as with so many other areas of emerging technology, there's a pressing need for long-term thinking about possible pitfalls. This month, leaders from business, government, and academia met in San Francisco as part of the Low Carbon Technology Partnerships Initiative to examine the problems and prospects for sustainable fuels. A new initiative called below50 is aiming to identify sustainable fuels which new fuels can actually reduce carbon emissions by more than 50 percent relative to fossil fuels and also demonstrate sustainability according to a range of broader standards; from local food security and human rights through to water use and land conservation.
Elon Musk's latest announcement highlights an important step toward sustainable transportation. Paired with battery storage options like Tesla's Powerwall, electric vehicles and home solar can go a long way toward reducing emissions. But, given the reality that gas tanks aren't going to disappear anytime soon, we also need green innovation in liquid form.