One pathway is biofuels, which are fuels synthesized from plants, crops, and waste materials. Biofuels aren’t new. In the United States, they’re actually old enough to have a complicated reputation because every non-electric car that runs on gasoline includes at least 10% ethanol — a biofuel that, depending on how it’s produced, could emit more CO₂ than it saves. Growing the corn to make ethanol requires fertilizer, and eventually, as you grow more and more ethanol crops, that means cutting down forests or overtaking space that could otherwise be used to grow food for humans.
Aerial view of an algae biofuel project
There are ways of making biofuel that don’t require heavy agriculture or mass deforestation — like algae. It’s a great source of lipids, which are hydrocarbons — the building blocks of any liquid fuel. A company called Viridos believes they can produce algae so lipid rich, they can grow fuel in ponds as cheaply as oil companies drill it from the ground.
Another option is to leave plants aside and make the hydrocarbons ourselves using clean electricity. Engineers do this by pulling carbon out of the air with direct air capture technology, then combining that carbon with hydrogen, which can come from splitting apart the H from the H₂0 molecules in seawater, from natural hydrogen deposits in the Earth’s crust, or from myriad other ways of making clean hydrogen.
These fuels are called electrofuels — or e-fuels — and the manufacturing process is exactly as complicated (and expensive) as it sounds. According to analysis by the Rhodium Group, sustainable aviation fuel is currently three to five times more expensive than regular jet fuel.
Over the next three decades, a trillion dollars is needed to help the fuel industry scale and reduce its Green Premium — and that’s just for commercial planes. Fuel for ships and trucks will require even more.
A firefighter battling a blaze
In fact, clean hydrogen will be especially vital to the shipping industry, which is notoriously difficult to decarbonize and accounts for three percent of all emissions. Right now, the fuel ships use is dirt cheap, meaning there’s little incentive to switch. What’s more, conventional container ships can carry far more cargo and go much longer distances than electric ships. Figuring out how to transform it into a fuel that's easy, cheap, and safe to transport in cargo ships will require more innovation and public-private collaboration.
An Update on Carbon Removal & Direct Air Capture
When making the case for net zero, climate experts often refer to the “bathtub analogy.” The atmosphere is like a bathtub that’s slowly filling up with water. (In this case, the water is carbon dioxide (CO₂). Even if we slow the flow of water — or CO₂ — to a trickle, the tub will eventually fill up and water will come spilling out onto the floor. What makes this process even more complex and challenging is that there are multiple spigots — electricity, transportation, buildings, manufacturing, agriculture — so you can’t simply turn one knob. That’s why it will be extremely difficult to shut off all the water before the bathroom floods. So in addition to turning off the spigots, we also need to mop up the spilled water on the floor.
That’s where carbon capture, storage, and removal come in. Most of this report focuses on how to reduce our emissions by switching to renewable energy, decarbonizing steel and cement, and fostering innovation in technologies like hydrogen and fusion and other promising technologies. But that still won’t be enough to completely avoid disaster, because there’s already too much carbon in the air .
A bathtub overflowing with water
Before we go any further, we need to make one thing clear: Carbon capture is not an excuse to keep emitting greenhouse gases (GHGs).
Many climate experts worry that this technology gives people the wrong idea: Why stop emitting carbon when we can suck it out of the air? This is neither practical nor economically efficient. But over the last decade it’s become abundantly clear carbon capture is one necessary tool, in a larger tool kit, we can use to achieve net zero.
There are many ways to capture or remove CO₂ from the air. The oldest technological capture method is called point-source capture, which involves new builds or retrofitting industrial sites and power plants with special devices that capture the CO₂ before it even reaches the atmosphere.