All over the world, countries and corporations  have committed to becoming carbon-neutral by 2050.   In fact, up to 70% of companies in major industries — like road vehicles, cement, and electricity — have announced net-zero  targets.

But what does that even mean?   I, for one, net-zero every time I try to play  basketball. But that’s neither here, nor there…  nor in the basket.

But I can nerd-splain to you that being carbon-neutral means reaching no net carbon emissions. For that, we’d need  to both reduce emissions and offset the ones we can’t avoid by extracting carbon from the air. And just like my basketball training, it’s going to take a lot of work.

We'll need some crafty solutions, plus a good way of measuring  decarbonization. Because the solutions marketed   as “green” or “eco-friendly” don’t always  tell the whole story.

Hi hi! I’m M Jackson, and this is Crash Course Climate and Energy. [INTRO MUSIC]

In Episodes 5 and 6, we learned about  biofuels: versatile fuels that can help   fill the gaps in decarbonizing heating and  transportation. Biofuels are liquid fuel   substitutes often made from plants. And in  theory, they’re carbon-neutral by nature.

That’s because these plants have only recently removed carbon dioxide from the atmosphere via photosynthesis. So, when the biofuels are burned, it returns the carbon the plants  recently removed from the system. Burning biofuels is like returning a friend’s shirt that you borrowed a week ago. You’re  not adding to their wardrobe when you return it —   you’re just kind of… putting it back.

On the  other hand, when we burn traditional fossil fuels,   we’re releasing carbon that’s been locked  up for millions of years. And that’s enough   to seriously change the balance of  greenhouse gases in the atmosphere. That’s not like returning a shirt you borrowed  last week; it’s like returning a pile of clothes   you borrowed in preschool. And now, your  friend’s closet is overflowing, and they   really don’t need those kid-sized overalls.

Because biofuels seem so much better than fossil fuels by comparison, they’re already a big  part of our lives. If you live in the U. S.,   at least ten percent of the gas you pump  into your car is probably not gasoline at all:   it’s likely corn ethanol biofuel. Corn ethanol is an alcohol made by fermenting   the starch in corn.

And it's been added to gas  for several decades to help minimize the emissions   from transportation. So, following that logic,  it doesn't seem like it’d be too big of a leap to   replace all our fossil fuels with biofuels, and  decarbonize transportation in one fell swoop. Except… growing corn and turning it into biofuel  takes a lot of energy.

You have to clear huge   areas of land, douse it with fertilizer, harvest  and transport your corn with heavy machinery,   and then process it in specially-made facilities.  All of these steps involve fossil fuels. It’s such an energy-intensive process that you  barely get the same energy out that you put in.   Kind of like making a really complicated celery  dish — It takes a long time, and you’re still   hungry at the end. And because each step releases  greenhouse gases, the emissions from making this,   “carbon-neutral” biofuel, can be higher  than the emissions from burning gasoline!

When you add up the carbon emissions of  everything involved in a product like this,   it’s called carbon accounting. And just like regular  accounting helps you subtract losses from profits   to understand the total picture, carbon  accounting helps us figure out the total   emissions involved in making and using something. But it’s not as easy as opening a spreadsheet   or checking your bank account.

Take  something even simpler than the fuel   that powers your car. Imagine, say, a single  car door. Let’s head to the Thought Bubble.

Over at the car door factory, business is  booming. Car-Doors-R-Us is buying iron and coal to manufacture shiny steel doors. Then,  they’re selling those doors to a car company,   who will assemble a vehicle to sell  to a consumer like you or me.

In line with worldwide trends, Car-Doors-R-Us has  committed to a goal of net-zero emissions —   and they seem on-track! They’re buying more efficient  furnaces so they don’t have to burn as much coal.   And they’re advertising their process as  “greener” than their competitors. Except, the way they measure emissions is flawed.

If they're using the current standard   emission measuring practice, called the  GHG Protocol, Car-Doors-R-Us probably isn't   counting all the emissions from their  raw material providers. For example,   it may not include things like emissions from the  trucks that deliver their raw sheet steel or the   electricity used by the factory that produced it. That makes it hard for consumers who care about   climate change to make informed decisions  — and it makes it harder for everyone  to accurately measure our progress towards carbon  neutrality.

So, economists are now working to develop better ways of carbon accounting, such  as E-Liability Accounting. In this system,   the emissions follow a product from start to finish.  Think about a stray dog that follows you home.   Stick with me here; it’ll make sense in a minute. When Car-Doors-R-Us buys raw materials,   it’s not just buying iron and coal: It’s also  acquiring responsibility, like when you found out you had to walk and train the dog, not  just love on it.

But for Car-Doors-R-Us,   the responsibility is for the emissions involved  in mining and transporting the raw materials.   After that, the company adopts more stray dogs  — or, picks up more liability as they generate emissions during the manufacturing process. But when they sell that finished door,   they pass on the liability to the car company, and  ultimately to you, the consumer. So at that point,   you might actually receive a report card on the  quantity of emissions involved in your car to date.

And hopefully it has a better score than  the one doggy day care sent home. Thanks, Thought Bubble! Now, a company like Car-Doors-R-Us is doing their best  with carbon accounting.

But sometimes,  companies promote their products as being  “green” or carbon-neutral, while intentionally   not counting parts of the production process. When this happens, it’s part of a phenomenon   called corporate greenwashing, where companies  make misleading claims about how “green” their   business is. And it can show up in marketing  for products that use supposedly carbon-neutral   biofuels, like ethanol.

But that doesn’t mean  that all biofuels are secretly high-carbon. For instance, there is a kind of green fuel that  looks pretty good, even with your accounting goggles on: cellulosic biofuels from a plant  called switchgrass. Here, the energy in the  biofuel comes from breaking down long, durable  molecules of cellulose instead of starch.

And unlike corn, switchgrass is a plant  that’s native to the North American prairie,   so the ground doesn’t need to be intensively  plowed and fertilized for it to grow.  That means you can get close to five times the energy  from switchgrass biofuel than you put into making it. Less like a celery sorbet; more like a protein  bowl. But because of those hardy cellulose fibers,   converting switchgrass into a biofuel isn’t as  easy as making it from corn, and the technology   and infrastructure are still lagging behind.

So if you’re interested in agriculture or engineering —    or even politics, since  new technologies often need political support —   this kind of thing is a gap you might  step into. Because like I’ve said before,   climate change is a group project that needs all kinds of  thinkers. And the future isn’t set in stone.  There is still time to develop switchgrass-processing  technology, and other solutions for biofuels   that go easy on the emissions.

There are other strategies as well   for getting closer to net-zero emissions.  There’s the side of the coin where we release   less emissions in the first place — and then  there’s the side of the coin where we try to   clean up the ones we’ve already let loose. That  side is called carbon capture. The idea is that,   in the cases where it’s not possible to avoid  emissions entirely, we capture the greenhouse gases   before they heat up our atmosphere.

One method of doing this is called point-source carbon capture. It’s just what it sounds like: it captures emissions where they’re emitted.   Basically, it’s a carbon filter that’s  installed directly onto a chimney or outlet of   a power plant or factory. It’s like the  air filter on your furnace or AC unit.  But instead of stopping allergens or pollutants  from getting into your home, this filter stops  greenhouse gases from reaching the atmosphere.

This method could capture emissions at the source   from processes like concrete production, which  are difficult to decarbonize. And point-source   carbon capture may even be able to bring the  factories where ethanol is made closer to true   net-zero emissions. But tilling land, shipping car  doors, mining iron — greenhouse gas emissions like these are a lot harder to capture right at the  source, because they’re much more spread out.

And that’s where direct air capture comes in. This  method pulls greenhouse gases straight out of the air, regardless of where they were emitted.  This system takes in air from the atmosphere,   then passes it through special filters or chemical  mixtures to remove the carbon altogether. It sounds kind of magical, because not  only can it capture carbon from anywhere,   it could even partially undo the damage that’s  been done over the last couple of centuries.   This could theoretically take levels of carbon dioxide  in the atmosphere back to pre-industrial levels.

Unfortunately, direct air capture is stubbornly  difficult, and expensive. Right now, there’s more   carbon dioxide and greenhouse gases in the  atmosphere than there has been in millenia,   but our atmosphere is huge. And greenhouse gases  only make up a tiny portion.

That’s why we use   the unit of parts per million when talking  about the amount of carbon in the atmosphere. Today in 2023, there are around 420 molecules of  carbon dioxide for every million molecules of air.   So, you have to filter a lot of air to capture any  significant amount of greenhouse gases. That means direct air carbon capture is really inefficient.

Imagine you were looking for one specific shell   that you dropped in the ocean. You’re sorting  through thousands that aren’t what you’re   looking for, and it’s taking FOREVER. Except it’s  millions of shells that we need to re-capture.   From a space a lot bigger than the ocean.

Cost-wise, it’s much cheaper to capture the   gases when they’re concentrated at  the emissions source. Unfortunately,   that means that our historical emissions are  probably here to stay, at least for a while. There’s no silver bullet for climate change  here — which hopefully isn’t surprising at this point.

I mean, we wouldn’t have buried  that bombshell in Episode 7. Plus, once you’ve   captured the carbon with methods like these, you  still have to figure out what to do with it. So, researchers are exploring various storage  solutions, a lot of which are pretty rocky.   Literally.

One option is to inject gases  into the sediments at the bottom of the ocean,   where they’ll be held in place by the crushing  pressure of thousands of kilograms of seawater. Alternatively, the carbon could be  stored in actual rocks. Ironically,   it’d be stored in the holes left behind after  miners extracted fossil fuels — the same fuels   that started this problem in the first place.  Right now, though, there’s no single storage   solution that’s watertight, or airtight even.

Another possibility is to not let that carbon go to waste:   We could use what’s captured to make  things like fuel and chemicals. This may only  be a short-term solution if the carbon ends up back in the atmosphere eventually, but it is much cheaper than locking up the gases for eternity. So, if we might slip on our carbon accounting goggles  one more time, carbon capture  promises great things.

On the face of it,   it could even lead us down a path to negative  carbon emissions. But the current status of   carbon capture technology would likely only help  us reduce our annual carbon emissions by about   3.5 billion tons by 2050. That’s a huge amount,  but no match when compared to the 51 billion tons of emissions we release each year.

So, there’s a lot of room for scientists,   engineers, investors, economists,  communications professionals — maybe YOU — to get involved in this part of  the problem, and its possible solutions. In the end, climate change will require a  whole host of solutions. Avoiding greenhouse gas emissions where possible, yes.

But also, where that’s not possible, alternatives like   biofuels and carbon capture can take us a  long way towards carbon neutrality by 2050. Plus, with accurate carbon accounting,  companies can make sure their emissions   goals are really on the right track. That’ll  become more important than ever as the effects   of climate change are being felt around the  world.

We’ll get into that story next time. Special thanks to Indija-ka Siriwardena, our  basketball coach for this episode. Thanks to you,   I can now score a three-pointer — don’t make  me prove it.

We’ll get there eventually!   Thanks for supporting us on Patreon! Crash Course Climate and Energy is produced by Complexly   with support provided by Breakthrough  Energy and Gates Ventures. This episode was filmed   at the Castle Geraghty Studio and was made with  the help of all these nice people.

If you want   to help keep Crash Course free for everyone,  forever, you can join our community on Patreon.