This is how algae is turned into plastic.

One company bets this green powder can replace at least some plastic in almost any product...

While also cleaning the air and water.

Too much algae can hurt natural ecosystems and sometimes make toxins that endanger humans and animals.

Can this invention rid the world of harmful algae and fight greenhouse gases?

We visited two factories on opposite sides of the globe to find out.

It's a race against time to clean harmful algae out of waterways before it dies.

It'll sink to the bottom.

It'll decompose.

It'll release those nutrients back into the water column.

And then with sunlight and water, again, you're going to have another bloom.

Rotting algae also releases methane--

A greenhouse gas over 25 times stronger than carbon dioxide.

Ryan Hunt cofounded Bloom in the hope that monetizing algae will lead to cleaner waterways.

But first, you have to get microscopic algae out of the water.

Bloom made a machine that can do that on the spot.

Engineering firm AECOM rents the harvester.

And it has used it to clean up harmful blooms in New York and Florida.

Bloom buys algae from around the world and turns it into plastic pellets at its headquarters in Mississippi.

First, workers run the algae through a grinding machine.

This equipment allows us to mill the algae into a very fine powder and select the particle size that we need for our process.

Then they blend the powder with plastic.

The machine creates hot strings of the mixture.

A blade cuts the strings into pellets.

And water passes through the system.

The pellets are cooled out of the molten state into a rigid form.

And they're dropped into a Super Sack--

Where we can store them and we can package them for use by our customers.

Nearly every plastic product is made from pellets.

Brands can buy Bloom's algae pellets to replace traditional ones in their products.

We started with making flowerpots.

That's evolved into making sneakers for Adidas and a whole bunch of other products.

Such as sports grips and traction pads.

Now, Bloom's pellets are mostly used in foam for shoes.

Algae can be a good substitute for plastic.

Because it contains lots of protein.

But algae pellets can't completely replace regular ones.

Or the final foam wouldn't be springy enough.

Typically, we'll use anywhere from 10% to maybe as high as 30% of the algae in the final foam--

Just depending on that performance need.

One of Bloom's customers makes its product here, in Dongguan, China.

This factory produces sock liners--

The foam part of a shoe that sits under your foot.

It's made from 15% Bloom pellets mixed with traditional plastic ones.

Technicians carefully measure out the two types.

And then a machine mixes them together.

After that, it's business as usual for the foam factory.

Workers knead the pellet mixture and shape it into sheets.

Then a machine heats the sheets under pressure until they expand into foam.

Workers trim the foam sheets and mold them into the finished sock liner.

Bloom shares data on the environmental impact of the pellets--

Which brands can use for marketing.

We can calculate the environmental impact on a gram-per-gram basis.

We can tell you exactly how much water was cleaned...

And how much carbon was captured in that shoe.

Ryan says each pair of sock liners kept about 8 grams of carbon dioxide out of the atmosphere and cleaned about 17 liters of water.

Dr Scholl's Shoes has made more than 2 million pairs of sock liners since it started working with Bloom--

Which the companies say kept about 17 metric tons of CO2 from the atmosphere.

That number includes carbon dioxide removed from the air by algae and emissions that were prevented by using algae in place of plastic.

But at the end of the day, it's still more plastic, right?

Most shoes made with Bloom are not any more recyclable than regular ones.

We are faced with a difficult challenge.

Because the footwear materials typically are made in a way that is not conducive to directly recycling them through traditional means.

And they're usually not biodegradable.

But when it comes to storing greenhouse gases inside an object, not breaking down is the whole point.

If the product degraded, it would release the carbon back into the atmosphere.

Experts say this type of technology can help fight climate change.

Right now, we just send CO2 into the trash heap in the sky.

But if you can take any of that CO2, bind it in a stable form, use it to make money in a valuable product, you want to do that.

But even if all the world's plastic contained recycled carbon, it wouldn't make a dent in emissions.

Right now, we emit 51 billion tons of carbon dioxide every year.

The worldwide volume of plastic that's made every year is about 1 billion tons.

So we cannot solve climate on the back of plastic.

It's just too small.

Nowhere close.

So is it worth it?

That depends what problem you're trying to solve.

Ryan says the main benefit of Bloom's work is cleaner water.

Algae has become a major issue...

Thanks mainly to wastewater pollution from farms.

Fertilizers are full of nutrients...

Like nitrogen and phosphorus--

Which make algae grow faster.

Runoff creates overgrown algae that removes oxygen from the water.

And it blocks light to creatures living below.

This is called a harmful algal bloom.

It can kill fish, whales, and dolphins and make seafood unsafe to eat.

In some cases, blooms can release toxins and make people sick.

43 states have documented illnesses or death of humans or animals caused by freshwater blooms.

And satellite images show bloom intensity on the rise in lakes on four continents since the 1980s.

But no matter how much algae you remove, blooms will keep happening if wastewater pollution continues.

The way that we ultimately address harmful algae blooms in a long-term scenario is addressing the source of nutrients from the beginning.

That means cleaning up wastewater before it reaches rivers and lakes.

The company can do this by intentionally growing algae at water-treatment plants to help remove nutrients that cause blooms.

Our hope is, over time, as the scale increases, we will be able to intercept more pollution upstream--

Which will cause less algae blooms in nature.

Bloom gets about half of its algae from lakes...

And half from treating wastewater.

But what about the environmental impact of processing the algae and shipping it back and forth across the globe?

It does take energy to get the algae into this usable form.

A consulting firm called EarthShift analyzed Bloom's processes.

And it found that even after you factor in these costs, algae pellets are more sustainable than plastic ones.

We're avoiding the massive amount of emissions associated with drilling for oil, extracting the oil, refining it into a specific polymer or a specific chemical.

Algae also requires less land, water, and energy than other bioplastic crops.

Like corn and soybeans.

Ultimately, Bloom's long-term mission is to teach people that harmful algae can be put to good use.

Every city has a wastewater plant.

Every wastewater plant has an algae problem.

But no one's addressing it.

No one's recognizing the value.

If people knew that the green scum in the back of their pond had value, you bet people would be harvesting it.