need

A new way to recycle plastic

April 18, 2025 By EarthWise Leave a Comment

Researchers at Northwestern University have developed a new method for recycling plastic that is safer, cleaner, cheaper, and more sustainable than those currently in use. The U.S. is the world’s largest plastic polluter per capita, and we only recycle 5% of our plastics. There is a pressing need for better technologies for processing different types of plastic waste.

The Northwestern method is designed to break down polyethylene terephthalate or PET, which is the most common type of polyester plastic. PET plastic is used in food packaging and beverage bottles and represents 12% of total plastics used globally. It does not break down easily and is therefore a major contributor to plastic pollution. It mostly either ends up in landfills or, over time, degrades into tiny microplastics or nanoplastics that end up almost everywhere.

The non-toxic, environmentally friendly, solvent-free Northwestern process first uses an inexpensive molybdenum catalyst to break apart the bonds in PET. Then the broken plastic is exposed to ambient air. Just from the trace amounts of moisture in air, the broken-down PET is converted into monomers, which are the building blocks of plastic. The monomers could then be recycled back into PET products or used to make other valuable materials.

The process is fast and effective and takes just a few hours. The catalyst is durable and recyclable, meaning it can be used over and over again. It only works on polyesters, which means it can be used for recycling mixed plastics without sorting them since it will select only the PET from its inputs.

**********

Web Links

Plastic recycling gets a breath of fresh air

Photo, posted August 10, 2013, courtesy of Lisa Risager via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Giant batteries in the Earth

December 23, 2024 By EarthWise 1 Comment

The wind and the sun are inexhaustible sources of energy, and we are tapping into them to produce electricity at a growing rate around the world. But neither of them is always available when we need them. When the sun isn’t shining and the wind isn’t blowing, they don’t work.

An opposite problem also exists. When our energy needs are low, but it is sunny or windy, solar and wind power are all dressed up with nowhere to go. Energy storage is the answer to both of these problems. When there is excess generation, store the energy for later use. When there is need for energy and not enough is being generated, tap into the energy that is stored.

Giant banks of lithium-ion batteries are the rapidly growing form of energy storage, and they are increasingly providing resilience in the electric grid. But battery storage is short-term energy storage. Even the largest battery banks can only provide a few hours of electricity.

So, there is a real need for “long-duration energy storage” – systems that provide at least 10 hours of backup power and sometimes much more – for the grid to be fully reliable.

Pumped hydro storage, which uses water from elevated reservoirs to drive turbines, has been around for a long time. Historically, this is the largest form of energy storage in the world. Other methods include pumping compressed air into underground caverns or lifting massive blocks into elevated positions. All of these techniques use excess electricity to place things like water, air, or cement into a position where they can be used to drive electrical generators.

The grid of tomorrow will store energy in giant battery banks, but also in the ground, in reservoirs, and in large structures.

**********

Web Links

How giant ‘batteries’ in the Earth could slash your electricity bills

Photo, posted March 21, 2024, courtesy of Sandra Uecker/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Moisture swing carbon capture

November 10, 2023 By EarthWise Leave a Comment

As the world grapples with limiting the amount of carbon dioxide in the atmosphere, there is a growing need to capture the carbon dioxide that is emitted as well as preventing it from being emitted in the first place. Carbon capture can be accomplished at the source of emissions (such as power plants) or it can be done by taking it out of the atmosphere. The latter is called “direct air capture”.

It is not at all clear whether direct air capture can be accomplished on a scale that would really make a difference and at an acceptable cost either in dollars or energy expended. But if it can be done that way, it would be a major tool in combatting climate change.

Direct air capture technology generally makes use of sorbent materials whose capacity to capture carbon dioxide and later release it is a function of temperature. The process requires significant amounts of energy to release the carbon dioxide that has been captured.

New research from Northwestern University makes use of the “moisture-swing” technique which uses materials whose ability to capture and release carbon dioxide depends on humidity rather than temperature. While it takes some amount of energy to humidify the volume of air containing the sorbent material, it is very small compared to temperature-driven systems.

There are many groups working with moisture-swing technology, but the Northwestern Group has identified a number of new sorbent materials with superior properties.

The fundamental questions of scalability and cost remain, but moisture-swing is a promising approach to direct air capture. If carbon dioxide can be pulled out of the atmosphere in large volumes, it can be concentrated and stored or converted into useful products.

*********

Web Links

Pulling carbon dioxide right out of the air

Photo, posted May 15, 2020, courtesy of James Watt via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Planting Rocks To Capture Carbon | Earth Wise

September 8, 2023 By EarthWise Leave a Comment

Getting humanity to stop dumping carbon dioxide into the atmosphere continues to be very challenging regardless of how increasingly apparent the need to do so becomes. For this reason, climate change mitigation strategies increasingly include interventions in the form of removing carbon dioxide that is already there. There are a variety of ways to draw carbon dioxide out of the atmosphere, but they face a host of technological, economic, and even environmental difficulties.

A new study at Yale University evaluated a type of climate intervention called enhanced rock weathering. Rock weathering is a natural chemical process by which certain minerals absorb carbon dioxide over time. Enhanced rock weathering is simply speeding up weathering such so it can have beneficial results soon enough to make a difference.

The study explored the potential of applying crushed basalt, which is a fast-weathering rock that forms when lava cools, to agricultural fields around the world. Basically, the idea is for farmers to mix the crushed rocks into their fields. There is no real downside to doing this. In fact, adding crushed basalt to fields rejuvenates depleted soils and helps counter ocean acidification.

The study simulated the results of enhanced rock weathering on 1,000 agricultural sites around the world. Over a 75-year period, these sites would remove 64 billion tons of carbon dioxide from the atmosphere. This is roughly the amount climate scientists believe is needed to take out of the atmosphere.

Enhanced rock weathering has been used on a small scale on farms around the world. Perhaps it is time to ramp up its use.

**********

Web Links

‘Planting’ rocks in farms, along with emissions reductions, could help meet key IPCC carbon removal goal

Photo, posted January 14, 2023, courtesy of Ron Reiring via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Compressed Air Energy Storage

October 23, 2019 By EarthWise Leave a Comment

The increasing use of solar and wind power has created a growing need for technology to store up the energy they generate for use when it is most needed.

Historically, pumped hydropower has provided the largest amount of storage capacity, but it is limited to only certain geographic locations. Battery energy storage has been growing rapidly, with the technology becoming better and cheaper over time. But there are various other ways to store energy that have potential and may well find their place in the changing energy infrastructure.

One of these is compressed air energy storage, which has been around for more than a century. It has been used as a backup method for restarting power plants. But to date, the economic viability of using it at a large scale has been lacking.

A Canadian startup company called Hydrostor is developing compressed air energy storage technology that it believes can be used on a utility scale.

The way it works is excess renewable energy is used to run compressors that compress air. Compressing the air heats it up and the heat is captured and stored in insulated hot water tanks. The compressed gas is then injected into underground caverns. When energy is needed, the compressed air is released, the stored heat is added, and the warmed gas is run through turbines to generate electricity. Additional features improve the system’s efficiency.

Hydrostore has built a 1 MW pilot project in Ontario, Canada and is now commissioning a 2MW system as well. It is funded to build a 5 MW system in Australia next year and it is bidding for 300 MW and 500 MW systems in North America. The company has received equity funding from Baker Hughes, a large oil-and-gas services and equipment company.

**********

Web Links

Storing energy in compressed air could finally become cheap enough for the big time

Photo courtesy of Hydrostor.

Earth Wise is a production of WAMC Northeast Public Radio.

How Safe Is Drinking Water?

March 26, 2018 By EarthWise Leave a Comment

Water is life. It’s a fundamental need for every human being on the planet. Each person requires more than five gallons of clean and safe water a day for drinking, cooking, and keeping clean. Dirty water, on the other hand, can be deadly. An estimated 1.8 million people die every year as a result of diarrheal diseases like cholera. And tens of millions of people are seriously sickened by water-related maladies.

Removing Heavy Metals From Water

September 7, 2017 By EarthWise

Clean and abundant water is the most essential need for all human societies and the supply of it is threatened by increasing populations and volatile climate patterns. The quality of water is threatened by a host of contaminants, most of our own making.