#carbon negative

This cargo ship from 1909 is starting to make zero-emissions deliveries again

Sailcargo doesn’t expect to replace the massive industry. But as companies look for ways to reduce emissions, it can offer a solution that works now. Because it doesn’t use shipping containers—goods are loaded on pallets—it also has some logistical advantages. “Some of these fast vessels have to wait at port often up to two weeks, because they’re dependent on the port infrastructure,” says Doggett. “They need the big crane to unload the container. We do not—we can unload ourselves.”

Doggett, who started sailing on tall ships as a 13-year-old, started thinking about the potential to revive traditional cargo shipping more than a decade ago. In 2014, she and two partners launched the company and later began working on building a traditional vessel from scratch. While traveling, Doggett had also run across the Vega. The ship, built in 1909, had been retired in the 1960s, as fossil-fueled container ships started to dominate trade routes. It was headed for the scrapyard when a family of Swedish shipbuilders rescued it and spent years restoring it; Doggett, who loved the design, stayed in touch with them and eventually made a deal to buy it.

June 16, 2025, Kaleigh Harrison

Verde and Ergon have signed a memorandum of understanding to scale the use of carbon-negative asphalt binders in U.S. infrastructure projects. The collaboration is designed to integrate Verde’s binder technology into Ergon’s existing national operations, making low-carbon asphalt available at commercial scale.

While efforts to cut operational emissions have advanced, the embedded emissions in materials such as asphalt remain a significant hurdle. By targeting these often-overlooked emissions, Verde and Ergon’s collaboration provides a practical, near-term solution that can be implemented within current roadbuilding practices.

Unlike many emerging carbon-reduction technologies, Verde’s binder is already compatible with existing asphalt standards and construction methods. This allows roadbuilders to adopt the material without the need for design changes, new equipment, or extensive retraining—critical factors for gaining market acceptance in the risk-averse construction sector.

Ergon brings established strengths to the partnership, including a nationwide network of asphalt refining and blending facilities and relationships with departments of transportation, contractors, and material suppliers. Leveraging this infrastructure provides a clear pathway to moving beyond pilot projects to full-scale market rollout.

Tackling Embodied Carbon in Road Construction

Pavement materials, including asphalt, contribute a significant share of the total carbon footprint of infrastructure projects.

Verde’s technology addresses this issue by capturing and converting CO₂ into a high-performance binder that replaces traditional petroleum-based materials. The resulting asphalt products are designed to meet or exceed current performance standards while delivering a lower carbon profile.

Imagine if every time you threw out your lawn and garden waste, you were actively fighting global warming? That’s the capacity a new soil amendment technology hopes to unleash across the world.

This potentially-revolutionary method of making fertilizer that almost completely removes greenhouse gas emissions has received a grant from Bloomberg Philanthropies to be incorporated into 7 major cities’ landscaping programs.

Making “biochar” as it’s called, has been modernized recently in Sweden, and is done by putting grass trimmings, hedge clippings, tree branches, or any other kind of yard waste, into an enclosed space and “pyrolyzing it” in such a way as to avoid the rapid oxidation of CO2.

More than three decades ago a radically new building material started gaining popularity - in Europe: The benefits of hempcrete (a.k.a. hemplime) include exceptional thermal performance, highly effective transmission of humidity, resistance to mould, and acoustic insulation. It is also fireproof, and sequesters more carbon than its industrial production requires. Given all these incredible benefits, it may sound surprising that until now hempcrete has been not been permitted in US building codes. This had to do with hemp being considered an illegal plant. With the legalization of cannabis for medical and even recreational use in many states, the US is finally ready to include hempcrete as a permitted material in its residential building codes.

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What is Hempcrete?

When separating the woody inner portion of the hemp stalk from the main fiber, we get what's called shives. They are also very fibrous, but unlike the main fiber, which is threaded into rope, shives are coarse, broken pieces. This material is what makes up the bulk of hempcrete. The other part is a limestone binder, using either hydrated or hydraulic lime. This is an industrial product, requiring the calcination of lime at very high temperatures in kilns, similar to the production of cement for concrete.

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After the hemp shives are mixed with the lime binder, and combined with the addition of water, the curing process starts. Depending on the type of binder, this could take up to a month. For this reason, the hempcrete is usually molded into blocks, similar to cinder blocks. In comparison, however, hempcrete tends to be lighter, and less brittle than concrete.

An Alternative to Concrete?

Before I continue comparing the characteristics of hempcrete to concrete, I want to get its most important drawback out of the way: Hempcrete has about 5% of the compressive strength of residential grade concrete. This means, it is never meant to be used as a structural material to bear great loads! However, excluding this main disadvantage, hempcrete outperforms concrete in so many other aspects, that it would be a waste dismissing this amazing material for its mere structural weakness.

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First of all, hempcrete is not only highly insulative, but it also has a good thermal mass. Normally these would be contradictory properties, since most other materials with plenty of thermal mass tend to be poor insulators, and vice versa. Hempcrete is a great exception to this rule, due to its efficient R value of between 0.67/cm (1.7/in) and 1.2/cm (3.0/in) and a specific heat capacity of between 1000 J/kg K to 1700 J/kg K. At the same time, hempcrete "breathes", meaning it is great at transmitting humidity, keeping the interior air dry, which creates a comfortable warm sensation.

Other beneficial attributes of hempcrete are that it is fireproof, resistant to moulds, and is highly effective at insulating against acoustic disturbances. Its most notable feature, however, has to do carbon sequestration, making it highly interesting for modern applications, as we are facing an overabundance of carbon in our atmosphere.

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Carbon-neutral... or Carbon-negative?

Even before it is turned into hempcrete, the hemp plant is already highly effective at taking up carbon from the atmosphere. At 15 tons of CO2 per hectare it does this much faster than any forest or commercial crop, while it is fast growing and doesn't require much care or delicate conditions. So growing hemp is already a great way to combat CO2, but hempcrete takes this carbon sequestration a step further.

In its natural cycle, the hemp plant stops taking up carbon once it dies. Sure, by that time it will likely have reproduced, and its offspring can continue the good work, but in the form of hempcrete even the dead hemp plant can continue this process thanks to the lime binder it is mixed with. Due to the carbonation process, the lime continues absorbing CO2, not only during its curing phase, but throughout its entire existence. The amount of this is estimated around -1.6 to -79 kg CO2e/m2.

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This means that even though the production of the lime binder involves a good amount of carbon emissions, it is all made up by the joint effects of growing hemp and converting it into hempcrete. So you could say that hempcrete is not only a carbon-neutral building material, but it is in fact carbon-negative, removing more carbon from the atmosphere than it has put into it.

Time to Start the Future?

Given its amazing properties, and time tested practicality in Europe, there are many ambitious projects related to hempcrete. One such proposed application are the Urban Sequoias, enormous high-rise buildings that are supposed to sequester 1,000 tons of CO2 per year, about the amount of 48,500 trees. Although no Urban Sequoia has been built so far, the technology is highly promising.

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Also, now that the United States has incorporated hempcrete as a permitted material in its 2024 International Residential Code, it can be expected that this it will find further appeal and acceptance among builders, architects, and engineers in far reaching applications.

Excerpt from this story from ABC News (Australia):

Tasmania has become one of the first parts of the world to become not just carbon neutral but carbon negative by reducing logging, researchers say.

Scientists from the Australian National University (ANU) and Griffith University "drilled into" the national greenhouse gas inventory and looked at each state's contribution.

They saw Tasmania had made a "remarkable achievement".

"Tasmania has gone from being the emitter of carbon dioxide to now removing more than it is emitting to the atmosphere," Griffith University researcher Brendan Mackey said.

"The mitigation benefit is about 22 million tons of carbon dioxide a year."

Professor David Lindenmayer from the ANU said "we hear a lot about carbon neutral but not carbon negative".

"This is one of the first times on the planet that anybody has ever done this kind of reversal," he said.

Researchers then examined native forest harvesting and concluded the change in carbon footprint could be attributed to the reduction in native forest logging, meaning the forests would continue to grow, all the while "removing carbon from the atmosphere".

"Most people don't realise that when you log native forests, it has a huge carbon footprint," Professor Mackey said.

"And when you change the forest management to reduce the amount of native forest logging you use, you avoid very significant amounts of CO2 emissions."