Sea the possibilities: to fight climate change, put seaweed in the mix

Nadya Peek/Flickr, CC BY-SA

Adam Bumpus, University of Melbourne

The next stage of humanity’s fight to reduce greenhouse emissions may revolve around seaweed, according to tonight’s episode of ABC’s Catalyst, presented by Professor Tim Flannery, which asks the question “can seaweed save the world?”

With the help of me and colleagues around the world, the documentary explores seaweed’s enormous potential to reduce greenhouse gases and draw CO₂ out of the atmosphere. In the case of seaweed, that could include giant kelp farms that de-acidify oceans, or feeding algae to cattle and sheep to dramatically reduce their methane emissions.

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Read more: How farming giant seaweed can feed fish and fix the climate

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But while these possibilities are exciting, early adopters are dealing with unproven technology and complex international treaties. Globally, emissions are likely to keep rising, which means seaweed-related carbon capture should only be one part of a bigger emissions reduction picture.

Net negative emissions

To stay within the Paris climate agreement’s 2℃ warming threshold, most experts agree that we must remove carbon from the atmosphere as well as reduce emissions. Many scientists now argue that 2℃ will still cause dangerous climate change, and an upper limit of 1.5℃ warming by 2100 is much safer.

To achieve that goal, humanity must begin reducing global emissions from 2020 (in less time than it takes an undergrad enrolling now to finish their degree) and rapidly decarbonise to zero net emissions by 2050.

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Read more: We need to get rid of carbon in the atmosphere, not just reduce emissions

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Zero net carbon emissions can come from radical emissions reductions, and massive geoengineering projects. But it could be vastly helped by what Flannery calls “the third way”: mimicking or strengthening Earth’s own methods of carbon capture.

Studies support the need to remove carbon from the atmosphere, but there are serious technical, economic and political issues with many large-scale plans.

On the other hand, seaweed solutions could be put to work in the biologically desert-like “doldrums” of the ocean, and have positive side effects such as helping to clear up the giant ocean rubbish patches. However, there are many technical problems still to be solved to make this a reality.

We probably haven’t reached peak emissions

Removing carbon from the atmosphere is an attractive proposition, but we can’t ignore the emissions we’re currently pumping out. For any negative emissions technology to work, our global emissions from fossil fuels must start to drop significantly, and very soon.

But wait a second, haven’t we already hit peak emissions? It’s true that for the third year in a row, global carbon dioxide emissions from fossil fuels and industry have barely grown, while the global economy has continued to grow strongly.

This is great news, but the slowdown in emissions growth has been driven primarily by China, alongside the United States, and a general decline of emissions in developed countries.

China’s reductions are impressive. The country peaked in coal consumption in 2014, and tends to under-promise and over-deliver on emissions reductions. However, under the Paris agreement, China has committed to a 60-65% reduction in emissions intensity, which means there’s still room for them to rise in the future.

India’s emissions, on the other hand, are major wild card. With a population of 1.3 billion and rising, about 300 million of whom are still not connected to an electrical grid, and potential increases in coal use to provide energy, India will be vital to stabilising greenhouse gases.

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Read more: To slow climate change, India joins the renewable energy revolution

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India’s emissions today match those of China in 1990. A study that combined India’s Paris agreement targets with OECD estimates about its long-term economic growth, suggested India’s CO₂ emissions could still grow significantly by 2030 (although per capita emissions would still be well below China and the US).

The emissions reduction relay race

So how do we deal with many competing and interconnected issues? Ideally, we need an array of solutions, with complementary waves of technology handling different problems.

Clearly the first wave, the clean energy transition, is well under way. Solar installations are breaking records, with an extra 75 gigawatts added to our global capacity in 2016, up from 51 gigawatts installed in 2015. But this still represents just 1.8% of total global electricity demand.

In addition to renewable energy generation, limiting warming to below 1.5°C also means we must increase the efficiency of our existing grid. Fortunately, early-stage financiers and entrepreneurs are focusing on a second wave of smart energy, which includes efficiency and optimisation technologies. Others in Australia have also noted the opportunities offered by the increasing use of using small, smart devices connected to the internet that respond to user demand.

Although early user results have been mixed, research shows better system control reduces the emissions intensity of energy generation. These energy efficient devices and optimisation software are on the cusp of becoming widely commercially available.

Critically, these efficiency technologies will be needed to complement structural change in the fossil fuel energy mix. This is especially in places where emissions are set to grow significantly, like India. Building renewable energy capacity, optimising with new software and technologies, and better understanding the opportunity for net negative emissions all play an important part in the emissions reductions relay race over the next 50 years to get us to 1.5°C.

With further research, development, and commercialisation, the possibilities offered by seaweed – outlined in more detail in the Catalyst documentary – are potentially game-changing.

But, as we saw with the development of renewable energy generation technology, it takes a long time to move from a good idea to wide implementation. We must support the scientists and entrepreneurs exploring zero-carbon innovations – and see if seaweed really can save the world.

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Can Seaweed Save the World? airs on the ABC on Tuesday 22 August at 8.30pm.

Adam Bumpus, Senior Lecturer, Environment & Innovation, University of Melbourne

This article was originally published on The Conversation. Read the original article.

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Greening the concrete jungle: how to make environmentally friendly cement

With some tweaks to the recipe, cement and concrete can be made kinder to the planet.
Postman Photos/Shutterstock.com

Rackel San Nicolas, University of Melbourne

Cement is the world’s most widely used material apart from water, largely because it is the key ingredient in concrete, the world’s favourite building material.

But with cement’s success comes a huge amount of greenhouse emissions. For every tonne of cement produced in Australia, 0.82 tonnes of CO₂ is released. That might not sound like much, especially when compared with the 1.8 tonnes emitted in making a tonne of steel. But with a global production of more than 4 billion tonnes a year, cement accounts for 5% of the world’s industrial and energy greenhouse emissions.

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Read more: The problem with reinforced concrete.

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The electricity and heat demands of cement production are responsible for around 50% the CO₂ emissions. But the other 50% comes from the process of “calcination” – a crucial step in cement manufacture in which limestone (calcium carbonate) is heated to transform it into quicklime (calcium oxide), giving off CO₂ in the process.

A report published by Beyond Zero Emissions (BZE) (on which I was a consultant) outlines several ways in which the sector can improve this situation, and perhaps even one day create a zero-carbon cement industry.

Better recipes

The cement industry has already begun to reduce its footprint by improving equipment and reducing energy use. But energy efficiency can only get us so far because the chemical process itself emits so much CO₂. Not many cement firms are prepared to cut their production to reduce emissions, so they will have to embrace less carbon-intensive recipes instead.

The BZE report calculates that 50% of the conventional concrete used in construction can be replaced with another kind, called geopolymer concrete. This contains cement made from other products rather than limestone, such as fly ash, slag or clay.

Making this transition would be relatively easy in Australia, which has more than 400 million tonnes of fly ash readily available as stockpiled waste from the coal industry, which represents already about 20 years of stocks.

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Read more: Eco-cement, the cheapest carbon sequestration on the planet.

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These types of concrete are readily available in Australia, although they are not widely used because they have not been included in supply chains, and large construction firms have not yet put their faith in them.

Another option more widely known by construction firm is to use the so-called “high blend” cements containing a mixture of slag, fly ash and other compounds blended with cement. These blends have been used in concrete structures all over the world, such as the BAPS Shri Swaminarayan Mandir Hindu temple in Chicago, the foundation slab of which contains 65% fly ash cement. These blends are available everywhere in Australia but their usage is not as high as it should due to the lack of trust from the industry.

Built on the fly (ash): a Hindu temple in Chicago.
BAPS.org/Wikimedia Commons, CC BY-SA

It is even theoretically possible to create “carbon-negative cement”, made with magnesium oxide in place of traditional quicklime. This compound can absorb CO₂ from the air when water is added to the cement powder, and its developer Novacem, a spinoff from Imperial College London, claimed a tonne of its cement had a “negative footprint” of 0.6 tonnes of CO₂. But almost a decade later, carbon-negative cement has not caught on.

Capturing carbon

The CO₂ released during cement fabrication could also potentially be recaptured in a process called mineral carbonation, which works on a similar principle as the carbon capture and storage often discussed in relation to coal-fired electricity generation.

This technique can theoretically prevent 90% of cement kiln emissions from escaping to the atmosphere. The necessary rocks (olivine or serpentine) are found in Australia, especially in the New England area of New South Wales, and the technique has been demonstrated in the laboratory, but has not yet been put in place at commercial scale, although several companies around the world are currently working on it.

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Read more: The ‘clean coal’ row shouldn’t distract us from using carbon capture for other industries.

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Yet another approach would be to adapt the design of our buildings, bridges and other structures so they use less concrete. Besides using the high-performance concretes, we could also replace some of the concrete with other, less emissions-intensive materials such as timber.

Previously, high greenhouse emissions were locked into the cement industry because of the way it is made. But the industry now has a range of tools in hand to start reducing its greenhouse footprint. With the world having agreed in Paris to try and limit global warming to no more than 2℃, every sector of industry needs to do its part.

Rackel San Nicolas, Academic specialist, Infrastructure Engineering, University of Melbourne

This article was originally published on The Conversation. Read the original article.

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