CLIMATE & CO2
In our ongoing climate series, we look at ways to reduce greenhouse gases not by reducing emissions, but by removing some of the carbon dioxide already in the atmosphere.
Global warming can only be slowed if we declare all-out war on carbon dioxide and other greenhouse gases. The climate army is developing new weapons for air, land and water, turning beaches green, using carboneliminating liquid, and developing huge ‘carbon vacuum cleaners’.
You could once see the ocean inlet from here, looking east out of the apartment window. Now you look directly out at a rising harbour wall, watching workers in yellow suits make it taller still. The wall is the city’s latest defence against storm surges and ocean levels that are rising 5cm a year. You open the window to catch a breeze; the summers are increasingly warm and moist, and even at night, temperatures are rarely below 30 degrees. Air-conditioning has been banned to reduce energy consumption, and the window’s finemeshed fly-screen prevents fresh air from entering. Welcome to Australia in 2100 – and a world that is six degrees warmer.
The risk is, in fact, minimal that global warming will get so far out of hand as to make temperatures rise by six degrees during this century. But it could happen. Meanwhile in 2015, the political leaders of the world agreed to try to limit the temperature rise to approximately 1.5 degrees above levels at the start of the industrial revolution, when greenhouse gas emissions gained their rising momentum.
This target of temperature rise below 1.5 degrees can probably only be met by limiting the emissions of greenhouse gases such as carbon dioxide (CO ). But the transition is proceeding too slowly from fossil fuels such as coal, oil and gas to green ones that take advantage of wind, sunlight, and water. So instead, scientists are now working to develop new weapons to be used against greenhouse gases. They aim to combat carbon dioxide levels with hungry minerals, biochar, and photosynthesis – and these new climate warriors are poised to take action.
Mineral absorbs carbon dioxide
Scientists are fighting on two fronts in their war against CO . The first step is to remove 2 large quantities of the problematic greenhouse gas that have already entered the atmosphere. Using sophisticated chemistry and huge CO capturers, or by accelerating 2 natural processes, they aim to extract the greenhouse gases from the atmosphere.
In this connection, the greenish olivine mineral is proving to be a true CO killer. 2 When the mineral comes into contact with water it absorbs carbon dioxide, converting the gas into harmless substances such as orthosilicic acid, which helps ocean algae to build their shells. Calculations show that
the world’s existing CO emissions can be 2 counteracted if 1000 large cargo ships were to spread olivine on beaches throughout the world.
Another approach is to capture carbon dioxide from chimney filters and other emission points, but the harder step may be storing it once captured, so the greenhouse gas no longer contributes to global warming. One solution is to bind the carbon dioxide in warm rock. In Iceland, a group of scientists has managed to convert CO from the air 2 into minerals embedded in basalt.
Emissions are still on the rise
The sooner these different CO weapons are 2 ready to be used, the better. In spite of the international agreements on limiting the climate effect, carbon dioxide is still rising from the world’s chimneys, exhaust pipes and farmland.
The most recent data from the International Energy Agency (the IEA, an intergovernmental
organisation that aims to ensure clean energy supply) reveals that the world’s total energy consumption rose by 2.3% in 2017/18. The data also shows that the burning of coal, oil and gas was responsible for the majority of the increase. The total emissions of greenhouse gases rose by 1.7% in 2017/18, showing how things are still developing in the wrong direction – as they have been for more than 150 years.
Since the industrial revolution gained ground in the mid-1800s, mankind has contributed some 2000 billion tonnes of CO to the atmosphere. Back then, the concentration was some 280 carbon dioxide molecules per one million air molecules. That figure is now more than 410 CO molecules per one million air molecules. It may not seem a high proportion in itself, but the increase of 46% in just 150 years is significantly rapid. With CO acting as a greenhouse gas, these higher concentrations have seen global temperatures increase by approximately 1°C already in this time.
In other words, we have only an increase of some 0.5 degree left before we hit the 1.5°C ceiling on which world leaders agreed in 2015. And as the temperature rise is a delayed effect compared to the rises in greenhouse gas emitted, scientists believe that we can emit only another 770 billion tonnes of carbon dioxide into the atmosphere if the temperature rise is to have a 50% chance of remaining below 1.5°C.
If we wish to improve those odds to 67%, then we can emit only another 570 billion tonnes of CO . With the nations of the world currently pumping 40-50 billion tonnes of carbon dioxide into the atmosphere annually, the sums become simple: we can afford only 10-12 years of current emission levels before the 1.5°C limit is reached. And doing so only by preventing more greenhouse gas emissions now seems unrealistic.
More weapons to win the war
It is both expensive and time-consuming to prevent carbon emissions by making wholesale changes to the world’s transport systems, the way we produce food and consumer goods, and the introduction of climate-friendly alternatives such as electric cars, solar cells, and wind turbines. These may be valuable and necessary changes, but they simply won’t be enough. Power stations based on fossil fuels such as coal, oil and gas are still being built for future use, and their estimated emissions will consume half of
that tight ‘budget’ of 570 billion tonnes of CO in advance – unless these plants are closed down before their expected lifetime or are converted to reduce emissions.
This is where the concept of CO elimination enters the scene. Scientists from England, the US, Scotland and Austria have analysed available knowledge and ideas on how to fight CO , and they delivered several central conclusions. The most important is that the removal of carbon dioxide and other greenhouse gases from the atmosphere is “a biological necessity” to meet the international requirement of a maximum global temperature rise of 1.5 degrees. If the aim were two degrees, we might still make it by restructuring the energy sector to focus on renewable energy sources and choosing green solutions whenever possible.
The scientists also concluded that one weapon against CO will not be enough, so they recommend a carefully selected range of technologies, at the same time pointing out that a much swifter pace is required in
financing, research and development, as the weapons must be employed within 10 years, when the need to combat CO is expected to be critical. Indeed the scientists highlight a handful of methods that are already highly efficient and so simple that we could be using them already.
First wave: wood and chemistry
All studies agree that new forest is one of the cheapest ways to combat CO in the atmosphere at a price of less than A$72 per tonne captured, with those costs covering purchasing land, planting small trees, plus continuous control and care. One of the challenges for this method is that large areas of farmland will need to be covered to make a difference, and such spare land is increasingly unavailable, with agricultural production rising to feed the world’s growing population. The planet already includes 7.7 billion people, with the number likely to rise to 9.8 billion by 2050. So scientists have set an upper estimate of 3.5 billion tonnes of removed CO per year that could come from new and reestablished forest – about 10% of the present annual emissions.
The longterm destiny of the trees from such forests is also important. Unless the trees are treated correctly when they get old and die, the greenhouse gas will escape again as the trunks rot on the forest floor. So the trees must be felled when they are ready, and either burned in power plants with chimney filters collecting and storing the carbon dioxide, or used as timber in high-quality furniture or houses that will have lifespans lasting decades.
The potential of chemically removing CO from chimney smoke is obvious, but at present the methods remain expensive because of the high energy expended in the process. If a plant powered by coal or natural gas is to be carbon neutral, 10-25% of its electricity production must be used to capture the emitted carbon dioxide. But there are other ways to use these technologies. Instead of preventing greenhouse gases at the point of emission, they might reduce the CO concentration of the wider atmosphere.
Increasing pressure
The first such experiments are already taking place, and in several places. One company at an advanced development stage is Climeworks of Switzerland. The company has test set-ups with huge CO capturers in several locations including Hinwil, south-east of Zurich. The technology is mature and ready to be employed.
Climeworks’ method is, however, expensive. To remove the greenhouse gas from the atmosphere requires even more energy than from chimney smoke, because atmospheric concentrations are lower. The company estimates that the price per tonne of captured CO is currently as much as A$1000, although cofounder Christoph Gebald estimates that the price will fall rapidly to less than
A$150 with rising demand and increased scale. Yet if the energy to power the CO capturer is supplied by a coal-powered plant, the plant produces more
CO than Climeworks captures. Today, the test set-ups are powered by green energy, but if the system were to be upscaled to tens of thousands of plants throughout the world, it could put pressure on available solar, wind, and hydro energy. Furthermore the process itself does not store the captured carbon, so the efficiency of further use or of carbon storage also impacts upon the positive effects.
In spite of the challenges, these new climate warriors hope to have a wellequipped arsenal and a detailed action plan against CO within 5-10 years. This does, however, not mean that it is the best solution to the climate crisis. Many scientists point out that the possibility of removing carbon dioxide emissions from the atmosphere can be used as an excuse for doing less in the way of the necessary transition to greener technologies and practices. As in other conflicts, a solution reached around the negotiating table is always preferable to all-out war.