New technology offers hope for storing carbon dioxide underground


Dom Wolff-Boenisch, Curtin University

To halt climate change and prevent dangerous warming, we ultimately have to stop pumping greenhouse gases into the atmosphere. While the world is making slow progress on reducing emissions, there are more radical options, such as removing greenhouse gases from the atmosphere and storing them underground.

In a paper published today in Science my colleagues and I report on a successful trial converting carbon dioxide (CO₂) to rock and storing it underground in Iceland. Although we trialled only a small amount of CO₂, this method has enormous potential.

Here’s how it works.

Turning CO₂ to rock

Our paper is the culmination of a decade of scientific field and laboratory work known as CarbFix in Iceland, working with a group of international scientists, among them Wallace Broecker who coined the expression “global warming” in the 1970s. We also worked with the Icelandic geothermal energy company Reykjavik Energy.

The idea itself to convert CO₂ into carbonate minerals, the basis of limestone, is not new. In fact, Earth itself has been using this conversion technique for aeons to control atmospheric CO₂ levels.

However, scientific opinion had it up to now that converting CO₂ from a gas to a solid (known as mineralisation) would take thousands (or tens of thousands) of years, and would be too slow to be used on an industrial scale.

To settle this question, we prepared a field trial using Reykjavik Energy’s injection and monitoring wells. In 2012, after many years of preparation, we injected 248 tonnes of CO₂ in two separate phases into basalt rocks around 550m underground.

Most CO₂ sequestration projects inject and store “supercritical CO₂”, which is CO₂ gas that has been compressed under pressure to considerably decrease its volume*. However, supercritical CO₂ is buoyant, like a gas, and this approach has thus proved controversial due to the possibility of leaks from the storage reservoir upwards into groundwater and eventually back to the atmosphere.

In fact, some European countries such as the Netherlands have stopped their efforts to store supercritical CO₂ on land because of lack of public acceptance, driven by the fear of possible leaks in the unforeseeable future. Austria went even so far as to ban underground storage of carbon dioxide outright.

The injection well with monitoring station in the background.
Dom Wolff-Boenisch, Author provided

Our Icelandic trial worked in a different way. We first dissolved CO₂ in water to create sparkling water. This carbonated water has two advantages over supercritical CO₂ gas.

First, it is acidic, and attacks basalt which is prone to dissolve under acidic conditions.

Second, the CO₂ cannot escape because it is dissolved and will not rise to the surface. As long as it remains under pressure it will not rise to the surface (you can see the same effect when you crack open a soda can; only then is the dissolved CO₂ released back into the air).

Dissolving basalt means elements such as calcium, magnesium, and iron are released into pore water. Basaltic rocks are rich in these metals that team up with the dissolved CO₂ and form solid carbonate minerals.

Through observations and tracer studies at the monitoring well, we found that over 95% of the injected CO₂ (around 235 tonnes) was converted to carbonate minerals in less than two years. While the initial amount of injected CO₂ was small, the Icelandic field trial clearly shows that mineralisation of CO₂ is feasible and more importantly, fast.

Storing CO₂ under the oceans

The good news is this technology need not be exclusive to Iceland. Mineralisation of CO₂ requires basaltic or peridotitic rocks because these types of rocks are rich in the metals required to form carbonates and bind the CO₂.

As it turns out the entire vast ocean floor is made up of kilometre-thick oceanic basaltic crust, as are large areas on the continental margins. There are also vast land areas covered with basalt (so-called igneous provinces) or peridotite (so-called “ophiolitic complexes”).

The overall potential storage capacity for CO₂ is much larger than the global CO₂ emissions of many centuries. The mineralisation process removes the crucial problem of buoyancy and the need for permanent monitoring of the injected CO₂ to stop and remedy potential leakage to the surface, an issue that supercritical CO₂ injection sites will face for centuries or even millennia to come.

On the downside, CO₂ mineralisation with carbonated water requires substantial amounts of water, meaning that this mineralisation technique can only succeed where vast supplies of water are available.

However, there is no shortage of seawater on the ocean floor or continental margins. Rather, the costs involved present a major hurdle to this kind of permanent storage option, for the time being at least.

In the case of our trial, a tonne of mineralised CO₂ via carbonated water cost about US$17, roughly twice that of using supercritical CO₂ for storage.

It means that as long as there are no financial incentives such as a carbon tax or higher price on carbon emissions, there is no real driving force for carbon storage, irrespective of the technique we use.

*Correction: The sentence has been corrected to note that gas volume rather than density decreases when it is compressed. Thankyou to the readers who pointed out the error.

The Conversation

Dom Wolff-Boenisch, Senior Lecturer, Western Australian School of Mines, Curtin University

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

Farming in 2050: storing carbon could help meet Australia’s climate goals


Brett Anthony Bryan, CSIRO

Australia’s agricultural lands help to feed about 60 million people worldwide, and also support tens of thousands of farmers as well as rural communities and industries.

But a growing global population with a growing appetite is placing increasing demands on our agricultural land. At the same time, the climate is warming and in many places getting drier too.

Agriculture, and particularly livestock, is currently a major contributor to greenhouse gas emissions. But new markets and incentives could make storing carbon or producing energy from land more profitable than farming, and turn our agricultural land into a carbon sink.

How might these competing forces play out in changing Australian land use? Our research, published in Global Environmental Change, assesses a range of potential pathways for Australia’s agricultural land as part of CSIRO’s National Outlook.

Changing landscapes

The only constant in landscapes is change. Ecosystems are always changing in response to natural drivers such as fire and flood.

Humans have complicated things. Indigenous Australians manipulated the Australian landscape and climate through burning for millennia, sustaining a population of around 750,000 and underpinning a culture.

European colonisation brought a different and more pervasive change, clearing land, building cities, damming rivers and establishing an increasingly mechanised and industrialised agriculture.

These iconic but changed landscapes inspired the romantic art of Arthur Streeton and poetry of Banjo Paterson among many others — and helped forge a young nation’s identity.

‘Still glides the stream, and shall for ever glide’, 1890. Arthur Streeton. The Art Gallery of NSW describes the painting as ‘an idealised vision of the Yarra River at Heidelberg, with the Doncaster Tower in the middle distance and the Dandenong Ranges beyond’.

Change can happen surprisingly quickly. Often before we know it we’ve gone too far and need to scramble for fixes that are so often costly, slow and ultimately inadequate.

For example, in South Australia, researchers in the early 1960s raised the alarm that the feverish post-war period of soldier resettlement, land clearance and agricultural development threatened entire native plant and animal communities with extinction. The government’s response over the following 30 years was to expand greatly the conservation reserve network and eventually prohibit land clearing.

https://www.google.com/maps/d/u/0/embed?mid=zXUWIAKxCpHk.kLpt_wSpBC7U

History repeating?

Agricultural lands produce a range of goods and services. But in many places the focus on agricultural productivity has come at the expense of ecosystems. Biodiversity, soil and water are all on downward trends.

Is the balance right? Opinion varies. Many would say no, and consider the status quo to be stacked strongly against the environment.

Others see agriculture as entering a boom time, driven by growing population and rising food prices. Substantial interest from overseas investors in Australian agricultural land reflects this opportunity.

Parts of Australia’s agricultural land continue to change fast. Lessons hard-learned by South Australia seem to have been forgotten. Rates of land clearance in Queensland are rising again since 2010 after a long-term trend of decline.

In the 1990s, new financial incentives led to the planting of over 1 million hectares of forest in southern Australia. Now a failed business model, many of these plantations are being returned to agriculture.

Demand for more secure sources of energy has generated rapid expansion of coal seam gas and wind power generation, and the development of northern Australia remains a bipartisan priority.

Worldwide, Australia is not alone — many international examples also exist of recent, massive, rapid and accelerating changes in how land is used.

Australia has historically taken a hands-off approach to managing land use change, instead focusing on increasing the productivity and competitiveness of agriculture. Apart from a handful of planning and environmental regulations, the use of land has been subject to minimal governance or strategic direction.

Where to from here?

What is it that Australians really want from our land? We know what we don’t want: wall-to-wall crops, pasture, buildings, gas wells, mines, wind farms or trees.

We can expect healthy debate around the margins, but, in general, diversity, productivity and sustainability seem to be widely valued. Most of us want to leave the place in decent condition for future generations.

Europe has had this conversation and knows what it wants from its landscapes — and it’s not afraid to pay for it (for instance, through agricultural subsidies). A deep aesthetic and cultural heritage is the central objective, with a balance of recreation opportunities, tourism, a clean and healthy environment and high-quality produce all being high priorities.

Once we know what we want, we can work out how to get there.

That’s where science can help. We now have the ability to project changes in land use in response to policy and global change, and the environmental and economic consequences.

CSIRO’s recent National Outlook mapped Australia’s potential future pathways. A companion paper in Nature found that it is possible to achieve strong economic growth and reduce environmental pressure, if we put the right policies in place now. It provides a glimpse of how our rural lands might respond to coalescing future change pressures.

Farming carbon

In our modelling, carbon sequestration in the land sector plays a key role of Australia’s future. Land systems can help with the heavy lifting required to hold global warming to 2℃ as recently agreed in Paris.

There are several factors that could drive this change, including climate, carbon pricing, global food demand and energy prices.

We modelled the economic potential for land use change and its impacts in over 600 scenarios (full data available here), combining a suite of global outlooks and national policy options.

A carbon price, which enables landholders to make money from storing carbon in trees and soils (often much more money than from farming), may increase pressure to shift farmland to restored forests.

Who knows? A pay rise while watching trees grow could be an attractive proposition for our ageing farmers. Complementary biodiversity payments could also help arrest declines in wildlife and help it adapt to climate change.

If we redouble our focus on productivity, by 2050 agriculture will produce more than today, even as farmland contracts. The least productive areas are less able to compete with reforestation and other new land uses, leaving the most efficient agricultural land in production.

But trade-offs are likely. Trees use a lot more water than crops and pasture, so we will need to think carefully about managing water resources.

Economic potential for land use change and sustainability impacts from 2013 to 2050 under national global environmental and economic conditions consistent with 2℃ warming by 2100

Australians care about their land and are more aware than ever about what is happening to it. While we can have some control over the future of our land, and we do exercise this control in certain circumstances (such as urban planning), our long-term approach to rural land has been to let environmental and economic forces play out and let the invisible hand of economics determine what will be.

Given the pace at which change can happen, a smarter approach will be to start the conversation, work out what it is we want from our land, and put the policies and institutions in place to get us there.

The Conversation

Brett Anthony Bryan, Principal Research Scientist, Environmental-economic integration, CSIRO

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