I have to admit to being a fan of Karl Popper’s notion that, basically, what distinguishes science from non-science is that it is refutable. Or, looking at it another way, aiming to knock down theories is a key part of the scientific enterprise, while cosy unquestioning consensus should make us wary. I therefore see as healthy the climate science debates we have seen in recent months, largely sparked by revelations of what appear to be some very dubious practices at the University of East Anglia in the UK.
At the same time, where there is residual uncertainty, regulators quite rightly err on the side of caution, so it seems that the pressure to decarbonise will be undiminished over the coming years, despite the lack of anything substantial coming out of Copenhagen, and entrenched opposition to climate change legislation in some countries, notably in the senates of Australia and the USA. It is significant that the US environmental regulator, the EPA, has finally made a pronouncement that greenhouse gases, including, of course, CO2, “threaten the public health and welfare of the American people” – what it calls its “endangerment finding.”
So carbon capture and storage (CCS) is unlikely to slip down the fossil power industry’s agenda any time soon. But, as we have said in this column on several previous occasions, what would really help move things forward would be what might be termed a “killer”, or at least productive, application for the vast quantities of CO2 that carbon capture will produce, in addition to enhanced oil recovery (which is not always feasible, and assumes there is a handy depleted oil/gas field nearby). This would be much better than just shoving the stuff underground.
Could cement manufacture be the answer? Bechtel clearly thinks so as it has just announced a strategic alliance with California-based Calera to develop and construct facilities to take the carbon dioxide from flue gases and turn it into calcium and magnesium carbonates, which can be used to make cement, a high value commodity currently commanding a price of about $100/t, and aggregates.
As the founder of Calera, Brent Constantz, puts it, “a roadway is a good place to store CO2.” He believes that the emphasis on underground geological storage that we find in current CCS initiatives, including for example inherent in the wording of US energy and climate bills, is essentially the result of good work by the oil and gas
lobbyists. He thinks the power sector has been “suckered into” a geological mindset and suggests that it “should be talking to the cement industry, not the oil and gas business.”
Of course he would say that; his background is cement, medical applications in particular. But his technology, which he describes as “above ground sequestration” or “sequestering in the built environment”, does seem to have a lot going for it. For example: it looks to be deployable in the relatively near term and avoids the risks (regulatory and otherwise) associated with geological storage; it can produce large quantities of potable water as a byproduct (a key consideration in Australia’s Latrobe Valley, where a demo project is underway (at the Yallourn plant)); it can deal with SO2 as well as CO2 and is robust in terms of the levels of other pollutants in the flue gas; and it has promising energy balances, particularly when it is assumed that the cement produced displaces that produced by conventional, highly energy intensive, processes.
It is also worth noting that coal power stations are already geared up to supplying materials into the construction industry, eg gypsum and fly ash, and are often located near to where there is a demand for cement and aggregates.
Another key aspect of the Calera concept – perhaps the key feature – is that, if it works (and two years of results from test facilities at Moss Landing, California, appear encouraging) the process of decarbonising power plant flue gas would become a profit centre not a cost : game-changing indeed.
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