Carbon storage a dead-end

There are several cheaper, quicker and more long-term sustainable methods to reduce emissions from steel production than CCS. Photo: Jean-Etienne Minh-Duy Poirrier/flickr.com/ CC BY-SA

CCS could make sense for industrial emissions. Or, then again, maybe not.

CCS is a technological solution that was much hyped in the early 2000s, promoted by the George W. Bush administration, by UK and German governments, by the IEA and the European Union, and most of all by Norway and Vattenfall.
After a thousand conferences and PowerPoint presentations, all the efforts of the last 15 years can be summed up as follows: nothing happened, except for some enhanced oil recovery projects and three irrelevant projects in or by Norway, where CO₂ from natural gas processing was captured and stored.

If CO₂ is pushed into oil wells so as to squeeze out more oil, it obviously results in more CO₂ compared to no CCS.  It is not an alternative or complement to renewable energy or more efficiency. It is not a bridge to sustainability. It is not mitigation.

Storage of CO₂ from natural gas processing, as in Snöhvit, Sleipner and In Salah, Algeria, (with Norwegian Statoil as one of three owners) is clearly an improvement on doing nothing. But the separation has to be done anyway, as CO₂ is not wanted in the product, natural gas. This CO₂ stream is miniscule compared with CO₂ emissions from combustion of fuels. The CO₂ content of a ton of raw natural gas is a few per cent, say 25 kg. But when you burn that ton of gas, it produces three tons of CO₂.

This is still optimistic, as not all gas processing plants are close to a good site for storage. Clearly this is no major way to stop climate change.

The really overwhelming CO₂ problem is emissions from power generation, especially coal power, and the CCS projects so far show next to nothing about its viability.

But because so much money, prestige and emotion have been invested in CCS, there is a widespread wish to find some corner where it might work.

Biomass CCS is one candidate. Burning biomass for power and heat does not add CO₂ to the atmosphere, but if you can burn biomass and then store the CO₂, you will get negative emissions!

The IPCC writes:
“Combining bioenergy with CCS (BECCS) offers the prospect of energy supply with large-scale net negative emissions which plays an important role in many low-stabilization scenarios, while it entails challenges and risks.”¹

The IPCC report is however very abstract and does not specify where and how BECCS might be feasible.

Biomass includes a wide range of materials: sewage sludge, household waste, demolition timber, waste products from forestry such as bark and branches, waste products from agriculture and the food industry, such as straw and olive pits, and finally dedicated biomass such as short-rotation coppice, eucalyptus and some grasses.

Almost all of these cost more to transport than coal, oil or gas, because they have a lower energy density. This means that biomass generally speaking is a local fuel, in the 1–100 megawatt scale, unlike the gigawatt scale for coal power, and several hundred-megawatt scale for gas power.

On the whole, biomass is more expensive than coal; it is simply cheaper to steal than to work. This also means that biomass is mainly used either for heat or as process fuel in the pulp industry or for combined heat and power, typically with an efficiency of 85 per cent.

It is not, and should not be, often used in gigawatt scale power plants, because then some 60 per cent of the energy is wasted. There is not enough biomass in the world to allow for that on a large scale.

If there is no economic case for coal power CCS – and we do not see this happening anywhere in the world – there is even less of a case for biomass power or heat CCS, because there is an economy of scale. A hundred 20 MW or a thousand 2 MW separation units clearly cost more than one 2,000 MW plant. The same goes for transport to storage sites. It obviously costs more to build a thousand small storage sites than a single big one, and it even more obviously costs more to build CO₂ pipelines to a single big storage site from a thousand small plants than to build a pipeline from one big power plant.

It is not going to happen.

Other candidates for CCS are steel, cement, lime, mining, metals and paper/pulp industries. The idea² is that as they cannot reduce their emissions very much in any other way, so we have to use CCS there, especially if we emit too much before 2050.

The paper/pulp industry is similar to biomass power and heat. While collectively a large source of CO₂, both fossil and biogenic, the individual plants are much smaller as point sources of CO2 than big coal power plants. They are spread out through the forests, and many are not near a suitable storage site. Plants use different technologies and differ in size and design, so the separation stage will have to be more individually tailored for each, at a substantial cost. There are some fairly big point sources.

Steel is produced either from ore or from scrap. Scrap re-melting is not much of a CO₂ source. Ore-based steel, on the other hand, is a major emitter because the reduction of iron oxides to iron metal almost always uses coal as a reductant. Some steelworks are very big point sources of CO₂. The three blast furnaces in Sweden emit 12 per cent of the national CO₂ emissions. But none of them are close to a potential CO₂ storage site, and even if they were, it is an enormous investment with no value chain in sight.

There are several cheaper, quicker and more long-term sustainable methods to address the issue. Reduce: better steel and better designs so less of it is needed. In many applications, steel can be substituted with lighter metals, ceramics, polymers or wood or carbon fibres. Recycling rates can be improved, and this is easier if the total use of steel is minimized. The blast furnace was invented 2,000 years ago and is far from an optimal design, even if it is considered as the only way to make iron from ore with coal. Real-world furnaces all over the world are often old and inefficient by any standard, and many were built and maintained with large government subsidies for reasons of national prestige. They leak heat. Process control is not impressive. Scrap steel is thrown in as a method of cooling the melt. Instead of recirculating combustible gases to reduce the ore, they burn the gases and add more coal instead. Coke is a form of coal with especially high emissions, and could be replaced by direct coal injection. Even better would be to replace some coal with natural gas, biomass or hydrogen from electrolysis.   

All such options would open up with stricter environmental legislation and/or higher price for coal and carbon. At present the whole European steel sector is subsidized by the ETS, as the steelworks get more CO₂ allowances than they can use.
End customers would usually not have a big problem with a slightly higher steel price, as it is seldom more than a very small part of the input cost, for example in the car or construction industries.

Cement contributes about 5 per cent of global CO₂ emissions. Cement factories are also big point sources of CO₂, for two reasons. One is that fossil fuels are used for heating, the other is that CO₂ is driven out of the limestone, which is inevitable if you use limestone as feedstuff.

Other feedstuffs that do not emit CO₂ are however possible. British Novacem³  made promising tests with magnesium silicate. The process also uses much lower temperatures and thus less energy input. Part of the formula is magnesium carbonate, where the carbon is taken from the atmosphere. This could even result in a carbon-negative cement.

Novacem, a small spin-out from Imperial College, could not find venture capital to build a pilot plant and was sold off to an Australian company in 2012, after which nothing much was heard. Maybe the Novacem cement was not viable, maybe it just takes a lot more effort to compete against traditional Portland cement.

There are other ideas4. A different mix⁵ of calcium/silica may cut emissions by more than half. Other feedstuffs are possible, such as fly ash from coal power.

Cement is mainly used to glue together the sand and stone in concrete, and makes up about 12 per cent of the weight. If buildings can be made lighter with the same strength, less concrete and less cement are needed.

Steel-reinforced concrete may not be the ultimate construction material. We use it because we are used to it. It is heavy and needs heavy machinery and vehicles for transport. It does a bad job of retaining heat in cold weather, or keeping it out in hot weather. The mechanical strength per weight is not impressive and it does not have good acoustic properties.

Transforming the building industry is one of the pillars of sustainability, but to do so requires a lot of tax-funded research, development and political focus in the face of a very conservative and not very research-intensive construction industry.

A high CO₂ price would help a lot, but will not be seen anytime soon. And according to the IEA⁶, always a champion of CCS, the direct cost for the cheapest CO₂ capture method (oxyfuel) would be almost 40 euros per ton, not including costs for CO₂ transport and storage.

This translates to more than 50 euros, all-inclusive, and more than 100 euros in the pre-commercialization phase – assuming that the IEA is not on the optimistic side. Cement is a traded commodity, so no producer can compete if they have a much higher cost than the rest.

CO₂ emissions from cement can, however, be cut by other means, such as building regulations, environmental policy, standardization, requirements for energy efficiency, requirements under Green Building schemes etc.  An approach to produce better buildings and building materials with a smaller carbon footprint could produce results pretty soon, but they would not include CCS.

There is just no credible market dynamics for cement CCS or indeed any other industrial CCS.

Such far-fetched ideas should be compared to what is actually being achieved in the power sector.

Wind power has produced 3,100 TWh globally between 2000 and 2013. If wind power replaces old coal power emitting 1kg CO₂ per kWh, that is three billion tons of CO₂ avoided, at least 50 times as much as all the CCS projects put together so far. Wind power production doubled from 2010 to 2013 and may double again by 2016 or 2017. Solar quadrupled between 2010 and 2013, to 125 TWh, and may quadruple again by 2016. Efficiency improvements also deliver results. Electricity consumption fell in the OECD between 2007 and 2013, thanks to more efficient lighting, fridges and TV sets.

Wind power works, solar works, the Ecodesign directive works. Right now. CCS does not.

Fredrik Lundberg

¹ IPCC Climate Change 2014 5AR, Mitigation, WG III, SPM p 21
² See for example: www.parliament.uk/business/publications/research/briefing-papers/POST-PN...
³ www.wbcsdcement.org/pdf/CSIForum2010/05%20Novacem%20at%20CSI%20Forum.14%...
⁴  See e.g. www.luxresearchinc.com/sites/default/files/International%20Cement%20Revi...
⁵ http://newsoffice.mit.edu/2014/stronger-greener-cement-0925
⁶ http://ieaghg.org/docs/General_Docs/IEAGHG_Presentations/J._Davison_IEAG...