Carbon Commentary newsletter

1, Enhanced Rock Weathering. UK company UNDO says it has agreed a deal with Microsoft to capture almost 29,000 tonnes of CO2 via the weathering of very small particles of wollastonite, a silicon-based rock. This is the third purchase from UNDO by Microsoft. In this contract, 90,000 tonnes of wollastonite particles will be spread over about 30,000 acres/12,000 hectares of Canadian agricultural fields. (ERW helps add fertility to most soils). Calculating exactly how much CO2 in rainwater has been captured and turned into a bicarbonate is the critical issue. Microsoft said ‘Enhanced rock weathering is a promising pathway to gigatonne-scale carbon removal’ and it expressed confidence in UNDO scientific rigour on carbon measurement.

2, Green cement. French supplier Hoffmann Green Cement said it had achieved full technical authorisation for the use of its low carbon product to make wind turbine foundations, a world first. A typical turbine base will use about 700 cubic metres of concrete and the continuous stresses from the wind mean that the material has to be of the highest quality. So this authorisation makes it likely that Hoffmann will be able to sell its cement to almost all industries. The company makes its product from the wastes of steelworks, among other sources, and claims to reduce the heat needed in manufacturing by 90% or more. As importantly, no CO2 is added to the atmosphere in the process of making the cement, unlike conventional Portland cement manufacturing in which limestone decomposition drives off carbon dioxide. Zero carbon cement will probably reduce the already very low footprint of wind power by at least 25%.

3, Low carbon steel. The likely route to decarbonisation isn’t looking any clearer. Sweden’s Stegra said it would raise another €1bn to fund overruns on the construction of its new plant in northern Sweden, amid growing pessimism about the cost of the hydrogen that will used to make its steel. However competitor Salzgitter said last week that it expects that the metal will be cheaper to make using hydrogen rather than coal early in the next decade, depending on how the prize of hydrogen evolves. Across the Atlantic, Electra, which will make iron using by dissolving the ore in an acidic aqueous solution and then passing electricity through the liquid to separate out the metal, announced that it would open a small demonstration plant at its Colorado headquarters. The iron will be bought by Nucor, the largest US steelmaker, and other manufacturers for conversion into steel. Separately, Meta said it would buy environmental certificates from Electra to improve its own environmental record, presumably because of the huge carbon footprint of the steel in new data centres. Electra will be a very small producer indeed over the next few years but its relatively simple process will probably use far less than energy than either the coal or hydrogen routes. It can also use lower grade ore than Stegra will need in Sweden.

4, Wood ‘vaulting’ or burying. Wood buried several metres underground is extremely slow to rot. The bacteria that usually digest fallen wood do not prosper in anaerobic conditions. So instead of gradually releasing captured CO2 as it rots, wood would near-permanently store the carbon. Some scientists suggest that wood ‘vaulting’, which is the technical term for preserving the carbon captured during the growing process, may provide the lowest cost route to net emissions reduction. A recent study estimated that permanently storing the large amounts of wood debris produced globally in managed forests, particularly as the trees are cut down and initially processed, could reduce net emissions by over ten gigatonnes a year, or about a quarter of man-made greenhouse gas flows into the atmosphere. The only cost to this process would arise from the need to dig holes that might be three metres deep into which the waste wood would dropped. There are the usual problems, of course: who will pay this limited cost and what guarantee do we have that the wood will stay undisturbed? Nevertheless, this option has to be pursued assiduously.

5, Iridium in PEM electrolysers. Iridium is needed for PEM electrolysers, a plausible candidate for dominance of the technologies for making clean hydrogen. I used to say that an iridium shortage was the most likely material bottleneck in the move to clean technologies, but it looks like I was wrong. (Let’s discuss copper shortages at another time). Iridium is currently only produced as a by-product of platinum mining and just 7 tonnes is sold each year across the world. Rapid growth of PEM electrolysers would use that up very quickly and as platinum production declines as a result of declining use in catalytic converters in cars, the position can only get worse. Iridium is a significant fraction of the manufacturing cost of a PEM electrolyser and the growing shortage would add further to costs. But manufacturer Plug Power and Netherlands nano-material specialist VSPARTICLE said that new research has reduced the amount of iridium needed by up to 90%. This will have a very significant impact on the eventual cost of green H2.

6, Vertical farming. A slew of financial failures has dented enthusiasm for vertical farming. But, as usual with new low carbon industries, this hasn’t stopped China. A new 200 sq. metre 20 storey farm produces 50 tonnes of salad a year, about 200 times the productivity of a conventional horizontal farm. One striking aspect is that the farm operates entirely without human labour. Another innovation is the use of a light spectrum that generates more rapid growth in the plants, raising energy efficiency.

7, E-scooters in Africa. Spiro raised $100m to continue its breakneck growth across Africa. It sells or leases electric scooters that act as taxis with the passenger sitting at the back. The core innovation Spiro has brought is battery swapping stations that enable drivers to work near-continuously during the working day. By the end of this year, Spiro expects to have 100,000 scooters in its network across six countries, four times the level at the beginning of the year. The e-scooters are cheaper than the gasoline alternatives and cost less to run. As the CEO says, India has 13 times the number of motorbikes as Africa’s 25m despite having a similar population. The wide opportunity for the rapid development of an entirely new zero carbon industry in Africa that doesn’t have to overturn an existing technology is obvious.

8, Heat batteries. Whether or not the economics of heat batteries are appealing, interest is rising in their use for medium (and longer) duration storage. Newly installed conventional batteries still tend to only offer 4 hours at most. Rondo Energy announced the completion of the world’s largest dispatchable heat store, providing 100 MWh of up to 1000 degree heat created by resistive heating inside a huge pile of bricks and then by blowing air through the installation which is used to generate steam. Unfortunately, in this first commercial heat battery that steam is being used to increase production at a Californian oil field but Rondo can’t be too picky about how its customers use its product. The electricity here comes from on-site solar array but most of Rondo’s customers will probably use overnight low prices for power to ‘charge up’ their heat stores for the next day.

9, Textile recycling. Textile waste is an apparently intractable problem with less than 1% being fully recycled in the EU. (About 25% is reused but is mostly turned into lower value products). A very large recycling project showed that a much higher percentage is possible. Dutch recycler Boer ran a project over 8 months that collected 24 tonnes of clothing (50,000 garments) in France before separating the individual textiles by colour and fibre type in the Netherlands and then spinning the yarns and remaking clothing in Italy. Each new item contains about 70% recycled textiles. Dutch retailer Zeeman sold the clothing saying that ‘we have proven that post-consumer textile waste can be turned into new, high-quality products that our customers love to buy’. Sweaters were a particular success, said the retailer.

10, Unconventional pumped hydro. Italian start-up Sizable Energy raised €8m to build a pumped hydro site in the sea off Sicily, Italy. The company’s approach is to use surplus power to raise heavy salt-saturated water from the deep ocean to the surface in a closed loop. When electricity is needed, the water is allowed to sink back hundreds of metres to the sea floor, driving turbines as it falls. Sizable claims that it can build gigawatt scale systems at costs that are even lower than future lithium-ion batteries. Several ideas such as this are floating around. In North Wales, for example, a mining company proposes to work with RheEnergise to use very heavy fluids from the 280m deep mine as the energy storage medium. The logic is that fluids heavier than 100% water can provide more gravitational energy, making smaller installations potentially more financially feasible. (Thanks to Jonathan Dean).