Carbon Commentary newsletter

Fortnight ending 9th November 2025

1, Concrete supercapacitors. Electricity can be stored in capacitors but growth of this medium has been held back by the low voltage of the electricity output and the limited storage density. But a paper published by MIT scientists reported a ten times increase in the last two years in the potential electricity output of concrete doped with carbon black and electrolytes. This means that a typical house might be able to store its daily electricity need in a single large wall. A supercapacitor made of concrete will probably last longer than a battery, take up no extra space and may eventually cost less. But existing concrete cannot be turned into a capacitor so it will only be new materials that will be able to offer electricity storage. (Thanks to Scott Bishop).

2, Carbon storage in buried biomass. A recent note in this newsletter referred to a study estimating that burying wood in the absence of oxygen might offer 10 billion tonnes of permanent carbon storage a year. Rewind, an Israeli company, completed the first large scale storage project of this type in the country of Georgia saying that a deep mine there will store about 50,000 tonnes of CO2 a year in the form of sawdust and wood offcuts. The biomass will be added to the slurry that is used to fill up mine tunnels before an abandoned area is sealed. I could find no figures for the prospective cost per tonne stored but Rewind believes that this route will offer the best way of achieving economical carbon capture.

3, Flexible power use in data centres. An ability to ramp down electricity use in data centres at times of scarcity will be particularly valuable. Startup Emerald AI in partnership with Nvidia is providing the software to allow a new data centre in Virginia to shift the time and the geography of electricity use. One estimate is that the software might allow a reduction of 25% in power demand at critical times. Emerald AI also announced a trial with the UK’s National Grid for later this year, once again working with Nvidia. The press release wrote ‘By changing computing activity when the grid is under pressure, the demonstration will prove that AI data centres can act as responsive partners to the electricity network while maintaining performance standards for mission-critical workloads.’ (Thanks to Ivar Valstad).

4, Renewables records. The isolated grid in the far south west of Australia (SWIS) hit a new record of 89% renewables on November 3^rd. 64% was rooftop solar. Other areas in Australia with good connections to neighbouring areas have seen renewables shares well above 100% but the SWIS performance this week has demonstrated that grids with no pumped hydro can perform well even without reliance on connections to surrounding networks. (I saw this on RenewEconomy). The Indian ministry of power noted that the country had seen non-fossil sources of electricity exceed fossil fuel capacity for the first time, that five times more renewable capacity than new fossil fuel sources were added in the first half of this financial year and that one short period in the summer saw more non-fossil electricity than all other sources combined.

5, Improvement in PV efficiency. Silicon cells have a well-defined limit of less than 30% on how much of the sun’s light energy that they can capture. Breaching this limit requires either the use of second (tandem) layer of a material such as a perovskite or, second, the use of a surface coating that splits incoming photons in the blue portion of the spectrum into two separate packets of energy. This is called ‘singlet fission’ and can push two electrons rather than one into becoming part of the electricity output. Two sources I looked at gave different figures for the maximum efficiency that might be possible with singlet fission but numbers in excess of 40% seem theoretically possible. The University of New South Wales, one of the key centres for PV research over the last half century, published work demonstrating that a simple and cheap molecule can be an effective producer of singlet fission. This is a long way from commercial viability but demonstrates for the first time that this technique may offer a cheaper, long-lasting and more substantial improvement in solar PV than perovskites.

6, Chinese oil demand. We’ve been waiting for convincing evidence that the switch to EVs in China - now about 50% of all small vehicle sales - is cutting fossil fuel demand. A Chinese research company estimated that October gasoline/petrol demand fell by 9% from the level of a year earlier. Reuters also reported that oil imports into the country this year are expected to fall by 4% compared to 2024, saying that wider EV adoption is ‘heralding the approaching end of (China’s) decades-long role as the main driving force of new global oil demand’.

7, Kenya green ammonia. Ammonia production using hydrogen made from electrolysis is likely to be the first industrial sector to switch away from fossil fuels. Two new projects in the last few days illustrate this hypothesis. In Kenya, geothermal-generated electricity will provide the power for a 165 MW plant that will make 100,000 tonnes a year of green ammonia. A Chinese company is partnering with a Kenyan electricity supplier to build this $800m project. A similar-sized project in Paraguay raised $100m from the International Finance Corporation (IFC) as it prepares for a final investment decision by year-end. In both cases, very cheap electricity is a critical prerequisite for the commercial viability of fertiliser manufacture.

8, High efficiency heat pumps. Chinese manufacturer Fairland launched a heat pump in Europe with a claimed coefficient of performance (COP) of 7, far higher than the typically achieved figure of 3-4. Fairland says that the exceptional performance is due to the use of AI to improve efficiency, combined with innovations such as capturing the heat generated by the control board. (Perhaps AI won’t add to power demand after all?). Forecasting future temperature and sunlight levels also means that the pump can be trained to use electricity at times of low prices or high output from solar panels on the building.

9, Catalysts for synthetic fuels. The catalysts for some of the key chemical reactions necessary to decarbonise sectors such as aviation are often expensive, inefficient and subject to rapid degradation. Research in Korea demonstrates the value of a new form of catalyst that may significantly improve the selectiveness and temperature requirements of the reaction which turns CO2 into carbon monoxide (CO). This reaction is a vital step in the chemistry which enables the production of synthetic kerosene, the fuel for jet engines. Temperature requirements fall from 800 to 400 degrees, no other gases such as methane are produced and output nearly doubles. Synthetic aviation fuel currently costs around 4 times as much as products made from oil and this catalyst may help reduce that multiple.

10, Hydrogen for heat and power. The Orkney islands off the north of Scotland are a centre for energy innovation. A recent trial used hydrogen to fuel a combined heat and power installation that provided all the electricity and hot water for the heating system for the operation of the main airport. Orkney has frequent periods of excess wind that cannot be exported to the mainland but which can be used for inexpensive hydrogen manufacture.

11, PET recycling. Carbios, the leader in full enzymatic recycling of plastics, said it would licence its technology to a Chinese company for use across in Asia. This is the first international licencing deal for Carbios, a French business, and will see a full scale ‘biorecycling’ factory built in China, with an eventual capacity across several sites of a million tonnes of PET a year. (About 2% of global sales). Carbios’ partner in this agreement is the fourth largest PET producer in the world and also provided €5m of investment. This looks like another case of an important European technology that has struggled to find financing in its home country being taken up faster in China.

12, The impact of high renewables imports of power. I wrote a short article that showed how international imports of electricity into the UK are affected by the percentage of electricity generated by renewables. The need for renewables is quite constant at around 5 GW until the share of wind and solar in electricity production rises above 55%. Beyond that level, international interconnector flows decline sharply, typically falling to less than 1GW when these renewable sources exceed 75% of total need. As wind and solar capacity rises over the next decade, and therefore provide increasing shares of electricity, import needs will fall, improving the UK’s trade balance by perhaps a billion pounds ($1.3bn) a year. The fierce argument in the UK over whether encouraging the growth of renewables has been good for the economy might take this benefit into account.