Left: Low-carbon production methods for materials like concrete and steel are improving nuclear’s balance of plant carbon footprint
development, prepared by Ricardo Energy and Environment with third party assessment by WSP Environmental. It found that “the core construction stage is the highest contributor per generated kWh for the majority of the environmental indicators assessed. Within this core construction life cycle assessment (LCA) stage, it was observed that in general, the highest contributing substage was that of the materials required to construct the [Hinkley Point C] HPC development, particularly those associated with the steel and concrete used.” It went on to say that 77% of the global warming potential
(GWP) value associated with construction was from energy and material usage. The energy needed for construction contributed 30%, which was split 50/50 between grid electricity and diesel. Some 47% came from the embodied carbon of the construction materials required such as reinforcing steel (15%) and concrete (just under 10%). Transportation of construction materials and earth works to the site and of construction wastes offsite was responsible for 12% of the core infrastructure construction’s GWP.
Improving primary resource performance Average carbon emissions from the UK grid electricity required for construction have already fallen significantly since 2017. In that year the UK government published a greenhouse gas ‘conversion factor’ for grid electricity, used by companies for annual reporting, of 0.35kg/kWh. In 2023 the government’s figure, based on the grid electricity mix in 2022, was down by more than a third, to 0.21kg/kWh. Diesel generators are not supplied from a network but the trend is in the same direction. For example, one company that provides rental diesel engines, Aggreko, set out in 2022 a pledge to cut the amount of diesel used by its organisation by 50% before 2030. It said, “specifically, we intend to phase out offering diesel with our fuel management services from April, instead solely providing hydrotreated vegetable oil (HVO)”. It is also investigating the use of other potential low-carbon fuels such as methanol and hydrogen in fuel cells for future applications where diesel engines would previously have been used. What about the carbon emissions embodied in the large
material requirements? The concrete and steel sectors both have ambitious targets to reach Net Zero by 2050, but progress in the next decades requires some major technology developments. Hanson is a major concrete supplier and counts Hinkley
Point C among its customers. Cement is a key ingredient in concrete and Hanson’s cement business is responsible for 90% of all of its carbon emissions. Some of this arises
from the energy used but around 70% is from the chemical processes involved in cement production. As a result, the only way to stop the carbon dioxide being emitted is carbon capture and storage (CCS). Hanson’s parent company Heidelberg Materials will capture and store 10 million tonnes of carbon until 2030 through CCUS projects it has in
development. In the UK, Hansen has three projects: ● It is proposing to invest around £400m (US$506m) to build CCS at its Padeswood cement works, near Mold in north Wales. It would transport the captured carbon via the HyNet North West underground pipeline and store it under the seabed and it is targeted to enable Hanson to produce net zero carbon cement by 2027.
● A project at its Ketton cement works in Rutland will use a solvent to selectively capture the CO2
produced. This
may require less energy than some other carbon capture technologies. The feasibility study is now complete and the demonstration unit is expected to be installed later this year.
● Along with Heidelberg Materials’ R&D team, at its Ribblesdale cement works Hanson demonstrated enforced carbonation of recycled concrete paste within the plant’s existing wet scrubber. This removes emissions from the production process and produces a secondary material that can then be used to replace virgin limestone in cement and concrete production.
These developments are expected to allow the company to move to low-carbon concrete by 2030. In the meantime, it has been able to cut emissions with changes to its concrete composition. The EcoCrete range replaces some of the cement in its concrete with Regen GGBS (ground granulated blast furnace slag). As well as reducing carbon emissions, using GGBS has increased the long-term durability of structures, does not require quarrying and reduces the need to dispose of slag. The Ricardo report noted that there was a difference between ‘standard’ concrete and high density nuclear concrete because it requires heavy aggregates such as magnetite or iron shot. But (in accordance with the fact, noted above, that cement carries a large party of the carbon load) it found that for the core construction stage, and thus for the total generated kWh, “generally, the sensitivity analysis indicates that whilst substituting the dataset for normal concrete with that of heavy weight concrete in the key core main HPC infrastructures, the model is not highly sensitive to this change.” British Steel is also a major supplier to Hinkley Point C. Its decarbonisation strategy aims to reduce carbon
www.neimagazine.com | September 2023 | 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49
