Counting on … day 88

17th April 2024

Green steel and cement alternatives 

Steel, cement and concrete are major contributors to global climate emissions using manufacturing process that are challenging to green. Therefore one approach to safeguarding the environment is to reduce the use of new steel, cement and concrete. 

This could be by not wantonly discarding things before the end of their lifespan. Where I live, it is not infrequently that someone will buy a house only to knock it down and replace it with a new one. This unnecessarily adds to local carbon emissions. The same can also be true of commercial buildings. Simply demolishing an office building to replace it with another is a poor use of resources. 

Where buildings or other structures are of necessity demolished, the prudent use of resources would see the different building materials being salvaged and reused. Equally before demolishing a structure, consideration could be given to re-purposing the building – upcycling!

The same approach of making full use of an item over its lifespan could equally apply to vehicles, domestic appliances, etc. 

When building new structures, alternative materials with a lower carbon footprint can be used. This might be using timber for beams and columns, straw for insulation, compressed clay for bricks as well as recycling materials from other buildings. However if using naturally renewable resources such as timber, there has to be an awareness of the time frame and forwarded planning needed to ensure an ongoing supply of such materials. Trees may need to be up to 80 years old before being used to create    structural building elements – and that timescale also implies large areas of land being set aside for trees (which is not a bad thing but needs to be planned). 

Did you know you can buy bicycles made with a bamboo frame?  – https://www.nethambamboobikes.co.uk/

Further reading:

https://www.weforum.org/agenda/2021/11/sustainable-mass-timber-green-building

https://www.bbc.co.uk/news/science-environment-61580979

Counting on … day 80

5th April 2024

Green Steel 

Steel manufacturing produces more CO2 than any other heavy industry, comprising around 8% of total global emissions. 

Traditionally steel is made in a blast furnace where the iron ore is he@ted at high temperatures together with coal. As the coal burns it produces carbon monoxide which bonds with and removes oxygen in the iron ore so purifying it to produce metallic iron. The carbon monoxide binding with oxygen becomes carbon dioxide and is one of the main sources of carbon emissions. Other sources of emissions will vary depending how the furnace is heated etc. 

The industry is developing various ways of producing steel without – or with reduced – carbon dioxide emissions – known as green steel.

Replacing coal with hydrogen: Green steel can be produced by using hydrogen to remove the oxygen from the the ore – producing water (H2O). Ideally this would be green hydrogen – ie hydrogen produced using renewable energy. This method of producing steel requires heating the furnace to a higher temperature.

Reusing existing steel: steel can easily be recycled in arc furnaces powered by electricity – which ideally would be electricity from renewable energy sources with no carbon dioxide emissions.

Around 30% of the world’s steel is made from recycled steel. However steel cannot be recycled endlessly without loss of quality. Each time it is recycled the proportion of unwanted elements such as copper, nickel and tin increases. On the other hand steel has  long in-use life which means that the amount of steel made available for recycling does not at present keep up with the growing demand for more steel. Our modern economies are big users of steel!

(For more detail see https://theconversation.com/green-steel-is-hailed-as-the-next-big-thing-in-australian-industry-heres-what-the-hype-is-all-about-160282)

Which ever form of green steel is produced, the availability of large amounts of renewable energy is going to be critical. 

As important will be the way the transition is managed as furnaces are large and highly expensive pieces of kit – ie needing substantial investment – and can take years to install which in some instances has led to workers being laid off – as is proposed at the Tata steel works in Port Talbot. (https://www.theguardian.com/uk-news/2024/mar/25/tata-port-talbot-job-losses-labour-subsidy?CMP=Share_iOSApp_Other). 

Other important issues to address are how steel is used – with product design ensuring a long life, whether other materials could be used – timber for example in building construction, and how effectively scrap  steel is collected and recycled.

Further reading – https://www.bbc.co.uk/news/business-64538296