Amey PLC United Kingdom 17/11/2020 12:48:59

A Lockdown on Capital Carbon

An interesting fact that was brought to my attention recently was that the equivalent carbon emissions associated with UK construction has risen by 60% between 2010-18. However, the emissions associated with the operation of such assets have decreased by 60% over the same period.

This indicates that while we are learning to create systems that consume less energy, that are less reliant on the transportation of manpower and goods, and our National Grid continues to adopt greener power generation, much improvement is needed in the way we approach construction projects.

The equivalent carbon emissions associated with construction are better known as Capital Carbon, whereas the later emissions associated with asset operation are classed as Operational Carbon. We use the term “carbon” because CO2 accounts for 76% of global greenhouse gas emissions. But different greenhouse gases have varying atmospheric lifetime and associated impact severity on global warming. For example, sulfur hexafluoride (SF6) which is used as an insulator and to suppress arcs in electrical switchgear, has a staggering global warming potential of 23,900 times that of CO2 over a period of 100 years, however it is far less abundant in the atmosphere. Consequently, Capital Carbon describes all these different greenhouse gases in one common unit, the capital carbon equivalent (kgCO2e).

So why is Capital Carbon on the rise? There is a strong argument that the UK is investing in more construction projects now, however data highlights that we are simply not improving our construction practices and are still too reliant on heavy materials, like concrete and steel, that require enormous levels of energy to produce, transport and dispose of. Looking out from a train window one can see how reliant we are on such materials particularly where overhead electrification is provided.

In 2013, the ORR asked Network Rail to “measure and reduce the amount of carbon embedded in new infrastructure”. This led to the requirement for designers on Network Rail projects to undertake capital carbon assessments for projects in excess of £1m. However, carbon reduction on infrastructure projects in the rail industry still tends to be viewed as a supplement, or even a “nice to have”, rather than being a key driver behind decision making. My own experience has often shown this transition to a carbon reduction culture to be met with rolling eyes in the meeting room.

Front-End Investment

Effective capital carbon reduction requires investment in the early project development stages to allow us to perform a realistic analysis of the equivalent carbon in each design option considered. This includes determining the embodied carbon in the materials and products we specify, the transportation of such materials/products to site, energy used in the construction process, staff travel transportation and disposal. While we have some great tools available to help us with this (e.g. the RSSB Rail Carbon Tool), engineers still need to invest a substantial amount of time to perform these calculations if they are to be anywhere near realistic, and this costs money upfront.

It is no secret that cost is undoubtedly taken very seriously by clients and this will now be further compounded by the drain to the UK economy following the COVID-19 pandemic. The government will be forced to respond to this crisis by either raising taxes, borrowing more money or cutting public spending. A combination of these is likely but cuts to public spending are almost inevitable. This will put greater pressure to deliver rail projects with less money. This further expedites the risk that time invested in early GRIP stage capital carbon analysis will be cut or turned into a quick box-ticking exercise to demonstrate contractual requirements have been met, as opposed to having any real impact on the design option selected and later constructed.

It is well-known that operational carbon savings is synonymous with financial savings, and fortunately, experience has shown that the same often applies to capital carbon savings. For example, Amey recently designed out 1,510,890 TCO2e on the Western 650V Cable Renewals GRIP 1-4 project and much of this was from proposing the use of TroTrof cable containment which is likely to save the project approximately £500,000 in procurement and construction costs at GRIP 5-8 when compared with the conventional method of using surface concrete troughing. Procurement and construction savings often dwarf the costs and time spent undertaking detailed carbon analysis during the GRIP 3 option selection phase which further emphasises the value of front-end investment.

The conventional construction process often means that engagement with material and product suppliers is last on the list, however early consideration and consultation with them is paramount. This allows us to understand the embodied carbon in their products that can be baselined against the commonplace solution. Suppliers are already starting to detail the % constituent materials in their products, packaging weight and end of life recyclability potential. Some are even going one step further by providing the embodied carbon footprint figure per unit length/weight of their products. Such suppliers are likely to benefit from providing such data as designers are more likely to specify/recommend the use of products that wear their carbon footprint on their sleeve as it facilitates the carbon analysis process. Furthermore, it motivates the supply chain to reduce the embodied carbon of their products by optimising raw material extraction and product processing practices or looking for more local suppliers.

Using Less

Bad climate change management is analogous to food diets. The planet gets sick from overindulgence in the way people get fat and we seek to remedy it by spending money on diets. But why not just eat less? In this disposable age we now live in, we can learn much from our ancestors about re-using, recycling and making products last longer. My late grandmother could make a pair of slippers last a lifetime. Perhaps we should seek opportunities to extend the life of assets already installed as well as those new ones we procure. For example, opportunities could be sought to design new assets so that existing foundations and walkways could be reused. Soil that has been excavated could potentially be treated and reused. By engaging more with maintainers and other rail projects in the UK we could enquire about using procured or recovered materials/equipment that could be reused or refurbished for our projects.

Consider power supply cables. Signalling power cables are now provided with water blocking tape which is a simple way to maximise the lifespan. Many projects in the past have invested heavily in signalling power cable replacement with little improvement seen on network insulation resistance. Following some FSP switchgear replacement work in in the Bury St Edmonds and Brighton areas, iLECSYS observed that leakage capacitance on feeders due to a breakdown in insulation resistance was not always due to cable insulation degradation/damage and was actually arising from the cable termination points.

Despite the energy expended in the creation of electronic devices, technology can often offer serious savings in both capital and operational carbon. Often the implementation of smarter control systems can be used to minimise the requirement for so many new assets or to reduce power consumption. Network Rail has already invested heavily in improving asset management through its ORBIS programme which has introduced a suite of apps and models to allow maintainers to understand their assets better, reduce energy and time spent travelling to site and to predict when certain faults may arise to allow engineers to target maintenance work. Returning to the signalling power example, rather than renewing entire feeders, capital carbon and financial savings can be made by using the data from Tier 1 insulation monitoring systems to target the individual faulty FSPs or cables that need replacing, which serves to maximise the life of the remaining cables and switchgear. Moreover, such insulation monitoring eliminates the need for cable testing, hence reduces boots on ballast time and the fuel in travelling to site.

One might point to German and Dutch electrical companies Osram and Philips for this disposable product culture we now live in. In 1932 they orchestrated a global agreement with major electrical companies that made it illegal to make a light bulb with a lifespan of greater than six months by purposely designing flaws into them. This kickstarted the era of engineers designing products that were disposable, so the products had a predetermined lifespan, with the intent of keeping people buying. However, our railway signalling engineers were smart enough to outwit them and they altered the tappings in the signal head transformer for old SL35 bulbs to lower the voltage from 12V to 10.7V to prolong the bulb’s life.

Although a slightly reduced supply voltage may not always extend the lifespan of modern electrical and electronic equipment, it can offer savings in Operational Carbon and energy bills by reducing the electrical power demand to voltage dependent equipment whose power usage is proportional to applied voltage. Rather than following predetermined volt drop limits prescribed in standards, designers should look to tailor circuit design to manufacturers’ specification where power usage can be optimised with no risk to equipment operation. This voltage optimisation can easily be achieved where transformers are required as a simple tap change is all that is required. Alternatively, the use of voltage regulators could be used in larger railway installations. Care must always be taken to allow for voltage dips due to transient power surges on the DNO networks, but conversely, operating at this lower voltage can protect equipment from excessive heat and accelerated deterioration due to overvoltage on the upstream networks.

Reduce waste and buy locally

Re-using, recycling and choosing products with longer lifespans is also effective in reducing capital carbon by mitigating waste. Landfill produces methane which is 80 times more warming to the atmosphere than CO2 over a 20-year period. According to the United Nations University, 44.7 million metric tonnes of electronic waste was generated globally in 2016 and only 20% of that waste was recorded as being recycled. When choosing new products and materials we should prioritise those with a higher recycled content (e.g. locally recycled aggregates) and request that suppliers remove packaging from all our orders where possible. We should also seek to avoid products that are less likely to break in transit or during construction as this not only reduces waste but avoids the need for requiring extra deliveries or over-ordering (e.g. concrete cable trough).

Transportation of goods to worksites can be a significant contributor to capital carbon. Designers and procurement teams should look to source materials from suppliers that are local to worksites which has the added value of supporting the local communities. Where transportation is required, consideration should be given to optimising the load in transit and enquiring about alternative options to traditional diesel/petrol-based road lorries, for example electric vehicles or rail transport where this is practical.

Moving forward together

We are routinely forewarned by scientific studies that climate change is our number one priority. 12 years ago, the UK legally committed itself to reducing carbon emissions by 80% by 2050, later to endorse the Paris Agreement on Climate Change in 2016, which aims to limit global warming this century to well below 2°C. Network Rail recently announced they are to become the first railway in the world to commit to cutting emissions to limit warming to 1.5°C. We are all part of this exciting journey!

The rail industry is currently in a transitional period as it moves from away from the conventional way of approaching engineering design. For such safety-conscious industry that is often restricted by long-embedded methods and processes, we have seen some successful transitions recently with things like BIM, electronic documentation systems and improved asset management. This year has seen remarkable achievements in the way we have adapted to home working and continued to deliver rail projects, e.g. the Leeds Station Capacity project which was recently shortlisted in the British Construction Industry Awards for their efforts to sustain activity during the Coronavirus pandemic. We have the resilience and flexibility to apply this same innovation to capital carbon reduction. I have always felt very proud working in the rail industry and now feels like a particularly ground-breaking time.

Topics: Environmental sustainability Clean growth