by Sarah Greenham, Emma Ferranti, David Jaroszweski, Lee Chapman, Andrew Quinn and Ruth Wood
On Earth Day 2021, the 22nd April, USA President Joe Biden hosted a virtual summit with 40 world leaders, announcing new pledges to decrease greenhouse gas emissions. These reductions are to meet the objectives of the 2015 Paris Agreement; an international agreement to reduce global warming to well below 2℃ compared to pre-industrial levels. 2℃ is considered the critical tipping point in global temperatures after which changes in the climate system may become irreversible. In some respects, the USA is catching up with the rest of the world – currently, 124 nations have pledged carbon neutrality.
The Climate Change Act 2008 mandates UK reductions in greenhouse gas emissions; the first country in the world to do so. The revision of this Act in 2019 changed the target from an 80% reduction to 100% reduction in net greenhouse gas emissions, from a 1990 baseline by 2050. In other words, by 2050, the UK should no longer be a net emitter of greenhouse gases, achieving “Net Zero”. There are also interim targets, 68% reduction by 2030 and 78% by 2035. However, in order to transition to Net Zero, the energy, water, transport and Information Communications Technology (ICT) sectors will need to modify or rebuild their infrastructure, or change the way they operate. The Net Zero goal now means that the transitions need to be more ambitious, and possibly accelerated. The difference in the trajectories are shown below in Figure 1.
Figure 1. The difference in greenhouse gas emission trajectories over time based on the original Climate Change Act target (red) compared to the new Net Zero target (green). The black line is historic data. Source: Committee on Climate Change’s 2019 Progress report to Parliament.
Despite the need to reduce emissions, there is no denying that changes in the climate are already taking place: 2020 was one of the warmest years on record, and 2011-2020 was the warmest decade on record. There is evidence that this warming has already led to observed changes in extreme weather, such as heat waves, drought and heavy rainfall events. Consequently, extreme weather affects infrastructure directly, for example:
- Flooded substations affecting electricity provision,
- Drought reducing water supply,
- Railway tracks buckle in a heat wave affecting service levels.
There are also indirect consequences of extreme weather on infrastructure, such as:
- Increased energy consumption during a heat wave to operate more air conditioning units,
- Periods of drought increasing demand in water supplies,
- Loss of power to an electrified train service if a severe flood damages its respective power supply elsewhere.
Therefore, any changes in the energy, water, transport and ICT sectors to reduce greenhouse gas emissions may need to take into account the expected impacts of climate change on their changing infrastructure so they can continue to operate. This complicated area is emerging in infrastructure risk assessments, as it will become imperative that infrastructure decisions on mitigating and adapting to climate change do not negatively affect each other. Here, we outline how Net Zero changes may affect infrastructure’s resilience, broken down by each sector.
The energy sector has a very large role to play in reaching UK’s the Net Zero goal. This includes the growth of renewable energy infrastructure such as solar, wind, hydro and tidal alongside biomass, nuclear, hydrogen and carbon capture and storage (CCS) technologies. Increasing levels of intermittent, weather dependent generation presents challenges in managing the power network as outputs vary daily and seasonally across the UK. This could be particularly challenging when there are sharp peaks in diurnal demand that coincide with low renewable outputs e.g. cloudy, still days.
On this basis, an array of supporting measures are included, including new nuclear and biomass with CCS, energy storage and various demand response solutions. Hydrogen generation is also emerging as both a medium of energy storage via electrolysers and a fuel for more energy intensive users such as HGVs and trains. Some estimates have a new hydrogen economy supplying comparable levels to the current gas-fired power station infrastructure. In addition, nuclear plants are likely to remain in place as a low carbon source of energy, although the level of deployment is uncertain as the growth of renewables expects to provide lower future costs. To reduce the life cycle greenhouse gas emissions to zero from these supporting measures, CCS is required. It is a process of capturing emissions at the source, transported via pipelines or shipping and stored back deep into the ground. It prevents carbon dioxide, the primary greenhouse gas, from entering the atmosphere in the first place.
All of these changes in energy infrastructure: renewables, hydrogen, new nuclear and CCS are vulnerable to climate impacts, with their exposure dependent on their location. For renewables, the implications are variable. On one hand, wind speeds up to a cut-off point of 25m/s can increase output; and heavy rain can increase hydropower output. However, on the other hand, a period of drought could lead to crop damage and loss of biomass feedstock. A balance of technologies and their geographic spread are necessary to manage fluctuations in outputs especially as we may see increases in extreme weather events. This is why investing in demand side response and storage technologies are options to reduce the impacts of variable outputs from renewables. As for hydrogen and CCS, both are dependent on water availability. Infrastructure rollout is in early stages and sites have not yet been selected so the impacts are less clear. CCS infrastructure requires more water compared to traditional thermal generation, and hydrogen generation also requires water so there is as assumed risk to these processes during periods where water supply is low, or during a drought, or in water stressed areas, such as the southeast of England. As for hydrogen, if supply in the future uses the existing pipeline network used for gas, there are potentially similar risks to current levels of knowledge.
The water sector is responsible for providing water supplies to society but also for treating wastewater, which requires energy and produces greenhouse gas emissions. As climate projections for the UK anticipate warmer, wetter winters and hotter, drier summers, managing water resources year-round is necessary to meet Net Zero targets.
As water supply and treatment infrastructure is located where waterways are, they are unlikely to change. However, a lot of the opportunity to reduce greenhouse gas emissions is in electrifying processes instead of using fossil fuels: either through the national grid or additional decentralised infrastructure on-site. Compulsory metering of water for customers is a possible way of reducing water consumption, ultimately reducing the energy required at water treatment facilities. In addition, a recommendation to manage nationwide water supply is through creating a national water transfer network.
Sustainable drainage systems (SuDS) infrastructure has grown across the UK as a way of managing storm water locally. They mimic natural drainage and passively treat flood and pollution risks due to urban runoff. Examples include designing new swales, wetlands and reed beds, such as that in Figure 2. SuDS can reduce the amount of water entering combined sewers, also reducing the energy demand at water treatment facilities. It requires collaborative work with the water sector and bodies such as Local Authorities and the Environment Agency. This intervention provides additional climate adaptation benefits with studies indicating green (vegetation) and blue (water) infrastructure can reduce urban temperatures.
Figure 2. Award-winning SuDS designed in the recently built residential area of St. Andrew’s Park in Uxbridge, the London Borough of Hillingdon. Source: Greater London Authority, Susdrain.
The climate change impact of the changes required for the water sector are not yet clear. An assumed risk may be related to the increased dependency on a changed energy supply for wastewater treatment. For example, if the energy sector cannot produce enough electricity, it affects the water sector’s ability to treat wastewater. A similar risk would also apply if the water sector supplier’s on-site renewable energy supply was insufficient, or without appropriate energy storage. For coastal infrastructure, this would also be a challenge regarding sea level rise. There may be increased stresses on treatment and pumping of seawater, as well as the threat of coastal erosion to the physical infrastructure. In addition, national water transfer infrastructure could increase risks such as higher energy demands and hastening the spread of invasive and/or non-native species through water. As for SuDS, future risk to them is also not clear.
Road, rail and aviation infrastructure requires significant changes in order to meet Net Zero targets. Vehicle use is a major contributor to greenhouse gas emissions and a switch to electric vehicles and a phase-out of petrol and diesel is critical. Electrification of rail infrastructure and hydrogen train trials are underway, as well as research into lower carbon intensive fuels for planes, such as using biomass. Changing modes of transport also helps reduce greenhouse gas emissions e.g., private car use replaced with public transport (bus and/or rail); shorter car journeys replaced with active travel modes (walking and cycling); air travel replaced with high-speed rail.
The transport sector as a whole is very complex as there are many stakeholders and owners of the infrastructure across the UK. Therefore, changes to its infrastructure will require collaborative work between sectors, transport operators and government bodies at multiple levels. For example, the infrastructure required to support a growing fleet of electric vehicles (i.e. charging points) affects a range of stakeholders, through multiple national government schemes:
The Automated and Electric Vehicles Act 2018 also makes provisions about electric vehicles, including charging infrastructure, and gives the government powers to ensure motorway services provide them.
The transition to Net Zero for the transport sector will have an increased dependency on electricity, particularly for road and rail due to electrification. Therefore, there is a greater risk if things go wrong in electricity supply, especially due to the transitions in the sector. Some other risks across the transport sector are specific to the mode, such as:
- Rail: Overhead lines (increased due to electrification) are more susceptible to sag during high temperatures.
- Active travel: health related risks from heat exposure, or injury from surface run-off due to extreme rainfall (although from a public health perspective a modal shift to active travel will have many benefits).
Information Communications Technology
Our dependency on ICT has increased rapidly in recent years. This infrastructure was first made of copper cables, but the transition to Net Zero requires a transition to fibre optic cables. This is because not only do they provide better internet speeds, but also use less energy. The National Infrastructure Commission recommend that full nationwide coverage of fibre broadband is delivered by 2033, allowing for a copper infrastructure switch-off by 2025. This improved coverage could also support the growing demand for remote or home-based work, therefore reducing commuting trips and contributing further to Net Zero goals. However, as other sectors increase their use of smart technologies, reliance upon ICT increases with the potential for cascading failures cause by ICT outages.
The ICT representative report to the Government’s Second Adaptation Reporting Power outlines some of the climate adaptation related risks to this transition. For instance, copper and fibre have different vulnerabilities. Due to the electronic circuitry, a fibre cabinet is more likely to suffer catastrophic damage if flooded compared to a copper cabinet. In addition, ICT infrastructure changes more rapidly than any other infrastructure sector, which may present more unknown risks and vulnerabilities in future.
The infrastructure sectors in the UK are at different stages of their pathway to Net Zero, with differing risk profiles to climate change. In particular, there are growing interdependencies of water, transport and ICT on the energy sector. There are indications of increased electricity use for the Net Zero transition, which exposes other networks to the impacts on the energy sector through cascading failures. Similarly, there is an increasing reliance on ICT for the operation of the power network and other sectors using ‘smart’ grids and other ‘smart’ technologies. Therefore, it is extremely important to address this between the sectors in order to collaborate on solutions that protect against cascading failures. As Net Zero transition is necessary, adapting this changing infrastructure to the effects of climate change is equally as necessary.