Crossrail is committed to calculating and reducing our carbon footprint. We have worked with our design teams to minimise the operational energy use in our stations and we have set out specifications for our rolling stock provider with the aim of minimising energy use during operation. This is an important element of the whole life carbon and energy story of Crossrail as it accounts for by far the greatest component of energy usage. We are also working to reduce construction related energy use by choosing the right material and efficient plant.
Find out more about our work to reduce energy consumption below:
- Carbon Footprint
- Rolling stock specification
- Reducing station energy consumption
- Tunnel alignment
- Targeting construction energy
- Hybrid equipment
- Hydrogen fuel cell
- LED lighting
- Solar panels
- Power factor correction
Crossrail’s Carbon Footprint model predicts net carbon dioxide emissions (measured in tonnes of CO2) resulting from the construction and operation of the railway.
Total emissions of carbon dioxide from the construction phase of the Crossrail project are estimated to be in the order of 1.7 million tonnes of CO2. Once the railway is operational, there will be annual savings in the order of 70,000 to 225,000 tonnes of CO2, largely due to the displacement of car journeys and replacement of diesel trains on the existing network. The “payback” period is therefore between 7 and 26 years after opening, beyond which there will be net savings in CO2. The variation in the figures also factor in possible differences in service operating patterns and specification of rolling stock.
Construction carbon emissions
Crossrail’s target for the reduction of construction related carbon emissions is eight per cent. With over 60 per cent of construction completed at FYE 2014-15 and many of the energy intensive activities reducing, Crossrail has achieved a reduction of close to 11 per cent against the baseline. This equates to a saving of about 52,000 tonnes of CO2 emissions. This is a slight reduction from 2013-14 but remains close to Crossrail’s stretch target.
Crossrail is evaluating the application of the new Greenhouse Gas (GHG) Protocol for the treatment of carbon reductions for green tariff electricity. Electrical energy (known as Scope 2) has been treated inconsistently by the industry and the Protocol, (Greenhouse Gas Protocol, Scope 2 Guidance, The World Resources Institute) finally provides a common accounting methodology.
Energy consumption of the tunnel boring machines was considerably lower than the original estimates made in 2010. Work will be undertaken to quantify and confirm that reporting of carbon savings is against a robust baseline.
Work was undertaken to reduce the embodied carbon in construction materials. The biggest opportunities in this area are the reduction of material quantities in construction and the reduction of cement used in concrete.
Cement production is carbon intensive as the conversion of calcium carbonate to calcium oxide, one of the key components of Ordinary Portland Cement, releases carbon dioxide. In addition, the heat required for cement kilns is derived from hydrocarbon based fuels. Any reduction in cement will achieve a reduction in the inherent carbon in concrete.
Crossrail’s concrete specification requires a minimum of
50 per cent cement replacement but replacement of up to as much as 72 per cent has been achieved in instances where cement performance requirements and curing time has allowed this change.
Collaboration with the supply chain to identify opportunities to increase cement replacement will continue.
Other carbon reduction measures
Given the nature of underground stations and the tight physical constraints of Crossrail sites, it has not been possible to harness renewable energy on any scale. However, it was recognised early on that the construction of Crossrail would provide a unique opportunity to future-proof the oversite developments (commercial developments above train stations) by incorporating technology designed to extract ground heat from around the station structure.
Crossrail stations have a design life of a minimum of 120 years (they are expected to last considerably longer). A typical commercial development in central London, however, would not be expected to last this long and is likely to be replaced at least twice during the lifetime of the station. If the station does not have the provision for the capture of this ground heat, then the opportunity is lost forever. This technology has therefore been installed and work is being undertaken with prospective developers of Crossrail sites to ensure that the capability to capture both heating and cooling from this provision is utilised when the first developments are built.
Whitechapel station has provided the only opportunity for a solar photovoltaic array that can provide a viable proportion of the station’s energy requirements. This will be included as part of the final design.
It was reported last year that the lifts and escalators that will be used in the new stations are significantly more energy efficient that those currently used on the underground system. Procurement for these commenced this year. All new stations will also have sophisticated lighting controls and electricity sub-meters installed. This will be integrated into a sophisticated building management system that will allow for optimisation of station energy performance.
It is forecasted that 2.5 million tonnes of carbon savings will be achieved by Crossrail from the start of the construction programme through to operation for the next 120 years. This is close to a 20 per cent increase on Crossrail’s baseline figure.
It is important to manage the operational energy over the lifetime of the project as it equates to 78 per cent of the railway’s total carbon footprint. The focus on keeping train weight to a minimum and ensuring an uninterrupted service with minimal signal failures will help to minimise operational carbon emissions.
Energy savings in construction
Construction by its nature is energy intensive. Many initiatives have been implemented to reduce the fuel and electricity costs and associated carbon.
These initiatives are forecast to reduce the fuel and electricity required to complete the project by eight per cent against industry norms. As a consequence, there are financial benefits of about £2 million to the project as well as a positive environmental impact from lower CO2 emissions. Greater awareness of energy savings activities has been seen on both construction and office sites with many of the changes requiring little or no cost to establish.
LED lighting whole life benefits
Detailed research into LED lighting technology was completed and will help ensure the delivery of reliable, low maintenance and low energy solutions.
The new underground tunnels and stations in the central section will be lit with LED lighting – a design solution that was achieved in the last year as a result of collaboration with the lighting manufacturers, designers and future asset operators. This lighting solution will be extended to tunnel maintenance and emergency access lighting.
The decision to move from conventional to LED lighting in stations will result in a significant whole life cost and carbon savings.
The switch to LED lighting has a positive environmental and financial impact through enhanced energy efficiency, greater longevity of bulbs and reduced maintenance requirements. The reduced operating and maintenance costs do more than offset the initial implementation costs reinforcing it as a viable alternative to conventional lighting. LED lights also bring health and safety benefits to workers and commuters.
Rolling stock specification
The development and review phase of the Class 345 Rolling Stock programme, Crossrail’s new trains, commenced in 2014 and is due to be completed before construction of the trains begins in autumn 2015. The review process indicates that the trains will meet Crossrail’s energy usage commitments.
Train mass and aerodynamics – the principal determinants of energy consumption on moving trains – remain within specification and the smart on-board control systems that curb waste on heating and cooling have begun to take shape. The aspiration to use LED lighting inside the trains has been met. Areas to be explored in the year ahead include the approach to validate energy performance and the ways to ensure operational practice, such as energy efficient timetabling, use of the driver advisory speed guidance systems and the optimisation of Automatic Train Operation, maximise energy efficient design.
In addition to the new trains, Bombardier, the supplier awarded the contract to deliver Crossrail’s new rolling stock, is required to develop the design for the maintenance depot at Old Oak Common and to ensure an energy efficient and low carbon design solution. A number of energy efficient design features were confirmed in the last year. These include roof mounted solar thermal photovoltaic panels, energy piles and a gas fired combined heat and power system. Whilst the primary purpose of piles are to support the building structure, this design incorporates water filled pipework loops that allow heat extraction from the ground to be used to heat the depot.
Other indirect carbon savings will derive from rain water harvesting, which will capture water required to wash the trains. This reduces the need to use mains water.
The use of these combined technologies for the depot is expected to reduce operational carbon emissions by up to 35 per cent. If achieved, this will surpass Crossrail’s current target reduction rate of 20 per cent.
Operation of the railway is the biggest energy impact over the lifetime of Crossrail. The rolling stock is specified to include the following features:
- Lightweight construction with the total mass of train limited to a maximum of 350 tonnes. Crossrail seeks to reverse the trend of other recent UK rolling stock builds which equate to nearly 400 tonnes for a 200 metre long train.
- Energy consumption targets benchmarked against ‘best in class’ UK and European performance.
- Regenerative braking - the ability to use motors in reverse as an electric brake which returns energy to the electrical grid.
- Smart control of lighting, heating and air conditioning systems.
- Driver advisory systems which guide the driver to use optimal energy efficient driving techniques.
Reduced station energy consumption
Crossrail is designing and specifying a range of energy efficient materials and systems into our stations. For example, we have specified a “heavy duty metro” escalator which is more efficient than the escalators used in most existing underground stations and we are investigating operational aspects such as the use of variable speed operation. We are also designing intelligent lighting control systems (DALI lighting controls) and we have specified the use of LED lights in public station areas. LED lights are more efficient than standard lighting solutions and also have benefits related to reduced maintenance requirements.
As the Crossrail trains approach the deep central area stations, they will be on a slight uphill gradient which will assist with braking.
They will leave the station on a slight downhill gradient that will assist acceleration. This will help minimise long-term energy use.
Targeting construction energy
Having established our carbon footprint, Crossrail are seeking ways to reduce this figure and have set a target to achieve 8% (or greater) reduction in energy used for construction against that predicted.
The project is currently on target to meet the 8% reduction in construction related energy. This equates to some 30,000t of carbon saved during the construction phase on energy efficiency measures alone. Further initiatives to reduce the embodied carbon in materials through the use of cement substitutes are being investigated and will contribute to greater savings.
When you hear the word ‘hybrid’ you might think of cars or bikes. But it's time to think again as this technology is now being embraced by construction plant suppliers.
Hybrid equipment combines an energy storage system with an internal power producer such as a combustion engine or an electric motor. They reduce the amount of fuel required, emit less CO2 and improve operative controllability compared with the traditional combustion engine only equipment. They are being used on some of our sites already, but we're encouraging all sites to consider how they can use hybrid equipment for their operations.
Our contractor on the Western Tunnels is using a hybrid excavator and hybrid tower lighting. The VT1 Hybrid Tower has reduced the carbon footprint by 47%. Our Thames Tunnel contractor is also using hybrid technology through their hybrid mobile elevated working platforms.
Hydrogen fuel cell
Hydrogen fuel cells have been used at the Crossrail Pudding Mill Lane site to power a noise monitor. Access to the noise monitor was limited and use of generators would compromise the monitoring results and batteries did not have a long enough life span.
The fuel cell provides electrical power by utilising energy stored in hydrogen and provides enough power to operate the monitor for a year (approximately 6000Wh) which is the equivalent of 20 car batteries or 140,000L diesel (small diesel generator). The carbon savings over the past 12 months of use of the fuel cell have been calculated to be 101t and included within the Pudding Mill Lane Carbon Footprint.
Shine the light on energy saving
The teams on our Eastern Running Tunnels and Whitechapel Station are leading the way in energy saving with plans to install new LED lighting systems. LED lighting is also currently being used on Crossrail construction sites at Northfleet, Whitechapel, Bond Street and Paddington where it is being placed on hoarding and mounted on mobile hybrid lighting towers.
LED lighting can save money and increase site efficiency because it consumes significantly less energy. It is being installed on 17.9km of Crossrail's eastern running tunnels and will dim to 15% when there is no activity through presence detectors on each light. On average the system will use just 12% of the energy used by the current system.
At Whitechapel, the entire Cambridge Heath Shaft site will be kitted out with their new LED lighting system, which uses 47% less energy that the conventional lighting. The team has managed to negotiate with the supplier to provide the equipment for free, to use the site as a demonstration project.
It's in your power
All sites are being encouraged to use Power Factor Correction to increase the efficiency of power use. The Farringdon Station contractor has made changes to their power distribution board resulting in £100k of savings in 2 years and over 516 tonnes of CO2.
The amount of electricity you receive is not always equivalent to the amount of electricity you use. Many consumers are billed on ‘wasted’ electricity and you are liable to pay for the amount supplied, even if you aren’t able to use all of it.
Power Factor Correction is a technology commonly used in the building industry to minimise Power Factor inefficiencies. Power Factor is the measure of how efficiently electrical power is consumed."
Any improvement in Power Factor Correction means that the draw requirements from the electricity supply will reduce, leading to reduced costs and CO2 footprint.
The power of sunlight
Solar panels can be spotted from your calculator to the roof tops of London, and now on some Crossrail sites.
Paddington is using the technology to power their 3D scanners for monitoring ground movement and at our North Woolwich and Connaught tunnels we are using it to provide LED sign lighting at night on Albert Road.