Illuminated River

Diller Scofidio + Renfro

LONDON ENERGY SPINE [Resource Exchange Infrastructure]

As we enter the ‘Urban Millennium,’ cities are poised to grow drastically in population and density. In light of this new reality, urban communities around the world, including London, are beginning to reevaluate existing relationships between public, infrastructural, and industrial landscapes in order to find new ways of accommodating and sustaining increased levels of demand for power, water, and social space.

The anticipated demand increases are so large that conventional renewable resource and efficiency strategies will not suffice. Urban networks of energy production and distribution will require an evolution towards a resource exchange model that is better integrated into existing public and ecological infrastructure. Synchronizing the City will act as an important catalyst in transforming London’s infrastructure. It calls for a holistic rethinking of a substantial swathe of the River Thames and London at large, with the intention of modifying multiple aspects of water, lighting, and transportation networks. At this scale, the project has the potential to not only develop sustainable practices for its own energy consumption, but also to lay the initial groundwork for future projects that, together with Synchronizing the City, establish a net positive energy exchange between London’s electrical grid and adjacent neighborhoods. The sustainability proposal for the Synchronizing the City project includes three phases. Each lays the foundation for a resource exchange model built on the concept of the River Thames acting as an ‘Energy Spine’ for the surrounding boroughs. The three phases integrate ongoing city infrastructure initiatives within the project area, enhancing the effectiveness of each individual initiative and reducing costs by pooling investments in capital improvements.

Phase (1) establishes a net zero energy exchange between new energy harvesting systems installed as part of the project and London’s electrical grid. Leveraging both river currents and solar radiation, the project will provide London’s electrical grid with enough energy over the year to meet the power demands of Synchronizing the City. The project will use ‘Alternating Current’ micro-turbines attached to the bridge piers and ‘Solar Paths’ along select pedestrian walkways on the bridges to generate public awareness and meet baseline energy demands.

Phase (2) creates a stronger relationship between the river tides, bridge lighting, and public spaces along the riverbanks. In 1957, the Thames River was declared biologically dead due to high concentrations of pollution and low oxygen levels. Today, the River Thames is among the cleanest urban waterways in the world. In spite of this transformation, many challenges and opportunities remain in aligning London’s infrastructure with public and natural ecosystems.

Phase 2 will dovetail with Tideway initiatives to help restore habitats along the river’s edge and increase public access to the foreshore at low tide. The focus will be on developing ‘Tidal Recharge’ points, open and visible to the community, which will redirect sewage overflow away from the Thames and soften its concrete edges with native habitats that absorb and filter stormwater. They will also harvest energy from daily changes in water elevation to be networked back to Phase (1) and into London’s grid. This additional power source will generate a net positive energy exchange during select times of year for use in the adjacent boroughs.

Phase (3) involves the Greater London Authority piloting Licence Lite certificates from Ofgem to the boroughs in and around the project area, enabling the creation of a networked ‘Energy Spine’ infrastructure. The ultimate goal is for each borough to become its own decentralized energy generator and supplier, and to establish a district energy market through resource exchanges with adjacent boroughs and private suppliers. This will stabilize a peer-to-peer distribution model that sets a precedent for adapting power and water infrastructure and sustains density levels well into the ‘Urban Millennium.’

ALTERNATING CURRENTS [Bridge Restoration/Construction + Grid Expansion]

The Thames River is a tidal estuary with strong currents ranging from 2 to 3 m/s. These currents increase in velocity when bridge piers splice the natural flow of the river, creating favorable conditions for energy harvesting turbines. Additionally, the dense array of bridges crossing the Thames greatly amplifies the energy potential of the river, producing an ideal environment for a distributed generation strategy that utilizes existing transportation infrastructure. The distributed turbines will yield a constant energy supply that serves as a backbone for the local resource exchange.

The micro-turbines are kinetic systems that harness the water stream's natural pathways. With a capacity of approximately 5kW, each will be able to extract energy from the river without significantly interfering with its ecosystem. The rotor blades will be specifically designed to turn based on the direction of the currents.

SOLAR PATHS [Infrastructure Maintenance + Public Awareness]

Cities around the world are blanketed with an ever-expanding tapestry of pavement to support safe pedestrian and vehicular movement. This transportation infrastructure is largely responsible for the growing heat island effect and consumes a large portion of yearly operating/maintenance budgets. The Synchronizing the City project proposes resurfacing pedestrian pathways on the sunny side of the bridges with Solaroad, a photovoltaic material that can capture energy from solar radiation on areas of pavement that would typically produce the heat island effect. Solaroad promotes general safety and awareness and can be applied to existing bridges as part of routine maintenance programs. Individual elements of the photovoltaic technology can also remain lit during magic hour and into the night, serving both as a wayfinding device and as an aesthetic gesture.

This novel technology captures not only direct sunlight, but also diffuse light from the London sky. This is accomplished using amorphous solar cells switched in parallel to avoid partial shading effects. They are slip-proof and dirt resistant and are able to absorb point loads of up to 1000 pounds.

TIDAL RECHARGE [Sewer Management + Habitat Renewal]

London’s combined stormwater and sewer overflow system releases 39 million cubic meters of sewage into the river each year, while the obsolete concrete embankments alter the natural currents and provide no substrate for habitat renewal. Currently, the Tideway initiative focuses on two related objectives. The first is altering the concrete barrier edges to redirect the sewer outfalls for treatment prior to entering the estuary. The second is providing a softer environment both for public access and for habitat renewal that can absorb stormwater and tidal swells.

This remediation effort presents an opportunity to integrate tidal energy generation into the design of public access points. The Thames undergoes a seven-meter tidal level change four times a day. These public access points can absorb the swell at high tide and hold it until low tide. At low tide, the water will be released through small turbines, effectively translating the river’s height potential into energy. This surplus water will then also spill across the bridge turbines to co-generate additional electricity and amplify productivity across the entire network.

The tidal propeller turbines are electric power generators integrated into the water barrier, with a capacity of approximately 20 kW and measuring approximately 40cm in diameter. Four times a day, when the potential tension between the varying water levels is highest, they are able to release the water difference by filling or emptying the basin within half an hour.

PEER-TO-PEER DISTRIBUTION [Community Generation + Ownership]

In 2009, the U.K. regulator Ofgem introduced electricity-supply licence changes to allow generators of distributed energy to enter into arrangements with licensed third party senior suppliers. As a result, smaller, less intrusive distributed energy generators can participate in the energy trading market and can be seamlessly integrated into existing public infrastructure. Under this ‘Licence Lite’ program, the distributed energy generators enter into a contract with senior suppliers to manage the transportation of their electricity over public wires but retain ownership of the energy resource and can distribute freely to their own customer base. This is the foundation to establishing Energy Districts with Peer-to-Peer distribution that can share resources and redistribute it as required through the year.

The Greater London Authority wants to take the leading role in piloting Licence Lite certificates by working with London’s boroughs to identify distributed generator opportunities within their district, aiming to attract £8 billion of investment in new electricity infrastructure in the city prior to 2025.