Energy symbiosis on the Yangtse Delta

Newcastle, UK - Parsons Brinckerhoff is working with One North East (the regional development agency for the north-east of England) and the Shanghai Jiaotong University of China to develop proposals for an energy infrastructure on the three Chongming islands in the Yangtse Delta. The aim is to develop the islands in an ecologically and economically sustainable fashion, making them a showcase for green development.

As part of the research initiative, Newcastle University undertook a study to identify how the islands could meet their future energy demands by making maximum use of their indigenous resources and adopting advanced technologies. These technologies have been combined to minimise the carbon footprint of energy consumption and to exploit energy synergies – termed ‘energy symbiosis’ by the researchers.

The study has identified significant renewable energy resources, particularly biomass and wind where several hundred MW of electrical capacity from each is possible.

- Biomass consists principally of crop residues and animal wastes, supplemented by more limited forestry and municipal wastes.

- The potential for large wind generation appears to be in the North district (both onshore and offshore) and on Changxing Island.

- The solar energy resource for both electricity and hot water provision is also important, with the most appropriate use of this resource being as small building-integrated units distributed across the islands.

- Geothermal energy (in the form of ground- or water-source heat pumps) has the potential to supply a significant proportion of domestic space heat demand. In addition, the hydrogeology of the islands is well suited to using the ground and its aquifers as heat stores to balance seasonal heat and cooling demand.

- Tidal resources of the islands are limited by shipping constraints in the south estuary channel, the shallow nature of the North Channel, and the high silt content of the water. Further work is needed to understand this resource better.

Peak electricity demand on the islands is predicted to increase from less than 500 MWe today to 795 MWe in 2012 and perhaps 1,500 MWe in 2020, equivalent to 6,660 GWh per year. Significant new electricity and heat capacity will be required to meet demand of this magnitude.

Overall, the identified renewable energy capacity on the islands could provide approximately 500 MW of the required 1,500 MW electricity capacity. On an annual basis, renewables could supply 25% of electricity consumption. Most of the remaining energy demand would be met by fossil fuels, for example expanded coal-to-syngas or electricity generation on Changxing Island.

The location of the energy resources and demand is such that significant energy transfers will be required from the North, Central and Changxing districts to the South district. The project team consider that the most suitable means to do this is via a syngas network connecting the major resource and demand centres.

Fuel would be gasified near its source – for example in the North/Central districts for biomass, and on Changxing for coal – and transferred as syngas to local CHP units in the population centres of the South district. This approach of distributing electricity generation to the demand centres allows the reject or surplus heat from electricity generation to be used to supply local heat loads.

Such a network would also allow local plants generating hydrogen fuel, either from the syngas by separation, or by the electrolysis of water from wind energy, to be established close to demand (eg on major transport routes to supply hydrogen vehicles). Small wind, solar photovoltaics, solar thermal and ground-source heat pumps would, meanwhile, provide renewable electricity and power in more rural areas, supplemented as needed by the electricity grid and conventional ‘packaged’ fuels such as compressed gas in cylinders.

Large wind farms in the North and Changxing districts and offshore in the north channel of the estuary would be connected to an expanded electricity grid.

This energy supply approach would have the potential to reduce carbon dioxide emissions from electricity and heat supply by approximately 30%, compared to centralised electricity generation from coal and natural gas and the use of electrical heating. This does not take account of any storage or sequestration of carbon dioxide, which would be facilitated by the syngas approach and the presence of suitable saline aquifers which could be used as repositories for the C02 .

Besides the generating plants themselves, the proposed supply system would require extra infrastructure in the form of a syngas pipeline network between the major resource and demand areas; installation of district heating schemes in the major population centres; and a likely strengthening of the electricity grid to accommodate wind generation in the North district.