Towards the less unsustainable city

The ultimate challenge will be to transform existing towns and cities so that they become less of an 'ecological black hole'. The city is an epicentre of consumption, but also capable of being the highest visible manifestation of civilisation - 'civis' the city. Cities have powerful symbolic resonance which means that there are considerable constraints on change. Over the next 50 years, barring catastrophes like sea level rise, the basic form and infrastructure of European cities will not change all that much. Even after the 1940s blitz which destroyed the heart of many great cities like Liverpool, the reconstruction process in most cases followed the routes of the original infrastructure. As much as anything this was because of services routes and the complexities of land ownership.

Individual buildings will be replaced or radically upgraded and the economics of the process will depend on uncertainties like the value of land and the price of energy. As suggested at the beginning energy prices as likely to rise steeply as demand increasingly outstrips supply. But the most important priority is for towns and cities to make drastic reductions in their demand for fossil-based energy and in this respect there is a borough in the UK heading in the right direction.

Woking: a pace-setting local authority

Woking is south east of London close to the M25 motorway with a population of over 89 000. It can claim to have one of the most environmentally progressive local administrations in the UK which has committed the authority to eight key themes under the headings:

• energy services;

• planning and regulation;

• education and promotion;

• management of natural habitats;

• adapting to climate change.

Energy services

It is in this sphere that the local council has been particularly far sighted by recognising that energy has both immediate social and long-term global implications. On the one hand it seeks to eliminate fuel poverty and, on the other, drastically reduce CO2 emissions. They have subscribed to the Royal Commission on Environmental Pollution's targets of a 60 per cent reduction in emissions by 2050 and an 80 per cent by 2100.

In order to implement its energy strategy a council-owned company was formed called Thameswey Limited to act as an Energy and Environmental Services Company. The company has entered into an agreement with the borough to act as its contractor to provide combined heat and power to the borough. In 1999 Thameswey Energy Limited was formed in partnership with a Danish energy service company (ESCO) International ApS. Its purpose is to build, finance and operate CHP stations of up to 5 MW capacity throughout the town and offer energy services to institutional, business and residential customers.

The first project was a CHP station supplying heat and chilled water services by private pipes and electricity by private grid to the

Figure 19.2

Combined heat, cooling and power grid, Woking town centre principal energy users in the town centre including the council offices. It was officially commissioned in 2001 (Figure 19.2).

The most innovative enterprise by Thameswey Energy is the Woking Park project. The park complex includes a 200 kWe fuel cell, together with plans to include an 836 kWe CHP reciprocating gas powered engine, two 75 kWe CHP engines and 9.11 pkW PV installation. These together with heat fired absorption cooling and a thermal store add up to a CHP capacity of 1.195 MWe.

The fuel cell is of the phosphoric acid type which uses hydrogen reformed from natural gas. It supports the heating and power needs of the pool in the park and leisure centre, with surplus heat in summer used to generate absorption cooling and dehumidification. There is also provision to direct surplus electricity to sheltered housing accommodation (Figure 19.3).

The extensive use of photovoltaics also features in the borough's strategy. Brockhill, an 'extra care' sheltered housing scheme, was the first in the UK to use a combination of CHP and PVs to serve its energy needs. In all 117 sheltered housing tenants receive PV electricity, including Prior's Croft. This development is also served by a small CHP unit producing 22 kWe and 50 kW of heat backed up by a 6 X 50 kW boiler (Figure 19.4).

In order to sidestep the problems of supplying small amounts of PV electricity to the grid at an uneconomic rate, the council has created a mini-distribution system of private wires enabling it to sell PV and CHP electricity direct to customers. The CHP stations achieve 80-90 per cent

Natural Gas supply

Public Electricity Grid

Figure 19.2

Combined heat, cooling and power grid, Woking town centre

Natural Gas supply

Public Electricity Grid

Woking Town Centre Chp

Figure 19.3

Phosphoric acid 200 KWe fuel cell, Woking Park efficiency compared with coal fired power stations at 25-35 per cent. This is because of the utilisation of heat from the engine and compact grids with minimum distribution losses.

Planning and regulation

The main concerns are:

• sustainable construction.

The concept of 'environmental footprint' is a prime consideration in land use policy. This is particularly concerned with the CO2 emissions that are generated by the current use of the land. The aim is that, when land use is changed, the new use should represent an 80 per cent reduction in CO2 emissions.

As regards location, the council operates a measure called Public Transport Accessibility Level Rating (PTAL), ranging from 1 to 7 with 7 being the most proximate to public transport. New development proposals are assessed according to where they feature on the scale. Most new development in the borough scores near the top of the scale.

Planning policy promotes housing layouts which maximise passive solar design and a preference for terrace housing and flats which minimise heat loss through external walls. It is estimated that such measures reduce energy use by 20 per cent.

Passive External Warming

In terms of landscaping the planting of trees and shrubs is encouraged with benefits that include a reduction in the heat island effect, solar shading in summer and protection from wind.

Energy use in buildings is targeted by encouraging insulation standards above those required by the Building Regulations, installing community heating, building integrated renewable energy systems and requiring water conservation measures to be adopted. The council has the most energy efficient public housing stock in the UK with an average NHER rating of 8. The target for all the stock is NHER 9 or SAP 74 with the aim of limiting energy costs to 10-15 per cent of income of those dependent on a state pension. This should eliminate fuel poverty in this sector.

In the private sector the council had topped up government grants to provide full insulation measures to 3026 homes up to 2002. It aims to solve the fuel poverty problem in this sector, especially in rented accommodation, by 2010-11.

Waste

The council has adopted plans for a borough-wide zero waste strategy ultimately to reduce the need for landfill disposal to 10 per cent of current use. It operates a two-bin domestic waste system with a division into dry goods and organic waste. The anaerobic digestion of organic waste provides gas for CHP engines and compost. Thermal gasification of other waste provides the hydrogen for the fuel cell. Diverting waste from landfill could equate to a CO2 reduction of 100 000 tonnes. Recycling also plays a major part in its waste strategy, especially in terms of the reuse of materials in construction. The council operates an energy recycling fund which benefits from saving due to energy and water efficiency measures and the recycling/reuse of materials. Sums from the fund are ploughed back into energy efficiency projects.

Transport

Council promotional campaigns seek to raise awareness of the benefits of alternative fuel vehicles at the same time encouraging local filling stations to provide liquid petroleum gas (LPG), compressed natural gas (CNG), liquid natural gas (LNG) and hydrogen. The council also intends to ensure that its own vehicles will be low carbon technology (i.e. less than 100g/km of CO2 equivalent) by 2010-11 when such vehicles should be in volume production.

Procurement

Where possible the council obtains materials from local sources reducing carbon miles. It ensures that timber is obtained from sustainably managed forests. It encourages its contractors also to adopt sustainable procurement policies.

The conclusion to be drawn from these case studies is that sustainable design is a holistic activity and demands an integrated approach. Reducing the demand for energy and generating clean energy are two sides of the same coin. Examples have been cited where buildings and transport are organically linked with building integrated renewables providing power for electric cars. BedZED, Malmo and Woking are signposts to new and more sustainable and agreeable patterns of life.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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Responses

  • Carlene
    How build mini power grid?
    7 years ago

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