ICE - Institution of Civil Engineers - Virtual Library

A number of authors have suggested that the UK faces a ‘looming energy gap’ in the coming decade because of an increasing dependence on imported fuels, the closure of a number of electricity generators and a perceived lack of investment in new generating capacity. Focusing on electricity generation, this paper seeks to clearly define what an energy gap is, explain why there may be concerns over such a gap and identify the reasons why a gap may or may not materialise. A central contention of this paper is that there is confusion over the two forms of energy gap, namely a ‘fuel gap’ that would occur if insufficient fuel were available to generators to produce electricity and a ‘capacity gap’ that would occur with insufficient generation capacity to convert available fuel into electricity. This conflation is unhelpful because the reasons for, and policy responses to, these two forms of gap may be quite distinct. The paper goes on to explore the issues surrounding these two manifestations of an energy gap and how they relate to policy.

Bioenergy will need to play a significant role in the future of Europe's energy provision in order to maintain energy security and sustainability. In this context, a regional assessment of biomass availability for energy use has been carried out for the south west region of England. Current bioenergy production, the maximum present resource availability and the maximum available future feedstock (at around 2020) in the region have been evaluated on the basis of a resource flow analysis. Extensive agricultural land (over 80% of the total land cover) and optimum climatic conditions of the region make it favourable for bioenergy feedstock development. Nevertheless, the slow uptake of bioenergy technologies has resulted in only modest feedstock growth and supply. Bioenergy production in the region at present is comparatively low at around 1300 GWh (approximately 4·32 PJ) of primary energy, with a significant portion of this resource being recovered from waste. It is therefore argued that a shift towards the use of perennial crops is desirable, along with increased farm-waste energy recovery. The regional bioenergy potential by around 2020 is estimated to be 5500–13 800 GWh (20–50 PJ) of primary energy, which would provide 4–9% of the region's primary energy consumption.

This paper describes various walling systems capable of providing an ultra low U-value wall construction for use in a domestic application. The target U-value is 0·11 W/m²K −36% less than the minimum requirement for the German ‘Passivhaus’ standard and some 60–70% more onerous than current UK building regulations; this value was chosen because of the high degree of challenge it presents whilst remaining technologically achievable. The paper briefly discusses whether static U-value is truly relevant to most domestic applications in the UK, or whether it is the less understood dynamic U-value that should be the focus of attention. The positive and negative characteristics, including wall thicknesses, embodied energy, toxicity, expected lifespan and ease of installation, of various systems are discussed. Test data provided by manufacturers to support U-value claims are carefully examined. The walling systems discussed cover a broad range of technologies, including structural insulated panels (SIPs), vacuum insulation panels (VIPs), insulating concrete formwork, traditional cavity wall masonry, external insulation of masonry and cellulose-based systems such as straw. The paper concludes by summarising the benefits of each system type and recommending applications that are particularly suitable for each type of wall.