No one should doubt the present surge in progress of energy innovation. For me, much is exciting and innovative, especially when the technologies reduce adverse environmental impacts yet at the same time give improved service. Yet there is always a ‘Doubting Thomas’ nearby to complain and carp at the very technologies that inspire me. The papers of this issue of Energy provide excellent examples of authors standing firm for their respective progressive technologies.
Technology 1 – wind power, subject ‘variability’. How often have you heard Doubting Thomas say that windfarms need ‘back-up’ thermal power stations of similar capacity that are permanently on standby to take over when the wind drops? David Milborrow knocks this fallacy on the head with his carefully expounded paper, ‘Quantifying the impacts of wind variability’. He does not deny that wind power varies, nor does he suggest that we can control the wind. However, just as an uncontrollable load on an electrical grid does not destroy the service, nor does uncontrollable generation – it is the grid as a whole that must have reserve capacity for outages, be these due to disrupted nuclear power supply or to windfarms. Considering only the variability of wind power, David Milborrow assesses the impacts on thermal generation if wind is always treated as ‘must take’ and as wind capacity increases. Thus if carbon-free UK wind power should one day provide 40% of annual electricity, the effective extra capacity for ‘standby’ would add at most 5% to electricity costs, which could be reduced by load management, improved forecasting and smart grids.
Technology 2 – biofuels. When crop plants are combusted as fuels, the mass of carbon in the CO2 emitted, in principle, equals the mass of carbon absorbed at plant growth by photosynthesis, so such fuels are ‘carbon neutral’. However, in practice fossil fuels are used in agriculture and processing, so Doubting Thomas berates the implied fossil-carbon abatement of using biofuels.
Nigel Mortimer reviews the life-cycle of fossil-carbon dioxide, methane and nitrous oxide abatement of a range of biofuels for transportation, especially of biodiesel and bioethanol. This may sound simple, but unbelievable complexity emerges when crops, say food and fuels, are compared together with associated by-products and co-products, different reference systems and alternative production methods. Six standard procedures are compared. The ‘worst’ biofuel is bioethanol from US maize, where, for instance, coal is used to generate electricity for processing, and the ‘best’ is pressurized biomethane from pig slurry, which would have otherwise released methane to the atmosphere. Doubting Thomases will find examples for their scepticism, but before negating all liquid biofuels, they should read Mortimer’s guarded optimism for second-generation liquid biofuels, for instance processed lignin. There are no simple answers.
Dermot Roddy reviews the production of biofuels globally, with frequent reference to EU policy and to impacts on developing countries. With wide-ranging argument and evidence, he concludes that present biofuel production does not reduce food supplies. Environmental factors dominate, but Roddy considers such challenges pragmatically for increasing biofuel targets to about 20% of energy needs. He concludes that biofuels can, in principle, be produced with minimal harm, but all too often best practice is not followed. He puts his trust in improved agricultural methods and advanced technologies for next-generation biofuels. With such guarded optimism (and, I would add, improved vehicles) Doubting Thomas can be confronted.
Technology 3 – combined heat and power using local ‘microgrids’. In principle, the ejected heat of thermal power stations should always be gainfully used as combined heat and power (CHP). Doubting Thomas points to the difficulty of matching local heat loads. Microgeneration allows supply substitution at wholesale rather than retail prices, but the mismatch of electrical and heat loads handicaps its use for isolated houses. Success requires connection to both electrical and heat grids, so the Southampton University group (Papafragkou et al.) use simulation modelling to analyse CHP operation and building performance of clusters of 10 houses. Heat is stored in building fabric and in additional insulated water-tanks. A range of financial and carbon emission criteria were used for assessment. The results show that multi-house load aggregation, especially for heating, allows larger CHP plant arrangements to perform better than individual condensing boilers and imported utility electricity. However, with the scenarios chosen, the improvements are marginal. Doubting Thomas may still not be convinced about the benefit of such small schemes.
Technology 4 – domestic house adaptation for future heat-waves. The research-in-progress ‘Briefing’ by Porritt, Goodier and Shao considers a fictional climate changed heat-wave in the 2080s and passive temperature reduction in UK housing. The example given is an analysis of the simplest of ameliorations – reflective light-coloured exterior walls and using external shutters for shading on Victorian terraced housing. However, I would hope that by then even Doubting Thomas would be living in an externally insulated house of large thermal capacity with full passive-solar design, thus providing comfort throughout the year at low cost.
