Energy generation: Micro-Renewables

It is tempting to abandon the issue of energy conservation because it is too difficult, and to resort to trying to solve the energy supply problem either by large scale or by micro-renewables.

Large scale renewable energy:

There is no doubt that large scale renewables such as hydro, wind, or tidal power are effective technologies. There is also no doubt that they are not sufficiently effective to cope with existing demand, and certainly not growing demand, in the short term (by which I mean the next 20 to 30 years). In fact it may be stated that there cannot be an energy supply solution of any sort without the demand side being considerably reduced. If we reduce the building demand, this will make a huge impact on our demands on supply.

For example, if, over the period between 2010 and 2020, all new buildings were built to reduce CO2 emissions to 30% of the UK average set at 2003 ( ie a reduction from the average emissions of the building stock in 2003 of 70% - which is not actually a very high or stretching target, unlike Passive House technology) then the whole building stock would dramatically improve its energy performance and the energy generation requirement of the UK would have been radically reduced. Figures calculated by David Olivier show that the savings in energy from building all new houses to this standard over this period would be the equivalent of an average size windfarm being erected per week, or over 12 million 2kW Photovoltaic systems. This figure also represents the equivalent amount of energy savings to the UK Government’s target renewable energy production of 10% to 20% in this period.

Microgeneration is not an answer:

There is a temptation to think that putting micro-renewables, such as wind turbines or solar photovoltaic panels, on buildings is a way to solve our energy problems, without us having to address the more basic issue of energy use in buildings. In fact there are good arguments to show that micro-renewables are not only a distraction and an opportunity cost (due to the fact that the money could be better spent elsewhere) but that their total life cycle impact in some instances is not to reduce CO2 . Below is an assessment done of the cost effectiveness of different energy saving and renewable energy measures for a sight in St Austells, Cornwall, as part of a bid for a carbon neutral development: (click to make bigger)

The thicker grey columns are the amount of CO2 that could be saved over above the average UK house by introducing the individual measures and the thinner blue columns are the cost of these technologies over a 60 year life, in thousands of pounds per tonne of CO2 saved. All the figures are taken from practical evidence rather than theory, or sales blurb. It is immediately apparent that sorting out the shell of the building and the interaction between humans and their technology are the most effective measures, followed by tested renewable heating systems such as solar thermal water heating and biomass boilers. The only renewable electrical generation that makes sense is off site large scale wind or other (such as wave, hydro).

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