Renew On Line (UK) 70

6. CAT s Zero carbon plan

In 1977, the Centre for Alternative Technology in Wales produced the UK s first Alternative Energy Strategy , which had a big impact at the time, and still looks impressive. Thirty years on, CAT is trying to build a fresh consensus around an equally radical new energy strategy: zero carbon britain. It takes current UK fossil fuel consumption down to zero in 2 decades, and powers up renewables to meet the emerging demand- by 2027, ~100% of UK electricity comes from renewables, 50% from wind, and overall energy demand is cut by a half. The main driver for action is the imposition of personal carbon credits- Tradable Energy Quotas (TEQs). On the technology side there is a massive a shift from oil to renewable electricity for transport, with electric vehicles dominating and lots of energy storage (much of it in electric vehicle batteries)- all supplied by huge offshore wind programmes plus major contributions from wave, tidal, PV etc. With nuclear phasing out of course.

CAT say: Heat demand for buildings is expected to decline by 50% and electricity demand by around 10%. New buildings will be effectively zero-carbon from 2012. There will also be a vigorous programme to refurbish older buildings for lower energy consumption. Some heating will come from biomass CHP, some from surplus renewable electricity. The benefits of electrical heating will be multiplied by the use of heat-pumps. Some of the intermittent surpluses in renewable generation may also be stored as heat.

It s certainly breathtaking stuff- audacious and challenging. And all to be achieved in 20 years... Definately pushing the limits.

How could it work?

CAT say that With declining oil and gas, the electricity supply will be increased to compensate, requiring reinforcement of the National Grid. Compared to large-scale fossil fuelled generation, a grid with a high penetration of intermittent and variable renewables requires more sophisticated systems for integration and balancing of supply . They accept that There will be times when renewables are generating more energy than is needed in a local area. In these situations, energy will be exported to other areas, or stored in vehicle-to-grid systems, flow batteries, pumped storage or geological hydrogen stores . They go on In the opposite situation, when the available renewable resource is insufficient to meet local demand, grid distribution brings power from other parts of the country. This is followed by shedding demand on economy tariffs and retrieving power from storage systems. Beyond this, power is acquired from firm renewables such as biomass fuelled CHP. If required, further energy reserves can be accessed from discharge of electric vehicle batteries and CHP from national strategic hydrogen reserves.

They say that their Island Britain scenario demonstrates that the country can not only provide all its energy from renewables, but that its storage requirements are also achievable. The need for power balancing is minimised by intelligent load management, wide geographical distribution of renewable generators, plus firm renewables such as tidal and biomass fuelled CHP. Tidal energy, unlike wind and solar electric, is highly predictable and regular. The 11% of Britain s electricity that this technology can supply is equivalent to the predictable and continuous baseload currently provided by nuclear generation. Generation sources include a strategic mix covering the different conditions throughout the year. Britain s solar resource can deliver both electricity and heat in summer, complementing wind and marine renewables. With its good match to the demand profile across the year, wind will provide the greatest proportion of electricity in the scenario, at around 50% of total supply.

First Reactions

Sir John Houghton, former Co-chair of the Intergovernmental Panel on Climate Change and former Director General of the UK Met Office said, The authors of zerocarbonbritain present a time-scale for action that begins now. I commend their imagination (coupled with realism), their integrated view and their sense of urgency, as an inspiration to all who are grappling with the challenge that climate change is bringing to our world.

While it s clearly visionary, CAT says it also adopts a fairly pragmatic approach and uses only existing and proven technologies . However the programme isn t really costed and there are bound to be disagreements about some of their proposals & assumptions. For example, is tidal energy really firm ? Do we really want tidal barrages? Why only 16TWh from tidal stream? Can we really get so much from wind, 474TWh p.a. by 2027? And wave power- 250TWh by 2027? What about CSP imports? And more politically, should we buy in carbon credits? And will personal carbon rationing be acceptable- or effective? CAT do say that TEQ s will avoid the rebound effect (respend of energy savings), but as we ve argued before, they could be socially divisive. We could go on! But we review the CAT report in detail in Renew 171. Meanwhile take a look at: http://www.zerocarbonbritain.com