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Nuclear or renewables – two new scenarios

By Dave Elliott

Guest posts by Energy Matters’ commentators Alex Terrell and Andy Dawson present two rival UK scenarios for 2050 with, respectively, high nuclear and high renewables. It’s an interesting exercise. They looked at DECC’s 2050 Pathways models, but say ‘it’s far from clear if the underlying models take adequate account of variations in demand’. So they developed their own demand projections.

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Pipe Dreams

Construction has started on the first part of the ‘Leningrad II’ nuclear plant on the existing nuclear plant site on the outskirts of what is now St Petersburgh. The first 1170 MWe pressurised water reactor is scheduled for commissioning in October 2013 and the second a year later, at a cost of $3.0-3.7 bn per pair. Leningrad II will eventually have four new reactors.They are claimed to be super safe, with passive as well as active safety features.

As well as supplying electricity to the grid, the four new Leningrad II reactors, like the existing plant there, will also provide heat to the city- 9.17 petajoules per year of district heating. In well insulated pipes, heat losses over 10-20 km are relatively low and the demand for heat in Russia is high given the climate. Nuclear Cogeneration/Combined Heat and Power (CHP) capacity in Russia will then be supplying about 12 petajoules of heat per year, and it plans to have 5 GW of small nuclear reactors for electricity generation and district heating by 2018 at Arkhangelsk, Voronezh, Chukoyka and Severodvinsk.

So will others follow the lead and install nuclear plants in or near cites- and feed the waste heat into district heating pipes? So far most nuclear plants in the West have been located in relatively remote areas- for safety reasons and to be near sources of cooling water. But there are economic attractions in being able to use the otherwise wasted heat produced by the steam turbines. As with all steam raising power plants, whatever the fuel, the losses represents nearly 70% of the heat energy produced from the fuel, more than half of which can be reclaimed by operating in CHP mode i.e. supplying heat and well as electricity.

Even if you don’t like the idea of urban nukes (and if nothing else it could have a significant impact on property values!), there are some other interesting and possibly equally controversial ideas related to CHP/district heating. We are all used to the standard argument that putting insulation on buildings is the cheapest energy option. ‘The cheapest watt is the negawatt,’ and so on. But is it always so? Studies by CHP consultants Orchard Partners London Ltd have suggested that, in terms at least of retrofit/rehab options, it may be cheaper and lead to more carbon emission savings, to provide piped heat from urban gas-fired CHP plants, than to install insulation, especially for some hard to access high rise flats. Put simply, the argument is that it’s easier and cheaper to insulate pipes than whole buildings. They have developed a clever kerb stone pipe module that they say makes urban retro-installation easy. They claim that ‘Houses, when connected to low CO2 piped heat supply would immediately achieve the highest rating for buildings without any investment in demand side measures. The disruption to residents and traffic with the new route that has been identified will be minimal compared to the disruption replacing an unsustainable gas network under the roads and minimal for residents compared to retrofitting insulation and glazing to existing premises particularly all our pre 1950s stock.’

If you also moved to biomass, or biowaste /biogas fuelled CHP plants, then you would be more or less zero carbon- and cities have a lot of biowastes, sewage biogas for example being one of the cheapest energy sources around. At present much of it is used just for electricity production, but CHP is the logical next step. With interest in renewable heat supply growing (heating accounts for about 40% of UK energy use) some fascinating new ideas are emerging about new ways of supplying consumers’ needs- using pipes. At present we transmit electricity long distances from large power plants, with up to 10% transmission loses and even more local distribution losses. But you could have a large remote biomass fired plant, perhaps using biogas from a landfill site, which transmits heat to consumers in cities. Or a large anaerobic biogas digestor on the edge of a town or city, or even miles away, using municipal waste, and feeding biogas along a pipe to an inner city CHP plant. More likely biogas will just be added into the conventional gas main – that’s actually now been agreed as an acceptable option and some projects are underway or planned. But one way or another we may be seeing a lot more pipes in future…whether running heat or gas, the attraction over electricity being that both can be stored. We may even see the return of the classic large inner city gasometer for gas storage, along with local buffer heat stores, as are used in parts of northern Europe as a part of local district heating systems

Other renewable energy sources can also be run into heat stores- solar heat for example, allowing for variable supply to be matched to variable demand. There are even some inter-seasonal solar heat stores in operation. Once again, put simply, while no one is suggesting we don’t do both where appropriate, it’s easier to insulate a heat store than a whole house. And it’s not just solar heat, or geothermal heat, we could store. Dr Mark Barrett, senior researcher at the UCL Energy Institute, has suggested that we could use our domestic hot water cylinders as a national distributed heat store, storing excess energy from wind turbines and other large but variable electricity supplying renewables, like wave and tidal power, ready for use to reduce heat demand peaks.

Plenty of new ideas then to suit all tastes, and good news for plumbers and pipelayers! And an interesting challenge to those who think in terms of an ‘all-electric’ future.

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