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Renew your energy: July 2009 Archives

Pipe Dreams

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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.

Dealing with nuclear waste has proved to be the Achilles heal of the nuclear fuel cycle. Although there are plans, no one has yet established a full-scale long-term repository for high-level waste. However, enthusiasts for reprocessing spent nuclear fuel have claimed that, as well as producing more fuel, this is a way to reduce the amount of high level wastes.

That's true up to a point, in that reprocessing basically is about extracting the plutonium and also left over uranium- so what's left is lower or medium grade waste. But that doesn't change the total amount of radioactive material. Indeed the chemical separation process used for plants like THORP at Sellafied leads to a lot of secondary activated materials- more low and medium grade wastes to deal with. And the separation process is complex, expensive and a major source of radiation exposure risk problems for both workers and the public e.g. most of the accidental leaks and also allowed emissions from the nuclear cycle have come for reprocessing plants. It's been estimated that nearly 80% of the collective occupational radiation dose associated with the complete nuclear fuel cycle comes from reprocessing activities, measured on the basis of the dose per kWh of power finally generated.

The UK government has decided that fuel from any new reactors built here should not be reprocessed. It is cheaper and easier to dry store the spent fuel. Quite apart from the cost, that's not a surprising decision given that THORP has been out of action since an internal leak in 2005- it's not clear if it will ever reopen fully before it's due for final decommissioning. Moreover, we don't now need plutonium for weapons (we have enough) or to fuel Fast breeder reactors- the UK Fast Breeder programme at Dounreay was closed a decade or so ago. Some of the existing stock of plutonium has been turned into a new fuel, mixed with uranium oxide, called MOX, but the plant for making this has also had problems and may soon be abandoned.

The UK and France have been the only countries with major reprocesssing plants- they have reprocessed fuel for other countries. The US backed away from reprocessing in the 1970's- there were worries about the cost and about the risk of illegal diversion of plutonium. But President (W) Bush reinstated the idea- as part of a major US led global nuclear push, the Global Nuclear Energy Partnership (GNEP). One version of the idea was that the USA would supply small sealed nuclear plants (e.g. mini nukes of the sort being developed for remote sites) to client states around the world, focussing on developing countries, the spent fuel from which would be brought back to the US for reprocessing- to extract the plutonium and uranium. This material could then be used in a new fleet of US nuclear plants, including possibly fast breeder reactors. The claim was that this would be a closed fuel cycle, controlled by the US, with no (or less) risk of proliferation/diversion.

Enthusiasts talked up the role that could be played by the proposed Integral Fast Reactor (IFR) linked in with on-site pyroprocessing to recycle spent fuel. That approach is claimed to produce much less secondary waste than conventional chemical PUREX reprocessing. And it was claimed that some wastes could actually be burnt up in the reactor itself.

See: http://www.nationalcenter.org/NPA378.html and http://bravenewclimate.com/integral-fast-reactor-ifr-nuclear-power.

However, President Obama seems much less enamoured of the nuclear option. While not opposed to it, his pre-election New Agenda web site said 'Before an expansion of nuclear power is considered, key issues must be addressed including: security of nuclear fuel and waste, waste storage, and proliferation'.

And in office he withdrew $50billion in loan guarantees for new nuclear plants that had been expected to be included in the US Economic Stimulus funding, and also halted work on the proposed nuclear waste repository at Yukka Mountain in Nevada. It was expected to cost $96.2 bn. About $13.5 bn has already been spent on it. Other sites may now be looked at.

Most recently the US Dept of Energy cut its assessment work on the US part of the Global Nuclear Energy Partnership programme, since, as the World Nuclear News services put it, the US ' is no longer pursuing domestic commercial reprocessing, which was the primary focus of the prior administration's domestic GNEP program'. It added that 'As yet, DoE has no specific proposed actions for the international component of the GNEP program'.

25 countries had joined the GNEP, but the US was the leader, so it's unclear what will happen to it - and to reprocessing. Japan has been trying to develop its own reprocessing capacity, but at $20 billion, it's proved to about three times more expensive than originally budgeted. And as the world's only non-nuclear weapons state operating such a facility, the project attracted substantial national and international opposition. Overall, while it's certainly not yet abandoned everywhere, it does seem clear that reprocessing is increasingly falling out of favour around the world- except perhaps in countries seeking a way to make bombs!

It's well known that cats kill many more birds than anything human beings have come up with, including cars and aeroplanes, but there's an interesting survey of avian deaths from wind, fossil and nuclear plants: 'Contextualizing avian mortality: A preliminary appraisal of bird and bat fatalities from wind, fossil-fuel, and nuclear electricity', by Benjamin K. Sovacool in Energy Policy 37 (2009) 2241-2248.

Based on operating performance in the US and Europe, this study offers an approximate calculation for the number of birds killed per kWh generated for each systems. It estimates that wind farms and nuclear power stations are responsible each for between 0.3 - 0.4 fatalities per gigawatt-hour (GWh) of electricity, while fossil-fuelled power stations are responsible for about 5.2 fatalities/GWh. Although this is only as a preliminary assessment, the estimate means that wind farms killed approx. 7000 birds in the USA in 2006, but nuclear plants killed about 327,000 and fossil-fuelled power plants 14.5 million. However, the data is sparse, especially on bats, and the paper concludes that further study is needed.

Even so it provides a useful introduction. It notes that coal, oil, and natural gas-fired power plants induce avian deaths at various points throughout their fuel cycle: e.g. during coal mining, through collision and electrocution with operating plant equipment and transmission cables, and from poisoning and death caused by acid rain, mercury pollution and climate change. The scale of the direct impacts is quite surprising. e.g. an observation of 500m of power lines feeding a 400MW conventional power plant in Spain estimated that they electrocuted 467 birds and an additional 52 were killed in collisions with lines and towers over the course of two years. By comparison wind turbines seem quite benign (birds tend to avoid moving objects), although they too will have power grid links, and there were some early major problems with multiple bird strikes when wind farms were located in migratory paths e.g. in Southern Spain. Clearly sites like that should be avoided and we must also reduce casual impacts to the minimum possible, by sensitive location.

That is something the Royal Society for the Protection of Birds is keen to improve. It has come out with a positive approach to wind farm spatial planning, which it says can avoid problems and help ensure the development of wind power - which it backs as a response to climate change and energy security problems.

The RSPB report, 'Positive Planning for Onshore Wind', warns that 'inappropriately sited wind farms can damage fragile wildlife and habitats, through habitat loss, mortality through collisions and a range of different disturbance effects' but Ruth Davis, RSPB's head of climate change policy, said 'Left unchecked, climate change threatens many species with extinction. Yet, that sense of urgency is not translating into action on the ground to harness the abundant wind energy around us. This report shows that if we get it right, the UK can produce huge amounts of clean energy without time-consuming conflicts and harm to our wildlife. Get it wrong and people may reject wind power. That could be disastrous.'

It now wants to see a UK system of strategically chosen areas. That was the basis of Welsh "TAN8" planning policy introduced in 2005, which set out seven "Strategic Search Areas" that wind developers were to consider for wind farms. However, TAN8 has had mixed results so far, although the RSPB suggests there wasn't enough consultation over the selection of the Strategic Search Areas. Scotland is now beginning to implement a "spatially explicit" new approach to onshore wind planning, via local development plans, but the RSPB report also highlights successful systems in Germany and Denmark- the RSPB commissioned a report from the Institute for European Environmental Policy, which found that wind farms were being developed rapidly on the Continent without harmful impacts on bird populations.

* A one year research programme carried out in the USA by the Bats and Wind Energy Cooperative, a partnership of the wind industry, government and conservation groups, at the Mountaineer windfarm in W. Virginia, and at the Meyersdale windfarm in Somerset County, Pennsylvania, found "substantial" mortality of bats at two U.S. windfarms, with a daily kill rate of 0.7 bats per turbine. At both windfarms, most bats were killed on nights when average wind speeds and power production were low, but while turbine blades were still moving at relatively high speeds, with fatalities increasing just before and after the passage of storm fronts and when bat activity was highest in the first two hours after sunset. Temporary close down during such periods is one possible remedial response.

Why fusion?

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One of the big hopes for the energy future is nuclear fusion- not messy uranium fission, with all its problems, but allegedly clean and hopefully prolific hydrogen based nuclear fusion. However, it's a long time coming - and it's costing a lot. $20 billion so far globally, and more soon. The cost of the new ITER project at Cadarache in Southern France. has risen from £9 billion to, reportedly, around £18 billion. It's a joint EU, Russia, US, China, Japan and S. Korea project toward which it seems the UK is contributing around £20m p.a. That's in addition to the £26 m for nuclear fusion research in the UK through the Engineering and Physical Sciences Research Council for 2007-8.

For comparison, government expenditure on research and development for all the renewable energy sources in 2007-8 was £ 15.92 million via the Research Councils and £ 7.53m via the Technology Strategy Board, plus some related policy work via the UK Energy Research Centre and Tyndall Centre for Climate Change Research.

Fusion is clearly getting favourable treatment compared to renewables. Is this wise? After all there is a wide range of renewable technologies, a dozen or more very different systems, not just one. Why the imbalance?

The claim is that fusion offers, as the EURATOM web site says, 'an almost limitless supply of clean energy'. And yet the UK Atomic Energy Authority say that, assuming all goes well with ITER and the follow up plants that will be needed before anything like commercial scale is reached, fusion only 'has the potential to supply 20% of the world's electricity by the year 2100.' That's not a misprint - 20%, if all goes well, in 90 years time. Renewables already supply that now globally, including hydro, and the new renewables like wind, solar, tidal and wave power, are moving ahead rapidly- and could be accelerated.

By comparison, the prospects for fusion are actually rather mixed. The physics may be sorted, up to a point. The UK's JET experiment at Culham managed to generate 16MW briefly (but not of course net- it needed 23MW input). But the engineering is going to be complicated. How do you generate electricity from a radioactive plasma at 200 million degrees C? The answer it seems is by absorbing the neutron flux in a surrounding blanket that then gets hot, and has pipes running through to extract the heat, which is then used it to boil water and raise steam -as with traditional power plants. Not very 21st century...

As yet, few people would hazard a guess as to the economics of such systems. The ITER web site (www.iter.org) says 'it is not yet possible to say whether nuclear fusion based on magnetic confinement will produce a competitive energy source'.

But at least there won't be any fission products to deal with. However, the neutron flux will activate materials in the fusion reactor which will interfere with its operation, and will have to be stripped out regularly- so there will still be a radioactive waste storage problem, albeit a lesser one. The materials will only have to be kept secure for a hundred years or so, rather than thousands of years as with some fission products.

The risk of leaks and catastrophic accidents is said to be lower than with fission. Fusion reactions are difficult to sustain, so in any disturbance to normal operation the reaction would be likely to shut itself down very rapidly. But it is conceivable that some of the radioactive materials might escape. The main concern is the radioactive tritium that would be in the core of the reactor, which if accidentally released, could be dispersed in the environment as tritiated water, with potentially disastrous effects. To put it simply, it could reach parts of the body, which other isotopes couldn't.

Finally what about the fuel source? The basic fuels in the most likely configuration to be adopted would be deuterium, an isotope of hydrogen, which is found in water, and tritium, another isotope of hydrogen, which can be manufactured from Lithium. Water is obviously plentiful while it is claimed that Lithium reserves might last for perhaps 1000 years, depending on the rate of use. That presumably depends on the competing use in Li Ion batteries in consumer electronics and possibly soon, on a much larger scale, in electric vehicles.

While that could be a problem for the future, there is a long way to go before we need worry about fuel scarcity. The ITER project is small (500 Megawatt rated) and won't start operating until 2018, and, even assuming all goes well, it's only a step toward a commercial pilot plant. And that at best is decades away. There could of course be breakthroughs. While the ITER magnetic constriction device is seen as the main line of attack, the US is also looking at laser fusion. But, even if it works, that too is unlikely to provide a practical energy source for some while.

We need to start responding to the climate problem now. So why then are we spending so much taxpayers money on fusion? It might eventually be useful for powering space craft. But on Earth? Wouldn't it make more sense to speed the development and deployment of full range of renewable technologies, and make use of the free energy we get from fusion reactor we already have- the sun.