Saturday, April 1, 2017

Small Nuclear

Small Modular Reactors (SMRs) of up to a few hundred megawatts capacity are being touted by some as the way ahead for nuclear power since they are expected to be quicker to build than large gigawatt scale plants and so less costly to finance, with mass production also reducing unit costs. They might also be located in or near cities so that the waste heat they produce could be fed to district heating networks, the use of this extra output offsetting their cost further. It may also be possible, it is claimed, that their power output could be more easily varied, so that they could play a role in grid balancing, though, as with large nuclear plants, that would undermine their economics- it is best to run them flat out.

There has certainly been much enthusiasm expressed for the idea, with various vendors offering their wares, for example http://www.westinghousenuclear.com/New-Plants/Small-Modular-Reactor   Estimates of costs vary, but in the US context it has been claimed by NuScale that ‘first of kind’ SMRs might generate at around 101cents/MWh, falling to 90c/MWh on mass production, cheaper than new large advanced nuclear plants at 96c/MWh, and also cheaper that coal fired plants, but not competitive with unabated combined cycle gas plants (64-66c) or wind plants (80c) or hydro (85c). http://www.nuscalepower.com/images/nuscale_smr_benefits/Right_Column/nuscale-operating-costs.jpg
Some of the designs for SMRs are quite exotic, based on the use of fuel dissolved in molten salt which then acts as both reaction medium/moderator and heat transfer /coolant medium. Terrestial Energy amongst others is pushing this Molten Salt Reactor idea, and is seeking US government backing: http://www.world-nuclear-news.org/NN-Terrestrial-Energy-to-complete-US-loan-guarantee-application-1409167.html It may take a while to happen- this is new ground. But some of the less radical ideas might be faster to develop. The UKs Energy Technologies Institute says SMRs could be up and running in the UK by 2030 if R&D work gets underway soon and should be designed to be able to run in CHP mode, so that they can provide heat as well as electricity: http://www.eti.co.uk/insights/the-role-for-nuclear-within-a-low-carbon-energy-system/

Although much work will have to be done to modify the technology for civil power (and possibly heat), it is claimed that civil SMRs can be based on existing nuclear submarine propulsion technology, which is well established, with companies like Rolls Royce being well placed to develop suitable units: www.telegraph.co.uk/business/2016/03/19/rolls-royce-could-power-britains-nuclear-future-with-mini-reacto/ However the submarine and civil contexts are very different, with very different operational requirements and operating regimes. Safety and reliability is obviously a key issue in all contexts, but even in the closely managed military environment things can go wrong: www.theguardian.com/world/2011/mar/10/royal-navy-nuclear-submarine-reactor-flaws  And spreading SMRs around in urban areas could pose safety and security risks, with local public acceptability potentially being a big issue.

In the USA however, the Tennessee Valley Authority (TVA) claims that SMRs could be put close to population zones and it is looking to reduce the risk of issues such as emergency
planning evacuation zones slowing operating project approval. They say that, given safety
upgrades, ‘based upon the preliminary information which we've received from the four vendors, we are confident that all of them can be supported by a two-mile emergency plan [zone] and at least one has capability of site [only] boundary’ i.e. no safety zoning beyond the plant site. That compares with 10 miles typically required for a large reactor. http://analysis.nuclearenergyinsider.com/us-operator-seeks-swift-smr-licensing-optimize-low-carbon-output

That seems a little provocative. Will anyone accept mini nukes in their backyards? And what about security?  SMRs will pressumably be sealed modular units, making access to the fissile material hard, but, unless they are very carefully guarded, they might still provide an enticing and convenient target for terrorist attack. In terms of safety, the US Union for Concerned Scientists says that ‘Multiple SMRs may actually present a higher risk than a single large reactor, especially if plant owners try to cut costs by reducing support staff or safety equipment per reactor.’ It adds that some proponents have suggested siting SMRs underground as a safety measure. However, underground siting is a double-edged sword- it reduces risk in some situations (such as earthquake) and increases it in others (such as flooding). It can also make emergency intervention more difficult. And it increases cost.’
There are thus a range of technical, economic, safety and security issues to face, not least the issue of social acceptance, with there being no clear indication that they can be resolved: http://www.academia.edu/8114310/One_size_doesn_t_fit_all_Social_priorities_and_technical_conflicts_for_small_modular_reactors

From the industry side however, enthusiasm remains strong, and there is much debate about exactly how to proceed and on what basis. For example, should SMRs replace large nuclear plants in any future programme?  In the UK context, ETI’s 2015 report on The role for nuclear within a low carbon energy system’ said that contrary to the claim SMRs might be better than large nuclear plants, large reactors are best suited for baseload electricity production’. However, it notes that, based on using existing (nuclear) sites for them, there is ‘an upper capacity limit in England and Wales to 2050 from site availability of around 35 GWe,’ while there could be room for at least 21GW of SMRs in the UK, given that more sites could be available for them, including near cities, where the heat option offered a key economic compensation. So, although SMRs ‘may be less cost effective for baseload electricity production, SMRs could fulfil an additional role in a UK low carbon energy system by delivering combined heat and power (CHP) - a major contribution to the decarbonisation of energy use in buildings’, assuming the necessary district heating infrastructure was available, with SMRs delivering heat into cities ‘via hot water pipelines up to 30km in length’.
In this context it is interesting that, more recently, the Newcastle-based SMR enthusiasts Penultimate Power thinks SMRs will work best as ‘complementary to, rather than competing with’ the large-scale nuclear plants: http://www.chroniclelive.co.uk/business/business-news/newcastle-company-forefront-technology-small-10869984

A SMR assessment programme has been launched by the UK government, and SMR programmes are going ahead in the USA and elsewhere: http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspxThis is all in a context where, according to the UK National Nuclear Laboratory, the potential market for SMRs might be up to 85 GWe by 2035:  http://www.world-nuclear-news.org/NN-UK-considers-how-to-use-small-reactor-opportunity-1910161.html   That may be optimistic. The OECD says ‘up to 21 GWe of SMRs could be added globally by 2035’. http://www.oecd-nea.org/ndd/pubs/2016/7213-smrs.pdf  And there is no shortage of critical comment on the whole idea:

It’s not a new idea: in addition to the small units developed for the US military in 1940’s, (for planes and ships) there were may attempts to build small civilian nuclear plants in the USA in the 1950s, mostly with poor results: http://spectrum.ieee.org/energy/nuclear/the-forgotten-history-of-small-nuclear-reactors The current flurry of enthusiasm for SMRs seems to be mainly driven by the failure of conventional nuclear to expand as fast as the industry would like.  It’s stalled or declining in many parts of the world, due to poor economics and local opposition, and the existence of better, cheaper renewable alternatives. However, SMRs may not offer much help in changing this situation. There will no doubt be some prototype projects around the world in selected sites, and some projects may be suited to specialised applications, for example in remote sites or for some industrial processes: http://www.sciencedirect.com/science/article/pii/S0301421512000249
However, in terms of widespread use for public power and heat production, given the practical problems of finding acceptable sites and the uncertain economics, plus all the usual problems with nuclear, including what to do with the radioactive wastes that are produced, it could be that SMRs may not prove to be that significant. But it’s also possible that they may boom, if a wider market emerges and/or if there are some major technological breakthroughs: http://www.powermag.com/market-small-modular-reactors/


All this and much more is covered in Dave Elliott’s new book for the Institute of Physics: ‘Nuclear Power: Past, present and Future’, out soon.

Wednesday, February 1, 2017

CCS is vital say some

‘Carbon capture and storage (CCS) is the only technology able to deliver significant emissions reductions from the use of fossil fuels’. So said the International Energy Agency in a report last year. It went on ‘CCS can reduce emissions not only from power generation, but also from industrial sectors such as iron and steel, refining, petrochemical, and cement manufacturing.’  According to its modeling, ‘CCS could deliver 13% of the cumulative emissions reductions needed by 2050 to limit the global increase in temperature to 2°C (IEA 2DS). This represents the capture and storage of around 6 billion tonnes (Bt) of CO2 emissions per year in 2050, nearly triple India’s energy sector emissions today.’ It adds ‘Half of this captured CO2 in the 2DS would come from industrial sectors, where there are currently limited or no alternatives for achieving deep emission reductions.  While there are alternatives to CCS in power generation, delaying or abandoning CCS in the sector would increase the investment required by 40% or more in the 2DS, and may place untenable and unrealistic demands on other low emission technology options.’
www.iea.org/publications/freepublications/publication/carbon-capture-and-storagethe-solution-for-deep-emissions-reductions.html
While some see CCS as just a way to allow fossil fuels to still be used, the IEA says ‘a 2oC pathway represents a significant departure from “business-as usual” for fossil fuels. Coal use in power generation falls to around one-third of current levels.’  However, it is still used, but emissions are reduced since 95% of coal-fired generators are equipped with CCS. It adds ‘40% of gas-fired power generation will also need to be equipped with CCS in 2050.’ It says ‘this has implications for decisions to invest in fossil fuel-based power generation and industrial facilities today, as most of these large capital investments are based on assumed lifetimes of several decades – 30 to 40 years for a power plant. Retrofitting of CCS would prolong the economic life of these assets and provide a form of insurance against asset stranding. China alone has an installed capacity of around 860 gigawatts (GW) of coal-fired power, and IEA analysis suggests that more than one-third of this fleet could be candidates for CCS retrofit. 
Is that really what we want- to make fossil fuel use viable long term? Is it actually possible technically? The IEA say yes on both counts and reports on some existing CCS projects. In addition to various Enhanced Oil Recovery CO2 injection project it says ‘the global portfolio of CCS projects now includes the Boundary Dam Project in Saskatchewan, Canada, which in October 2014 became the first operating coal-fired power plant to apply CCS. Two additional projects in the power sector, the Kemper County project in Mississippi and the Petra Nova Carbon Capture Project in Texas, are due to come into operation in 2016. The Shell Quest CCS project, launched in November 2015, is the world’s first CCS project to reduce emissions from oil sands upgrading’. And more are planned.  It concludes ‘Boosting the number of large-scale projects under development is a priority. These projects are critically important in providing commercial experience, enabling key technologies to be refined and cost reductions to be achieved’. Convinced? Well the UK government wasn’t: it scrapped the UK’s £1bn CCS competition.
The IEA however see CCS as ‘an essential part of the climate solution’. It claims that‘ a 2-degree pathway requires deployment of CCS in both industrial and power applications’ and notes that CCS is already a reality: ‘there are currently 15 large-scale CCS projects operating throughout the world, with 7 more expected to come online by 2018’.
It also claims that ‘CCS could be competitive with other dispatchable, low-emission generation technologies by 2030’, citing Concentrated Solar Power (CSP) as an example.  Moreover, CCS ‘is not just a coal technology. It is needed to reduce emissions from a range of applications, including steel and cement manufacturing’. And via BECCS, with biomass used as a fuel and the emissions captured, it can be carbon negative. All of this slowing climate change. Quite a sales pitch!
The economic case seems a little week. All sorts of green energy options might be viable by 2030, not just CSP, and many already are. The issue is whether it’s worth pursuing CCS now. And the case for that seems to rest on the belief that renewables can’t or won’t deliver to scale and in time, with progress being slow due to resistance to change. So lets start digging! But can we really bury all the emissions we will continue to produce safety forever?  Will that be any easier than getting renewables going fully?  If governments and companies, or the public, are not willing to push ahead with renewable fast enough for whatever reason, will they be any more inclined to support CCS? Or is it just that the fossil fuel lobby wants it, given that it has so much invested in fossil energy- and is very powerful. And if that slows the development of renewables, then from its perspective, that’s just too bad, but BECCS is dangled as a long-shot consolation. 
Pragmatically, a bit of CCS for difficult-to-deal-with industrial processes, and maybe BECCS, may be helpful, but bulk CCS for power generation seems a risky, inelegant technical fix, stuffing CO2 into strata deep underground in the hope it will stay there forever.  While potentially delaying the switch over to renewables.
CCS is not the only large-scale geoengineering option that’s been proposed. Some are even more fanciful and potentially risky: seeding the oceans with ferric compounds to absorb GHG, putting aerosols particles in the high atmosphere to reduce solar input. Here’s an overview: www.sciencedirect.com/science/article/pii/S1364032113008460  
Slightly more credible within this wide range of ideas is direct air capture of CO2:  https://absuploads.aps.org/presentation.cfm?pid=11396 And maybe photo-catalytical conversion of other GHGs and  pollutants. See: www.sciencedirect.com/science/article/pii/S1389556711000281 There is also a range of mega solar ideas, including mile high solar chimneys with solar heat updrafts from a vast solar greenhouses driving wind devices mounted inside the towers: www.sciencedirect.com/science/article/pii/S1364032110001292 and more recently: www.sciencedirect.com/science/article/pii/S0038092X14003284 and www.scientific.net/AMM.283.57
That may be a bit more credible and does avoid having to store wastes somewhere. But it still sounds like a long shot, compared to conventional renewables. Towers a mile or more high seem to be a little extreme. Just like digging deep into the earth. 

Re-afforestation and changed farming practices seem more likely to be successful (and cheaper) for large-scale carbon capture/retention than major geoengineering projects and also easier than giant solar projects. But these less aggressive sequestration approaches can only go so far. Most agree that the real answer is the more fundamental approach of reducing CO2 emissions at source by switching to renewables. The claim that they will not be developed fast enough and so there is an urgent need for new approaches to dealing with climate change, may lead some to back large-scale geoengineering and CCS as desperate measures. Some say we must accept the risks and ensure we have the full range of options available. In his recent book ‘Systems Thinking for Geoengineering Policy’, OU academic Robert Chris argues that we should promote approaches to dealing with climate change that are ‘robust against the widest range of plausible futures, rather than optimal only for the most likely’. Well maybe, options should not be foreclosed, but surely we should focus on renewables as the best option: www.tandf.net/books/details/9781138841178/