Monday, 6 March 2017

What's stopping Small Modular Reactors

Small modular reactors (SMRs) are a class of nuclear fission reactors that aim to address some of the shortcomings of existing large scale nuclear power plants. These shortcomings include the capital cost of the plant, the lead time for construction of the plant, the ability to process existing nuclear waste into fuel, requirements for the location of the power plant and the complexity of safety systems required. There are a number of different SMR designs that have been put forward over the last two or three decades that using various fuel sources, reaction physics and construction techniques. One thing they all share in common is that they have promised much and delivered little: few of them are even close to having production power plants in service.

This raises a big question in my mind: why have they failed to materialise? The benefits that the claim over the established large scale GenIII reactor and power plant designs would seem to be potential game changes in the nuclear energy industry. You'd expect a few companies at least to have made progress into a production system over the last three decades for a technology that promises so much with existing engineering and physics knowledge, but they haven't.  Why?

One reason is regulations. SMRs, like all nuclear power plants, require a huge effort to pass regulatory hurdles in most countries.  For good reasons, these regulations are very detailed, and thus expensive, to comply with. You don't want people building more dodgy reactor designs that have proved problematic in the past after all.

Thus only companies that have deep pockets can really successfully play in this field, unless governments step in to provide support. The regulations are also angled towards the large existing nuclear reactor designs we've had in the past, and its up to the SMR proponents to prove to the regulators that (if?) their reactor designs are inherently safer. The regulators need to be shown that failure modes have been removed without other new ones being introduced.  That costs money.

Unfortunately, a number of the newer GenIV SMR designs aren't being proposed by existing nuclear companies or by billionaire backed corporations. Instead, their initial designs have been proposed and developed on relatively low shoe string budgets.  To get through the regulatory barrier these potentially disruptive start ups need to attract a large amount of speculative investment, or have their ideas taken up/bought out by "one of the big boys".

The existing nuclear power companies don't really want anything disrupting their current game plans, and anyway many of them have big problems of their own financing their operations (see for example the pains of Westinghouse/Toshiba and EDF/Areva recently).  There are a few companies backed up with investment cash, and they're probably the best hope for the SMR market to develop at the moment. If even one of those gets into production and starts to turn a profit, investment capital may magically appear for some of their potential competitors.

Once past regulatory approval in one country, many of the SMR designs then rely on the promise of a production line assembly of power station modules in order to keep their overall costs down.  This is a great idea in principle - one of the reason that existing GenIII nuclear power plants cost so much is that each one is effectively a bespoke, one off project, even if they share a common basic reactor design. The production line would have to have a steady flow of orders coming in - the worst thing for a manufacturing industry is a bursty demand for its products, as it runs the risk of going bust in the lean times. 

To keep this production line going, the SMR company would need either a large market in the first country to approve its reactor design, or would need the approval in one country to smooth the path through nuclear regulations elsewhere (with "smooth" meaning "radically reduce the time and costs"). Thus getting a design approved for use in the UK, whilst a big hurdle to jump, only gives you ready access to a relatively small market.  Really these companies need to get approval in somewhere large like the USA, China or Russia to provide the steady flow of orders and income to keep them going whilst gain access to markets elsewhere.

And this really gets to the heart of the issue: so many things, with so much money involved, have to go right worldwide for SMRs to work out.  Its not a technology that can scale up from really small, cheap demonstrators and have relatively easy access to a wide range of markets worldwide. This is unlike solar PV technology for example: there you can build out power plants of different sizes, in different country all using the same factory produced PV panels and mounting hardware that can be shipped more or less anywhere.  It doesn't matter to the panel manufacturer if you're buying eight 250W panels to put on a terraced house roof in the UK, or several thousand to build a solar farm in a desert in the US as people are doing both, all over the world. You can scale the PV technology from cheaper, smaller setups with minimal governmental intervention right up to multi-megawatt power plants.  The same applies to the growing market for storage technologies - the same lithium cells are going into domestic battery packs and electric cars as are being put into utility scale grid storage systems and electric lorries and buses.

So what's the way out of this for the SMR proponents?  Will it be a technology that, like nuclear fusion, is always 20 years away?  Maybe the "small" in many SMR designs are still too big? There are some "very Small Modular Reactor" (vSMR) designs out there with less than 10MWe output.  Maybe one or more of those will crack the nut of regulation and production line manufacture for military or off-grid remote power setups that will then let the companies involved scale up to utility sized, grid connected power plants?

But really it seems to all come down to regulation and finance. Some countries appear to be moving in the direction of reassessing their regulatory framework and financing for new nuclear technologies, but it is a very slow movement and may be too slow for some of the companies pushing the more radical SMR designs. Time will tell, but it appears there may be more losers than winners in SMR, and this isn't going to be oft promised silver bullet to make new nuclear a big contributor to low carbon power transitions before 2030.

The confusing world of plant pot sizes

A wet spring weekend day provides a great opportunity to clean, sort and tidy our (rather large) collection of plant pots.  We've acquired quite a collection over a couple of decades of gardening, both from buying in plants but also inheriting pots from friends and family.

One thing that struck me when cleaning the pots was the number of different sizing systems in use.  Ignoring the really old clay pots (that had their own sizing system based on the number of pots made from a given amount of clay) there are a number of sizing systems for the plastic pots in the UK. Thankfully I can mostly ignore the US pot sizing here in the UK, though they have an ANSI standard for them. Of course the East and West coast seem to do it differently (one measures mostly by pot diameter whilst the other uses US gallon volumes).  Down under they seem to do measurements by pints too. So lets just stick to the pots we see in the UK, OK?

The old UK imperial measurement was in inches across the large top diameter and still appears on lots of pots, including quite a few relatively modern pots.  These often have metric equivalent measurements shown on the bottom too, which can be non-integer numbers (eg 7.6cm equates to a 3" pot).  To complicate things slightly, as well as the top diameter, pots can differ in their height.  As well as the "normal" height for each diameter you can get shallow "half", "squat" or "dwarf" pots which as roughly half the height, and "long toms" which are much deeper.  The dwarf pots are good for seed sowing and growing of many shallow rooted plants, whereas the long toms are well suited to deep root plants such as roses, some shrubs/trees and tomatoes.  A reference to a 5" pot usually means the "normal" depth - planting instructions will usually specify a shallow/half/squat/dwarf 5" or a deep long tom 5" if required.

Then we get to we have always jokingly called the "metric" pot sizing.  These pots have a number and a letter, such as 13F or 6E.  Whilst its common to see some of these mentioned in gardening product catalogues and on the bottom of pots, finding the standard that they are made to was tricky.  I'd sort of assumed it was a British, EU or ISO standard, or at least one from a major horticultural organisation. However no luck tracking it down yet.  I've had to cobble the table below together by trawling through several pot manufacturers catalogues, and I know I've seen other codes on my pots (such as 9B and 14A).  If anyone knows what the actual standard is and where to get it from, please pop a note in the comments.

CodeTop diameter (cm)Height (cm)Volume (ml)
6E65.7120
9F98.7370
10F108.7450
11F119.5600
12F1210.7830
13F13.511.71120
14T14.711.81500
16T16.813.32000
19F18.516.42400
19T19153000
21F2118.44300
21T20.916.54000
23F23.520.56200
23T22.517.85000
26F2623.88600
28T28.322.410000
32T3225.715000
38T37.525.720000

You may also see an angle in degrees printed on the base - this is the angle of the slope between the top and the slightly smaller base. Usual angles are 5 degrees for "normal" sized pots and 8 degrees for half/squat/dwarf styles.  Different manufacturers also have different hole sizing and spacing at the bottom of their pots, including some with base side drainage. Again these can appear in the coding, along with things like "R" and "RX" for deep and extra deep long tom versions of pots.

Of course this is all too simple, so just to complicate matters, pots are often also labelled by volume, usually in litres in the UK/EU.  However a 1 litre pot might have a variety of top diameter measurements, depending on the depth. The larger pots from 3 litres upwards are nearly all specified by volume - right up to over 100 litres for large, mature trees. Pots under 1 litre seem to be rarely referred to by volume, with the top diameter measurement being more commonly used.

Another common sort of pot that you may have kicking around are the square top pots.  These are handy for fitting into larger trays with no gaps between them - making them easy to fill and water en masse.  Most of these are "metric" sizes, but some have straight sides down to a (slightly) smaller square base, whilst others have sides that bring the square top down to a circular base.  The latter are known as "square/round" containers, and can more easily fit into existing marketing or "shuttle" trays designed for use with round pots in nurseries, garden centres and DIY stores.  There seems to be as many coding systems, wall designs and drainage hole layouts as there are manufacturers, so there's even less evident standardisation here than in the round plastic pots.

Sorting, stacking and storing your pots

Stacking and sorting this variety of pots can be tiresome at home, where a wide variety of different types and sizes will appear in your collections in small quantities. In commercial horticulture they often stick to a limited number of sizes from known suppliers, plus their stock will be constantly replenished as they sell plants to retail outlets and customers, so this isn't a problem for them.  A few tips though:
  • Start by sorting out "normal" round plastic pots from square, square/round, long toms, clay pots, modules, etc. Store/stack the latter separately.
  • Sort the remaining pots by the large top diameter.  Its easiest to do this in metric with a conversion guide to Imperial sizes to hand (having a large sheet of of paper or card with the sizes in metric & imperial written on it for everything from 6cm to 18cm can be useful for stacking - after a while a 9cm, 10cm and 11cm stack all begin to look the same! Put bigger pots to one side for storing separately (or even holding the other pots if you don't have too many).
  • Clean pots as you sort and stack so that they are ready for reuse.
  • Discard any pots with cracks or splits.
  • Stack dwarf/squat pots separately whilst sorting.  If you only have a few they can then go in the top of that size stack at the end, otherwise make a separate stack for them. If you intermingle them with "normal" pots, you'll end up with high stacks with far fewer pots than you could have.
  • Try to stack pots from the same manufacturer and/or with similar designs together within a size.  Again this reduces stack height.
  • Note that sometimes you need to just make a value judgement as to which stack an odd imperial equivalent metric size pot goes in. A 16.6cm pot could go in the 16cm pile or the 17cm pile - different manufacturers pot designs can stack better in one size than the other.
  • Stack no higher than about 50cm unless you've got a way to hold the stack together, otherwise they become unstable and fall over.
  • For smaller plastic pot sizes, old tights can be used to hang the stacks up out of the way in sheds, etc.  Don't do this with clay pots though as a fall from height can easily smash them.  Xmas tree nets are also useful (or indeed any net tube that's long and a bit stretchy).
  • Alternatively a large cardboard or plastic box is great for keeping sorted pots stacked neatly, and also makes it easy to transport them between storage areas and potting bench.
  • 13cm pots are a very handy size as they are a common 1 litre volume size that you often have to pot on many plants into.

So that's the fun that is plant pot sizes.  Then of course there are British Standard seed trays and the various modules that fit into those, as well as propagators and staging that they themselves fit on.  And the various marketing, carry, shuttle and propagation trays. And root trainer modules and...

Sunday, 31 January 2016

Don't buy this book!

I follow a jolly interesting chap on Twitter called Jeremy Leggett who has just written a book entitled "The Winning of The Carbon War". The Carbon War in the title is the battle for a clean energy future versus a dirty fossil fuel based one. The fight for ways to tackle climate change against the business as usual approach that will make global warming worse as time goes on.  Its a war every country is involved in, and which will affect us all whether we like it (or even know it) or not. I've been reading his book as a monthly part work since the first episode came out, and the whole thing is now finished.

But don't buy this book.

Jeremy was trained to look at rocks for oil and gas companies but "saw the light" many years ago and instead turned to running a solar company called Solarcentury. He's also involved with a charity that tries to get more solar power installed in Africa. He knows some of the great and good in the energy world, and a few of the bad as well. He gets invited to some exciting high powered investment meetings around the globe that help shape the future of energy, finance and the society we live in. Whilst not a "general" in the Carbon War, he's definitely one of the officer ranks, and the book shows us foot soldiers in the climate change trenches some of the decision processes at play.

But don't buy this book.

In the book he provides his view of the two years leading up to the UN's COP21 Paris negotiations in December 2015. Its mostly a first person narrative of his travels and meetings in those two years, with a liberal sprinkling of quotes from people he's heard, met or talked with thrown in. He addresses large meetings in halls, talks to campaigners in a village, gets invited to schmooze with captains of industry, chin wags with global politicians, see's first hand some of the victories and defeats of the clean energy industry, marches with protesters and helps direct some of the skirmishes in the Carbon War. Its a peek behind the curtain of the global stage that we rarely get to see and the mainstream media don't cover much.

But don't buy this book!

So why not buy this book?

Is it badly written?  No, it's a pretty good read with just a few typos and bits a proofreader should spot, but nothing serious. The style is quite informal and it draws you along through the world he moves in.

Is the subject matter boring then?  Absolutely not! Whilst a book detailing meeting after meeting sounds like the sort of dry tome that would send you to sleep, Jeremy's narrative style keeps you engaged, and some of the facts that spill out keep you turning the pages to find more. There's much to learn from in this book.

Is Jeremy's writing too biased? Well, obviously he's most definitely sitting on one side of the fence, so we can't say that he is at all neutral. Yet the book never claims to be anything other than his view of the process that he's involved in. Its certainly not a simple sales pitch for his solar company. I'm guessing we'll have to wait for one of the oil, coal or gas bosses or climate change denying politicians to come out with a similar travel diary from their point of view to see the other side of the debates.

No, the reason you shouldn't buy this book is the Jeremy has generously made it freely available for you to download. Now you could buy a paper copy, but I'm going to suggest to you that you don't because:

1) Its yet more "stuff" that needs to be made, stored, shipped and then takes up room in your house.  An e-book can have a lower impact on the planet for many reading habits, which is after all what he's talking about.

2) (much more important) Jeremy's charity in Africa, Solar Aid, needs your support for its mission to help rid the continent of dirty, unhealthy, expensive kerosene lamps and replace them with solar lighting. Rather than buy the paper book and have the profits go to Solar Aid, just give them all the money that you would have spent on the paper book.  Better yet, give them two or three times that.

So please don't buy this book.  Download it, read it, find out about the climate change process and then help Solar Aid tackle some of the problems. Be part of the winning army in the Carbon War.

EDIT: If you're really, really determined to buy this book, Jeremy now has it listed on both Amazon and Barnes and Noble. But come on folks - just give your cash to SolarAid!

Tuesday, 8 December 2015

Using Microsoft Graph API from a daemon process (in Perl on Linux!)

At work, I've been asked to look at how easy (or difficult) it will be to give folk using Microsoft Office365 access to the student timetables.  We already provide a feed into our Google Apps for Education accounts for the students, and this has been very popular.  However The Powers That Be have had a funny five minutes and decided to move future students to Office365 (no, none of us can work out why either!).

Now in the past we've bodged up a means of staff seeing time table information in Office365 (as they've been stuck in there for some years now) using iCal files.  This works but:

  • requires the user to make an active decision to register and then past the link into their Office365 Web Access (OWA) calendar setup
  • means that Microsoft's servers whack our servers ever 4 hours to update this iCal link (which is OK for a small subset of the staff, but would be less fun for our servers when 15000+ students start to hit them).
So I've been looking at the exciting new Microsoft Graph API that they released a week or two back. Actually its been lurking in beta for a while, but v1.0 appeared more or less as soon as we started to look at how to do this, which is supposed to be the first general release for production use.  According to some Microsoft folk we talked to, this API is going to be the way of the future, so its what we started to look at using (as opposed to the older SOAP based Exchange Web Services API).

The Graph API uses RESTful calls, JSON, and OAuth2.0, so it looks pretty sane.  That was a surprise for me: I'm used to Microsoft stuff looking awful from the start from the point of view of a Linux hacker.  Much of the documentation for the API's OAuth2.0 flows assumes that you're going to be writing a web delivered app.  In this case, the app interacts with the user to get them to log into Azure Active Directory and then delegate rights to do specified things as them to your code.  That isn't much use for a daemon process which is what we want, but luckily Microsoft also implement the "client credentials" flow in OAuth2.0.  This means that you can get a client token (aka client_id) for your daemon application and you can then use the API to swap the client token for a bearer access token that can access any user's data in your Office365 tenancy, limited to the scopes set by the admins. One initial stumbling block for me was that I'm not normally an AD admin in our tenancy, and it looks like you need to be in order to assign application authorization scopes to the app in the Azure management console (luckily our AD guys were OK with giving me admin access to a test tenancy where I could break things to my hearts content whilst working out how this all works).  Still, this is very similar to Google Apps, where you give access scopes to a service account that can then act as other users.

Just to make things a bit sicker, my end of the Graph API calls is coming from Perl scripts sitting on a Linux box.  I'm a Perl hacker, and I've already written Perl modules to wrap up some of the Google APIs in the past, so this isn't overly concerning to me.  Indeed one of the selling points of the Microsoft Graph API's RESTful, OData standards basis is that its pretty much language and platform agnostic.  Its just as happy talking to a Perl script on a Linux box as it is a C# program on a Windows server.

Being version 1.0, the current Microsoft Graph API has a few oddities. I'm not sure why these didn't get fixed in the beta period - maybe the fact that it was a beta put off normal Microsoft developers from using it (use Open Source folk are used to using alpha and beta releases in production, as we've got the code to fix things if they go wrong!).

For example, lets say you want to use Graph to add a member to a Unified Group.  Unified Groups which are an exciting new type of group that can have calendars, files and conversations associated with them (they have nothing to do with local AD groups, existing security or mail enabled groups, calendar groups or distribution groups.  Microsoft really need to stop using the word "group" for new collections of things!). That's easy: there's a documented RESTful call for adding members.  Simiilarly, you can list members of the group. Great - those all work a treat. Now how do you remove members from the group?  Ah.  There doesn't seem to be an API call for that.  Or at least if there is, its not currently documented or its not in the same place as the creating/list members calls. I've flagged it up on Stackoverflow, so hopefully someone will either point me in the right direction or fix the API/documentation. That would be a bit of a show stopper for us though - students are flighty, jittery types who do tend to jump around the modules they are studying so we need to be able to add and remove them from the groups easily (and preferably without them getting an email every time this happens).

On the flip side, Microsoft have said that Unified Groups have some interesting new features, such as being able to have calendars attached directly to them. That sounds like just want we need: we can have a Unified Group for each module's timetable, add the students (and staff teaching it) to this group (possibly by adding the existing local AD module groups into the Azure AD and then adding those groups as members of the Unified Groups) and then fill the group with calendar events for all the lectures, labs, seminars and tutorials. Unfortunately this doesn't seem to work at the moment... the API documentation seems to indicate it should, but I and others are getting errors that the Unified Groups don't have a mailbox.  The odd thing is that I can use the Graph API to add events to an individual user's calendar and if I set the attendees to be the group, it does appear in the group calendar in OWA.  That behaviour is... odd.  But then it could be because I'm not getting how Microsoft intend Office365 calendars to work  I'm used to Google's calendars - ACLs in Google calendars land actually seem to work fine for sharing calendars, although you do have to make quite a few API calls for large numbers of students when setting them up (which Microsoft's Unified Groups would do away with if it worked).

Anyway, I'll keep plugging away at it.  I just hope I don't accidentally turn into the department's Microsoft Graph API "expert".  That would be embarrassing for a Linux hacker!

UPDATE: According to the Marek Rycharski from Microsoft on Stackoverflow, it turns out that the Graph API can't (yet) handle calendars on Unified Groups.  Its "on the roadmap" but no immediate plans for implementing it in the near future.  Drat!  Still at least I got told how to remove users from the Unified Groups ready for when I do need it at some point in the distant future.


Sunday, 11 October 2015

Could graphene be used for super light space craft heat shields?

Last night I was watching an interesting video about a self-made billionaire who is spending 99% of his acquired fortune on funding innovation development to tackle energy, water and health issues. I'd not come across Manoj Bhargava or Billions in Change before, and some of the ideas seem a bit "out there", although if they work out then he's producing some badly needed solutions to world problems.

One of the ideas he's funding is a clean energy concept of bringing up heat from deep in the earth to drive electricity generation without using fossil fuels.  Geothermal energy has of course been done for years - Iceland gets most of its power that way.  However the new twist that Manoj and his engineers and inventors have is to use graphene to shift the heat from deep down below to the surface.

Graphene is the atom thick version of carbon that is the new wonder material for all sorts of applications. But Manoj claimed in the video that its heat transfer capability is tremendous - so much so that heat applied to one end of a graphene string will travel along to the other end, leaving the middle cool.  I'd not heard of this property before, but a quick Google search threw up this paper in which physicists have shown evidence of this marvellous heat transfer capability.

Of course there's a lot more research, not to mention engineering development, required before graphene heat pipes become a widely available thing.  But it got me wondering: assuming graphene does have this great heat transfer capability, could it be used in spacecraft heat shields? In effect I'm wondering if it would be possible to wrap a reentry capsule in a graphene matrix made of graphene strings, with one end of each string at the bottom and the other at the top.  As the heat shield warmed up, the heat from the bottom would be conducted over the sides of the capsule and then radiated from the top at the other end of the graphene strings?

I've not heard of graphene being considered for this application before, but then I'm not intimately involved in spacecraft design.  I bet its Elon Musk's radar if it is a possibility (everything is on Elon's radar!)

Friday, 28 August 2015

Wacky idea time: Nuclear powered ocean going freight islands?

Nuclear powered ocean going vessels have been around for decades.  As well as the well known nuclear power submarines with their deadly payloads of nuclear weapons that can stay submerged for months at a time, there are also nuclear powered aircraft carriers and icebreakers out there.  Nuclear power plants for shipping are expensive but have the advantage of large power outputs, less time spent refuelling and low carbon footprints.

The latter point on carbon footprints made me wonder: onshore nuclear power stations can offer low carbon electricity outputs, but are now massively expensive to build, get mired in politicial objections left, right and centre, and are often unpopular with the local residents around proposed sites.  We need to find a way to deal with long lived nuclear waste from the legacy nuclear power stations. At the same time we need to find low carbon ways to ship bulk goods around.  And it would be great if we could get cheap, renewable replacements for existing liquid fossil fuels so that we could keep more fossil fuels in the ground.  What if we could find a way round all of those issues?

So, my quick brain fart for today: build very large, ocean going freight vessels that are nuclear powered.

By "very large" I mean bigger than the largest oil tankers available today by an order of magnitude - effectively floating metal islands that can plough across the oceans from continent to continent.  Obviously they'd be too big for most ports to handle and many people may object to a nuclear powered vessel turning up in their local harbour (unless they're used to the military ones already).  However what about if these giant vessels went just to the edge of territorial waters and unloaded onto smaller vessels?  Those smaller vessel would be normal sized, conventionally power container ships and tankers.

If you build something big enough, you could effectively include a dock inside the huge ship for normal vessels to go into, protected from rough seas. The loading/unloading of the smaller ships could even be done enroute, which would mean that transshipment and handling time wouldn't be increased. Bringing boats inside a larger ship is already done: the US Navy have vessels that can take smaller boats inside for long distance transport, equipping and deployment.  Or if you're into sci-fi its like the James Bond baddie with the oil tanker that could swallow submarines. Paging Elon Musk on that one!

Manufacture of this mega-freighter would have to be modular so that existing ship yards could build them sections at a time.  Each completed section would be floated out of the dry dock and then joined up to other sections already held at sea.  That's the bit I'm really not sure about: how easy would it be to join up sections at sea that are floating? That would obvious require calm weather to do, but could the modules be designed to interlock easily like some sort of giant floating Lego bricks?  I don't know - I'm not a shipwright or naval architect.  However large floating structures have been joined together in the past, so I don't think its insurmountable.

These floating freight islands would have to be powered by nuclear reactors that provide propulsion power, "hotel" power to keep the crew (and maybe passengers) supplied with heat, light & electricity and potentially enough "extra" power to use the various Fischer-Tropsch processes to combine sea water with air to produce liquid hydrocarbon fuels.  We already know that works - the US military have tried it to produce jet fuel onboard their nuclear powered aircraft carriers.  The synthetic hydrocarbon fuels could then be used to fuel the smaller servicing freighters and/or provide av-gas for helicopters or VTOL aircraft for the short hops to and from shore.

By using the nuclear reactors for the long haul ocean part of the freight journey we'd be reducing the carbon footprint of the goods.  The reactors will effectively live out their lives at sea, many miles from the nearest land. If the reactors are designed using the proposed Gen-IV designs they'll be "walk away safe", and something so massive as this would also mean it would be unlikely to leak radioactive material into the sea (I assume the reactors would be in the heart of the floating metal island, so there could be a lot of steel and concrete between them and the water).  Indeed this might be a great application for the various designs of modular reactors - don't build a ship with one 1GW pressurised water reactor but instead 10 modular 100MW molten salt reactors that can be swapped in and out for refuelling and replacement.  That would help with the economies of scale that modular reactor designs really need if they are going to be constructed on a production line to bring costs down and safety up.

Tsunamis and earthquakes wouldn't be an issue for these reactors, and if they're making enough synthetic fuels as a by product of the reactor running they could even help provide low carbon fuels for import to the countries they visit.  Indeed if they moor up at a fixed off shore point, they could be hooked up to the Grid in that country by a relatively short undersea HVDC power cable.  It might transpire that some could even be nearly permanently moored like that as a safer place to put nuclear capacity for the Grid's low carbon base load supply.

I wonder what the limitations of build these would be?  Cost is an obvious one: a nuclear submarine costs a couple of billion US dollars to make, and this would be something far larger.  Yet Governments and companies are already handling projects that cost many tens of billions - things like new build on-shore nuclear power stations, failing Carbon Capture and Sequestration (CCS) projects, high speed rail lines, etc.

The anti-nuclear lobby would probably object to this as its another application of nuclear power, but if the Gen-IV design could make use of legacy high level nuclear wastes, it might be palatable as a way of cleaning up wastes from previous generations of nuclear reactors (which is after all one of the anti-nuclear groups' major concerns). Also there are already many nuclear reactors swimming around in the ocean and have been for decades.

I'm not sure what the legal position would be for nuclear reactors running on vessels in International waters that never actually enter territorial waters once launched. Would it be covered by the flag that the ship sails under? Could you pick a small country that doesn't have a huge amount of nuclear regulation red tape in order to make this viable?

Saturday, 2 May 2015

Energy storage and nuclear power

A couple of days ago, Elon Musk, the billionaire serial business creator, fronted a product launch at one of his companies - Tesla Motors.  Telsa is renowned for building high quality electric cars but this launch wasn't for a car: it was for batteries.  Elon was explaining how the battery technology originally developed for the Tesla cars will now be available to home owners and companies to provide electricity storage.  The news has naturally focused on the $3500 10kWh domestic battery pack, but I think the real killer is in the industrial, grid scale scalable storage that they are going to offer.  This is interesting enough for one un-named utility to already put their name down for 250MWh of capacity, and indeed its the industrial/utility side that analysts see as the major market.

Which got me thinking: how much solar/wind/etc generation and Tesla storage could you buy for, oooh, say the cost of EDF's proposed Hinkley Point C nuclear power station?  The estimated cost of Hinkley Point C keeps going up, but lets use the original EDF £16bn figure here.  Hinkley Point C is a 3.2GW station, so we need to try to match that using renewables for £16bn ($24.22bn at the current exchange rates).

Now first off I have to say that this is just me getting some ball park figures: its not an engineering analysis.  I just want to see if Tesla's batteries plus renewable generation can give us a stable base load power source to the National Grid that would look to the outside world as though a 3.2GW nuclear station were sitting there. To do this we'll need more than 3.2GW of renewable generation capacity: we not only have to match the nuclear station's peak output, but also fill the batteries so that we can also supply power at night and on calm, overcast days.  Lets assume that we want 3 days worth of energy in the batteries to cover these low generation periods to start with.

Now we don't know what cost Tesla's commercial utility scale power packs are going to be, but we do know that the residential 10kWh ones will cost $3500, or in other words $350 per kWh.  I would assume that an economy of scale kicks in when you're buying a huge amount of batteries for utilities that would reduce this $350 per kWh figure for the utility scale one.  Lets say it knocks $50 off the figure - yes, that's a wild, stab in the dark guess, but its seems vaguely sensible and conservative.  So we need three days worth of 3.2GW generation stored:

3 days x 24 hrs x 3.2GW = 230.4GWh = 230400000kWh

At my estimated $300 per kWh that will cost:

$300 per kWh x 230400000kWh = $69120000000 = $69.12bn.

Ah, that's blown the $24.22bn budget already, and we haven't even paid for any of the renewable generation yet - this is just the cost of 3 days of Hinkley Point C sized output storage.

Lets plough on though, and see what the final number is.  For large scale renewable power generation, the costs are falling (ie going the other way to nuclear!).  Large scale wind turbines cost $1.5m-$2m per MW of output.  Large scale solar farms cost ~ £1.6M ($2.42M) per MW if I've read the slightly confusing Solar Trade Association report right.  Lets pick $2M per MW as reasonable wet finger guesstimate of cost for both wind and solar then.

We need to generate more than 3.2GW though: we want to match Hinkley Point C's output when we're generating at our peak and have lots of excess generation capacity available then to fill up the Tesla batteries for the periods when its calm and dark.  Lets guess again and say that we need twice the generation capacity to do this.  We might need more, we might need less, but 6.4GW again seems like a reasonable first guess.

At our $2m per MW estimate of renewable generation costs, this 6.4GW will cost $12.8bn.  Well at least that bit is under the $22.42bn Hinkley Point C budget!

How much energy storage can we get for the $9.62bn difference?  At $300 per kWh estimate we get:

$9.62bn / $300 per kWh =~ 32GWh

So that's about 10 hours worth of storage if we're going to be sucking 3.2GW from the battery system. That's still not bad, but will it be enough to allow large scale solar and wind to challenge nuclear for base load power generation in a decarbonised Grid?  Some people think so, and the numbers will fall on the side of renewables+batteries if their cost trajectory keeps going down in the same direction whilst nuclear's costs keep rising.  It will be interesting to see how this plays out.