The Learning Curve

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I cut my teeth in the computer industry, where for decades Moore’s Law has pretty accurately described the way that year by year computers become more and more powerful for a given price. Or put another way, that every year transistors become cheaper and cheaper. Is this perhaps due to some magical property of transistors? No – as the picture below shows, it was happening before transistors were even invented, and it will surely continue to happen even after we abandon silicon for optical or quantum computing:

Figure 1 – Moore’s Law was operating even before transistors
Source: http://www.singularity.com/charts/page67.html

It turns out that Moore’s Law is in fact just a special case of a much more general law of Engineering known as the Learning Curve (or the Experience Curve). This states that the more we build of something – anything – the cheaper it will get, as engineers constantly find new ways to make the production more efficient. In one pithy phrase, the Learning Curve neatly summarises the true power of Technology and of Engineering.

To see the Learning Curve we plot a graph of “cumulative unit production to date” against “cost-per-item today”. If we plot the vertical cost axis logarithmically, then the Learning Curve is a roughly straight line showing how the cost-per-item continues to drop geometrically year by year (i.e. the cost each year reduces by a certain percentage relative to that of the previous year, and that percentage tends to remain constant).

The concepts underpinning the Learning Curve were first described in the Journal of the Aeronautical Science in 1936 by T. P. Wright in an article about aircraft production. I believe the term Learning Curve was then coined in the 1960’s by Bruce Henderson of the Boston Consulting Group. Quite simply, the more aircraft that were built, the cheaper they got:

Figure 2 – the Learning Curve for aircraft production
Source: C. Lanier Benkard, American Economic Review 2000

It turns-out that the Learning Curve applies equally-well to pretty much everything else technological. To pick a random example, Japanese Beer Production: as the cumulative volume of beer bottles made grows, so the price continues to fall.

Figure 3: The Learning Curve for Japanese Beer Production, 1951-1968
Source: William D Eggers, Deloittes, after Wally Rhines

And it turns-out it’s true for steam turbine generators too. The more we made, the cheaper they became:

Figure 4: The Learning Curve for Steam Turbine Generators
http://www.vectorstudy.com/management_theories/experience_curve.htm

The consequences

And therein lies a tale. In 1769 James Watt invented the world’s first efficient steam-engine, the precursor of those turbines. Now you might think that inventing a more efficient machine will result in a reduction in the input raw materials – after all, Watt’s steam engine could do the same work using less coal. But of course what it actually did was to light the blue touch paper on the industrial revolution. The machines were incredibly useful, so we built more of them. Thanks to the Learning Curve, building more of them made them cheaper and cheaper. So now more and more people could afford them, so even more were built, and so on.

The net result of all this is that world coal consumption has risen exponentially from that day to this. Shocking but true – yes, it’s still rising. And of course we now realise the consequences, as atmospheric CO2 rises in tandem:

Figure 5 – the rise of coal consumption, and consequent rise in atmospheric CO2
Source: Sustainable Energy – Without the Hot Air, p19

Hope

So the Learning Curve is a very powerful force. It has delivered all sorts of wonders to our everyday lives over the past 250 years, but it also has a dark side: it has wrought havoc with our environment.

So is there any way that we can use the power of the Learning Curve to dig ourselves out of this mess? Luckily, yes.

It turns out that the Learning Curve applies equally well to sustainable technologies too. Below we can see how the cost of renewable electricity from wind turbines is steadily falling as we build more of them:

Figure 6: The Learning Curve for wind turbines
Source: Bloomberg New Energy Finance, ExTool

That 14% number means that every time we double the cumulative production of turbines, the cost falls by 14%. Perhaps that doesn’t seem particularly significant in just one doubling, but like the grains of rice in the Biblical story it soon multiplies up. Over the course of the above graph, in less than 30 years we’ve gone from about 200MW to 200,000 MW total production. That is around 10 doublings in cumulative production, which means 10 lots of 14% reduction in cost, the cumulative effect of which is that costs have been driven down to roughly one quarter of what they were. And still they fall.

And the Learning Curve applies equally well to renewable electricity from Solar panels too. As with computing, the technologies may change but the relentless downward cost pressure continues:

Figure 7 : The Learning Curve in solar panel cost
Source: Ken Zweibel, GW Solar Institute, George Washington University

Hastening along the Learning Curve

Just this morning on the radio I heard Lord Lawson, formerly UK energy secretary, and then UK Chancellor in the 1980’s, and perhaps our most eminent climate change denier, railing about the “unaffordable cost of renewables”. Well yes of course renewables are expensive Nigel, but only because they haven’t yet had the benefit of fossil fuels’ 250 years’ Learning Curve. People concerned about the subsidies afforded to renewables need to understand that the purpose of these subsidies is NOT to build out a massive amount of renewables at today’s high costs. It is to hasten the Learning Curve along to the point where these technologies become cheap-enough to compete directly with their fossil-fuel cousins – so-called “parity” – at which point the market will take over and the learning curve will kick into a higher gear as they become the cheapest no-brainer choice.

The different between 20MW and 40MW of generation is insignificant to start with, but winding forwards a few decades it becomes for example the difference between 20% and 40% of the UK’s energy needs. Accelerating us through the early part of the learning curve now will pay a really big dividend later-on.

T2

Ray Anderson was founder of Flor, a floor-tile company. A successful if perhaps not very sexy business you may think, but Ray was passionate about it and had an epiphany when he realised that his business was not, in the simplest most literal sense of the word, sustainable. It could not go on doing as it was doing, because its business was based on consuming our oil reserves, which are finite. So he set out to make it sustainable. He documented his journey not long before he died in an excellent TED talk which I’d highly recommend watching. In it he refers to the “equation” popularised by Paul and Anne Erlich in their 1960’s book The Population Bomb. I = P x A x T. Our Impact on the environment is the product of our Population multiplied by its Affluence multiplied by its Technology. So technology multiplies our destructive reach.

But as Ray describes so well (and I hope I’ve made a case for above), there’s absolutely no reason why technology T should be the bad guy. We now need to ensure that in everything we do, as founders, engineers, industrialists, technologists, scientists, policy makers and consumers, our technology moves to the denominator, reducing our footprint. And then the learning curve will do its steady magic.

Figure 8: “T2”
Source: TED talk by Ray Anderson

To us as individuals, a T2 Learning Curve looks just like a T1 Learning Curve. Both bring us more good stuff, cheaper. But to the planet T1 is the road to hell, and T2 is the way back again.

With special thanks to Keith Walker who originally drew my attention to the fact that Moore’s Law is just a special case of the Learning Curve.

 

From Consumer to Producer

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Phew! After months of thought and planning, our home Solar Electricity (PV) Panels are finally up and running – just days before the government halves the FIT (Feed-In Tariff) subsidy.

Choosing what to fit… and who to fit it

There are plenty of good online guides about choosing and siting your solar panels. To receive the maximum subsidy you can fit up to 4kWp of panels (about 20) – enough to fill the roof of a largish house. Obviously they have to be largely south-facing and unshaded for much of the day!

When I started to explore solar electricity, since it was a relatively new market I decided there was no substitute for learning from those with real-world experience. So this summer I attended an Open Eco Homes day organised by Cambridge Carbon Footprint which allowed me to go poking around several local homes whose owners have installed a variety of sustainable technologies including solar electric and solar thermal panels, super-efficient insulation, solar heat stores etc.  Not only did their generous sharing of knowledge teach me a lot about the practicalities of installing and living with solar, it also gave me some excellent pointers for trusted local installers and as a result I chose local Cambridge solar provider Midsummer Energy.

There are really just two more choices to make: your panels and your inverter which converts the panel electricity into 240VAC mains. Panels by known brands such as Sanyo are significantly more expensive, but might be more reliable, or at least you might have a better chance of come-back if they have a quality problem. After deliberation and consultation we decided they were not worth the premium – other less well-known brands have built a good reputation with installers. Because of some shading challenges, our panels were to be installed across two roofs, and on our main house roof we chose very black Sunrise panels which blend well into our black slate tiles, and on a less prominent roof we chose cheaper EGing panels with aluminium frames.

   

Sunrise panels with black frames

EGing panels with aluminium frames

The choice of inverter was more interesting, as we faced the common problem that our roof – although generally south-facing – is partly shaded during early morning and late afternoon. The trouble with this is that in a conventional installation all the panels are electrically wired in series, so shading of just a single panel significantly reduces the output of the whole array. It is also not widely known that inverters typically don’t last very long – 5 years is not unusual. I happen to know some of the people involved in Enecsys, a fellow Cambridge company who make micro-inverters which are placed behind every panel, and therefore don’t suffer from these problems, and was delighted to find that they are now in full production so we were able to use them.

A big side-benefit of the Enecsys solution is that the inverters all speak ZigBee to each other, and connect via a hub gateway to the internet. Sound familiar?! So you can see a live view of all your panels’ production at any time.

 

Enecsys inverters mounted per panel

Enecsys online interface

The day of installation

Thanks to excellent planning on the part of the installers, the installation process went smoothly. It started with the rather alarming (and loud!) process of hacking under the existing slates with a slater’s tool to cut the nails to get the first tiles out, after which others could be lifted. Then brackets were installed under the slates, then horizontal tracks put on the brackets, and finally the inverters and panels are bolted onto the tracks. This is then all wired back inside the roof to the generation meter and thence to the main house consumer unit (“fusebox” to you and me!). Useful tip: The very helpful electrician made sure we had access to separate meter “tails” for generation and consumption separately, so we can clip-on a current clamp (like the AlertMe one) to each one, and thus measure our net import/export status, to see when we are a net producer to the grid (a good feeling!).

Do solar panels really make sense in the UK?

Opinions are divided. On the one hand, thanks to the government’s feed-in tariff subsidy you receive a guaranteed, index-linked return of about 10%, which looks pretty attractive in the current dismal investment climate. But it’s a long-term proposition: it takes about 9 years to get your money back, then you should make a return for the remainder of the 25-or-so year lifetime of the panels. And of course that subsidy is about to halve, then in April things get more complicated as we move into Green Deal territory. If you can’t afford the capital outlay (about £3500/kWp today) then you could go for a “rent-a-roof” scheme, where you at least get cheaper home electricity.

On the other hand, if you’re seeking to use your cash to make the world a better place, then there are alternatives which have a higher “amount of sustainability per pound spent” than solar panels. In Mike Berners Lee’s excellent book “How Bad are Bananas” he calculates that every £1 spent on solar panels saves about 3kg of CO2 equivalent … compared with a whopping 330kgCOe saved for each £1 spent on a well-managed rainforest preservation program. But the verifiability of solar panels is perhaps higher. Also, in either financial or eco terms you’re probably better-off spending money first on really good insulation, and then on solar thermal hot water heating. In purely environmental terms, PV panels take 2-3 years to pay back their production cost to the environment.

But at least solar panels are a positive financial investment with a negative environmental cost, and there’s not a lot else like that about. And there’s a feeling that you’re a part of the future, and that by taking part you are actively helping to increase adoption and therefore decrease prices, and move the world faster into a future where they are commonplace.

Maximising your return

So you’ve installed your panels. Is that it? Increasingly no. The cost of panels is falling, as is government subsidy. But the cost of electricity imported from the grid is likely to continue to rise. There are three key numbers to consider:

  • Electricity imported from the grid costs about 13p per unit (kWh).
  • A solar PV home exporting to the grid only receives around 3p per unit exported (the grid costs a lot to run).
  • The Feed-in Tariff works by paying you for every unit generated by your panels, regardless of what happens to it after that, i.e. whether you use it, or it is exported to the grid. This payment is currently at 43.3p per unit, and is about to halve to 21p per unit.

Against a generation rate of 43.3p, the 3p you get paid to export electricity is almost insignificant.

But the generation subsidy is now halving to 21p per unit. And if you can use that electricity you’ve generated, you are also saving the 13p it would have cost you to import it. So the net effect of using your own electricity is 13p on top of that 21p subsidy. Quite a difference. The seesaw is starting to tip…

As solar subsidies fall and grid prices rise, the incentive to use-up every drop of your precious sun-juice grows and grows. Which means using electricity when the sun shines, which is of course during the day, when you’re probably out. Where can you put it? The best use of it is in things like running the washing-machine or dishwasher, or charging your car – things that only electricity can do.  A less good use is to heat things, including your home and your hot water. Heat is a much lower grade of energy than electricity though, so if you do much of that you’d be better off installing a dedicated solar thermal solution. Perhaps you can see some ways that AlertMe might be able to help you manage all of this!

The future

Solar panel technology is undergoing a renaissance: Triple-junction cells can now harvest almost twice as much electricity. CPV arrays use concentrating mirrors or lenses to capture more power. Innovators have even managed to print panels onto flexible surfaces at much lower cost. Several analysts believe that solar will achieve “parity” in 5-10 years, meaning that electricity generated in this way will cost the same as that generated by large coal-fired power stations. And of course that is the tipping-point to a sustainable world.

If you’re considering helping the world along by installing solar PV, a good independent overview of the Feed In Tariff can be found on the Energy Saving Trust website.

What is “Smart”? User Experience and the Internet of Things

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Guest blog post for TSB’s Creative KTN 

In the developed world we’ve achieved 100% connectivity for humans and are working on connecting-up all the “things” around us too, offering the tantalising prospect of the Internet of Things – a world where autonomous devices get on with the business of making the world a better place, without needing too much attention from us. Or will they?

Gen Y is wise to technology’s dark side. In the face of ever-expanding device feature-lists,  the success of Apple products shows that many consumers now prize usability and simplicity above mere features. We are gadget-rich and time-poor.

The 1980’s were the heyday of geek chic – the remote control with 100 buttons, the VCR which few could program. Cryptic gifts from the Gods of engineering, with their internals laid bare. Unfortunately we haven’t quite left all that behind yet. But as an engineer I understand why this happens: it takes more effort to make something simple. To properly hide the technology under the hood, to test and refine the user experience until it is truly intuitive.

An approach to user-centric design which we’ve followed at AlertMe is “co-creation”, which can work well in new markets where the precise needs of the customer are hard to predict. Co-creation is a partnership with your customers – you release a product to market early, then your customers help you to iterate it rapidly using their real-world experience. This is particularly easy to do with today’s online products, as they can be modified in mid flight.

So back to the Internet of Things. Those of us who remember the arrival of the home PC also remember how we became the “IT support guy”. Imagine a time in the near future when instead of just a couple of computers in your home you have 10, or 100, to support.

Well, actually you probably already have this many, but today they are safely trapped inside their own little boxes – inside your TV, your oven, cooker, vacuum cleaner and so on. But gradually they are being connected-up to the internet, at first just to perform a dedicated function, e.g. the set-top-box that runs IPTV, but increasingly in a many-to-many way. So your Smart washing-machine will talk to your Smart Meter, see that electricity is expensive right now, but also talk to your Smart Solar panels and see that the sun is shining, so it can do that wash anyway. The technology to enable this connectivity is already largely present, but the work we have still to do is to order it into a coherent, useful, wonderful user experience.

What are the qualities that this Internet of Things must have, so that we are not overwhelmed by all these Smarts? My recent experience is with AlertMe, which I co-founded about 6 years ago. Our platform for the Smart Home offers a variety of end devices in the home which each do one simple thing, such as sense a quantity (e.g. temperature, energy, occupancy) , or act on something (e.g. heating, or switching appliances). These devices are networked together using ZigBee, and connected to the internet via your home broadband. The result is that you can now see what is going on in your home, and change things in your home, from anywhere, using almost any online means, from the web to a SmartPhone app, to an iGoogle gadget, to a humble text message.

So based on this experience, I’ve identified four key areas that deserve attention to ensure that the Smart Home “just works”:

  • Intelligence spread seamlessly: the consumer shouldn’t need to understand WHERE the smarts actually lie. They just tell the system as a whole (in our case, the house) what they want to happen, e.g. “turn down heating when house is empty”, and then all the technology should seamlessly work together to make this happen, without it being obvious who is doing what.
  • Easy to install & care for: the installation must require literally zero setup, it must “just work”.
  • Ignore the hardware, live the benefits: although for the first few days the customer will be aware of the various end-devices, they should quickly start to think of “the house” or “AlertMe” rather than those individual devices.
  • Subliminal UX (not modal): Watching TV is modal – we can’t do anything else at the same time. But the Smart Home is doing lots of things all the time, and if it claimed as much attention as the TV or PC does, it would quickly overwhelm you. So it must reduce interaction to the absolute minimum for the circumstances.

The Smart Home is coming, and I hope this has given a few insights into how we can make it truly useful.

 

Engineers do take showers

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and save £410/year!

Even as I have taken successive steps to reduce my bills and my carbon footprint, a remaining guilty pleasure is my good long soak in the shower every morning. Somehow it’s essential to wake up slowly. So I have tried various low-flow shower-heads, and after a couple of appalling “cold mist” experiences, finally found an aerating shower head (the EcoCamel) that still felt good and claimed to reduce flow substantially. But just how much was it really saving us?

The first step of my analysis was to measure the water flow – and that gave me a big surprise. The original head was a standard Aqualisa shower head fitted by the plumber at install, so I put that back on. I borrowed a measuring-jug from the kitchen, put it under the shower, turned it on and … it was full in a fraction of a second, far too fast to measure. Wow, that’s a lot of flow. Our hot water system uses mains water pressure, so I guess our showers are similar to a power shower experience.

So I went and got a bucket, which held 11 litres. The old shower head filled the bucket in 35 seconds. The new head in 94 seconds. So that’s 37% of the flow. Sounds good, but is it really significant for our household budget?

The above calculation shows that the old head uses 18.8L/minute. Or 188L for a 10 minute shower. Clearly my costs are going to be a combination of the water bill, and then the energy bill to heat it up, so let’s work each out separately.

Water Cost

Referring to my latest Anglia Water bill, I see that I am charged £0.81 for every cubic metre (m3). Doesn’t sound too bad – that’s a lot of water for less than a pound. But then I noticed that sewerage is ALSO charged on that – Anglia Water assume that 90% of what they supply as fresh water is then flushed down the drain again. And they charge £1.42/m3 for sewerage, so every cubic metre of water is deemed to cost me £1.28 in sewerage too, in other words I am charged a total cost of £2.09/m3. There are 1000 litres in a m3, so this is 0.209 pence per litre. Sounds pretty cheap compared to bottled water!

Energy Cost

Our gas boiler was installed pre-1998, so is the less efficient non-condensing type. Our heating system is of the “conventional” type, meaning that a big loop of water piping runs through the boiler and then around the house, heating the radiators and heating the hot water tank. A 3-way valve determines whether the heat goes to the radiators, the hot water tank or both.

On our last bill, gas cost us 3.6p per kWh (“unit”).

The specific heat capacity of water is 4186 Joules per (kg °C). A watt is a joule per second. So a watt-second is a joule. So a watt-hour is 3600 joules. So a kilowatt-hour is 3,600,000 joules.

Heat Added = specific_heat x mass x delta_temp

Comfortable shower water temp is 40°C (just above body temp)
Incoming water temp is 10°C. So delta is 30°C

1L of water weighs 1kg
So 1L of water raised 1°C takes 4186 Joules which is 0.00116kWh
So raising it 30°C takes 0.0349kWh
So every litre of water costs 0.126p to heat.

Aha, but when I consulted our wise friends in the Data Analytics team at AlertMe they pointed-out that this doesn’t take into account all the inefficiencies in my heating system. BRE’s BREDEM-8 model for our heating system type estimates its year-round average efficiency at 70%, plus a 15% of distribution loss (all that piping between the boiler and the tank gets warmed-up too, even in summer), plus an average storage loss in the hot water tank of 30%. This makes the net efficiency around 48%, so in fact my water is costing around twice as much to heat as I first calculated.

This puts the true cost of heating every litre of water at 0.263p.

Putting it all together

So every litre of water costs 0.209p to buy and 0.263p to heat = 0.472p total. A 10 minute shower with the old head consumed 188L and cost £0.89 per shower. So two such showers (me and my wife) taken every day for a year costs an amazing £650/year. And our Eco Camel head, by reducing the flow to 37% (i.e. by 63%), is saving us £410/year.