A reality check on renewables - David MacKay

when the Industrial Revolution started the amount of carbon sitting underneath Britain in the form of coal was as big as the amount of carbon sitting under Saudi Arabia in the form of oil and this carbon powered the Industrial Revolution it put the great in Great Britain and led to Britain's temporary world domination and then in 1918 coal production in Britain peaked and has declined ever since in due course Britain started using oil and gas from the North Sea and in the year 2000 oil and gas production from the North Sea also peaked and they're now on the on the decline these observations about the finiteness of easily accessible local secure fossil fuels this is a motivation for saying well what's next what is life after fossil fuels going to be like shouldn't we be thinking hard about how to get off fossil fuels another motivation of course is climate change and when people talk about life after fossil fuels and climate change action I think there's a lot of fluff a lot of green wash a lot of misleading advertising and I feel a duty as a physicist to try to guide people round the claptrap and help people understand the actions that really make a difference and to focus on ideas that do add up let me illustrate this with what physicists call back of envelope calculation we love back of envelope calculations you ask a question you write down some numbers and you get yourself an answer it may not be very accurate but it may make you say hmm so here's a question imagine if we said oh yes we can get off fossil fuels we'll use biofuels problem-solve transport we don't need oil anymore well what if we grew the biofuels for a road on the grass verge at the edge of the road how wide would the verge have to be for that to work out okay so let's put in some numbers let's have our cars go at 60 miles per hour let's say they do 30 per gallon that's the European average for new cars let's say the productivity of biofuel plantations is 1200 litres of biofuel per hectare per year that's true of European biofuels and let's imagine the cars are spaced 80 metres apart from each other and they're just perpetually going along this road the length of the road doesn't matter because the longer the road the more biofuel plantation we've got what do we do with these numbers well you take the first number and you divide by the other three and you get eight kilometers and that's the answer that's how wide the plantation would have to be given these assumptions and maybe that makes you say hmm maybe this isn't going to be quite so easy and it might make you think perhaps is an issue to do with areas and in this talk I'd like to talk about land areas and ask is there an issue about areas the answer is going to be yes but it depends which country you are in so let's start in the United Kingdom since that's where we are today the energy consumption of the United Kingdom the total energy consumption not just transport but everything I like to quantify it in light bulbs it's as if we've all got 125 light bulbs on all the time 125 kilowatt hours per day per person is the energy consumption of the UK so there's 40 light bulbs worth the transport 40 light bulbs worth for heating and 40 light bulbs worth for making electricity and other things are relatively small compared to those three big fish it's actually got a bigger footprint if we take into account the embodied energy and the stuff we import into our country as well and ninety percent of this energy today still comes from fossil fuels and ten percent only from others greener possibly goona sources like nuclear power and renewables so that's the UK and the population density of the UK is 250 people per square kilometer and I'm now going to show you other countries by these same two measures on the vertical axis I'm going to show you how much light bulbs what our energy consumption per person is and we're at 125 lightbulbs per person and that little blue dot there is showing you the land air year of the United Kingdom and the population density is on the horizontal axis and we're 250 people per square kilometer let's add European countries in blue and you can see there's quite a variety I should emphasize both of these axes are logarithmic as you go from one gray bar to the next great bar you're going up a factor of 10 next let's add Asia in red Middle Eastern North Africa in green sub-saharan Africa in blue black is South America purple is Central America and then in pukey yellow we have North America Australia and New Zealand and you can see the great diversity of population densities and of per capita consumptions countries are different from each other top left we have Canada and Australia with enormous land areas very high per capita consumption 200 or 300 light bulbs per person and very low population densities top right Bahrain has the same energy consumption per person roughly as Canada over 300 light bulbs per person but their population density is a factor of three hundred times greater a thousand people per square kilometer bottom right Bangladesh has the same population density as Bahrain but consumes a hundred times less per person bottom left well there's no one but there used to be a whole load of people here's another message from this diagram I've added on little blue tails behind Sudan Libya China India Bangladesh that's 15 years of progress where were they 15 years ago and where are they now and the message is most countries are going to the right and they're going up up and to the right bigger population density and higher per capita consumption so we may be off in the top right hand corner slightly unusual the United Kingdom accompanied by Germany Japan South Korea the Netherlands and a bunch of other slightly odd countries but many other countries are coming up and to the right to come and join us so we're a picture if you like of what the future energy consumption might be looking like in other countries - and I've also added in this diagram now some pink lines that go down and to the right those are lines of equal power consumption per unit area which I measure in watts per square meter so for example the middle line there 0.1 watts per square meter is the energy consumption per unit area of Saudi Arabia Norway Mexico in purple and Bangladesh 15 years ago and half of the world's population lives in countries that are already above that line the United Kingdom is consuming 1.25 watts per square meter shows Germany and Japan is consuming a bit more so let's now say why this is relevant why is it relevant well we can measure renewables in the same units and other forms of power production in the same units and renewables is one of the leading ideas for how we could get off our 90% fossil fuel habit so here comes from renewables energy crops deliver harper watt per square meter in european climates what does that mean and you might have anticipated that that result given what I told you about the biofuel plantation a moment ago well we consume 1.25 watts per square meter what this means is even if you covered the whole of the United Kingdom with energy crops you couldn't match today's energy consumption wind power produces a bit more 2.5 watts per square meter but that's only twice as big as 1.25 what's the square meter so that means if you wanted literally to produce a total energy consumption in all forms on average from wind farms you'd need wind farms half the area of the UK I've got data back to back up all these assertions by the way next let's look at solar power solar panels when you put them on a roof deliver about 20 watts per square meter in England if you really want to get a lot from solar panels you need to adopt adopt the traditional Bavarian farming method where you leap off the roof and coat the countryside with solar panels to solar parks because of the gaps between the panel's deliver less they deliver about 5 watts per square meter of land area and here's a solar Park in Vermont with real data delivering 4.2 watts per square meter remember where we are 1.25 watts per square meter wind farms 2.5 solar park about five so whatever whichever of those renewables you pick the message is whatever mix of those renewables you're using if you want to power the UK on them you're going to need to cover something like 20 percent or 25 percent of the country with those renewables and I'm not saying that's a bad idea we just need to understand the numbers I'm absolutely not Antti renewables I love renewables but I'm also Pro arithmetic concentrating solar power in deserts delivers larger powers per unit area because you don't have the problem of clouds and so this facility delivers 14 watts per square meter this 110 watts per square meter and this one in Spain five watts per square meter being generous to concentrating solar power I think it's probably credible it could deliver 20 watts per square meter so that's that's nice of course Britain doesn't have any deserts yet so here's a summary so far all renewables much as I love them are diffused they all have a small power per unit area and we have to live with that fact and that means if you do want renewables to make a substantial difference for a country like the United Kingdom on the scale of today's consumption you need to be imagining renewable facilities that are country sized not the entire country but a fraction of the country says a substantial fraction there are other options for generating power as well which don't involve fossil fuels so there's nuclear power and on this Ordnance Survey map you can see there's a size well be inside a blue square kilometer that's one gigawatt in a square kilometer which works out to a thousand watts per square meter so by this particular metric nuclear power isn't as intrusive as renewables of course other metrics matter to a nuclear power has all sorts of popularity problems but the same goes for renewables as well here's a photograph of a consultation exercise in full-swing in the little town of Pennycook just south just outside Edinburgh and you can see the children Penacook celebrating the burning of the effigy of the wind wind so people are anti everything and we've got to keep all the options on the table what can a country like the UK do on the supply side well the options are I'd say these three are renewables and recognising that they need to be close to country size other people's renewables so we could go back and talk very politely to the people in the top left-hand side of the diagram and say we don't want renewables in our backyard but please could we put min yours instead and that's a serious option it's a way for the world to to handle this issue so countries like Australia Russia Libya Kazakhstan could be our best friends for renewable production and a third option is is nuclear power so that's some supply-side options in addition to the supply levers that we can push and remember we need large amounts because at the moment we'll get 90 percent of our energy from fossil fuels in addition to those levers we could talk about other ways of solving this issue namely we could use demand and that means reducing population I'm not sure how to do that all reducing per capita consumption so let's talk about three more big levers that could really help on the consumption side first transport here are the physics principles that tell you how to reduce the energy consumption of transport and people often say oh yes technology can answer everything we can make vehicles that are a hundred times more efficient and that's almost true let me show you the energy consumption of this typical tank here is 80 kilowatt hours per hundred person kilometers that that's the average European car eighty kilowatt hours can we make something a hundred times better by applying those physics principles I just listed yes here it is is the bicycle it's 80 times better in energy consumption it is powered by biofuel by Weetabix and there are other options in between because maybe the lady in the tank would say no no that's a lifestyle change don't change my lifestyle please so well we could persuade her to get into a train and that's still a lot more efficient than a car but that might be lifestyle change or there's the eco car top left it comfortably accommodates one teenager and it's shorter than a traffic cone and it's almost as efficient as a bicycle as long as you drive it at 15 miles per hour in between perhaps a more realistic options on this lever transport lever are electric vehicles so electric bikes and electric cars in the middle perhaps four times as energy efficient as the standard petrol powered tank next is the heating lever heating is a third of our energy consumption in Britain and quite a lot of that is going into homes and upper buildings doing space heating and water heating so here's a typical crappy British house it's my house with the Ferrari out front what can we do to it well the laws of physics are written up there which describe what how the power the power consumption for heating is driven by the things you can control the things you can you can control the temperature difference between the inside and the outside and there's this remarkable technology called the thermostat you grasp it you rotate it to the left and your energy consumption in the home will decrease I've tried it it works some people call it a lifestyle change you can also get the fluff men in to reduce the leakiness of your building put fluff in the walls fluff in the roof and a new front door and so forth and the sad truth is this will save you money that's not sad that's good but the sad truth is it'll only get about 25 percent off the leakiness of your building if you do these things which are good ideas if you really want to get a bit closer to swedish building standards with a crappy house like this you need to be putting external insulation on the building as shown by this block of plants in london you can also deliver heat more efficiently using heat pumps which use a smaller bit of high-grade energy like electricity to move heat from your garden into your house the third demand side option I want to talk about the third way to reduce energy consumption is read young meters and people talk a lot about smart meters but you can do yourself use your own eyes and be smart read your meter and if you're anything like me it'll change your life here's a graph I made I was writing a book about sustainable energy and a friend asked me well how much energy do you use at home and I was embarrassed I didn't actually know and so I started reading the meter every week and the old meter readings are shown in the top half of the graph and then 2007 is shown in green at the bottom and that was when I was reading the meter every week and my life changed because I'd started doing experiments and seeing what made a difference and my gas consumption plummeted because I started tinkering with the thermostat and the timing on the heating system and I knocked more than a half off my gas bills there's a similar story for my electricity consumption where switching off the DVD players the stereos the computer peripherals that were on all the time and just switching them on when I needed them knocked another third off my electricity bills - so we need a plan that adds up and I've described for you six big levers and we need big action because we get 90% of our energy from fossil fuels and so you need to push hard on most if not all of these levers and most of these levers have popularity problems and if there is a lever you don't like the the use of well please do bear in mind that means you need even stronger effort on the other levers so I'm a strong advocate advocate of having grown-up conversations that are based on numbers and facts and I want to close with this map that just visualizes for you the requirement of land and so forth in order to get just 16 light poles per person from four of the big possible sources so if you wanted to get sixteen light poles remember today our total energy consumption is 125 lightbulbs worth if you wanted sixteen from wind this map visualizes a solution for the UK it's got 160 wind farms each one hundred square kilometres in size and that would be a 20-fold increase over today's amount of wind nuclear power to get 16 lightbulbs per person you'd need 2 gigawatts at each of the purple dots on the map that's a four-fold increase over today's levels of nuclear power biomass to get 16 lightbulbs per person you need a land area something like three and a half whales is worth either in our country or in someone else's country possibly Ireland possibly somewhere else and the fourth supply-side option concentrating solar power in other people's deserts if you wanted to get sixteen lightbulbs worth then we're talking about these eight hexagons down at the bottom right the total area of those hexagons is to Greater London's worth of someone else's Sahara and you'll need power lines all the way across Spain and France to being to bring the power from the Sahara to sorry we need a plan that adds up we need to stop shouting and start talking and if we can have a grown-up conversation make a plan that adds up and get building maybe this low-carbon revolution will actually be fun thank you very much for listening

Channel: TED-Ed

Views: 734,691

Rating: 4.7084193 out of 5

Keywords: \renewable energy\, energy, sustainability, \David, MacKay\, TED, TEDx, TEDxWarwick, TED-Ed, \TED, Ed\, TEDEducation

Id: E0W1ZZYIV8o

Length: 18min 35sec (1115 seconds)

Published: Wed Jun 26 2013

Reddit Comments

[u/systemrename]

AND it's helpful to remember that this has to be complete in Europe, UK, Canada, USA, Australia by 2035 and worldwide by 2050.

basically nobody is paying attention and it's nearly 2019

in another 5 or 6 years we'll still be talking about these projects and motoring down the highways.

[u/knuteknuteson]

I'd recommend his book, free on pdf:

https://www.withouthotair.com/download.html

He uses lot of numbers, nothing more than maybe 6th grade math, so if you disagree with him, you don't have to do anything except point out where his math is wrong.

Few people seem to like him, but will never show where he is wrong