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A reality check on renewables | David MacKay | TEDxWarwick

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    When the Industrial Revolution started,
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    the amount of carbon sitting
    underneath Britain in the form of coal
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    was as big as the amount of carbon
    sitting under Saudi Arabia
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    in the form of oil.
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    This carbon powered
    the Industrial Revolution,
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    it put the "Great" in Great Britain,
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    and led to Britain's temporary
    world domination.
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    And then, in 1918,
    coal production in Britain peaked,
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    and has declined ever since.
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    In due course, Britain started using
    oil and gas from the North Sea,
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    and in the year 2000,
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    oil and gas production
    from the North Sea also peaked,
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    and they're now on the decline.
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    These observations about the finiteness
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    of easily accessible, local,
    secure fossil fuels,
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    is a motivation for saying,
    "Well, what's next?
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    What is life after fossil fuels
    going to be like?
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    Shouldn't we be thinking hard
    about how to get off fossil fuels?"
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    Another motivation,
    of course, is climate change.
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    And when people talk
    about life after fossil fuels
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    and climate change action,
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    I think there's a lot of fluff,
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    a lot of greenwash,
    a lot of misleading advertising,
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    and I feel a duty as a physicist to try
    to guide people around the claptrap
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    and help people understand the actions
    that really make a difference,
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    and to focus on ideas that do add up.
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    Let me illustrate this
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    with what physicists call
    a back-of-envelope calculation.
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    We love back-of-envelope calculations.
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    You ask a question,
    write down some numbers,
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    and get an answer.
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    It may not be very accurate,
    but it may make you say, "Hmm."
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    So here's a question:
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    Imagine if we said, "Oh yes,
    we can get off fossil fuels.
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    We'll use biofuels. Problem solved.
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    Transport ... We don't need oil anymore."
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    Well, what if we grew
    the biofuels for a road
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    on the grass verge
    at the edge of the road?
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    How wide would the verge
    have to be for that to work out?
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    OK, so let's put in some numbers.
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    Let's have our cars go
    at 60 miles per hour.
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    Let's say they do 30 miles per gallon.
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    That's the European average for new cars.
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    Let's say the productivity
    of biofuel plantations
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    is 1,200 liters of biofuel
    per hectare per year.
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    That's true of European biofuels.
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    And let's imagine the cars are spaced
    80 meters apart from each other,
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    and they're perpetually
    going along this road.
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    The length of the road doesn't matter,
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    because the longer the road,
    the more biofuel plantation.
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    What do we do with these numbers?
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    Take the first number, divide by the other
    three, and get eight kilometers.
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    And that's the answer.
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    That's how wide the plantation
    would have to be,
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    given these assumptions.
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    And maybe that makes you say, "Hmm.
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    Maybe this isn't going
    to be quite so easy."
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    And it might make you think,
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    perhaps there's an issue to do with areas.
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    And in this talk, I'd like to talk
    about land areas, and ask:
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    Is there an issue about areas?
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    The answer is going to be yes,
    but it depends which country you are in.
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    So let's start in the United Kingdom,
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    since that's where we are today.
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    The energy consumption
    of the United Kingdom,
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    the total energy consumption --
    not just transport, but everything --
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    I like to quantify it in lightbulbs.
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    It's as if we've all got
    125 lightbulbs on all the time,
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    125 kilowatt-hours per day per person
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    is the energy consumption of the UK.
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    So there's 40 lightbulbs'
    worth for transport,
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    40 lightbulbs' worth for heating,
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    and 40 lightbulbs' worth
    for making electricity,
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    and other things are relatively small,
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    compared to those three big fish.
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    It's actually a bigger footprint
    if we take into account
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    the embodied energy in the stuff
    we import into our country as well.
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    And 90 percent of this energy, today,
    still comes from fossil fuels,
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    and 10 percent, only, from other,
    greener -- possibly greener -- sources,
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    like nuclear power and renewables.
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    So.
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    That's the UK.
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    The population density of the UK
    is 250 people per square kilometer.
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    I'm now going to show you other countries
    by these same two measures.
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    On the vertical axis, I'm going
    to show you how many lightbulbs --
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    what our energy consumption per person is.
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    We're at 125 lightbulbs per person,
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    and that little blue dot there
    is showing you the land area
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    of the United Kingdom.
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    The population density
    is on the horizontal axis,
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    and we're 250 people per square kilometer.
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    Let's add European countries in blue,
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    and you can see there's quite a variety.
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    I should emphasize,
    both of these axes are logarithmic;
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    as you go from one gray bar
    to the next gray bar,
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    you're going up a factor of 10.
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    Next, let's add Asia in red,
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    the Middle East and North Africa in green,
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    sub-Saharan Africa in blue,
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    black is South America,
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    purple is Central America,
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    and then in pukey-yellow,
    we have North America,
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    Australia and New Zealand.
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    You can see the great diversity
    of population densities
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    and of per capita consumptions.
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    Countries are different from each other.
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    Top left, we have Canada and Australia,
    with enormous land areas,
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    very high per capita consumption --
    200 or 300 lightbulbs per person --
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    and very low population densities.
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    Top right: Bahrain has
    the same energy consumption
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    per person, roughly, as Canada --
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    over 300 lightbulbs per person,
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    but their population density
    is a factor of 300 times greater,
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    1,000 people per square kilometer.
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    Bottom right: Bangladesh has
    the same population density as Bahrain,
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    but consumes 100 times less per person.
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    Bottom left: well, there's no one.
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    But there used to be
    a whole load of people.
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    Here's another message from this diagram.
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    I've added on little blue tails
    behind Sudan, Libya,
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    China, India, Bangladesh.
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    That's 15 years of progress.
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    Where were they 15 years ago,
    and where are they now?
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    And the message is,
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    most countries are going to the right,
    and they're going up.
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    Up and to the right:
    bigger population density
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    and higher per capita consumption.
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    So, we may be off in the top
    right-hand corner, slightly unusual,
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    the United Kingdom accompanied by Germany,
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    Japan, South Korea, the Netherlands,
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    and a bunch of other
    slightly odd countries,
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    but many other countries are coming
    up and to the right to join us.
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    So we're a picture, if you like,
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    of what the future energy consumption
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    might be looking
    like in other countries, too.
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    I've also added in this diagram
    now some pink lines
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    that go down and to the right.
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    Those are lines of equal
    power consumption per unit area,
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    which I measure in watts per square meter.
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    So, for example, the middle line there,
    0.1 watts per square meter,
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    is the energy consumption
    per unit area of Saudi Arabia,
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    Norway, Mexico in purple,
    and Bangladesh 15 years ago.
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    Half of the world's population
    lives in countries
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    that are already above that line.
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    The United Kingdom is consuming
    1.25 watts per square meter.
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    So is Germany, and Japan
    is consuming a bit more.
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    So, let's now say why this is relevant.
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    Why is it relevant?
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    Well, we can measure
    renewables in the same units
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    and other forms of power
    production in the same units.
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    Renewables is one of the leading ideas
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    for how we could get off
    our 90 percent fossil-fuel habit.
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    So here come some renewables.
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    Energy crops deliver
    half a watt per square meter
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    in European climates.
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    What does that mean?
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    You might have anticipated that result,
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    given what I told you about the biofuel
    plantation a moment ago.
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    Well, we consume 1.25 watts
    per square meter.
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    What this means is,
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    even if you covered the whole
    of the United Kingdom with energy crops,
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    you couldn't match
    today's energy consumption.
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    Wind power produces a bit more --
    2.5 watts per square meter.
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    But that's only twice as big
    as 1.25 watts per square meter.
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    So that means if you wanted, literally,
    to produce total energy consumption
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    in all forms, on average, from wind farms,
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    you need wind farms
    half the area of the UK.
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    I've got data to back up
    all these assertions, by the way.
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    Next, let's look at solar power.
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    Solar panels, when you put them on a roof,
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    deliver about 20 watts
    per square meter in England.
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    If you really want to get
    a lot from solar panels,
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    you need to adopt the traditional
    Bavarian farming method,
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    where you leap off the roof,
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    and coat the countryside
    with solar panels, too.
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    Solar parks, because of the gaps
    between the panels, deliver less.
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    They deliver about 5 watts
    per square meter of land area.
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    And here's a solar park
    in Vermont, with real data,
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    delivering 4.2 watts per square meter.
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    Remember where we are,
    1.25 watts per square meter,
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    wind farms 2.5, solar parks about five.
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    So whichever of those renewables you pick,
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    the message is, whatever mix
    of those renewables you're using,
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    if you want to power the UK on them,
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    you're going to need
    to cover something like
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    20 percent or 25 percent of the country
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    with those renewables.
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    I'm not saying that's a bad idea;
    we just need to understand the numbers.
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    I'm absolutely not anti-renewables.
    I love renewables.
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    But I'm also pro-arithmetic.
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    (Laughter)
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    Concentrating solar power in deserts
    delivers larger powers per unit area,
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    because you don't have
    the problem of clouds.
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    So, this facility delivers
    14 watts per square meter;
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    this one 10 watts per square meter;
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    and this one in Spain,
    5 watts per square meter.
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    Being generous
    to concentrating solar power,
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    I think it's perfectly credible it could
    deliver 20 watts per square meter.
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    So that's nice.
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    Of course, Britain
    doesn't have any deserts.
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    Yet.
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    (Laughter)
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    So here's a summary so far:
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    All renewables, much
    as I love them, are diffuse.
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    They all have a small power per unit area,
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    and we have to live with that fact.
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    And that means, if you do want renewables
    to make a substantial difference
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    for a country like the United Kingdom
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    on the scale of today's consumption,
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    you need to be imagining renewable
    facilities that are country-sized.
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    Not the entire country,
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    but a fraction of the country,
    a substantial fraction.
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    There are other options
    for generating power as well,
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    which don't involve fossil fuels.
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    So there's nuclear power,
    and on this ordinance survey map,
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    you can see there's a Sizewell B
    inside a blue square kilometer.
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    That's one gigawatt in a square kilometer,
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    which works out to 1,000 watts
    per square meter.
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    So by this particular metric,
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    nuclear power isn't
    as intrusive as renewables.
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    Of course, other metrics matter, too,
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    and nuclear power has
    all sorts of popularity problems.
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    But the same goes for renewables as well.
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    Here's a photograph of a consultation
    exercise in full swing
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    in the little town of Penicuik
    just outside Edinburgh,
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    and you can see the children
    of Penicuik celebrating
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    the burning of the effigy of the windmill.
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    So --
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    (Laughter)
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    People are anti-everything,
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    and we've got to keep
    all the options on the table.
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    What can a country like the UK
    do on the supply side?
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    Well, the options are,
    I'd say, these three:
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    power renewables,
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    and recognizing that they need
    to be close to country-sized;
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    other people's renewables,
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    so we could go back and talk very politely
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    to the people in the top left-hand side
    of the diagram and say,
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    "Uh, we don't want
    renewables in our backyard,
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    but, um, please could we put
    them in yours instead?"
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    And that's a serious option.
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    It's a way for the world
    to handle this issue.
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    So countries like Australia,
    Russia, Libya, Kazakhstan,
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    could be our best friends
    for renewable production.
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    And a third option is nuclear power.
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    So that's some supply-side options.
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    In addition to the supply levers
    that we can push --
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    and remember, we need large amounts,
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    because at the moment, we get 90 percent
    of our energy from fossil fuels --
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    in addition to those levers,
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    we could talk about other ways
    of solving this issue.
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    Namely, we could reduce demand,
    and that means reducing population --
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    I'm not sure how to do that --
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    or reducing per capita consumption.
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    So let's talk about three more big levers
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    that could really help
    on the consumption side.
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    First, transport.
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    Here are the physics principles
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    that tell you how to reduce
    the energy consumption of transport.
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    People often say,
    "Technology can answer everything.
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    We can make vehicles
    that are 100 times more efficient."
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    And that's almost true. Let me show you.
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    The energy consumption
    of this typical tank here
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    is 80 kilowatt hours
    per hundred person kilometers.
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    That's the average European car.
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    Eighty kilowatt hours.
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    Can we make something 100 times better
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    by applying the physics
    principles I just listed?
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    Yes. Here it is. It's the bicycle.
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    It's 80 times better
    in energy consumption,
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    and it's powered by biofuel, by Weetabix.
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    (Laughter)
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    And there are other options in between,
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    because maybe the lady
    in the tank would say,
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    "No, that's a lifestyle change.
    Don't change my lifestyle, please."
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    We could persuade her to take a train,
    still a lot more efficient than a car,
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    but that might be a lifestyle change.
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    Or there's the EcoCAR, top-left.
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    It comfortably accommodates one teenager
    and it's shorter than a traffic cone,
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    and it's almost as efficient as a bicycle,
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    as long as you drive it
    at 15 miles per hour.
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    In between, perhaps
    some more realistic options
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    on the transport lever
    are electric vehicles,
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    so electric bikes
    and electric cars in the middle,
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    perhaps four times as energy efficient
    as the standard petrol-powered tank.
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    Next, there's the heating lever.
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    Heating is a third of our energy
    consumption in Britain,
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    and quite a lot of that
    is going into homes
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    and other buildings,
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    doing space heating and water heating.
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    So here's a typical crappy British house.
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    It's my house, with a Ferrari out front.
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    (Laughter)
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    What can we do to it?
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    Well, the laws of physics
    are written up there,
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    which describe how the power
    consumption for heating
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    is driven by the things you can control.
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    The things you can control
    are the temperature difference
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    between the inside and the outside.
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    There's this remarkable technology
    called a thermostat:
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    you grasp it, rotate it to the left,
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    and your energy consumption
    in the home will decrease.
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    I've tried it. It works.
    Some people call it a lifestyle change.
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    (Laughter)
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    You can also get the fluff men
    in to reduce the leakiness
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    of your building -- put fluff
    in the walls, fluff in the roof,
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    a new front door, and so forth.
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    The sad truth is,
    this will save you money.
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    That's not sad, that's good.
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    But the sad truth is,
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    it'll only get about 25 percent
    of the leakiness of your building
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    if you do these things,
    which are good ideas.
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    If you really want to get a bit closer
    to Swedish building standards
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    with a crappy house like this,
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    you need to be putting
    external insulation on the building,
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    as shown by this block of flats in London.
  • 15:11 - 15:14
    You can also deliver heat
    more efficiently using heat pumps,
  • 15:14 - 15:18
    which use a smaller bit
    of high-grade energy like electricity
  • 15:18 - 15:20
    to move heat from your garden
    into your house.
  • 15:21 - 15:24
    The third demand-side option
    I want to talk about,
  • 15:24 - 15:27
    the third way to reduce energy
    consumption is: read your meters.
  • 15:27 - 15:29
    People talk a lot about smart meters,
  • 15:29 - 15:30
    but you can do it yourself.
  • 15:30 - 15:32
    Use your own eyes and be smart.
  • 15:32 - 15:36
    Read your meter, and if you're anything
    like me, it'll change your life.
  • 15:36 - 15:37
    Here's a graph I made.
  • 15:37 - 15:39
    I was writing a book
    about sustainable energy,
  • 15:39 - 15:40
    and a friend asked me,
  • 15:41 - 15:42
    "How much energy do you use at home?"
  • 15:42 - 15:44
    I was embarrassed; I didn't actually know.
  • 15:44 - 15:47
    And so I started reading
    the meter every week.
  • 15:47 - 15:50
    The old meter readings are shown
    in the top half of the graph,
  • 15:50 - 15:53
    and then 2007 is shown
    in green at the bottom.
  • 15:53 - 15:55
    That was when I was reading
    the meter every week.
  • 15:55 - 15:56
    And my life changed,
  • 15:56 - 16:00
    because I started doing experiments
    and seeing what made a difference.
  • 16:00 - 16:01
    My gas consumption plummeted,
  • 16:01 - 16:03
    because I started tinkering
    with the thermostat
  • 16:03 - 16:05
    and the timing on the heating system,
  • 16:05 - 16:07
    and I knocked more than half
    off my gas bills.
  • 16:07 - 16:10
    There's a similar story
    for my electricity consumption,
  • 16:10 - 16:14
    where switching off the DVD
    players, the stereos,
  • 16:14 - 16:17
    the computer peripherals
    that were on all the time,
  • 16:17 - 16:19
    and just switching them on
    when I needed them,
  • 16:19 - 16:21
    knocked another third
    off my electricity bills, too.
  • 16:23 - 16:25
    So we need a plan that adds up.
  • 16:25 - 16:27
    I've described for you six big levers.
  • 16:27 - 16:28
    We need big action,
  • 16:28 - 16:31
    because we get 90 percent
    of our energy from fossil fuels,
  • 16:31 - 16:35
    and so you need to push hard
    on most, if not all, of these levers.
  • 16:36 - 16:38
    Most of these levers
    have popularity problems,
  • 16:38 - 16:42
    and if there is a lever
    you don't like the use of,
  • 16:42 - 16:46
    well, please do bear in mind
    that means you need even stronger effort
  • 16:46 - 16:48
    on the other levers.
  • 16:48 - 16:51
    So I'm a strong advocate
    of having grown-up conversations
  • 16:51 - 16:53
    that are based on numbers and facts.
  • 16:54 - 16:57
    And I want to close with this map
    that just visualizes for you
  • 16:57 - 17:01
    the requirement of land and so forth
  • 17:01 - 17:04
    in order to get just
    16 lightbulbs per person
  • 17:04 - 17:07
    from four of the big possible sources.
  • 17:07 - 17:10
    So, if you wanted to get 16 lightbulbs --
  • 17:10 - 17:15
    remember, today our total energy
    consumption is 125 lightbulbs' worth --
  • 17:15 - 17:17
    if you wanted 16 from wind,
  • 17:17 - 17:20
    this map visualizes a solution for the UK.
  • 17:20 - 17:24
    It's got 160 wind farms,
    each 100 square kilometers in size,
  • 17:24 - 17:28
    and that would be a twentyfold increase
    over today's amount of wind.
  • 17:28 - 17:31
    Nuclear power:
    to get 16 lightbulbs per person,
  • 17:31 - 17:34
    you'd need two gigawatts
    at each of the purple dots on the map.
  • 17:34 - 17:38
    That's a fourfold increase
    over today's levels of nuclear power.
  • 17:39 - 17:41
    Biomass: to get 16 lightbulbs per person,
  • 17:41 - 17:46
    you'd need a land area something
    like three and a half Wales' worth,
  • 17:46 - 17:49
    either in our country,
    or in someone else's country,
  • 17:49 - 17:51
    possibly Ireland, possibly somewhere else.
  • 17:51 - 17:52
    (Laughter)
  • 17:52 - 17:54
    And a fourth supply-side option:
  • 17:54 - 17:57
    concentrating solar power
    in other people's deserts.
  • 17:57 - 18:00
    If you wanted to get 16 lightbulbs' worth,
  • 18:00 - 18:03
    then we're talking
    about these eight hexagons
  • 18:03 - 18:04
    down at the bottom right.
  • 18:04 - 18:08
    The total area of those hexagons
    is two Greater London's worth
  • 18:08 - 18:10
    of someone else's Sahara,
  • 18:10 - 18:13
    and you'll need power lines
    all the way across Spain and France
  • 18:13 - 18:17
    to bring the power
    from the Sahara to Surrey.
  • 18:17 - 18:18
    (Laughter)
  • 18:18 - 18:20
    We need a plan that adds up.
  • 18:21 - 18:23
    We need to stop shouting
    and start talking.
  • 18:25 - 18:29
    And if we can have
    a grown-up conversation,
  • 18:29 - 18:32
    make a plan that adds up and get building,
  • 18:32 - 18:35
    maybe this low-carbon revolution
    will actually be fun.
  • 18:35 - 18:36
    Thank you very much for listening.
  • 18:36 - 18:39
    (Applause)
Title:
A reality check on renewables | David MacKay | TEDxWarwick
Description:

How much land mass would renewables need to power a nation like the UK? An entire country's worth. In this pragmatic talk, David MacKay tours the basic mathematics that show worrying limitations on our sustainable energy options and explains why we should pursue them anyway.

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Video Language:
English
Team:
TED
Project:
TEDxTalks
Duration:
18:48

English subtitles

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