WEBVTT

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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?

00:13:07.571 --> 00:13:09.214
Yes. Here it is. It's the bicycle.

00:13:09.238 --> 00:13:11.884
It's 80 times better
in energy consumption,

00:13:11.908 --> 00:13:14.132
and it's powered by biofuel, by Weetabix.

00:13:14.156 --> 00:13:16.294
(Laughter)

00:13:16.318 --> 00:13:18.185
And there are other options in between,

00:13:18.209 --> 00:13:20.336
because maybe the lady
in the tank would say,

00:13:20.360 --> 00:13:23.516
"No, that's a lifestyle change.
Don't change my lifestyle, please."

00:13:23.540 --> 00:13:27.187
We could persuade her to take a train,
still a lot more efficient than a car,

00:13:27.211 --> 00:13:28.986
but that might be a lifestyle change.

00:13:29.010 --> 00:13:30.594
Or there's the EcoCAR, top-left.

00:13:30.618 --> 00:13:34.353
It comfortably accommodates one teenager
and it's shorter than a traffic cone,

00:13:34.377 --> 00:13:36.413
and it's almost as efficient as a bicycle,

00:13:36.437 --> 00:13:39.477
as long as you drive it
at 15 miles per hour.

00:13:39.899 --> 00:13:42.126
In between, perhaps
some more realistic options

00:13:42.150 --> 00:13:45.115
on the transport lever
are electric vehicles,

00:13:45.139 --> 00:13:47.518
so electric bikes
and electric cars in the middle,

00:13:47.542 --> 00:13:52.568
perhaps four times as energy efficient
as the standard petrol-powered tank.

00:13:53.378 --> 00:13:55.276
Next, there's the heating lever.

00:13:55.300 --> 00:13:58.791
Heating is a third of our energy
consumption in Britain,

00:13:58.815 --> 00:14:00.888
and quite a lot of that
is going into homes

00:14:00.912 --> 00:14:02.295
and other buildings,

00:14:02.319 --> 00:14:04.296
doing space heating and water heating.

00:14:04.320 --> 00:14:06.604
So here's a typical crappy British house.

00:14:06.628 --> 00:14:09.347
It's my house, with a Ferrari out front.

00:14:09.371 --> 00:14:10.436
(Laughter)

00:14:10.460 --> 00:14:11.613
What can we do to it?

00:14:11.637 --> 00:14:15.298
Well, the laws of physics
are written up there,

00:14:15.322 --> 00:14:20.570
which describe how the power
consumption for heating

00:14:20.594 --> 00:14:22.502
is driven by the things you can control.

00:14:22.526 --> 00:14:25.420
The things you can control
are the temperature difference

00:14:25.444 --> 00:14:27.127
between the inside and the outside.

00:14:27.151 --> 00:14:29.765
There's this remarkable technology
called a thermostat:

00:14:29.789 --> 00:14:31.525
you grasp it, rotate it to the left,

00:14:31.549 --> 00:14:34.078
and your energy consumption
in the home will decrease.

00:14:34.102 --> 00:14:37.205
I've tried it. It works.
Some people call it a lifestyle change.

00:14:37.229 --> 00:14:38.313
(Laughter)

00:14:38.337 --> 00:14:41.817
You can also get the fluff men
in to reduce the leakiness

00:14:41.841 --> 00:14:44.810
of your building -- put fluff
in the walls, fluff in the roof,

00:14:44.834 --> 00:14:46.628
a new front door, and so forth.

00:14:48.052 --> 00:14:50.637
The sad truth is,
this will save you money.

00:14:50.661 --> 00:14:52.001
That's not sad, that's good.

00:14:52.025 --> 00:14:53.203
But the sad truth is,

00:14:53.227 --> 00:14:56.426
it'll only get about 25 percent
of the leakiness of your building

00:14:56.450 --> 00:14:59.145
if you do these things,
which are good ideas.

00:14:59.169 --> 00:15:02.428
If you really want to get a bit closer
to Swedish building standards

00:15:02.452 --> 00:15:04.102
with a crappy house like this,

00:15:04.126 --> 00:15:07.572
you need to be putting
external insulation on the building,

00:15:07.596 --> 00:15:09.868
as shown by this block of flats in London.

00:15:11.252 --> 00:15:14.257
You can also deliver heat
more efficiently using heat pumps,

00:15:14.281 --> 00:15:17.751
which use a smaller bit
of high-grade energy like electricity

00:15:17.775 --> 00:15:20.340
to move heat from your garden
into your house.

00:15:21.276 --> 00:15:23.646
The third demand-side option
I want to talk about,

00:15:23.670 --> 00:15:26.816
the third way to reduce energy
consumption is: read your meters.

00:15:26.840 --> 00:15:28.669
People talk a lot about smart meters,

00:15:28.693 --> 00:15:30.040
but you can do it yourself.

00:15:30.064 --> 00:15:31.989
Use your own eyes and be smart.

00:15:32.013 --> 00:15:35.676
Read your meter, and if you're anything
like me, it'll change your life.

00:15:35.700 --> 00:15:37.132
Here's a graph I made.

00:15:37.156 --> 00:15:39.300
I was writing a book
about sustainable energy,

00:15:39.324 --> 00:15:40.478
and a friend asked me,

00:15:40.502 --> 00:15:42.316
"How much energy do you use at home?"

00:15:42.340 --> 00:15:44.360
I was embarrassed; I didn't actually know.

00:15:44.384 --> 00:15:46.585
And so I started reading
the meter every week.

00:15:46.609 --> 00:15:50.401
The old meter readings are shown
in the top half of the graph,

00:15:50.425 --> 00:15:52.650
and then 2007 is shown
in green at the bottom.

00:15:52.674 --> 00:15:54.996
That was when I was reading
the meter every week.

00:15:55.020 --> 00:15:56.186
And my life changed,

00:15:56.210 --> 00:15:59.565
because I started doing experiments
and seeing what made a difference.

00:15:59.589 --> 00:16:00.994
My gas consumption plummeted,

00:16:01.018 --> 00:16:03.237
because I started tinkering
with the thermostat

00:16:03.261 --> 00:16:05.060
and the timing on the heating system,

00:16:05.084 --> 00:16:07.297
and I knocked more than half
off my gas bills.

00:16:07.321 --> 00:16:10.204
There's a similar story
for my electricity consumption,

00:16:10.228 --> 00:16:13.790
where switching off the DVD
players, the stereos,

00:16:13.814 --> 00:16:16.608
the computer peripherals
that were on all the time,

00:16:16.632 --> 00:16:18.827
and just switching them on
when I needed them,

00:16:18.851 --> 00:16:21.476
knocked another third
off my electricity bills, too.

00:16:22.742 --> 00:16:24.508
So we need a plan that adds up.

00:16:24.532 --> 00:16:27.122
I've described for you six big levers.

00:16:27.146 --> 00:16:28.312
We need big action,

00:16:28.336 --> 00:16:31.098
because we get 90 percent
of our energy from fossil fuels,

00:16:31.122 --> 00:16:35.168
and so you need to push hard
on most, if not all, of these levers.

00:16:35.888 --> 00:16:38.174
Most of these levers
have popularity problems,

00:16:38.198 --> 00:16:41.864
and if there is a lever
you don't like the use of,

00:16:41.888 --> 00:16:45.705
well, please do bear in mind
that means you need even stronger effort

00:16:45.729 --> 00:16:47.610
on the other levers.

00:16:48.056 --> 00:16:51.207
So I'm a strong advocate
of having grown-up conversations

00:16:51.231 --> 00:16:53.492
that are based on numbers and facts.

00:16:53.516 --> 00:16:57.292
And I want to close with this map
that just visualizes for you

00:16:57.316 --> 00:17:00.853
the requirement of land and so forth

00:17:00.877 --> 00:17:03.941
in order to get just
16 lightbulbs per person

00:17:03.965 --> 00:17:06.653
from four of the big possible sources.

00:17:07.074 --> 00:17:10.233
So, if you wanted to get 16 lightbulbs --

00:17:10.258 --> 00:17:14.579
remember, today our total energy
consumption is 125 lightbulbs' worth --

00:17:14.603 --> 00:17:16.826
if you wanted 16 from wind,

00:17:16.849 --> 00:17:19.676
this map visualizes a solution for the UK.

00:17:19.701 --> 00:17:23.858
It's got 160 wind farms,
each 100 square kilometers in size,

00:17:23.882 --> 00:17:27.766
and that would be a twentyfold increase
over today's amount of wind.

00:17:27.790 --> 00:17:30.698
Nuclear power:
to get 16 lightbulbs per person,

00:17:30.722 --> 00:17:33.811
you'd need two gigawatts
at each of the purple dots on the map.

00:17:33.835 --> 00:17:38.018
That's a fourfold increase
over today's levels of nuclear power.

00:17:38.669 --> 00:17:41.367
Biomass: to get 16 lightbulbs per person,

00:17:41.391 --> 00:17:45.653
you'd need a land area something
like three and a half Wales' worth,

00:17:46.423 --> 00:17:49.005
either in our country,
or in someone else's country,

00:17:49.029 --> 00:17:51.072
possibly Ireland, possibly somewhere else.

00:17:51.096 --> 00:17:52.175
(Laughter)

00:17:52.199 --> 00:17:53.990
And a fourth supply-side option:

00:17:54.014 --> 00:17:56.731
concentrating solar power
in other people's deserts.

00:17:57.154 --> 00:17:59.593
If you wanted to get 16 lightbulbs' worth,

00:17:59.617 --> 00:18:02.632
then we're talking
about these eight hexagons

00:18:02.656 --> 00:18:03.967
down at the bottom right.

00:18:03.991 --> 00:18:08.216
The total area of those hexagons
is two Greater London's worth

00:18:08.240 --> 00:18:10.329
of someone else's Sahara,

00:18:10.353 --> 00:18:13.360
and you'll need power lines
all the way across Spain and France

00:18:13.384 --> 00:18:16.754
to bring the power
from the Sahara to Surrey.

00:18:17.195 --> 00:18:18.345
(Laughter)

00:18:18.369 --> 00:18:19.963
We need a plan that adds up.

00:18:20.895 --> 00:18:23.397
We need to stop shouting
and start talking.

00:18:24.809 --> 00:18:29.032
And if we can have
a grown-up conversation,

00:18:29.056 --> 00:18:31.517
make a plan that adds up and get building,

00:18:31.541 --> 00:18:34.545
maybe this low-carbon revolution
will actually be fun.

00:18:34.569 --> 00:18:36.307
Thank you very much for listening.

00:18:36.331 --> 00:18:38.837
(Applause)