0:00:00.493,0:00:02.991
When the Industrial Revolution started,

0:00:03.015,0:00:07.073
the amount of carbon sitting[br]underneath Britain in the form of coal

0:00:07.908,0:00:11.083
was as big as the amount of carbon[br]sitting under Saudi Arabia

0:00:11.107,0:00:12.445
in the form of oil.

0:00:13.431,0:00:15.966
This carbon powered[br]the Industrial Revolution,

0:00:15.990,0:00:17.705
it put the "Great" in Great Britain,

0:00:17.729,0:00:21.013
and led to Britain's temporary[br]world domination.

0:00:22.085,0:00:26.506
And then, in 1918,[br]coal production in Britain peaked,

0:00:26.530,0:00:28.297
and has declined ever since.

0:00:29.003,0:00:33.056
In due course, Britain started using[br]oil and gas from the North Sea,

0:00:33.080,0:00:34.991
and in the year 2000,

0:00:35.015,0:00:38.514
oil and gas production[br]from the North Sea also peaked,

0:00:38.538,0:00:40.684
and they're now on the decline.

0:00:42.136,0:00:44.799
These observations about the finiteness

0:00:44.823,0:00:48.690
of easily accessible, local,[br]secure fossil fuels,

0:00:49.427,0:00:52.377
is a motivation for saying,[br]"Well, what's next?

0:00:52.738,0:00:55.324
What is life after fossil fuels[br]going to be like?

0:00:55.348,0:00:58.814
Shouldn't we be thinking hard[br]about how to get off fossil fuels?"

0:00:58.838,0:01:01.802
Another motivation,[br]of course, is climate change.

0:01:02.314,0:01:04.815
And when people talk[br]about life after fossil fuels

0:01:04.839,0:01:06.710
and climate change action,

0:01:06.850,0:01:09.280
I think there's a lot of fluff,

0:01:09.304,0:01:12.168
a lot of greenwash,[br]a lot of misleading advertising,

0:01:12.192,0:01:16.681
and I feel a duty as a physicist to try[br]to guide people around the claptrap

0:01:16.705,0:01:20.479
and help people understand the actions[br]that really make a difference,

0:01:20.503,0:01:23.153
and to focus on ideas that do add up.

0:01:25.010,0:01:26.589
Let me illustrate this

0:01:26.613,0:01:29.796
with what physicists call[br]a back-of-envelope calculation.

0:01:30.228,0:01:32.073
We love back-of-envelope calculations.

0:01:32.097,0:01:34.168
You ask a question,[br]write down some numbers,

0:01:34.192,0:01:35.355
and get an answer.

0:01:35.379,0:01:38.579
It may not be very accurate,[br]but it may make you say, "Hmm."

0:01:38.603,0:01:40.025
So here's a question:

0:01:40.049,0:01:43.252
Imagine if we said, "Oh yes,[br]we can get off fossil fuels.

0:01:43.276,0:01:44.944
We'll use biofuels. Problem solved.

0:01:44.968,0:01:47.248
Transport ... We don't need oil anymore."

0:01:47.272,0:01:53.706
Well, what if we grew[br]the biofuels for a road

0:01:53.730,0:01:56.504
on the grass verge[br]at the edge of the road?

0:01:57.274,0:02:01.487
How wide would the verge[br]have to be for that to work out?

0:02:01.511,0:02:03.159
OK, so let's put in some numbers.

0:02:03.183,0:02:05.893
Let's have our cars go[br]at 60 miles per hour.

0:02:05.917,0:02:07.727
Let's say they do 30 miles per gallon.

0:02:07.751,0:02:10.586
That's the European average for new cars.

0:02:10.939,0:02:13.263
Let's say the productivity[br]of biofuel plantations

0:02:13.287,0:02:16.387
is 1,200 liters of biofuel[br]per hectare per year.

0:02:16.411,0:02:18.982
That's true of European biofuels.

0:02:19.351,0:02:22.891
And let's imagine the cars are spaced[br]80 meters apart from each other,

0:02:22.915,0:02:25.091
and they're perpetually[br]going along this road.

0:02:25.115,0:02:26.955
The length of the road doesn't matter,

0:02:26.979,0:02:29.710
because the longer the road,[br]the more biofuel plantation.

0:02:29.734,0:02:31.322
What do we do with these numbers?

0:02:31.346,0:02:35.375
Take the first number, divide by the other[br]three, and get eight kilometers.

0:02:35.399,0:02:36.555
And that's the answer.

0:02:36.579,0:02:38.939
That's how wide the plantation[br]would have to be,

0:02:38.963,0:02:40.814
given these assumptions.

0:02:41.296,0:02:44.029
And maybe that makes you say, "Hmm.

0:02:44.053,0:02:46.484
Maybe this isn't going[br]to be quite so easy."

0:02:48.230,0:02:50.384
And it might make you think,

0:02:50.862,0:02:53.267
perhaps there's an issue to do with areas.

0:02:53.291,0:02:57.188
And in this talk, I'd like to talk[br]about land areas, and ask:

0:02:57.212,0:02:58.695
Is there an issue about areas?

0:02:58.719,0:03:03.379
The answer is going to be yes,[br]but it depends which country you are in.

0:03:03.403,0:03:05.441
So let's start in the United Kingdom,

0:03:05.465,0:03:07.757
since that's where we are today.

0:03:07.781,0:03:10.126
The energy consumption[br]of the United Kingdom,

0:03:10.150,0:03:13.837
the total energy consumption --[br]not just transport, but everything --

0:03:14.558,0:03:16.364
I like to quantify it in lightbulbs.

0:03:16.388,0:03:19.870
It's as if we've all got[br]125 lightbulbs on all the time,

0:03:19.894,0:03:23.570
125 kilowatt-hours per day per person

0:03:23.594,0:03:26.284
is the energy consumption of the UK.

0:03:26.688,0:03:29.454
So there's 40 lightbulbs'[br]worth for transport,

0:03:29.478,0:03:31.130
40 lightbulbs' worth for heating,

0:03:31.154,0:03:33.682
and 40 lightbulbs' worth[br]for making electricity,

0:03:33.706,0:03:35.620
and other things are relatively small,

0:03:35.644,0:03:38.277
compared to those three big fish.

0:03:38.301,0:03:41.031
It's actually a bigger footprint[br]if we take into account

0:03:41.055,0:03:44.677
the embodied energy in the stuff[br]we import into our country as well.

0:03:44.701,0:03:49.435
And 90 percent of this energy, today,[br]still comes from fossil fuels,

0:03:49.459,0:03:53.137
and 10 percent, only, from other,[br]greener -- possibly greener -- sources,

0:03:53.161,0:03:55.134
like nuclear power and renewables.

0:03:56.233,0:03:57.518
So.

0:03:57.542,0:03:58.799
That's the UK.

0:03:58.823,0:04:04.044
The population density of the UK[br]is 250 people per square kilometer.

0:04:04.068,0:04:07.330
I'm now going to show you other countries[br]by these same two measures.

0:04:07.354,0:04:10.490
On the vertical axis, I'm going[br]to show you how many lightbulbs --

0:04:10.514,0:04:12.954
what our energy consumption per person is.

0:04:12.978,0:04:15.097
We're at 125 lightbulbs per person,

0:04:15.121,0:04:18.735
and that little blue dot there[br]is showing you the land area

0:04:18.759,0:04:20.449
of the United Kingdom.

0:04:20.473,0:04:23.262
The population density[br]is on the horizontal axis,

0:04:23.286,0:04:26.009
and we're 250 people per square kilometer.

0:04:26.033,0:04:28.602
Let's add European countries in blue,

0:04:28.626,0:04:31.127
and you can see there's quite a variety.

0:04:31.151,0:04:34.228
I should emphasize,[br]both of these axes are logarithmic;

0:04:34.252,0:04:36.807
as you go from one gray bar[br]to the next gray bar,

0:04:36.831,0:04:38.586
you're going up a factor of 10.

0:04:39.547,0:04:41.888
Next, let's add Asia in red,

0:04:41.912,0:04:44.398
the Middle East and North Africa in green,

0:04:45.413,0:04:47.806
sub-Saharan Africa in blue,

0:04:48.925,0:04:50.847
black is South America,

0:04:52.394,0:04:54.239
purple is Central America,

0:04:54.985,0:04:57.788
and then in pukey-yellow,[br]we have North America,

0:04:57.812,0:04:59.529
Australia and New Zealand.

0:05:00.450,0:05:03.350
You can see the great diversity[br]of population densities

0:05:03.374,0:05:05.961
and of per capita consumptions.

0:05:06.317,0:05:08.556
Countries are different from each other.

0:05:08.580,0:05:12.136
Top left, we have Canada and Australia,[br]with enormous land areas,

0:05:12.160,0:05:16.648
very high per capita consumption --[br]200 or 300 lightbulbs per person --

0:05:16.672,0:05:19.509
and very low population densities.

0:05:20.330,0:05:23.492
Top right: Bahrain has[br]the same energy consumption

0:05:23.516,0:05:25.499
per person, roughly, as Canada --

0:05:25.523,0:05:27.765
over 300 lightbulbs per person,

0:05:27.789,0:05:30.811
but their population density[br]is a factor of 300 times greater,

0:05:30.835,0:05:32.664
1,000 people per square kilometer.

0:05:32.688,0:05:37.565
Bottom right: Bangladesh has[br]the same population density as Bahrain,

0:05:37.589,0:05:40.440
but consumes 100 times less per person.

0:05:41.179,0:05:43.662
Bottom left: well, there's no one.

0:05:43.686,0:05:45.782
But there used to be[br]a whole load of people.

0:05:45.806,0:05:47.759
Here's another message from this diagram.

0:05:47.783,0:05:51.149
I've added on little blue tails[br]behind Sudan, Libya,

0:05:51.173,0:05:52.684
China, India, Bangladesh.

0:05:52.708,0:05:54.843
That's 15 years of progress.

0:05:54.867,0:05:57.388
Where were they 15 years ago,[br]and where are they now?

0:05:57.412,0:05:58.570
And the message is,

0:05:58.594,0:06:01.467
most countries are going to the right,[br]and they're going up.

0:06:01.491,0:06:03.638
Up and to the right:[br]bigger population density

0:06:03.662,0:06:05.602
and higher per capita consumption.

0:06:05.626,0:06:09.581
So, we may be off in the top[br]right-hand corner, slightly unusual,

0:06:09.605,0:06:11.992
the United Kingdom accompanied by Germany,

0:06:12.016,0:06:13.986
Japan, South Korea, the Netherlands,

0:06:14.010,0:06:16.375
and a bunch of other[br]slightly odd countries,

0:06:16.399,0:06:20.704
but many other countries are coming[br]up and to the right to join us.

0:06:20.728,0:06:22.771
So we're a picture, if you like,

0:06:22.795,0:06:24.770
of what the future energy consumption

0:06:24.794,0:06:27.566
might be looking[br]like in other countries, too.

0:06:28.973,0:06:31.892
I've also added in this diagram[br]now some pink lines

0:06:31.916,0:06:33.805
that go down and to the right.

0:06:33.829,0:06:37.670
Those are lines of equal[br]power consumption per unit area,

0:06:37.694,0:06:39.765
which I measure in watts per square meter.

0:06:39.789,0:06:43.636
So, for example, the middle line there,[br]0.1 watts per square meter,

0:06:43.660,0:06:47.512
is the energy consumption[br]per unit area of Saudi Arabia,

0:06:47.536,0:06:51.717
Norway, Mexico in purple,[br]and Bangladesh 15 years ago.

0:06:52.637,0:06:55.826
Half of the world's population[br]lives in countries

0:06:55.850,0:06:57.955
that are already above that line.

0:06:59.710,0:07:04.902
The United Kingdom is consuming[br]1.25 watts per square meter.

0:07:04.926,0:07:07.948
So is Germany, and Japan[br]is consuming a bit more.

0:07:09.258,0:07:13.188
So, let's now say why this is relevant.

0:07:13.212,0:07:14.599
Why is it relevant?

0:07:14.623,0:07:17.489
Well, we can measure[br]renewables in the same units

0:07:17.513,0:07:20.318
and other forms of power[br]production in the same units.

0:07:20.728,0:07:23.471
Renewables is one of the leading ideas

0:07:23.495,0:07:27.469
for how we could get off[br]our 90 percent fossil-fuel habit.

0:07:27.802,0:07:29.214
So here come some renewables.

0:07:29.238,0:07:31.898
Energy crops deliver[br]half a watt per square meter

0:07:31.922,0:07:33.279
in European climates.

0:07:34.709,0:07:35.860
What does that mean?

0:07:35.884,0:07:37.866
You might have anticipated that result,

0:07:37.890,0:07:41.078
given what I told you about the biofuel[br]plantation a moment ago.

0:07:41.102,0:07:44.098
Well, we consume 1.25 watts[br]per square meter.

0:07:44.122,0:07:45.279
What this means is,

0:07:45.303,0:07:48.690
even if you covered the whole[br]of the United Kingdom with energy crops,

0:07:48.714,0:07:51.522
you couldn't match[br]today's energy consumption.

0:07:52.636,0:07:56.470
Wind power produces a bit more --[br]2.5 watts per square meter.

0:07:56.494,0:08:00.507
But that's only twice as big[br]as 1.25 watts per square meter.

0:08:01.043,0:08:05.165
So that means if you wanted, literally,[br]to produce total energy consumption

0:08:05.189,0:08:07.420
in all forms, on average, from wind farms,

0:08:07.444,0:08:10.076
you need wind farms[br]half the area of the UK.

0:08:11.579,0:08:15.000
I've got data to back up[br]all these assertions, by the way.

0:08:15.643,0:08:17.552
Next, let's look at solar power.

0:08:18.119,0:08:20.137
Solar panels, when you put them on a roof,

0:08:20.161,0:08:24.476
deliver about 20 watts[br]per square meter in England.

0:08:25.900,0:08:28.282
If you really want to get[br]a lot from solar panels,

0:08:28.306,0:08:31.110
you need to adopt the traditional[br]Bavarian farming method,

0:08:31.134,0:08:32.485
where you leap off the roof,

0:08:32.509,0:08:35.013
and coat the countryside[br]with solar panels, too.

0:08:35.037,0:08:38.233
Solar parks, because of the gaps[br]between the panels, deliver less.

0:08:38.257,0:08:41.664
They deliver about 5 watts[br]per square meter of land area.

0:08:41.688,0:08:44.990
And here's a solar park[br]in Vermont, with real data,

0:08:45.014,0:08:47.538
delivering 4.2 watts per square meter.

0:08:48.061,0:08:50.968
Remember where we are,[br]1.25 watts per square meter,

0:08:50.992,0:08:54.043
wind farms 2.5, solar parks about five.

0:08:54.897,0:08:58.327
So whichever of those renewables you pick,

0:08:58.351,0:09:01.900
the message is, whatever mix[br]of those renewables you're using,

0:09:01.924,0:09:04.105
if you want to power the UK on them,

0:09:04.129,0:09:06.230
you're going to need[br]to cover something like

0:09:06.254,0:09:09.112
20 percent or 25 percent of the country

0:09:09.136,0:09:10.775
with those renewables.

0:09:11.150,0:09:14.662
I'm not saying that's a bad idea;[br]we just need to understand the numbers.

0:09:14.686,0:09:17.258
I'm absolutely not anti-renewables.[br]I love renewables.

0:09:17.282,0:09:18.918
But I'm also pro-arithmetic.

0:09:18.942,0:09:20.647
(Laughter)

0:09:20.671,0:09:24.803
Concentrating solar power in deserts[br]delivers larger powers per unit area,

0:09:24.827,0:09:27.178
because you don't have[br]the problem of clouds.

0:09:27.202,0:09:30.406
So, this facility delivers[br]14 watts per square meter;

0:09:30.430,0:09:32.141
this one 10 watts per square meter;

0:09:32.165,0:09:34.921
and this one in Spain,[br]5 watts per square meter.

0:09:34.945,0:09:37.119
Being generous[br]to concentrating solar power,

0:09:37.143,0:09:40.807
I think it's perfectly credible it could[br]deliver 20 watts per square meter.

0:09:40.831,0:09:41.997
So that's nice.

0:09:42.021,0:09:44.573
Of course, Britain[br]doesn't have any deserts.

0:09:44.955,0:09:46.111
Yet.

0:09:46.135,0:09:47.820
(Laughter)

0:09:47.844,0:09:50.209
So here's a summary so far:

0:09:51.035,0:09:53.659
All renewables, much[br]as I love them, are diffuse.

0:09:53.683,0:09:55.722
They all have a small power per unit area,

0:09:55.746,0:09:57.541
and we have to live with that fact.

0:09:58.271,0:10:03.563
And that means, if you do want renewables[br]to make a substantial difference

0:10:03.587,0:10:05.375
for a country like the United Kingdom

0:10:05.399,0:10:07.491
on the scale of today's consumption,

0:10:07.515,0:10:11.916
you need to be imagining renewable[br]facilities that are country-sized.

0:10:11.940,0:10:13.253
Not the entire country,

0:10:13.277,0:10:16.644
but a fraction of the country,[br]a substantial fraction.

0:10:17.684,0:10:20.231
There are other options[br]for generating power as well,

0:10:20.255,0:10:21.939
which don't involve fossil fuels.

0:10:21.963,0:10:25.118
So there's nuclear power,[br]and on this ordinance survey map,

0:10:25.142,0:10:28.881
you can see there's a Sizewell B[br]inside a blue square kilometer.

0:10:28.905,0:10:30.908
That's one gigawatt in a square kilometer,

0:10:30.932,0:10:33.357
which works out to 1,000 watts[br]per square meter.

0:10:33.381,0:10:35.517
So by this particular metric,

0:10:35.541,0:10:40.736
nuclear power isn't[br]as intrusive as renewables.

0:10:41.322,0:10:43.317
Of course, other metrics matter, too,

0:10:43.341,0:10:46.051
and nuclear power has[br]all sorts of popularity problems.

0:10:46.964,0:10:49.001
But the same goes for renewables as well.

0:10:49.025,0:10:51.853
Here's a photograph of a consultation[br]exercise in full swing

0:10:51.877,0:10:54.565
in the little town of Penicuik[br]just outside Edinburgh,

0:10:54.589,0:10:57.083
and you can see the children[br]of Penicuik celebrating

0:10:57.107,0:10:59.477
the burning of the effigy of the windmill.

0:10:59.501,0:11:00.660
So --

0:11:00.684,0:11:01.734
(Laughter)

0:11:01.758,0:11:03.087
People are anti-everything,

0:11:03.111,0:11:05.769
and we've got to keep[br]all the options on the table.

0:11:06.328,0:11:09.967
What can a country like the UK[br]do on the supply side?

0:11:09.991,0:11:12.910
Well, the options are,[br]I'd say, these three:

0:11:12.934,0:11:14.112
power renewables,

0:11:14.136,0:11:17.847
and recognizing that they need[br]to be close to country-sized;

0:11:17.871,0:11:19.117
other people's renewables,

0:11:19.141,0:11:21.268
so we could go back and talk very politely

0:11:21.292,0:11:24.329
to the people in the top left-hand side[br]of the diagram and say,

0:11:24.353,0:11:26.604
"Uh, we don't want[br]renewables in our backyard,

0:11:26.628,0:11:29.222
but, um, please could we put[br]them in yours instead?"

0:11:29.246,0:11:31.211
And that's a serious option.

0:11:31.235,0:11:34.819
It's a way for the world[br]to handle this issue.

0:11:34.843,0:11:38.975
So countries like Australia,[br]Russia, Libya, Kazakhstan,

0:11:38.999,0:11:41.999
could be our best friends[br]for renewable production.

0:11:43.356,0:11:45.392
And a third option is nuclear power.

0:11:45.416,0:11:47.632
So that's some supply-side options.

0:11:47.656,0:11:50.948
In addition to the supply levers[br]that we can push --

0:11:50.972,0:11:53.007
and remember, we need large amounts,

0:11:53.031,0:11:56.558
because at the moment, we get 90 percent[br]of our energy from fossil fuels --

0:11:56.582,0:11:57.942
in addition to those levers,

0:11:57.966,0:12:01.017
we could talk about other ways[br]of solving this issue.

0:12:01.041,0:12:04.437
Namely, we could reduce demand,[br]and that means reducing population --

0:12:04.461,0:12:06.276
I'm not sure how to do that --

0:12:06.300,0:12:09.112
or reducing per capita consumption.

0:12:09.136,0:12:11.599
So let's talk about three more big levers

0:12:11.623,0:12:13.949
that could really help[br]on the consumption side.

0:12:13.973,0:12:15.127
First, transport.

0:12:15.151,0:12:16.694
Here are the physics principles

0:12:16.718,0:12:19.768
that tell you how to reduce[br]the energy consumption of transport.

0:12:19.792,0:12:22.238
People often say,[br]"Technology can answer everything.

0:12:22.262,0:12:25.038
We can make vehicles[br]that are 100 times more efficient."

0:12:25.062,0:12:27.042
And that's almost true. Let me show you.

0:12:27.066,0:12:29.534
The energy consumption[br]of this typical tank here

0:12:29.558,0:12:32.982
is 80 kilowatt hours[br]per hundred person kilometers.

0:12:33.006,0:12:36.801
That's the average European car.

0:12:37.347,0:12:38.498
Eighty kilowatt hours.

0:12:38.522,0:12:40.610
Can we make something 100 times better

0:12:40.634,0:12:42.947
by applying the physics[br]principles I just listed?

0:12:42.971,0:12:44.614
Yes. Here it is. It's the bicycle.

0:12:44.638,0:12:47.284
It's 80 times better[br]in energy consumption,

0:12:47.308,0:12:49.532
and it's powered by biofuel, by Weetabix.

0:12:49.556,0:12:51.694
(Laughter)

0:12:51.718,0:12:53.585
And there are other options in between,

0:12:53.609,0:12:55.736
because maybe the lady[br]in the tank would say,

0:12:55.760,0:12:58.916
"No, that's a lifestyle change.[br]Don't change my lifestyle, please."

0:12:58.940,0:13:02.587
We could persuade her to take a train,[br]still a lot more efficient than a car,

0:13:02.611,0:13:04.386
but that might be a lifestyle change.

0:13:04.410,0:13:05.994
Or there's the EcoCAR, top-left.

0:13:06.018,0:13:09.753
It comfortably accommodates one teenager[br]and it's shorter than a traffic cone,

0:13:09.777,0:13:11.813
and it's almost as efficient as a bicycle,

0:13:11.837,0:13:14.877
as long as you drive it[br]at 15 miles per hour.

0:13:15.299,0:13:17.526
In between, perhaps[br]some more realistic options

0:13:17.550,0:13:20.515
on the transport lever[br]are electric vehicles,

0:13:20.539,0:13:22.918
so electric bikes[br]and electric cars in the middle,

0:13:22.942,0:13:27.968
perhaps four times as energy efficient[br]as the standard petrol-powered tank.

0:13:28.778,0:13:30.676
Next, there's the heating lever.

0:13:30.700,0:13:34.191
Heating is a third of our energy[br]consumption in Britain,

0:13:34.215,0:13:36.288
and quite a lot of that[br]is going into homes

0:13:36.312,0:13:37.695
and other buildings,

0:13:37.719,0:13:39.696
doing space heating and water heating.

0:13:39.720,0:13:42.004
So here's a typical crappy British house.

0:13:42.028,0:13:44.747
It's my house, with a Ferrari out front.

0:13:44.771,0:13:45.836
(Laughter)

0:13:45.860,0:13:47.013
What can we do to it?

0:13:47.037,0:13:50.698
Well, the laws of physics[br]are written up there,

0:13:50.722,0:13:55.970
which describe how the power[br]consumption for heating

0:13:55.994,0:13:57.902
is driven by the things you can control.

0:13:57.926,0:14:00.820
The things you can control[br]are the temperature difference

0:14:00.844,0:14:02.527
between the inside and the outside.

0:14:02.551,0:14:05.165
There's this remarkable technology[br]called a thermostat:

0:14:05.189,0:14:06.925
you grasp it, rotate it to the left,

0:14:06.949,0:14:09.478
and your energy consumption[br]in the home will decrease.

0:14:09.502,0:14:12.605
I've tried it. It works.[br]Some people call it a lifestyle change.

0:14:12.629,0:14:13.713
(Laughter)

0:14:13.737,0:14:17.217
You can also get the fluff men[br]in to reduce the leakiness

0:14:17.241,0:14:20.210
of your building -- put fluff[br]in the walls, fluff in the roof,

0:14:20.234,0:14:22.028
a new front door, and so forth.

0:14:23.452,0:14:26.037
The sad truth is,[br]this will save you money.

0:14:26.061,0:14:27.401
That's not sad, that's good.

0:14:27.425,0:14:28.603
But the sad truth is,

0:14:28.627,0:14:31.826
it'll only get about 25 percent[br]of the leakiness of your building

0:14:31.850,0:14:34.545
if you do these things,[br]which are good ideas.

0:14:34.569,0:14:37.828
If you really want to get a bit closer[br]to Swedish building standards

0:14:37.852,0:14:39.502
with a crappy house like this,

0:14:39.526,0:14:42.972
you need to be putting[br]external insulation on the building,

0:14:42.996,0:14:45.268
as shown by this block of flats in London.

0:14:46.652,0:14:49.657
You can also deliver heat[br]more efficiently using heat pumps,

0:14:49.681,0:14:53.151
which use a smaller bit[br]of high-grade energy like electricity

0:14:53.175,0:14:55.740
to move heat from your garden[br]into your house.

0:14:56.676,0:14:59.046
The third demand-side option[br]I want to talk about,

0:14:59.070,0:15:02.216
the third way to reduce energy[br]consumption is: read your meters.

0:15:02.240,0:15:04.069
People talk a lot about smart meters,

0:15:04.093,0:15:05.440
but you can do it yourself.

0:15:05.464,0:15:07.389
Use your own eyes and be smart.

0:15:07.413,0:15:11.076
Read your meter, and if you're anything[br]like me, it'll change your life.

0:15:11.100,0:15:12.532
Here's a graph I made.

0:15:12.556,0:15:14.700
I was writing a book[br]about sustainable energy,

0:15:14.724,0:15:15.878
and a friend asked me,

0:15:15.902,0:15:17.716
"How much energy do you use at home?"

0:15:17.740,0:15:19.760
I was embarrassed; I didn't actually know.

0:15:19.784,0:15:21.985
And so I started reading[br]the meter every week.

0:15:22.009,0:15:25.801
The old meter readings are shown[br]in the top half of the graph,

0:15:25.825,0:15:28.050
and then 2007 is shown[br]in green at the bottom.

0:15:28.074,0:15:30.396
That was when I was reading[br]the meter every week.

0:15:30.420,0:15:31.586
And my life changed,

0:15:31.610,0:15:34.965
because I started doing experiments[br]and seeing what made a difference.

0:15:34.989,0:15:36.394
My gas consumption plummeted,

0:15:36.418,0:15:38.637
because I started tinkering[br]with the thermostat

0:15:38.661,0:15:40.460
and the timing on the heating system,

0:15:40.484,0:15:42.697
and I knocked more than half[br]off my gas bills.

0:15:42.721,0:15:45.604
There's a similar story[br]for my electricity consumption,

0:15:45.628,0:15:49.190
where switching off the DVD[br]players, the stereos,

0:15:49.214,0:15:52.008
the computer peripherals[br]that were on all the time,

0:15:52.032,0:15:54.227
and just switching them on[br]when I needed them,

0:15:54.251,0:15:56.876
knocked another third[br]off my electricity bills, too.

0:15:58.142,0:15:59.908
So we need a plan that adds up.

0:15:59.932,0:16:02.522
I've described for you six big levers.

0:16:02.546,0:16:03.712
We need big action,

0:16:03.736,0:16:06.498
because we get 90 percent[br]of our energy from fossil fuels,

0:16:06.522,0:16:10.568
and so you need to push hard[br]on most, if not all, of these levers.

0:16:11.288,0:16:13.574
Most of these levers[br]have popularity problems,

0:16:13.598,0:16:17.264
and if there is a lever[br]you don't like the use of,

0:16:17.288,0:16:21.105
well, please do bear in mind[br]that means you need even stronger effort

0:16:21.129,0:16:23.010
on the other levers.

0:16:23.456,0:16:26.607
So I'm a strong advocate[br]of having grown-up conversations

0:16:26.631,0:16:28.892
that are based on numbers and facts.

0:16:28.916,0:16:32.692
And I want to close with this map[br]that just visualizes for you

0:16:32.716,0:16:36.253
the requirement of land and so forth

0:16:36.277,0:16:39.341
in order to get just[br]16 lightbulbs per person

0:16:39.365,0:16:42.053
from four of the big possible sources.

0:16:42.474,0:16:45.634
So, if you wanted to get 16 lightbulbs --

0:16:45.658,0:16:49.979
remember, today our total energy[br]consumption is 125 lightbulbs' worth --

0:16:50.003,0:16:52.226
if you wanted 16 from wind,

0:16:52.250,0:16:55.077
this map visualizes a solution for the UK.

0:16:55.101,0:16:59.258
It's got 160 wind farms,[br]each 100 square kilometers in size,

0:16:59.282,0:17:03.166
and that would be a twentyfold increase[br]over today's amount of wind.

0:17:03.190,0:17:06.098
Nuclear power:[br]to get 16 lightbulbs per person,

0:17:06.122,0:17:09.211
you'd need two gigawatts[br]at each of the purple dots on the map.

0:17:09.235,0:17:13.418
That's a fourfold increase[br]over today's levels of nuclear power.

0:17:14.069,0:17:16.767
Biomass: to get 16 lightbulbs per person,

0:17:16.791,0:17:21.053
you'd need a land area something[br]like three and a half Wales' worth,

0:17:21.823,0:17:24.405
either in our country,[br]or in someone else's country,

0:17:24.429,0:17:26.472
possibly Ireland, possibly somewhere else.

0:17:26.496,0:17:27.575
(Laughter)

0:17:27.599,0:17:29.390
And a fourth supply-side option:

0:17:29.414,0:17:32.131
concentrating solar power[br]in other people's deserts.

0:17:32.554,0:17:34.993
If you wanted to get 16 lightbulbs' worth,

0:17:35.017,0:17:38.032
then we're talking[br]about these eight hexagons

0:17:38.056,0:17:39.367
down at the bottom right.

0:17:39.391,0:17:43.616
The total area of those hexagons[br]is two Greater London's worth

0:17:43.640,0:17:45.729
of someone else's Sahara,

0:17:45.753,0:17:48.760
and you'll need power lines[br]all the way across Spain and France

0:17:48.784,0:17:52.154
to bring the power[br]from the Sahara to Surrey.

0:17:52.595,0:17:53.745
(Laughter)

0:17:53.769,0:17:55.363
We need a plan that adds up.

0:17:56.295,0:17:58.797
We need to stop shouting[br]and start talking.

0:18:00.209,0:18:04.432
And if we can have[br]a grown-up conversation,

0:18:04.456,0:18:06.917
make a plan that adds up and get building,

0:18:06.941,0:18:09.945
maybe this low-carbon revolution[br]will actually be fun.

0:18:09.969,0:18:11.707
Thank you very much for listening.

0:18:11.731,0:18:14.237
(Applause)