0:00:23.693,0:00:26.191
When the Industrial Revolution started,

0:00:26.215,0:00:30.273
the amount of carbon sitting[br]underneath Britain in the form of coal

0:00:31.108,0:00:34.283
was as big as the amount of carbon[br]sitting under Saudi Arabia

0:00:34.307,0:00:35.645
in the form of oil.

0:00:36.631,0:00:39.166
This carbon powered[br]the Industrial Revolution,

0:00:39.190,0:00:40.905
it put the "Great" in Great Britain,

0:00:40.929,0:00:44.213
and led to Britain's temporary[br]world domination.

0:00:45.285,0:00:51.066
And then, in 1918,[br]coal production in Britain peaked,

0:00:51.230,0:00:52.997
and has declined ever since.

0:00:53.703,0:00:57.756
In due course, Britain started using[br]oil and gas from the North Sea,

0:00:57.780,0:00:59.691
and in the year 2000,

0:00:59.715,0:01:03.214
oil and gas production[br]from the North Sea also peaked,

0:01:03.238,0:01:05.384
and they're now on the decline.

0:01:06.836,0:01:09.499
These observations about the finiteness

0:01:09.523,0:01:13.390
of easily accessible, local,[br]secure fossil fuels,

0:01:14.127,0:01:17.077
is a motivation for saying,[br]"Well, what's next?

0:01:17.438,0:01:20.024
What is life after fossil fuels[br]going to be like?

0:01:20.048,0:01:23.514
Shouldn't we be thinking hard[br]about how to get off fossil fuels?"

0:01:23.538,0:01:26.502
Another motivation,[br]of course, is climate change.

0:01:27.014,0:01:29.515
And when people talk[br]about life after fossil fuels

0:01:29.539,0:01:31.410
and climate change action,

0:01:31.450,0:01:33.880
I think there's a lot of fluff,

0:01:33.904,0:01:36.768
a lot of greenwash,[br]a lot of misleading advertising,

0:01:36.792,0:01:41.281
and I feel a duty as a physicist to try[br]to guide people around the claptrap

0:01:41.305,0:01:45.079
and help people understand the actions[br]that really make a difference,

0:01:45.103,0:01:47.753
and to focus on ideas that do add up.

0:01:49.610,0:01:51.189
Let me illustrate this

0:01:51.213,0:01:54.396
with what physicists call[br]a back-of-envelope calculation.

0:01:54.828,0:01:56.673
We love back-of-envelope calculations.

0:01:56.697,0:01:58.768
You ask a question,[br]write down some numbers,

0:01:58.792,0:01:59.955
and get an answer.

0:01:59.979,0:02:03.179
It may not be very accurate,[br]but it may make you say, "Hmm."

0:02:03.203,0:02:04.625
So here's a question:

0:02:04.649,0:02:07.852
Imagine if we said, "Oh yes,[br]we can get off fossil fuels.

0:02:07.876,0:02:09.544
We'll use biofuels. Problem solved.

0:02:09.568,0:02:11.848
Transport ... We don't need oil anymore."

0:02:11.872,0:02:18.306
Well, what if we grew[br]the biofuels for a road

0:02:18.330,0:02:21.104
on the grass verge[br]at the edge of the road?

0:02:21.874,0:02:26.087
How wide would the verge[br]have to be for that to work out?

0:02:26.111,0:02:27.759
OK, so let's put in some numbers.

0:02:27.783,0:02:30.493
Let's have our cars go[br]at 60 miles per hour.

0:02:30.517,0:02:32.327
Let's say they do 30 miles per gallon.

0:02:32.351,0:02:35.186
That's the European average for new cars.

0:02:35.539,0:02:37.863
Let's say the productivity[br]of biofuel plantations

0:02:37.887,0:02:40.987
is 1,200 liters of biofuel[br]per hectare per year.

0:02:41.011,0:02:43.582
That's true of European biofuels.

0:02:43.951,0:02:47.491
And let's imagine the cars are spaced[br]80 meters apart from each other,

0:02:47.515,0:02:49.691
and they're perpetually[br]going along this road.

0:02:49.715,0:02:51.555
The length of the road doesn't matter,

0:02:51.579,0:02:54.310
because the longer the road,[br]the more biofuel plantation.

0:02:54.334,0:02:55.922
What do we do with these numbers?

0:02:55.946,0:02:59.975
Take the first number, divide by the other[br]three, and get eight kilometers.

0:02:59.999,0:03:01.155
And that's the answer.

0:03:01.179,0:03:03.539
That's how wide the plantation[br]would have to be,

0:03:03.563,0:03:05.414
given these assumptions.

0:03:05.896,0:03:08.629
And maybe that makes you say, "Hmm.

0:03:08.653,0:03:11.084
Maybe this isn't going[br]to be quite so easy."

0:03:12.830,0:03:14.984
And it might make you think,

0:03:15.462,0:03:17.867
perhaps there's an issue to do with areas.

0:03:17.891,0:03:21.788
And in this talk, I'd like to talk[br]about land areas, and ask:

0:03:21.812,0:03:23.295
Is there an issue about areas?

0:03:23.319,0:03:27.979
The answer is going to be yes,[br]but it depends which country you are in.

0:03:28.003,0:03:30.041
So let's start in the United Kingdom,

0:03:30.065,0:03:32.357
since that's where we are today.

0:03:32.381,0:03:34.726
The energy consumption[br]of the United Kingdom,

0:03:34.750,0:03:38.437
the total energy consumption --[br]not just transport, but everything --

0:03:39.158,0:03:40.964
I like to quantify it in lightbulbs.

0:03:40.988,0:03:44.470
It's as if we've all got[br]125 lightbulbs on all the time,

0:03:44.494,0:03:48.170
125 kilowatt-hours per day per person

0:03:48.194,0:03:50.884
is the energy consumption of the UK.

0:03:51.288,0:03:54.054
So there's 40 lightbulbs'[br]worth for transport,

0:03:54.078,0:03:55.730
40 lightbulbs' worth for heating,

0:03:55.754,0:03:58.282
and 40 lightbulbs' worth[br]for making electricity,

0:03:58.306,0:04:00.220
and other things are relatively small,

0:04:00.244,0:04:02.877
compared to those three big fish.

0:04:02.901,0:04:05.631
It's actually a bigger footprint[br]if we take into account

0:04:05.655,0:04:09.277
the embodied energy in the stuff[br]we import into our country as well.

0:04:09.301,0:04:14.035
And 90 percent of this energy, today,[br]still comes from fossil fuels,

0:04:14.059,0:04:17.737
and 10 percent, only, from other,[br]greener -- possibly greener -- sources,

0:04:17.761,0:04:19.733
like nuclear power and renewables.

0:04:20.833,0:04:22.118
So.

0:04:22.142,0:04:23.399
That's the UK.

0:04:23.423,0:04:28.644
The population density of the UK[br]is 250 people per square kilometer.

0:04:28.668,0:04:31.930
I'm now going to show you other countries[br]by these same two measures.

0:04:31.954,0:04:35.090
On the vertical axis, I'm going[br]to show you how many lightbulbs --

0:04:35.114,0:04:37.554
what our energy consumption per person is.

0:04:37.578,0:04:39.697
We're at 125 lightbulbs per person,

0:04:39.721,0:04:43.335
and that little blue dot there[br]is showing you the land area

0:04:43.359,0:04:45.049
of the United Kingdom.

0:04:45.073,0:04:47.862
The population density[br]is on the horizontal axis,

0:04:47.886,0:04:50.609
and we're 250 people per square kilometer.

0:04:50.633,0:04:53.202
Let's add European countries in blue,

0:04:53.226,0:04:55.727
and you can see there's quite a variety.

0:04:55.751,0:04:58.828
I should emphasize,[br]both of these axes are logarithmic;

0:04:58.852,0:05:01.407
as you go from one gray bar[br]to the next gray bar,

0:05:01.431,0:05:03.186
you're going up a factor of 10.

0:05:04.147,0:05:06.488
Next, let's add Asia in red,

0:05:06.512,0:05:08.998
the Middle East and North Africa in green,

0:05:10.013,0:05:12.406
sub-Saharan Africa in blue,

0:05:13.525,0:05:15.447
black is South America,

0:05:16.994,0:05:18.839
purple is Central America,

0:05:19.585,0:05:22.388
and then in pukey-yellow,[br]we have North America,

0:05:22.412,0:05:24.129
Australia and New Zealand.

0:05:25.050,0:05:27.950
You can see the great diversity[br]of population densities

0:05:27.974,0:05:30.561
and of per capita consumptions.

0:05:30.917,0:05:33.156
Countries are different from each other.

0:05:33.180,0:05:36.736
Top left, we have Canada and Australia,[br]with enormous land areas,

0:05:36.760,0:05:41.248
very high per capita consumption --[br]200 or 300 lightbulbs per person --

0:05:41.272,0:05:44.109
and very low population densities.

0:05:44.930,0:05:48.092
Top right: Bahrain has[br]the same energy consumption

0:05:48.116,0:05:50.099
per person, roughly, as Canada --

0:05:50.123,0:05:52.365
over 300 lightbulbs per person,

0:05:52.389,0:05:55.411
but their population density[br]is a factor of 300 times greater,

0:05:55.435,0:05:57.264
1,000 people per square kilometer.

0:05:57.288,0:06:02.165
Bottom right: Bangladesh has[br]the same population density as Bahrain,

0:06:02.189,0:06:05.040
but consumes 100 times less per person.

0:06:05.779,0:06:08.262
Bottom left: well, there's no one.

0:06:08.286,0:06:10.382
But there used to be[br]a whole load of people.

0:06:10.406,0:06:12.359
Here's another message from this diagram.

0:06:12.383,0:06:15.749
I've added on little blue tails[br]behind Sudan, Libya,

0:06:15.773,0:06:17.284
China, India, Bangladesh.

0:06:17.308,0:06:19.443
That's 15 years of progress.

0:06:19.467,0:06:21.988
Where were they 15 years ago,[br]and where are they now?

0:06:22.012,0:06:23.170
And the message is,

0:06:23.194,0:06:26.067
most countries are going to the right,[br]and they're going up.

0:06:26.091,0:06:28.238
Up and to the right:[br]bigger population density

0:06:28.262,0:06:30.202
and higher per capita consumption.

0:06:30.226,0:06:34.181
So, we may be off in the top[br]right-hand corner, slightly unusual,

0:06:34.205,0:06:36.592
the United Kingdom accompanied by Germany,

0:06:36.616,0:06:38.586
Japan, South Korea, the Netherlands,

0:06:38.610,0:06:40.975
and a bunch of other[br]slightly odd countries,

0:06:40.999,0:06:45.304
but many other countries are coming[br]up and to the right to join us.

0:06:45.328,0:06:47.371
So we're a picture, if you like,

0:06:47.395,0:06:49.370
of what the future energy consumption

0:06:49.394,0:06:52.166
might be looking[br]like in other countries, too.

0:06:53.573,0:06:56.492
I've also added in this diagram[br]now some pink lines

0:06:56.516,0:06:58.405
that go down and to the right.

0:06:58.429,0:07:02.270
Those are lines of equal[br]power consumption per unit area,

0:07:02.294,0:07:04.365
which I measure in watts per square meter.

0:07:04.389,0:07:08.236
So, for example, the middle line there,[br]0.1 watts per square meter,

0:07:08.260,0:07:12.112
is the energy consumption[br]per unit area of Saudi Arabia,

0:07:12.136,0:07:16.317
Norway, Mexico in purple,[br]and Bangladesh 15 years ago.

0:07:17.337,0:07:20.526
Half of the world's population[br]lives in countries

0:07:20.550,0:07:22.655
that are already above that line.

0:07:24.410,0:07:29.602
The United Kingdom is consuming[br]1.25 watts per square meter.

0:07:29.626,0:07:32.648
So is Germany, and Japan[br]is consuming a bit more.

0:07:33.958,0:07:37.888
So, let's now say why this is relevant.

0:07:37.912,0:07:39.299
Why is it relevant?

0:07:39.323,0:07:42.189
Well, we can measure[br]renewables in the same units

0:07:42.213,0:07:45.018
and other forms of power[br]production in the same units.

0:07:45.328,0:07:48.071
Renewables is one of the leading ideas

0:07:48.095,0:07:52.069
for how we could get off[br]our 90 percent fossil-fuel habit.

0:07:52.402,0:07:53.814
So here come some renewables.

0:07:53.838,0:07:56.498
Energy crops deliver[br]half a watt per square meter

0:07:56.522,0:07:57.879
in European climates.

0:07:59.309,0:08:00.460
What does that mean?

0:08:00.484,0:08:02.466
You might have anticipated that result,

0:08:02.490,0:08:05.678
given what I told you about the biofuel[br]plantation a moment ago.

0:08:05.702,0:08:08.698
Well, we consume 1.25 watts[br]per square meter.

0:08:08.722,0:08:09.879
What this means is,

0:08:09.903,0:08:13.290
even if you covered the whole[br]of the United Kingdom with energy crops,

0:08:13.314,0:08:16.122
you couldn't match[br]today's energy consumption.

0:08:17.236,0:08:21.070
Wind power produces a bit more --[br]2.5 watts per square meter.

0:08:21.094,0:08:25.107
But that's only twice as big[br]as 1.25 watts per square meter.

0:08:25.643,0:08:29.765
So that means if you wanted, literally,[br]to produce total energy consumption

0:08:29.789,0:08:32.020
in all forms, on average, from wind farms,

0:08:32.044,0:08:34.676
you need wind farms[br]half the area of the UK.

0:08:36.179,0:08:39.600
I've got data to back up[br]all these assertions, by the way.

0:08:40.243,0:08:42.152
Next, let's look at solar power.

0:08:42.719,0:08:44.737
Solar panels, when you put them on a roof,

0:08:44.761,0:08:49.076
deliver about 20 watts[br]per square meter in England.

0:08:50.500,0:08:52.882
If you really want to get[br]a lot from solar panels,

0:08:52.906,0:08:55.710
you need to adopt the traditional[br]Bavarian farming method,

0:08:55.734,0:08:57.085
where you leap off the roof,

0:08:57.109,0:08:59.613
and coat the countryside[br]with solar panels, too.

0:08:59.637,0:09:02.833
Solar parks, because of the gaps[br]between the panels, deliver less.

0:09:02.857,0:09:06.264
They deliver about 5 watts[br]per square meter of land area.

0:09:06.288,0:09:09.590
And here's a solar park[br]in Vermont, with real data,

0:09:09.614,0:09:12.138
delivering 4.2 watts per square meter.

0:09:12.661,0:09:15.568
Remember where we are,[br]1.25 watts per square meter,

0:09:15.592,0:09:18.643
wind farms 2.5, solar parks about five.

0:09:19.497,0:09:22.927
So whichever of those renewables you pick,

0:09:22.951,0:09:26.500
the message is, whatever mix[br]of those renewables you're using,

0:09:26.524,0:09:28.705
if you want to power the UK on them,

0:09:28.729,0:09:30.830
you're going to need[br]to cover something like

0:09:30.854,0:09:33.712
20 percent or 25 percent of the country

0:09:33.736,0:09:35.375
with those renewables.

0:09:35.750,0:09:39.262
I'm not saying that's a bad idea;[br]we just need to understand the numbers.

0:09:39.286,0:09:41.858
I'm absolutely not anti-renewables.[br]I love renewables.

0:09:41.882,0:09:43.518
But I'm also pro-arithmetic.

0:09:43.542,0:09:45.247
(Laughter)

0:09:45.271,0:09:49.403
Concentrating solar power in deserts[br]delivers larger powers per unit area,

0:09:49.427,0:09:51.778
because you don't have[br]the problem of clouds.

0:09:51.802,0:09:55.006
So, this facility delivers[br]14 watts per square meter;

0:09:55.030,0:09:56.741
this one 10 watts per square meter;

0:09:56.765,0:09:59.521
and this one in Spain,[br]5 watts per square meter.

0:09:59.545,0:10:01.719
Being generous[br]to concentrating solar power,

0:10:01.743,0:10:05.407
I think it's perfectly credible it could[br]deliver 20 watts per square meter.

0:10:05.431,0:10:06.597
So that's nice.

0:10:06.621,0:10:09.173
Of course, Britain[br]doesn't have any deserts.

0:10:09.555,0:10:10.711
Yet.

0:10:10.735,0:10:12.420
(Laughter)

0:10:12.444,0:10:14.809
So here's a summary so far:

0:10:15.635,0:10:18.259
All renewables, much[br]as I love them, are diffuse.

0:10:18.283,0:10:20.322
They all have a small power per unit area,

0:10:20.346,0:10:22.141
and we have to live with that fact.

0:10:22.871,0:10:28.163
And that means, if you do want renewables[br]to make a substantial difference

0:10:28.187,0:10:29.975
for a country like the United Kingdom

0:10:29.999,0:10:32.091
on the scale of today's consumption,

0:10:32.115,0:10:36.516
you need to be imagining renewable[br]facilities that are country-sized.

0:10:36.540,0:10:37.853
Not the entire country,

0:10:37.877,0:10:41.244
but a fraction of the country,[br]a substantial fraction.

0:10:42.284,0:10:44.831
There are other options[br]for generating power as well,

0:10:44.855,0:10:46.539
which don't involve fossil fuels.

0:10:46.563,0:10:49.718
So there's nuclear power,[br]and on this ordinance survey map,

0:10:49.742,0:10:53.481
you can see there's a Sizewell B[br]inside a blue square kilometer.

0:10:53.505,0:10:55.508
That's one gigawatt in a square kilometer,

0:10:55.532,0:10:57.957
which works out to 1,000 watts[br]per square meter.

0:10:57.981,0:11:00.117
So by this particular metric,

0:11:00.141,0:11:05.336
nuclear power isn't[br]as intrusive as renewables.

0:11:05.922,0:11:07.917
Of course, other metrics matter, too,

0:11:07.941,0:11:10.651
and nuclear power has[br]all sorts of popularity problems.

0:11:11.564,0:11:13.601
But the same goes for renewables as well.

0:11:13.625,0:11:16.453
Here's a photograph of a consultation[br]exercise in full swing

0:11:16.477,0:11:19.165
in the little town of Penicuik[br]just outside Edinburgh,

0:11:19.189,0:11:21.683
and you can see the children[br]of Penicuik celebrating

0:11:21.707,0:11:24.077
the burning of the effigy of the windmill.

0:11:24.101,0:11:25.260
So --

0:11:25.284,0:11:26.334
(Laughter)

0:11:26.358,0:11:27.687
People are anti-everything,

0:11:27.711,0:11:30.369
and we've got to keep[br]all the options on the table.

0:11:30.928,0:11:34.567
What can a country like the UK[br]do on the supply side?

0:11:34.591,0:11:37.510
Well, the options are,[br]I'd say, these three:

0:11:37.534,0:11:38.712
power renewables,

0:11:38.736,0:11:42.447
and recognizing that they need[br]to be close to country-sized;

0:11:42.471,0:11:43.717
other people's renewables,

0:11:43.741,0:11:45.868
so we could go back and talk very politely

0:11:45.892,0:11:48.929
to the people in the top left-hand side[br]of the diagram and say,

0:11:48.953,0:11:51.204
"Uh, we don't want[br]renewables in our backyard,

0:11:51.228,0:11:53.822
but, um, please could we put[br]them in yours instead?"

0:11:53.846,0:11:55.811
And that's a serious option.

0:11:55.835,0:11:59.419
It's a way for the world[br]to handle this issue.

0:11:59.443,0:12:03.575
So countries like Australia,[br]Russia, Libya, Kazakhstan,

0:12:03.599,0:12:06.599
could be our best friends[br]for renewable production.

0:12:07.956,0:12:09.992
And a third option is nuclear power.

0:12:10.016,0:12:12.232
So that's some supply-side options.

0:12:12.256,0:12:15.548
In addition to the supply levers[br]that we can push --

0:12:15.572,0:12:17.607
and remember, we need large amounts,

0:12:17.631,0:12:21.158
because at the moment, we get 90 percent[br]of our energy from fossil fuels --

0:12:21.182,0:12:22.542
in addition to those levers,

0:12:22.566,0:12:25.617
we could talk about other ways[br]of solving this issue.

0:12:25.641,0:12:29.037
Namely, we could reduce demand,[br]and that means reducing population --

0:12:29.061,0:12:30.876
I'm not sure how to do that --

0:12:30.900,0:12:33.712
or reducing per capita consumption.

0:12:33.736,0:12:36.199
So let's talk about three more big levers

0:12:36.223,0:12:38.549
that could really help[br]on the consumption side.

0:12:38.573,0:12:39.727
First, transport.

0:12:39.751,0:12:41.294
Here are the physics principles

0:12:41.318,0:12:44.368
that tell you how to reduce[br]the energy consumption of transport.

0:12:44.392,0:12:46.838
People often say,[br]"Technology can answer everything.

0:12:46.862,0:12:49.638
We can make vehicles[br]that are 100 times more efficient."

0:12:49.662,0:12:51.642
And that's almost true. Let me show you.

0:12:51.666,0:12:54.134
The energy consumption[br]of this typical tank here

0:12:54.158,0:12:57.582
is 80 kilowatt hours[br]per hundred person kilometers.

0:12:57.606,0:13:01.401
That's the average European car.

0:13:01.947,0:13:03.098
Eighty kilowatt hours.

0:13:03.122,0:13:05.210
Can we make something 100 times better

0:13:05.234,0:13:07.547
by applying the physics[br]principles I just listed?

0:13:07.571,0:13:09.214
Yes. Here it is. It's the bicycle.

0:13:09.238,0:13:11.884
It's 80 times better[br]in energy consumption,

0:13:11.908,0:13:14.132
and it's powered by biofuel, by Weetabix.

0:13:14.156,0:13:16.294
(Laughter)

0:13:16.318,0:13:18.185
And there are other options in between,

0:13:18.209,0:13:20.336
because maybe the lady[br]in the tank would say,

0:13:20.360,0:13:23.516
"No, that's a lifestyle change.[br]Don't change my lifestyle, please."

0:13:23.540,0:13:27.187
We could persuade her to take a train,[br]still a lot more efficient than a car,

0:13:27.211,0:13:28.986
but that might be a lifestyle change.

0:13:29.010,0:13:30.594
Or there's the EcoCAR, top-left.

0:13:30.618,0:13:34.353
It comfortably accommodates one teenager[br]and it's shorter than a traffic cone,

0:13:34.377,0:13:36.413
and it's almost as efficient as a bicycle,

0:13:36.437,0:13:39.477
as long as you drive it[br]at 15 miles per hour.

0:13:39.899,0:13:42.126
In between, perhaps[br]some more realistic options

0:13:42.150,0:13:45.115
on the transport lever[br]are electric vehicles,

0:13:45.139,0:13:47.518
so electric bikes[br]and electric cars in the middle,

0:13:47.542,0:13:52.568
perhaps four times as energy efficient[br]as the standard petrol-powered tank.

0:13:53.378,0:13:55.276
Next, there's the heating lever.

0:13:55.300,0:13:58.791
Heating is a third of our energy[br]consumption in Britain,

0:13:58.815,0:14:00.888
and quite a lot of that[br]is going into homes

0:14:00.912,0:14:02.295
and other buildings,

0:14:02.319,0:14:04.296
doing space heating and water heating.

0:14:04.320,0:14:06.604
So here's a typical crappy British house.

0:14:06.628,0:14:09.347
It's my house, with a Ferrari out front.

0:14:09.371,0:14:10.436
(Laughter)

0:14:10.460,0:14:11.613
What can we do to it?

0:14:11.637,0:14:15.298
Well, the laws of physics[br]are written up there,

0:14:15.322,0:14:20.570
which describe how the power[br]consumption for heating

0:14:20.594,0:14:22.502
is driven by the things you can control.

0:14:22.526,0:14:25.420
The things you can control[br]are the temperature difference

0:14:25.444,0:14:27.127
between the inside and the outside.

0:14:27.151,0:14:29.765
There's this remarkable technology[br]called a thermostat:

0:14:29.789,0:14:31.525
you grasp it, rotate it to the left,

0:14:31.549,0:14:34.078
and your energy consumption[br]in the home will decrease.

0:14:34.102,0:14:37.205
I've tried it. It works.[br]Some people call it a lifestyle change.

0:14:37.229,0:14:38.313
(Laughter)

0:14:38.337,0:14:41.817
You can also get the fluff men[br]in to reduce the leakiness

0:14:41.841,0:14:44.810
of your building -- put fluff[br]in the walls, fluff in the roof,

0:14:44.834,0:14:46.628
a new front door, and so forth.

0:14:48.052,0:14:50.637
The sad truth is,[br]this will save you money.

0:14:50.661,0:14:52.001
That's not sad, that's good.

0:14:52.025,0:14:53.203
But the sad truth is,

0:14:53.227,0:14:56.426
it'll only get about 25 percent[br]of the leakiness of your building

0:14:56.450,0:14:59.145
if you do these things,[br]which are good ideas.

0:14:59.169,0:15:02.428
If you really want to get a bit closer[br]to Swedish building standards

0:15:02.452,0:15:04.102
with a crappy house like this,

0:15:04.126,0:15:07.572
you need to be putting[br]external insulation on the building,

0:15:07.596,0:15:09.868
as shown by this block of flats in London.

0:15:11.252,0:15:14.257
You can also deliver heat[br]more efficiently using heat pumps,

0:15:14.281,0:15:17.751
which use a smaller bit[br]of high-grade energy like electricity

0:15:17.775,0:15:20.340
to move heat from your garden[br]into your house.

0:15:21.276,0:15:23.646
The third demand-side option[br]I want to talk about,

0:15:23.670,0:15:26.816
the third way to reduce energy[br]consumption is: read your meters.

0:15:26.840,0:15:28.669
People talk a lot about smart meters,

0:15:28.693,0:15:30.040
but you can do it yourself.

0:15:30.064,0:15:31.989
Use your own eyes and be smart.

0:15:32.013,0:15:35.676
Read your meter, and if you're anything[br]like me, it'll change your life.

0:15:35.700,0:15:37.132
Here's a graph I made.

0:15:37.156,0:15:39.300
I was writing a book[br]about sustainable energy,

0:15:39.324,0:15:40.478
and a friend asked me,

0:15:40.502,0:15:42.316
"How much energy do you use at home?"

0:15:42.340,0:15:44.360
I was embarrassed; I didn't actually know.

0:15:44.384,0:15:46.585
And so I started reading[br]the meter every week.

0:15:46.609,0:15:50.401
The old meter readings are shown[br]in the top half of the graph,

0:15:50.425,0:15:52.650
and then 2007 is shown[br]in green at the bottom.

0:15:52.674,0:15:54.996
That was when I was reading[br]the meter every week.

0:15:55.020,0:15:56.186
And my life changed,

0:15:56.210,0:15:59.565
because I started doing experiments[br]and seeing what made a difference.

0:15:59.589,0:16:00.994
My gas consumption plummeted,

0:16:01.018,0:16:03.237
because I started tinkering[br]with the thermostat

0:16:03.261,0:16:05.060
and the timing on the heating system,

0:16:05.084,0:16:07.297
and I knocked more than half[br]off my gas bills.

0:16:07.321,0:16:10.204
There's a similar story[br]for my electricity consumption,

0:16:10.228,0:16:13.790
where switching off the DVD[br]players, the stereos,

0:16:13.814,0:16:16.608
the computer peripherals[br]that were on all the time,

0:16:16.632,0:16:18.827
and just switching them on[br]when I needed them,

0:16:18.851,0:16:21.476
knocked another third[br]off my electricity bills, too.

0:16:22.742,0:16:24.508
So we need a plan that adds up.

0:16:24.532,0:16:27.122
I've described for you six big levers.

0:16:27.146,0:16:28.312
We need big action,

0:16:28.336,0:16:31.098
because we get 90 percent[br]of our energy from fossil fuels,

0:16:31.122,0:16:35.168
and so you need to push hard[br]on most, if not all, of these levers.

0:16:35.888,0:16:38.174
Most of these levers[br]have popularity problems,

0:16:38.198,0:16:41.864
and if there is a lever[br]you don't like the use of,

0:16:41.888,0:16:45.705
well, please do bear in mind[br]that means you need even stronger effort

0:16:45.729,0:16:47.610
on the other levers.

0:16:48.056,0:16:51.207
So I'm a strong advocate[br]of having grown-up conversations

0:16:51.231,0:16:53.492
that are based on numbers and facts.

0:16:53.516,0:16:57.292
And I want to close with this map[br]that just visualizes for you

0:16:57.316,0:17:00.853
the requirement of land and so forth

0:17:00.877,0:17:03.941
in order to get just[br]16 lightbulbs per person

0:17:03.965,0:17:06.653
from four of the big possible sources.

0:17:07.074,0:17:10.233
So, if you wanted to get 16 lightbulbs --

0:17:10.258,0:17:14.579
remember, today our total energy[br]consumption is 125 lightbulbs' worth --

0:17:14.603,0:17:16.826
if you wanted 16 from wind,

0:17:16.849,0:17:19.676
this map visualizes a solution for the UK.

0:17:19.701,0:17:23.858
It's got 160 wind farms,[br]each 100 square kilometers in size,

0:17:23.882,0:17:27.766
and that would be a twentyfold increase[br]over today's amount of wind.

0:17:27.790,0:17:30.698
Nuclear power:[br]to get 16 lightbulbs per person,

0:17:30.722,0:17:33.811
you'd need two gigawatts[br]at each of the purple dots on the map.

0:17:33.835,0:17:38.018
That's a fourfold increase[br]over today's levels of nuclear power.

0:17:38.669,0:17:41.367
Biomass: to get 16 lightbulbs per person,

0:17:41.391,0:17:45.653
you'd need a land area something[br]like three and a half Wales' worth,

0:17:46.423,0:17:49.005
either in our country,[br]or in someone else's country,

0:17:49.029,0:17:51.072
possibly Ireland, possibly somewhere else.

0:17:51.096,0:17:52.175
(Laughter)

0:17:52.199,0:17:53.990
And a fourth supply-side option:

0:17:54.014,0:17:56.731
concentrating solar power[br]in other people's deserts.

0:17:57.154,0:17:59.593
If you wanted to get 16 lightbulbs' worth,

0:17:59.617,0:18:02.632
then we're talking[br]about these eight hexagons

0:18:02.656,0:18:03.967
down at the bottom right.

0:18:03.991,0:18:08.216
The total area of those hexagons[br]is two Greater London's worth

0:18:08.240,0:18:10.329
of someone else's Sahara,

0:18:10.353,0:18:13.360
and you'll need power lines[br]all the way across Spain and France

0:18:13.384,0:18:16.754
to bring the power[br]from the Sahara to Surrey.

0:18:17.195,0:18:18.345
(Laughter)

0:18:18.369,0:18:19.963
We need a plan that adds up.

0:18:20.895,0:18:23.397
We need to stop shouting[br]and start talking.

0:18:24.809,0:18:29.032
And if we can have[br]a grown-up conversation,

0:18:29.056,0:18:31.517
make a plan that adds up and get building,

0:18:31.541,0:18:34.545
maybe this low-carbon revolution[br]will actually be fun.

0:18:34.569,0:18:36.307
Thank you very much for listening.

0:18:36.331,0:18:38.837
(Applause)