TEDxWarwick
David MacKay: A reality check on renewables
Filmed:
Readability: 4.6
544,245 views
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.
David MacKay - Professor
As an information theorist and computer scientist, David MacKay uses hard math to assess our renewable energy options. Full bio
As an information theorist and computer scientist, David MacKay uses hard math to assess our renewable energy options. Full bio
Double-click the English transcript below to play the video.
00:16
When the Industrial Revolution started,
0
493
2304
00:18
the amount of carbon sitting underneath
1
2797
2048
00:20
Britain in the form of coal was as big as the amount
2
4845
3818
00:24
of carbon sitting under Saudi Arabia in the form of oil,
3
8663
4481
00:29
and this carbon powered the Industrial Revolution,
4
13144
2846
00:31
it put the "Great" in Great Britain,
5
15990
1574
00:33
and led to Britain's temporary world domination.
6
17564
4321
00:37
And then, in 1918, coal production in Britain peaked,
7
21885
4550
00:42
and has declined ever since.
8
26435
2060
00:44
In due course, Britain started using oil and gas
9
28495
2616
00:47
from the North Sea, and in the year 2000,
10
31111
3390
00:50
oil and gas production from the North Sea
11
34501
2360
00:52
also peaked, and they're now on the decline.
12
36861
5168
00:57
These observations about the finiteness of
13
42029
2711
01:00
easily accessible, local, secure fossil fuels,
14
44740
3715
01:04
this is a motivation for saying, "Well, what's next?
15
48455
3882
01:08
What is life after fossil fuels going to be like?
16
52337
2641
01:10
Shouldn't we be thinking hard about
17
54978
1762
01:12
how to get off fossil fuels?"
18
56740
1822
01:14
Another motivation, of course, is climate change.
19
58562
3904
01:18
And when people talk about life after fossil fuels
20
62466
2067
01:20
and climate change action, I think there's a lot of
21
64533
3396
01:23
fluff, a lot of greenwash, a lot of misleading advertising,
22
67929
4114
01:27
and I feel a duty as a physicist to try to
23
72043
2932
01:30
guide people around the claptrap and help people
24
74975
2220
01:33
understand the actions that really make a difference
25
77195
2641
01:35
and to focus on ideas that do add up.
26
79836
5245
01:40
Let me illustrate this with what physicists call
27
85081
2782
01:43
a back-of-envelope calculation.
28
87863
2406
01:46
We love back-of-envelope calculations.
29
90269
1363
01:47
You ask a question, you write down some numbers,
30
91632
1880
01:49
and you get yourself an answer.
31
93512
1403
01:50
It may not be very accurate, but it may make you say,
32
94915
2852
01:53
"Hmm."
33
97767
705
01:54
So here's a question: Imagine if
34
98472
2491
01:56
we said, "Oh yes, we can get off fossil fuels.
35
100963
2142
01:59
We'll use biofuels. Problem solved.
36
103105
1528
02:00
Transport, we don't need oil anymore."
37
104633
2415
02:02
Well, what if we grew the biofuels for a road
38
107048
6186
02:09
on the grass verge at the edge of the road?
39
113234
4040
02:13
How wide would the verge have to be for that to work out?
40
117274
4218
02:17
Okay, so let's put in some numbers.
41
121492
1570
02:18
Let's have our cars go at 60 miles per hour.
42
123062
2855
02:21
Let's say they do 30 miles per gallon.
43
125917
1607
02:23
That's the European average for new cars.
44
127524
2980
02:26
Let's say the productivity of biofuel plantations
45
130504
2568
02:28
is 1,200 litres of biofuel per hectare per year.
46
133072
3339
02:32
That's true of European biofuels.
47
136411
2511
02:34
And let's imagine the cars are spaced 80 meters
48
138922
2698
02:37
apart from each other, and they're just perpetually going
49
141620
2303
02:39
along this road.
50
143923
858
02:40
The length of the road doesn't matter, because the longer
51
144781
1910
02:42
the road, the more biofuel plantation we've got.
52
146691
2943
02:45
What do we do with these numbers?
53
149634
955
02:46
Well, you take the first number, and you divide by
54
150589
2140
02:48
the other three, and you get eight kilometers.
55
152729
2122
02:50
And that's the answer.
56
154851
1071
02:51
That's how wide the plantation would have to be,
57
155922
2697
02:54
given these assumptions.
58
158619
2219
02:56
And maybe that makes you say, "Hmm.
59
160838
2865
02:59
Maybe this isn't going to be quite so easy."
60
163703
4272
03:03
And it might make you think, perhaps there's an issue
61
167975
3511
03:07
to do with areas, and in this talk,
62
171486
2566
03:09
I'd like to talk about land areas, and ask,
63
174052
2546
03:12
is there an issue about areas? The answer is going to be
64
176598
3653
03:16
yes but it depends which country you are in.
65
180251
2795
03:18
So let's start in the United Kingdom,
66
183046
2070
03:21
since that's where we are today.
67
185116
2315
03:23
The energy consumption of the United Kingdom,
68
187431
2380
03:25
the total energy consumption, not just transport, but everything,
69
189811
4050
03:29
I like to quantify it in light bulbs.
70
193861
2073
03:31
It's as if we've all got 125 light bulbs on all the time,
71
195934
3960
03:35
125 kilowatt-hours per day per person
72
199894
3386
03:39
is the energy consumption of the U.K.
73
203280
3315
03:42
So there's 40 light bulbs' worth for transport,
74
206595
2553
03:45
40 light bulbs' worth for heating,
75
209148
1528
03:46
and 40 light bulbs' worth for making electricity,
76
210676
3029
03:49
and other things are relatively small
77
213705
1470
03:51
compared to those three big fish.
78
215175
3055
03:54
It's actually a bigger footprint if we take into account
79
218230
2555
03:56
the embodied energy in the stuff we import
80
220785
1932
03:58
into our country as well, and 90 percent of this energy today
81
222717
4571
04:03
still comes from fossil fuels, and 10 percent only
82
227288
3315
04:06
from other, greener -- possibly greener -- sources
83
230603
1924
04:08
like nuclear power and renewables.
84
232527
3204
04:11
So,
85
235731
1705
04:13
that's the U.K., and the population density of the U.K.
86
237436
3230
04:16
is 250 people per square kilometer,
87
240666
3278
04:19
and I'm now going to show you other countries
88
243944
1665
04:21
by these same two measures.
89
245609
1058
04:22
On the vertical axis, I'm going to show you
90
246667
2414
04:24
how much light bulbs -- what our energy consumption
91
249081
2524
04:27
per person is, and we're at 125 light bulbs per person,
92
251605
3185
04:30
and that little blue dot there is showing you the land area
93
254790
3302
04:33
of the United Kingdom,
94
258092
2080
04:36
and the population density is on the horizontal axis,
95
260172
2767
04:38
and we're 250 people per square kilometer.
96
262939
2665
04:41
Let's add European countries in blue,
97
265604
2654
04:44
and you can see there's quite a variety.
98
268258
2786
04:46
I should emphasize, both of these axes
99
271044
2147
04:49
are logarithmic. As you go from one gray bar
100
273191
2091
04:51
to the next gray bar you're going up a factor of 10.
101
275282
3783
04:54
Next, let's add Asia in red,
102
279065
2673
04:57
the Middle East and North Africa in green,
103
281738
3675
05:01
sub-Saharan Africa in blue,
104
285413
3188
05:04
black is South America,
105
288601
3244
05:07
purple is Central America,
106
291845
2912
05:10
and then in pukey-yellow, we have North America,
107
294757
3055
05:13
Australia and New Zealand.
108
297812
2568
05:16
And you can see the great diversity of population densities
109
300380
2604
05:18
and of per capita consumptions.
110
302984
3413
05:22
Countries are different from each other.
111
306397
2002
05:24
Top left, we have Canada and Australia, with enormous
112
308399
2585
05:26
land areas, very high per capita consumption,
113
310984
2743
05:29
200 or 300 light bulbs per person,
114
313727
2583
05:32
and very low population densities.
115
316310
3794
05:36
Top right, Bahrain has the same energy consumption
116
320104
2853
05:38
per person, roughly, as Canada,
117
322957
2248
05:41
over 300 light bulbs per person,
118
325205
2335
05:43
but their population density is a factor of 300 times greater,
119
327540
3172
05:46
1,000 people per square kilometer.
120
330712
1694
05:48
Bottom right, Bangladesh has the same population density
121
332406
3545
05:51
as Bahrain but consumes 100 times less per person.
122
335951
4810
05:56
Bottom left, well, there's no one.
123
340761
2925
05:59
But there used to be a whole load of people.
124
343686
2049
06:01
Here's another message from this diagram.
125
345735
1752
06:03
I've added on little blue tails behind Sudan, Libya,
126
347487
3686
06:07
China, India, Bangladesh.
127
351173
1303
06:08
That's 15 years of progress.
128
352476
2147
06:10
Where were they 15 years ago, and where are they now?
129
354623
2619
06:13
And the message is, most countries are going to the right,
130
357242
2812
06:15
and they're going up,
131
360054
782
06:16
up and to the right -- bigger population density
132
360836
2343
06:19
and higher per capita consumption.
133
363179
2317
06:21
So, we may be off in the top right-hand corner,
134
365496
2455
06:23
slightly unusual, the United Kingdom accompanied by
135
367951
2971
06:26
Germany, Japan, South Korea, the Netherlands,
136
370922
2782
06:29
and a bunch of other slightly odd countries,
137
373704
2215
06:31
but many other countries are coming up
138
375919
2568
06:34
and to the right to come and join us,
139
378487
1916
06:36
so we're a picture, if you like, of what the future energy
140
380403
3653
06:39
consumption might be looking like in other countries too.
141
384056
4259
06:44
And I've also added in this diagram now some pink lines
142
388315
3528
06:47
that go down and to the right.
143
391843
1986
06:49
Those are lines of equal power consumption
144
393829
2168
06:51
per unit area, which I measure in watts per square meter.
145
395997
3792
06:55
So, for example, the middle line there,
146
399789
1449
06:57
0.1 watts per square meter, is the energy consumption
147
401238
3360
07:00
per unit area of Saudi Arabia, Norway, Mexico in purple,
148
404598
4663
07:05
and Bangladesh 15 years ago,
149
409261
3607
07:08
and half of the world's population lives in countries
150
412868
2767
07:11
that are already above that line.
151
415635
3883
07:15
The United Kingdom is consuming 1.25
152
419518
3385
07:18
watts per square meter.
153
422903
1810
07:20
So's Germany, and Japan is consuming a bit more.
154
424713
4545
07:25
So, let's now
155
429258
2300
07:27
say why this is relevant. Why is it relevant?
156
431558
2736
07:30
Well, we can measure renewables in the same units
157
434294
3219
07:33
and other forms of power production in the same units,
158
437513
2829
07:36
and renewables is one of the leading ideas for
159
440342
2919
07:39
how we could get off our 90 percent fossil fuel habit.
160
443261
4417
07:43
So here come some renewables.
161
447678
1374
07:44
Energy crops deliver half a watt per square meter
162
449052
2760
07:47
in European climates.
163
451812
2446
07:50
What does that mean? And you might have anticipated
164
454258
2273
07:52
that result, given what I told you about the biofuel plantation
165
456531
2817
07:55
a moment ago.
166
459348
1417
07:56
Well, we consume 1.25 watts per square meter.
167
460765
3261
07:59
What this means is, even if you covered
168
464026
1321
08:01
the whole of the United Kingdom with energy crops,
169
465347
2832
08:04
you couldn't match today's energy consumption.
170
468179
4048
08:08
Wind power produces a bit more,
171
472227
1997
08:10
2.5 watts per square meter, but that's only twice as big
172
474224
3257
08:13
as 1.25 watts per square meter,
173
477481
3223
08:16
so that means if you wanted literally to produce total
174
480704
3470
08:20
energy consumption in all forms on average from
175
484174
2321
08:22
wind farms, you need wind farms half the area of the U.K.
176
486495
4910
08:27
I've got data to back up all these assertions, by the way.
177
491405
3767
08:31
Next, let's look at solar power.
178
495172
2496
08:33
Solar panels, when you put them on a roof,
179
497668
2493
08:36
deliver about 20 watts per square meter in England.
180
500161
5369
08:41
If you really want to get a lot from solar panels,
181
505530
2024
08:43
you need to adopt the traditional Bavarian farming method
182
507554
3006
08:46
where you leap off the roof and coat the countryside
183
510560
2688
08:49
with solar panels too.
184
513248
2056
08:51
Solar parks, because of the gaps between the panels,
185
515304
1896
08:53
deliver less. They deliver about 5 watts
186
517200
1961
08:55
per square meter of land area.
187
519161
2527
08:57
And here's a solar park in Vermont with real data
188
521688
2512
09:00
delivering 4.2 watts per square meter.
189
524200
3861
09:03
Remember where we are, 1.25 watts per square meter,
190
528061
2450
09:06
wind farms 2.5, solar parks about five.
191
530511
4386
09:10
So, whatever, whichever of those renewables you pick,
192
534897
3351
09:14
the message is, whatever mix of those renewables
193
538248
2577
09:16
you're using, if you want to power the U.K. on them,
194
540825
3015
09:19
you're going to need to cover something like
195
543840
2160
09:21
20 percent or 25 percent of the country
196
546000
2640
09:24
with those renewables.
197
548640
2223
09:26
And I'm not saying that's a bad idea.
198
550863
1596
09:28
We just need to understand the numbers.
199
552459
1276
09:29
I'm absolutely not anti-renewables. I love renewables.
200
553735
2726
09:32
But I'm also pro-arithmetic. (Laughter)
201
556461
4210
09:36
Concentrating solar power in deserts delivers
202
560671
2669
09:39
larger powers per unit area, because you don't have
203
563340
1806
09:41
the problem of clouds,
204
565146
1638
09:42
and so this facility delivers 14 watts per square meter,
205
566784
3289
09:45
this one 10 watts per square meter,
206
570073
2018
09:47
and this one in Spain 5 watts per square meter.
207
572091
2693
09:50
Being generous to concentrating solar power,
208
574784
2135
09:52
I think it's perfect credible it could deliver 20 watts
209
576919
2994
09:55
per square meter. So that's nice.
210
579913
1880
09:57
Of course, Britain doesn't have any deserts.
211
581793
3153
10:00
Yet. (Laughter)
212
584946
2629
10:03
So here's a summary so far.
213
587575
3326
10:06
All renewables, much as I love them, are diffuse.
214
590901
2718
10:09
They all have a small power per unit area,
215
593619
1900
10:11
and we have to live with that fact.
216
595519
2458
10:13
And that means, if you do want renewables
217
597977
3584
10:17
to make a substantial difference for a country like
218
601561
2517
10:19
the United Kingdom on the scale of today's consumption,
219
604078
3208
10:23
you need to be imagining renewable facilities
220
607286
2299
10:25
that are country-sized, not the entire country
221
609585
3245
10:28
but a fraction of the country, a substantial fraction.
222
612830
4334
10:33
There are other options for generating power as well
223
617164
2772
10:35
which don't involve fossil fuels.
224
619936
1839
10:37
So there's nuclear power, and on this Ordnance
225
621775
2808
10:40
Survey map, you can see there's a Sizewell B
226
624583
1895
10:42
inside a blue square kilometer.
227
626478
2130
10:44
That's one gigawatt in a square kilometer,
228
628608
2183
10:46
which works out to 1,000 watts per square meter.
229
630791
2448
10:49
So by this particular metric, nuclear power
230
633239
2761
10:51
isn't as intrusive as renewables.
231
636000
5193
10:57
Of course, other metrics matter too, and nuclear power
232
641193
2576
10:59
has all sorts of popularity problems.
233
643769
2510
11:02
But the same goes for renewables as well.
234
646279
2211
11:04
Here's a photograph of a consultation exercise in full swing
235
648490
2501
11:06
in the little town of Penicuik just outside Edinburgh,
236
650991
3253
11:10
and you can see the children of Penicuik celebrating
237
654244
2064
11:12
the burning of the effigy of the windmill.
238
656308
2736
11:14
So people are anti-everything, and we've got to keep
239
659044
4698
11:19
all the options on the table.
240
663742
2434
11:22
What can a country like the U.K. do on the supply side?
241
666176
3815
11:25
Well, the options are, I'd say, these three:
242
669991
2943
11:28
power renewables, and recognizing that they need to be
243
672934
2809
11:31
close to country-sized; other people's renewables,
244
675743
3164
11:34
so we could go back and talk very politely to the people
245
678907
2644
11:37
in the top left-hand side of the diagram and say,
246
681551
2223
11:39
"Uh, we don't want renewables in our backyard,
247
683774
2106
11:41
but, um, please could we put them in yours instead?"
248
685880
3259
11:45
And that's a serious option.
249
689139
1711
11:46
It's a way for the world to handle this issue.
250
690850
3529
11:50
So countries like Australia, Russia, Libya, Kazakhstan,
251
694379
4308
11:54
could be our best friends for renewable production.
252
698687
4669
11:59
And a third option is nuclear power.
253
703356
2060
12:01
So that's some supply side options.
254
705416
2240
12:03
In addition to the supply levers that we can push,
255
707656
3316
12:06
and remember, we need large amounts,
256
710972
2059
12:08
because at the moment,
257
713031
714
12:09
we get 90 percent of our energy from fossil fuels.
258
713745
2455
12:12
In addition to those levers, we could talk about other ways
259
716200
2824
12:14
of solving this issue, namely, we could reduce demand,
260
719024
3057
12:17
and that means reducing population
261
722081
2005
12:19
— I'm not sure how to do that —
262
724086
1759
12:21
or reducing per capita consumption.
263
725845
3291
12:25
So let's talk about three more big levers
264
729136
2487
12:27
that could really help on the consumption side.
265
731623
2350
12:29
First, transport. Here are the physics principles that tell you
266
733973
2341
12:32
how to reduce the energy consumption of transport,
267
736314
2989
12:35
and people often say, "Oh, yes, technology can answer everything.
268
739303
2328
12:37
We can make vehicles that are a hundred times more
269
741631
2000
12:39
efficient." And that's almost true. Let me show you.
270
743631
2769
12:42
The energy consumption of this typical tank here
271
746400
2728
12:45
is 80 kilowatt-hours per hundred person kilometers.
272
749128
3656
12:48
That's the average European car.
273
752784
4331
12:53
Eighty kilowatt-hours. Can we make something a hundred times
274
757115
2203
12:55
better by applying those physics principles I just listed?
275
759318
2763
12:57
Yes. Here it is. It's the bicycle. It's 80 times better in energy
276
762081
4680
13:02
consumption, and it's powered by biofuel, by Weetabix.
277
766761
3048
13:05
(Laughter)
278
769809
2031
13:07
And there are other options in between, because maybe
279
771840
2064
13:09
the lady in the tank would say, "No, no, no,
280
773904
1385
13:11
that's a lifestyle change. Don't change my lifestyle, please."
281
775289
2415
13:13
So, well, we could persuade her to get into a train,
282
777704
2816
13:16
and that's still a lot more efficient than a car,
283
780520
2048
13:18
but that might be a lifestyle change,
284
782568
1181
13:19
or there's the eco-car, top-left.
285
783749
1734
13:21
It comfortably accommodates one teenager
286
785483
1994
13:23
and it's shorter than a traffic cone,
287
787477
1609
13:24
and it's almost as efficient as a bicycle
288
789086
2026
13:27
as long as you drive it at 15 miles per hour.
289
791112
3494
13:30
In between, perhaps some more realistic options
290
794606
2290
13:32
on this lever, transport lever, are electric vehicles,
291
796896
2774
13:35
so electric bikes and electric cars in the middle,
292
799670
2958
13:38
perhaps four times as energy efficient
293
802628
2124
13:40
as the standard petrol-powered tank.
294
804752
3787
13:44
Next, there's the heating lever.
295
808539
2161
13:46
Heating is a third of our energy consumption in Britain,
296
810700
3416
13:50
and quite a lot of that is going into homes
297
814116
1863
13:51
and other buildings doing space heating and water heating.
298
815979
3401
13:55
So here's a typical crappy British house.
299
819380
2422
13:57
It's my house, with the Ferrari out front.
300
821802
4058
14:01
What can we do to it?
301
825860
1142
14:02
Well, the laws of physics are written up there,
302
827002
3025
14:05
which describe what -- how the power consumption
303
830027
5383
14:11
for heating is driven by the things you can control.
304
835410
2422
14:13
The things you can control are the temperature difference
305
837832
2578
14:16
between the inside and the outside, and there's this
306
840410
2024
14:18
remarkable technology called a thermostat.
307
842434
1968
14:20
You grasp it, you rotate it to the left,
308
844402
1918
14:22
and your energy consumption in the home will decrease.
309
846320
2329
14:24
I've tried it. It works. Some people call it a lifestyle change.
310
848649
4072
14:28
You can also get the fluff men in to reduce the leakiness
311
852721
4280
14:32
of your building -- put fluff in the walls, fluff in the roof,
312
857001
1920
14:34
and a new front door and so forth,
313
858921
3257
14:38
and the sad truth is, this will save you money.
314
862178
3361
14:41
That's not sad, that's good, but the sad truth is, it'll only
315
865539
2920
14:44
get about 25 percent of the leakiness of your building,
316
868459
3263
14:47
if you do these things, which are good ideas.
317
871722
2097
14:49
If you really want to get a bit closer to Swedish
318
873819
2845
14:52
building standards with a crappy house like this,
319
876664
2454
14:55
you need to be putting external insulation on the building
320
879118
3713
14:58
as shown by this block of flats in London.
321
882831
3821
15:02
You can also deliver heat more efficiently using heat pumps
322
886652
2953
15:05
which use a smaller bit of high grade energy like electricity
323
889605
3238
15:08
to move heat from your garden into your house.
324
892843
3383
15:12
The third demand side option I want to talk about,
325
896226
2488
15:14
the third way to reduce energy consumption is,
326
898714
1752
15:16
read your meters.
327
900466
1649
15:18
And people talk a lot about smart meters,
328
902115
1492
15:19
but you can do it yourself.
329
903607
972
15:20
Use your own eyes and be smart, read your meter,
330
904579
3550
15:24
and if you're anything like me, it'll change your life.
331
908129
2505
15:26
Here's a graph I made.
332
910634
1557
15:28
I was writing a book about sustainable energy,
333
912191
2534
15:30
and a friend asked me, "Well how much energy do you use
334
914725
2439
15:33
at home?" And I was embarrassed. I didn't actually know.
335
917164
2240
15:35
And so I started reading the meter every week,
336
919404
2151
15:37
and the old meter readings are shown
337
921555
2508
15:39
in the top half of the graph, and then 2007
338
924063
2146
15:42
is shown in green at the bottom, and that was when
339
926209
2216
15:44
I was reading the meter every week, and my life changed,
340
928425
2210
15:46
because I started doing experiments and seeing
341
930635
3064
15:49
what made a difference, and my gas consumption
342
933699
2080
15:51
plummeted because I started tinkering
343
935779
1137
15:52
with the thermostat and the timing on the heating system,
344
936916
2334
15:55
and I knocked more than a half off my gas bills.
345
939250
2300
15:57
There's a similar story for my electricity consumption,
346
941550
3391
16:00
where switching off the DVD players, the stereos,
347
944941
4060
16:04
the computer peripherals that were on all the time,
348
949001
2802
16:07
and just switching them on when I needed them,
349
951803
1824
16:09
knocked another third off my electricity bills too.
350
953627
4241
16:13
So we need a plan that adds up, and I've described for you
351
957868
2743
16:16
six big levers, and we need big action because we get
352
960611
2965
16:19
90 percent of our energy from fossil fuels,
353
963576
2650
16:22
and so you need to push hard on most if not all of these levers.
354
966226
4550
16:26
And most of these levers have popularity problems,
355
970776
2729
16:29
and if there is a lever you don't like the use of,
356
973505
3590
16:32
well please do bear in mind that means you need
357
977095
2131
16:35
even stronger effort on the other levers.
358
979226
3898
16:39
So I'm a strong advocate of having grown-up conversations
359
983124
3044
16:42
that are based on numbers and facts, and I want to close
360
986168
3561
16:45
with this map that just visualizes for you
361
989729
2709
16:48
the requirement of land and so forth in order to get
362
992438
4326
16:52
just 16 light bulbs per person
363
996764
1916
16:54
from four of the big possible sources.
364
998680
3591
16:58
So, if you wanted to get 16 light bulbs, remember,
365
1002271
3487
17:01
today our total energy consumption is 125 light bulbs' worth.
366
1005758
4033
17:05
If you wanted 16 from wind, this map visualizes a solution
367
1009791
4279
17:09
for the U.K. It's got 160 wind farms,
368
1014070
2209
17:12
each 100 square kilometers in size,
369
1016279
3003
17:15
and that would be a twentyfold increase
370
1019282
1442
17:16
over today's amount of wind.
371
1020724
2466
17:19
Nuclear power, to get 16 light bulbs per person, you'd need
372
1023190
2932
17:22
two gigawatts at each of the purple dots on the map.
373
1026122
2752
17:24
That's a fourfold increase
374
1028874
1710
17:26
over today's levels of nuclear power.
375
1030584
3192
17:29
Biomass, to get 16 light bulbs per person, you'd need
376
1033776
3135
17:32
a land area something like three and a half Wales' worth,
377
1036911
3785
17:36
either in our country, or in someone else's country,
378
1040696
3520
17:40
possibly Ireland, possibly somewhere else. (Laughter)
379
1044216
3031
17:43
And a fourth supply side option, concentrating solar power
380
1047247
3217
17:46
in other people's deserts,
381
1050464
1691
17:48
if you wanted to get 16 light bulbs' worth,
382
1052155
2442
17:50
then we're talking about these eight hexagons
383
1054597
3459
17:53
down at the bottom right.
384
1058056
926
17:54
The total area of those hexagons
385
1058982
2171
17:57
is two Greater London's worth of someone else's Sahara,
386
1061153
4600
18:01
and you'll need power lines all the way across Spain
387
1065753
1727
18:03
and France to bring the power from the Sahara to Surrey.
388
1067480
5570
18:08
We need a plan that adds up.
389
1073050
3245
18:12
We need to stop shouting and start talking,
390
1076295
3869
18:16
and if we can have a grown-up conversation,
391
1080164
3887
18:19
make a plan that adds up and get building,
392
1084051
2675
18:22
maybe this low-carbon revolution
393
1086726
1508
18:24
will actually be fun. Thank you very much for listening.
394
1088234
2338
18:26
(Applause)
395
1090572
3374
ABOUT THE SPEAKER
David MacKay - ProfessorAs an information theorist and computer scientist, David MacKay uses hard math to assess our renewable energy options.
Why you should listen
David MacKay is a professor of Natural Philosophy in the Physics department at the University of Cambridge and chief scientific adviser to the UK Department of Energy and Climate Change. He received a degree in Experimental and Theoretical Physics from Trinity College and a PhD. in Computation and Neural Systems as a Fulbright Scholar at Caltech. In 1992, MacKay was made the Royal Society Smithson Research Fellow at Darwin College at University of Cambridge and was elected a Fellow of the Royal Society in May 2009. He has also taught at the African Institute for Mathematical Sciences in Cape Town. In 2003, his book Information Theory, Inference, and Learning Algorithms was published and, in 2008, he self-published Sustainable Energy — Without the Hot Air. Both books are fully available for free online.
David MacKay | Speaker | TED.com