The slides for a talk I give on my next book. The Switch will be published by Profile Books in June '16.

1. 1

2. Central assumptions
Current position
2035
7-8 bn people
globally
Population Energy demand Total energy
per person demand
About 16
Terawatts (TW)
About 2 kW
9-10 bn people
globally
About 30
Terawatts (TW)
About 3 kW
2

3. Central assumption: rationale
• Energy demand broadly flat to declining in richest countries.
• China’s rate of increase clearly slowing
• Electrification of transport, heat will reduce total demand substantially
• Continuing increase in efficiency across processes, machines, appliances, lighting,
electronics,
5 kW
4 kW
1990 2014
UK primary energy demand per head
3

4. ‘Solar PV is too expensive ever to provide a significant
fraction of our energy needs’
Professor Sir Chris Llewellyn Smith FRS, director of Oxford energy research and former head of CERN
June 2013
4

5. ‘Solar PV is too expensive ever to provide a significant
fraction of our energy needs’
Professor Sir Chris Llewellyn Smith FRS, director of the Oxford energy programme and former head of CERN
June 2013
‘In years to come solar will be the dominant
backbone of our energy system’
Ben van Beurden, CEO Shell
September 2015
5

6. If the 7 percent decline in costs continues (and 2010 and
2011 both look likely to beat that number), then in 20 years
the cost per watt of PV cells will be just over 50 cents.
Ramez Naam (ex Microsoft) in Scientific American
March 2011
6

7. If the 7 percent decline in costs continues (and 2010 and
2011 both look likely to beat that number), then in 20 years
the cost per watt of PV cells will be just over 50 cents.
Ramez Naam (ex Microsoft) in Scientific American
March 2011
First Solar’s module costs are now 48 cents per watt
First Solar executive at EU PV Solar
Energy Conference (EU PVSEC)
September 2015
7

8. 0
50
100
150
200
250
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Accumulated global production of solar panels
Annual
production
growth rate
about 40%
over period
Gigawatts
(GW)
The reason for the fast cost reduction? The ‘experience curve’
8

9. The experience curve for solar PV modules
As accumulated
production volumes
double, the cost falls
by 20%
9

10. The experience curve in PV modules has been visible for decades
Dutch study published 2004
Source: Learning from the sun, G.J. Shaeffer et al. 2004
10
Experience
curve
slope of
20%

11. Will this process continue? Two mathematicians recently gave their
estimate, based on what has happened in many different industries
Source: How predictable is technological progress?, Farmer and Lafond, 2015, in press 11

12. Will the cost reductions continue? The crucial role of Perovskites
Source: Oxford PV 12

13. What happens if historic trends do continue?
2015 2020 2025
European full cost of 10 MW+ installation $1.25 Watt including whole system, not just module
Assumes: 20% experience curve
40% global PV growth a year
$1.25/w
76 cents/w
46 cents/w
13

14. What happens with less aggressive assumptions?
2015 2020 2025
European full cost of 10 MW+ installation $1.25 Watt including whole system, not just module
Assumes: 15% experience curve
30% global PV growth a year
$1.25/w
91 cents/w
70 cents/w
14

15. Capital cost reductions, combined with longer lives and lower
cost of capital, imply huge cuts in real cost of electricity
8.1
5.8
4.5
3.3
0
1
2
3
4
5
6
7
8
9
UK cost today Capital cost
reduction
Plus discount rate
reduction
Plus asset life
extension
£800 to
£550/kw
Change
6.0% to
2.5% real
20 to
35 years
Example: Southern England 2020
Grid Parity for UK
15

16. What might PV growth and experience curve mean for US electricity costs in 2020?
Using NREL Levelised Cost Calculator
40% Annual Growth 30% Annual Growth
20% Experience Curve 15% Experience Curve
Years of life 35 35
Discount
Rate 4.50% 4.50%
Capital cost $760 $910
Capacity
Factor 20% 20%
Fixed
O+M/kW $20 $20
Levelised Cost of
Energy 3.6cents/kWh 4.1cents/kWh
16

17. 230 GW
2015 4,300 GW 2025
152,000 GW 2035
What 40% annual growth in PV installations means for
installed global capacity
17

18. Possible total world energy demand and supply from PV
152,000 GW 2035
30 TW
Meets total global
energy need in 2035
20% capacity factor
18

19. This is an extremely aggressive target. Is it manageable?
1%
Percentage of world
land area required
Percentage of world
GDP invested in 2035
(peak year)*
4%
* Assumes 2% annual global product growth 2015-2035
Less than
current spend
on oil, gas, coal
19

20. 0
10
20
30
40
50
60
70
80
GW
Solar
Wind
Thermal and other
German electricity supply and demand: January 28th 2015
The only problem: the sun doesn’t always shine
20

21. 0
10
20
30
40
50
60
70
GW
Solar
Wind
Thermal and Other
German electricity supply and demand: August 21st 2015
And even on sunny days, PV will only generate for 12 hours or so
21

22. 0
20
40
60
80
100
120
German electricity demand and potential
supply if wind multiplied by 3 and solar by 8
January 28th 2015
Total electricity demand Wind (*3) and Solar (*8)
GW
22

23. 0
20
40
60
80
100
120
140
160
180
200
German electricity demand and potential
supply if wind multiplied by 3 and solar by 8
August 21st 2015
Total electricity demand Wind (*3) and Solar (*8)
GW
23

24. -140
-120
-100
-80
-60
-40
-20
0
20
40
60
Need for stored electricity during the two
days, Germany
Need for stored power (GWh) January 28th 2015
Need for stored power (GWh) August 21st 2015
GWh
January daily storage
need = 188 GWh
(about 15% daily total use)
August daily storage
need = 741 GWh
(about 60% daily total use)
Suggests total world need
for ‘storage’ capacity of at
least10 TW
24

25. California electricity supply
January 28sth 2015
25

26. California electricity supply
August 21st 2015
26

27. 0
100
200
300
400
500
600
Total daily need PV provided Wind provided
California electricity demand
January 28th 2015
GWh
30 times scale up needed
0
100
200
300
400
500
600
700
800
Total daily need PV provided Wind provided
California electricity demand
August 21st 2015
12 times scale up needed
27

28. Electricity is only part of the problem:
heat demand varies 10 fold across UK year
UK heat demand
Peak is 6
times
electricity
peak
28

29. Problem: However cheap it becomes, PV can never match demand
Potential solutions
Complementary
power sources
Short term storage,
eg electrons
Seasonal storage
29

30. Complementary potential power sources
90,000 TW
Direct solar radiation
Photosynthesis
products
Wind Wave Hydro
Sources of transmuted solar energy
870 TW 90 TW 7 TW 7 TW
Global
power
demand
2035
30 TW
30

31. Complementary potential power sources: wind
• Wind experience curve
slope driven by increasing
scale of turbines.
• Continuation likely at 9%
per doubling
• Future improvements may
come from radically lower
cost small turbines
31

32. • 3D Printed components
• Made from light sections of
aluminium
• Extremely low manufacturing costs
• Can be installed by farmer herself
• Levelised cost of energy – about 6
cents/kWH already, in windy
locations
Ultra-low cost wind turbines may be future – particularly for small
decentralised applications
Stealth wind energy company,UK
32

33. Complementary potential power sources: biomass
• At 90 TW, photosynthesis is second most important source of renewable energy as
complement to PV
• Photosynthesis produces biomass. Biomass may be fine as source of stored energy
– to be burnt, gasified, digested as needed – but has tended to divert food from
human consumption.
• Nevertheless, should be able to engineer system for using biomass that is neither
food, nor occupies land that could be used for food.
90 TW
1 TW
Energy converted into
biomass via photosynthesis
Global food need for
9-10 bn people 33

34. Complementary potential power sources: variable AD
• First AD plant in
the world
specifically
engineered to
deliver
complementary
power to PV
Prickly pear, a CAM plant that
grows well on semi-arid land
First commercial Anaerobic
Digestion(AD) plant in sub-Saharan Africa
Tropical Power Kenya
34

35. Growing drought tolerant crops on semi-arid land is possibly transformative
Semi-arid land area
= 3bn hectares
Use 1bn hectares
for CAM plants
Achieve 0.3 watts/m2
electricity production
(May double with fuel cells)
3 TW
35

36. Batteries are important, but energy storage capability is limited
Lithium required for
1 kWh storage
(At current cost of Li, about £4.50)
O.15 kg ( about 1/3lb)
World reserves of Lithium*
13.5 million tonnes
90 TWh storage capacity**
=
About 3-4 hours world
energy consumption 2035
Energy storage capacity of
world Lithium reserves
*As with other minerals, world ‘resources’ are possibly much larger
**About 120 times German electricity storage need on summer day (see Chart 24 ) 36

37. Short term storage
• Electron storage (‘batteries’) may work in some countries but not a
general solution
• Many other short term storage media also have severe capacity
limitations, particularly in higher latitude countries
• Electron storage may not fit with non-electricity energy requirements
(eg process heat, long distance heavy trucks)
90 TWh hour
battery capacity,
cycled daily
Equals average
energy flow of 3.75
TW
But world probably
needs at least 10 TW
37

38. Highest value Lithium battery applications are likely to be in homes and cars
Homes Cars
50 kWh**
10 kWh* Enough for 9bn homes,
3 times world maximum
in 2050
Enough for 1.8bn
cars, about likely
2050 level
Smart grid storage favours home use. Ultimate 2bn homes, still
allowing 50 kWh for 1.4bn cars
*Approximately average N. Europe overnight domestic winter use
**Approximately 200 mile range
38

39. Lithium Sulfur may become dominant Lithium type
battery, other than for consumer electronics*
* Volumetric density of Li S batteries less good than conventional Li ion.
Li ion Li Sulfur
2700 Wh/kg
500 Wh/kg
Theoretical maximum energy density
39

40. For larger-scale grid applications, Flow Batteries are likely to win out
• Currently more expensive than Li ion.
$350+/kW
• Getting cheaper, and clear benefits to
scaling battery size
• Indefinite number of cycles
• Very high reliability. No safety risks
• Work well at high temperatures
• Fully recyclable
• BUT, lower ratio of discharge rate to
energy stored
40 ft
40

41. Short term storage: good reason to believe that batteries are on steep
experience curve
41

42. CSP
Helios100
Crescent Dunes 110 MW with
integrated diurnal storage
First site in South Africa for Helios100,
with integrated diurnal storage
Short term storage: Concentrating Solar Power – small or large?
42

43. Short term storage: other potential large-scale technologies
• Sub $350/kWh (comparable to
flow batteries)
• Well-established components.
Limited technology risk
• Highly scalable
• Very long life/cycle numbers
• 60% AC/AC. More if heat
recovery
Liquid Air storage
Highview Power
43

44. In an interview Holliday said the energy industry
was undergoing a “tremendous transformation”
towards distributed generation, adding that
the traditional concept of large centralised
power plants generating baseload
power was “outdated”
Short term storage needs to adapt to trends in the generation of electricity
Steve Holliday, CEO National Grid, system operator for the UK and North East USA, Sept 2015
44

45. Long term storage: have to transmute electrons into liquids or gases.
Current Lithium ion Gasoline Methane
(natural gas)
15 kWh/kg
12 kWh/kg
0.15 kWh/kg
Almost 100
times energy
density of
today’s
batteries
45

46. Long term storage: Conversion of sunlight to carbon-based liquids
Schematic of a Joule Unlimited plant
Joule Unlimited
• Some industry experts
very sceptical of claims
• Joule claims
theoretical sun/carbon
fuel efficiency of 14%,
more than ten times
most plants
• Needs point source of
CO2
46

47. Long term storage: Power to gas
Schematic of Electrochaea electrolysis
and biological methanation plant
Electrochaea
• Now building first commercial
scale plant in Denmark
• Takes CO2/CH4 mix from
water treatment plant and
transmutes CO2 to CH4
• CH4 can then be put in gas
grid. (Germany has 200 days
storage in gas grid)
47

48. Long term storage: Artificial photosynthesis?
Peidong Yang’s research team at Berkeley/LBL
Artificial photosynthesis
• Many challenges
remain
• But will probably end
up as viable route to
carbon-based liquids
and gasses
48

49. 49