The Environmental Transition demands technological change, but people, planners, politicians etc. need to realise that change takes time.
Looking at data on how technologies have developed of in the past, we find that there is a general trend for this to be exponential. This can present a difficulty. People coming from a science/engineering background or from a finance/economics background (where it is familiar as compound interest) get it, but for most people it is not intuitive.
I suggest that we should adopt the term percent per year (% p yr) for discussion of rates of development, and promote the idea of a Guide Growth Rate of 0.41 % p yr a rate that is rarely exceeded, but there are a number of examples to show that it has been achieved.
0.41 % p yr = doubles every 2 years = 32 times in 10 years = a thousand times in 2 decades.
A period of 20 years seems to be significant. It is the life of a patent and is the sort of time it takes for developing an industrial, going from basic designs to a fully functional, well understood process with comprehensive service manuals.
Growth rate can be significant in three basic ways:
| Deployment, or build up of installed capacity. Key importance. | ||||
| % per year | Decades | |||
| Solar energy | 40 | 5 | ||
| Wind | 20 | 4 | ||
| Biofuel | 10 | 5 | ||
| Other renewables | 7 | 5 | ||
| Hydro | 2 | 5 | ||
| Nuclear | -1 | 2 | ||
| Increase in technical specification. | ||||
| Moore’s law | 41 | 5 | Number of gates on chip | |
| Haitz | 41 | 5 | Luminous efficiency of LEDs | |
| Cheapness (reciprocal of cost, so that we can talk of it as Growth). But see Guide Cost Decline | ||||
| Solar | 17 | 5 | ||
| Nuclear | -1 | 2 | ||
Conversion table
| Increment in two decades | Rate of Growth per year | |
| 1.00 | 0% | |
| 1.26 | 1.2% | |
| 1.58 | 2.3% | |
| 2.00 | 3.5% | |
| 2.51 | 4.7% | |
| 3.16 | 5.9% | |
| 3.98 | 7.2% | |
| 5.01 | 8.4% | |
| 6.31 | 10% | |
| 7.94 | 11% | |
| 10.0 | 12% | |
| 12.6 | 14% | |
| 15.8 | 15% | |
| 20.0 | 16% | |
| 25.1 | 17% | |
| 31.6 | 19% | |
| 39.8 | 20% | |
| 50.1 | 22% | |
| 63.1 | 23% | |
| 79.4 | 24% | |
| 100 | 26% | Guide Cost Decline |
| 126 | 27% | |
| 158 | 29% | |
| 200 | 30% | |
| 251 | 32% | |
| 316 | 33% | |
| 398 | 35% | |
| 501 | 36% | |
| 631 | 38% | |
| 794 | 40% | |
| 1000 | 41% | Guide Growth Rate |
| 1259 | 43% | |
| 1585 | 45% | |
| 1995 | 46% | |
| 2512 | 48% | |
| 3162 | 50% | |
| 3981 | 51% | |
| 5012 | 53% | |
| 6310 | 55% | |
| 7943 | 57% | |
| 10000 | 58% |
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