Green energy growth will eventually fade
ANDREW Blewett proclaims that “exponential rates of acceleration in clean energy growth…” will result in a fossil-free, 100% renewable future.
Exponential growth occurs when the rate of growth of a system, at any time, is proportional to the size of the system at that time. The rate at which it gets bigger actually increases as it grows. Unabated acceleration, quantified through a so-called “rate constant”.
The early stage of bacterial growth, for example, is often essentially exponential. 1 becomes 2, 2 become 4, 4 become 8, 8 become 16, …32…64…128, etc, sometimes very rapidly. Unchecked, such growth would soon fill the petri dish, then the lab, then the building, then…
Fortunately, it doesn’t persist, because the bacteria run out of nutrients and/or are poisoned by their own metabolic byproducts. Growth slows and eventually stops. Invariably, exponential growth is self-stifling and/or is decelerated by external factors. Real-world phenomena often manifest not exponential but so-called “logistic” growth. Initial acceleration (transiently exponential), then steady growth and, finally, deceleration to an unchanging value.
The global combined annual energy output from renewables, in TWh, has indeed grown roughly exponentially with time. But it can’t last. Remember, “exponential” is ever-accelerating. Ever more “green” energy requiring ever more, and bigger, panel and turbine farms. Real-life stifling influences are legion. Supply rate of rare elements. Fabrication rate of panels. Build rate of generators and rotors. Production rate of steel stanchions. Construction rate of concrete footings. Then there are transport and construction problems, grid connection complexities, intermittency issues and public dissent. None must impede acceleration.
Moreover, the rate constant for this miraculous green growth is not impressive. Despite growing exponentially for a few decades, combined global annual output from renewables now accounts only for about 13% of total global primary energy production. To compound matters, we stubbornly use more and more fossil fuel every year.
Bob Berrisford