Keeping tech at 1890s levels without fossil fuels

Question

How can I explain the technological stagnation at a level roughly equivalent to the late 19th and early 20th centuries. The world is Earth-like and has the following characteristics:

• Absence of naturally-occuring fossil fuels (coal, oil, natural gas etc.). Energy in this world will come from biodiesels, biomass, and renewable electricity. (Nevermind how the society got to this tech level in the first place I understand it would have an enormous butterfly effect)
• Population is quite low (think early-modern period). Polities are centered around influential and independent city-states and their spheres of influence, with some larger polities as well.
• As mentioned, I want technology to broadly be stuck in 1880s-1900s tech. (Iron/steel ships, railroads, repeating rifles, electricity, radios, high explosives and some mechanization). However, that same period is defined by how rapidly technology was progressing as it was the height of the industrial revolution.

How might I justify the tech level for the setting so that many of the defining technology of the 20th century (sophisticated airplanes, large scale motorization, synthetic fertilizers, personal computing, mass communication) develops much slower or remains stagnant?

I'm thinking that a lack of cheap fuel, resource scarcity, some convenient geography, and the low population might be enough to hand-wave it away, but would those same factors also preclude maintaining the tech level in the first place?

Answer 1

Your lower population is key

Population is quite low (think early-modern period)

Before fossil fuels become common, the industrial era was fueled by charcoal. Charcoal is cheaper and easier to mass produce and refine than fossil fuels, but equally capable of smelting steel. The only reason we transitioned to fossil fuels is because of deforestation. Europe cut down most of its natural forests during the industrial revolution and was unable/unwilling to replace them; so, they pivoted instead to coal and petroleum. Not because it was a better fuel source, but because it was what they had left. However, a society with a smaller population could sustainably grow enough trees to maintain a cheap, carbon neutral charcoal industry. If charcoal remains sustainable, then the lobbyists who do try to push for fossil fuels will lose debates that were won in our reality out of necessity.

If charcoal remains king though, then many of the polymer discoveries that came from researching petroleum specifically may have never happened. Many of the plastics, dyes, and asphalt products that make modern tech look so discernably different than 1890's manufactured goods may have never been invented (or grossly delayed) because these come from the waste products of refining petroleum into gasoline which you don't get when processing charcoal.

Smaller populations could have also prevented the World Wars which spurred most of the technological advancements of the 20th century. If populations were smaller, then the scarcity that drove the nations of Europe and Asia into political turmoil could have been avoided. Without the wars, the sciences of aviation, radio communication, nuclear physics, and computation would have had far less interest and funding than they did in our timeline.

Also, smaller populations mean that you can't achieve the same economy of scale as our modern world; so, certain inventions like space flight, micro processing, personal automobiles, interstate highway systems, etc. may never have received the funding required to explore with the same degree of success as we've seen in our world which further serves to stunt your growth.

In short, it is not "lack of cheap fuel" and "resource scarcity" that keeps you in the industrial age, but rather, never being forced to invest in more expensive fuels and alternative materials that will keep people doing the same-old same-old for many more generations.