In OTL the main coal fields of Europe lies in a banana up along the Rhine over the North sea and in Northen England, farther up in the North Sea the oil fields lies, while Mecklenburg are home to deep and rich lignite fields and Denmark (mostly in central Jutland) to more shallow one. So what if in Mecklenburg and Jutland we see deep and rich coal-fields.
Why this is interesting are because these areas are perfect for a industrialisation, barely outside the rich fertile areas of East Jutland and Holstein, they can feed a large population. Of course the societal structure make the Mecklenburgian coal field unlikely to be developed before the 19th century. Denmark on the other hand suffered from a fuel stortage through the 18th century, which resulted in the development of a large peat industry, and the creation of a kind of triangle trade, where Denmark bought coal from UK, Norway cereal from Denmark and UK timber from Norway, through Denmark monopolising the sale of cereal to Norway to keep the balance of payment.
With large coal fields in Jutland Denmark can develop them, the Danish economy was excellent set up in the periode for the development, with a strong capitalist class (both noble and burgher), a developed financial system, a strong central power and a focus on internal development and long periode of de facto peace 1721-1801.
The interesting thing are the bieffects, the area of central Jutland, where this would happen are quite rainy, which would mean that pumps would be needed, in OTL Denmark first tried to steal the design from English stream engines in the 1790s (to use in the naval industry), but had to give up because the design was to advanced, and it had to be bought from UK. Here it happens decades earlier so the design are more primitive, so we see the Danes produce stream enginer themself earlier (could have a big effect on steamships later).
The area are also rather low populated with a poor soil excellent for potato growth, so with the increased population, maybe we see a faster introduction of potatoes.
Of course the creation of a large industrial territorium in the area are also going to be interesting, especially because it was the centre of the later Danish textile industry, and there already existed a large Danish pre-industrial textile production in the area.
Last we come to the economical aspect, with a fuel source the only non-luxury products Denmark buy outside are iron, and even that was produced to some degree in Norway (through not in large enough quantities), so we have richer Denmark through the 18th century, with a strong proto-industry. Which with the policies at the time would be invested in more mercantile projects (like colonies, kontor and factories around the world), industrial projects and in a large navy and army. The peace would likely go on. We may also see a earlier drop of the cereal monopol to Norway, helping the Norwegian town develop faster and universal education (attempted in 1739 or 41, but dropped thank to the lack of money).
All in all we see a richer more developed Denmark enter the 19th century.
Thoughts?