I've now run through this game at least 30 times, and have never gotten to the 20% goal. Throughout all of those attempts, the single most consistent ending I've gotten is the 'low popularity' ending.
In my opinion: It's near impossible to get the good ending.
Nearly everything that you'll do will inevitably reduce your popularity, and by significant amounts. In order to get to the 20% goal, you'll be forced by the goal itself to construct:
- 1 Large hydropower plant;
- 1 Wind power plant; AND
- 1 Small hydropower plant, OR 1 Wind power plant.
Solar panels are out of the question; The cost overruns for alternative materials are way too expensive, and ignoring the dilemma eats away at your popularity.
The main problem: The initial popularity given is too low, and the popularity costs for each dilemma is too high. Resolving either one of these problems will make the game significantly easier.
Post-comment edit: Attempted 5 more times, and got the victory(?) screen on the last attempt. Critique still stands though; The semi-randomization of outcomes within the game makes it less meaningful when you win and more infuriating when you lose, as it denotes that your strategy wasn't the thing that helped you to succeed, it was your luck instead.