I just got the 22,000 energy tile and I am only at level 95. What I did was time the level-up to occur in the morning after running my high regeneration overnight (I got up early so it only got to 9,800 instead of 12,000).
To ensure that you will get the level-up, do all of at least one location except for one cheap tile. I actually set up 3: the Lumber Warehouse, one of the locations in the Viva Las Vegas event, and one of the locations in Scandinavia where I currently am. I put the game away needing only a couple of thousand experience points to get the level up. The level up gave me 11,000. As well, I created lots of food items in the cupboard and so I had 23,000+ to get the big tile.
Generally, I set up my game during the day to produce energy during the time I am away or busy. I will vary it from low of 1200 to a high of 5,000 or more. Like if we are going out for five hours, I adjust the amount being regenerated to be a little higher than the time I expect to be away. Overnight I aim to get 11,000 or 12,000 depending on when I get to bed.
In the evening when I can play a lot, I will set it up to "fully" generate at 1200 or 1800 as I can check in every half hour or 45 minutes and move something forward. In that way, I can restock the caravans and the kitchen, visit repeatable locations and move digging further along.
If you get low on coins, revisit Tutankamun's treasury. It is a cheap way to get a few coins, if you are really broke!
