John was kind enough to give me Power Grid: Power Plant Deck 2, so we spent some time playing around with the possibilities.
The first concept we played around with was "Green Power Grid" -- only renewable resources allowed, no Coal plants, no Oil plants. So we took all of the Wind, Garbage, Nuclear, and Fusion plants from both decks. We calculated that with 2 players, we could easily support building to 24 cities, so we used the Variant 3 table for the Step milestones. Finally we worked out a quick table for refreshing resources (Step 1: 5 trash, 2 uranium; Step 2: 6 trash, 3 uranium; Step 3: 7 trash, 4 uranium). The game started off slowly, and it felt like there were too many 1-2 city plants, and not enough 3-4 city plants, but that's not uncommon in a 2-player game. Things got more even as the game progressed, but at the end, I could power 24 cities and John could only power 23, giving me the game.
At this point we went out for dinner with friends.
For our second game, we decided to try Variant 2 (mix both decks). As the rules suggest, discarding the unused power plants is somewhat time consuming initially, but by turn 2 or 3 everything was running smoothly. I ended up with a slightly better mix of initial plants than John and I was able, over time, to turn that into a significant money lead (more than 100 elektro). Towards the end of the game I used that cash to intimidate John into letting me have the new 50 plant (2 uranium -> 8 cities) -- my opening bid was 150. That was almost my undoing, but it saved time. John bought himself a big hybrid plant and starved me out of coal for the turn, so instead of building I sat still for the turn (so that next turn he would be leading and I would get first pick of resources). At the end, we both connected and powered 21 cities, and I beat him by 3 elektro.
The new plants generally deliver more bang for the buck, either being cheaper to purchase, or cheaper to operate than their original counterparts. This results in more money available throughout the game. The top end plants can power 8 or 9 cities, allowing for games to reach to 20 or more cities. There are roughly the same numbers of each type of plant, but fewer plants that power 2-3 cities, and more plants that power 4-5 cities. This changes the dynamics of when to upgrade a power plant, and it will take some experimentation to find the best mix. With the original deck, a player could buy 2-3 early plants (power 1-3 cities), and then start buying end-game plants (power 5-7 cities) -- 4 city plants would have to be replaced too soon. With this deck you can survive having a couple of 4-city plants, if you can get an 8 or 9 plant at the end game.
All in all, I think the new power plant deck will result in more variation, and thus more reasons to play Power Grid.