Let me first start off by saying I usually love these Homer-Lisa episodes as they can be very touching and shows an underused relationship between the two polar opposites in the family. That being said this isn't one of those good examples.
This episode begins with a rather pointless trailer for an extremely stupid movie idea (Quick someone call Uwe Boll!). When Homer then starts to unplug all the electronics. This is very uncharacteristic for him especially considering he unplugged the TV but it's offset with his trait of being very stingy with money. Lisa recommends that they look at alternative energy so they head off to an expo which apparently takes place at night instead of daytime. I guess the only reason for that was to include a very stupid joke that Homer keeps EVERY light on to detract burglars (which doesn't work). Homer then decides to purchase a wind turbine to power his house and decides that instead of lowering his electric bill by sending electricity back to the nuclear plant, he wants to be totally dependent on a windmill he just bought. After realizing that his windmill is one that only provides power when the wind blows instead of storing energy for future use he decides that his family will live intermittently *cue montage with bad music*. probably the only funny part in that is when Bart and Lisa start fighting each other with the Wii-motes, er i mean Zii-motes. So after a little pointless exchange between Homer and Flanders, Lisa gets Bart to move the windmill so that she can watch House. After Bart prays for wind, God sends gusts similar to that of a category 1 hurricane. With so much wind the house gets overpowered and defies all laws of science by having the TV emit radiation instead of just blowing out. After all the damage, Bart and Lisa go out to see the damage done. They arrive at a beach to find a beached whale. Lisa immediately goes for help by asking the worst people she could possibly ask (really this thing of Lisa losing her smarts about this situation really detracts me from this plot). So she goes to tell her parents which leads to a pointless belt joke and a deus ex machina of Marge reading about beached whales dying. The rest of this plot in act 2 is essentially:
Springfield crowd: Let's do something! *fails*
Springfield crowd: Let's do something! *fails*
Springfield crowd: Let's do something! *fails*
Lisa stays behind and then dreams about her father doing something she should have done at the beginning: Get professional help. she wakes up to find her whale dead. The next few minutes of the episode is Lisa being mopey while hearing things that can't be helping her psychologically. She finds the whale's calf's and then sees them being attacked by sharks which leads to the most annoying lines of dialogue in the episode. Homer comes with a boat as environmentalists explain that she should let nature do it's thing. We then have an unfunny slapstick routine that is saved by the Whale's *insert relationship here*. The episode is ended with the whales rejoicing and the family is happy again.
My final grade for this episode is 4.5 out of 10. While the idea is nice, there are too many head slap moments to make this a good episode. It is heartwarming but I have to disagree with others about this being the best episode this season, I still reserve that for "Brother where Bart Thou". If only the dialogue was better and characters being more than just plot devices, this would be better.