With one side permanently light, and the other always dark, a significant surface temperature differential would exist. Stirling cycle engines do work better and better with increasing temperature difference, however; They depend on a working fluid shuttling back and forth between the heat source and the heat sink, so.....hundreds of miles of plumbing? Tens of thousands of miles? (Seriously, I'm asking the room....What would the transition zone be like, between light and dark hemispheres? Sharp and distinct, or broad and fuzzy?) The shorter the "pipes", the closer together the heat source and the sink, but the smaller the temperature gradient, and vice-versa. Between the efficiency losses in the "plumbing", and the mechanical losses of turning thermal into mechanical work, this approach begins to look less attractive. Mostly achieving only simple redistribution of energy, with little converted to useful work.
Since you can't get something for nothing, and the energy already present on either planet is a fixed and finite amount, we might do well to look most closely at the small, steady dose of new energy input from the sun. My gut tells me this is always a solid objective, regardless of which planet we propose to inhabit. I can't speak to current techniques of direct conversion of solar energy to power, but optimizing efficiency there should always appeals, wherever you live.
(Grossly oversimplified, ignoring much), whether rotating or not, the same amount of solar radiation reaches the planet in any given period of time. It's certainly hotter on the bright side, and the bright side's "day in the sun" never ends, but the planet as a whole is still receiving the same amount of solar energy at any given moment. But by all means, lets capture some of that incoming energy, turn it into electricity, with the contemporary technology. Now we have a bunch of panels in one region working 24 hours a day (to stick with the old, now invalid model of "time"), and half the planet permanently in darkness. On balance, system wide, I'm seeing only a lateral trade from the present situation of 50% duty cycle over 100% of the planet, to 100% duty cycle over 50% of the surface. At the end of the exercise, regardless of which of the two planets we inhabit, the problem may always come down to total power demand per unit time, vs. available energy supply. In the big picture, the amount of new energy arriving at the planet to be harnessed is still relatively small, per unit time. And never forget or underestimate the significance of the "time" component when calculating horsepower. Two of the principle disadvantages of direct solar have always been overall energy density, and the "on demand" problem. How much, how often, and when can you have it?
At the end of the day, nearly all of the power sources we are familiar and comfortable with have been in service for millennia, because they are cheap and easy; But few of these sources are much more than solar energy dressed up in new clothes; Solar radiation stored in some vast but finite reservoir over considerable time. Another redistribution of energy already here, from one location or form to another.
A 'Fractured Fairy Tales" version of some of the old solar energy models, with their understandable, inherent inefficiencies.
Sun heats water, water travels magically against gravity to new location, we stick something in the water, and harness some of the sun's energy as the water returns downhill.
Sun warms air, air moves around, we stick something in the air and again harness some of the sun's energy.
Sun shines on plants, plants rearrange elements into higher energy configurations, one atom at a time. We eat the plants, reverse the chemical reactions, and lift rocks all day, making pointy piles. mostly to worship the sun in the first place, grateful for all it's blessings....We have always known.
Sun shines on plants, plants rearrange elements into higher energy configurations, one atom at a time. Donkey eats plants, reverses some of those chemical reactions. We tie a rope around the donkey, and the donkey delivers some of the sun's power for us. Much better for us, in the short term!
Sun shines on plants, donkey eats plants, both donkey and plants rearrange elements in nifty ways, then drop dead.....Terrible in the short term, but repeat for millions and millions of years, and now we're getting somewhere, cookin' with gas!
Fossil fuels of all kinds have been the gold standard for much of human existence for very simple reasons, which bypass the inherent limitations of any direct conversion of solar energy. By "banking" tiny amounts of solar energy over decades, or even millions and millions of years, converting it into chemical energy, you wind up with substances which have truly remarkable energy density, are highly portable, and available whenever and wherever the consumer requires it.
The "inconvenient truth" of it becomes quickly apparent, however, once the observer resists selfish, (but natural) human tendencies, and looks farther ahead than the immediate needs and desires of the moment. The very, very rapid draw-down of any bank account or reservoir, solely fed by slow steady input, is acceptable in the short term, but never sustainable. The very, very rapid return of chemicals into a system which otherwise adjusts and balances over millennia, is unsustainable. The familiar and comfortable practices we have been engaged in for thousands of years are still generally sustainable, but evidence clearly indicates that the exponential growth of those patterns of behavior in recent years is not. Nor would they be on another imagined planet.
