North Dakota land area: 70,762 sq miles (183,272 km²)
Denmark crowds 131 people into a square kilometer, about 340 per square mile. Perhaps in a small, densely populated country with a nicer climate, they can get by with wind-up energy, But it won't work here.
Which is why, I suppose, Almighty God blessed us with Oil, Coal, and Natural Gas resources here to keep the frost off the walls. It seems like it would be a waste to not use it.