Yep, that's basically the whole task. To change the passage to become more 'upbeat', yet still share similar words to the previous words, the following could be changed to...
trudged= plodded
shuffled= staggered
scrutinised= questioned
sparse=meagre
closed in= confined
anxious= eager (Although eager and anxious generally do not share a similar definition, in this context they do as 'anxious' is used to describe being excited to do something, and share the same meaning of 'Very eager or concerned to do something or for something to happen'
Sentence 5 talks about looking for alternate energy sources but doesn't specifically mention solar energy so it is wrong. Sentence 10 says that solar energy is a "significant development" but it doesn't provide specific evidence so it is also not correct. Sentence 6 is the best answer - it shows that it is already being used and it has the potential to be used even more.
