To get Pulau Ubin from the mainland, you have to catch a train to Pasir Ris and then catch a bus towards the jetty at Changi Township. From there you need to catch a bumboat to kauai. The bumboats sit 12 people and pet owners will anticipate that haven't got the time until they leave. The boat fare is $2.50. On a weekend the boats will fill up in a lack of time. You might have to wait a bit more time on a weekday, about the other hand. The crossing itself takes about half an hour.
Portable generators are cheaper for essentially the most part when home standby systems and 50kw Diesel generator also need specialized help installing them. They run on various kinds of fuel but smaller sized models obtain their fuel from being a tank, which limits the gap of time they could be run, usually 10 hours or much less. There are some models (expensive) that can be hooked into a third party fuel source though.