How load a specific sheet from a Spreadsheet

You're almost there... what you want is to make that sheet 'active' so try this :

var sheet = SpreadsheetApp.getActiveSpreadsheet();
SpreadsheetApp.setActiveSheet(sheet.getSheetByName('Geração de Demanda'))

Hope all is well at your end,

You can also create a drop down list with all sheets names and run below script to automatically go to designated sheet.

function goto () {

var ss = SpreadsheetApp.getActiveSpreadsheet();
var nameRange = ss.getActiveSheet().getRange(2, 2);//the drop down is in B2 cell
var nameValue = nameRange.getValue();

ss.setActiveSheet(ss.getSheetByName(nameValue));

}

Hope that will help too

Have a good one