flow units cannot have start costs
Either a feature or issue: Flow units cannot have start costs in 2.x or current master, because objective function sums over uft_online and ch units are not included to uft_online
// Start-up costs, initial startup free as units could have been online before model started
+ sum(uft_online(unit, f, t),
+ sum(unitStarttype(unit, starttype)${ts_startupCost_(unit, starttype, t) or p_startupCost_(unit, starttype, 'useConstant')},