Energy provider Scottish and Southern Energy (SSE) is on course to deliver expected dividend growth, despite operating in a challenging environment."The last few months have been marked by unusually low output of renewable energy and increases in wholesale gas prices. In this challenging environment, we have achieved solid progress across our main operations and investment projects, which means we remain on course to deliver our dividend growth target for the year of at least 2% more than inflation," Ian Marchant, chief executive of SSI, told shareholders.In the second quarter of 2010 the number of electricity and gas supply customer accounts in the energy markets in Great Britain and Ireland increased by 100,000 to 9.45m.With home services contracts included SSE's total customer base is now 9.87m, up from 9.5m a year ago.Gas-fired power stations achieved 97% of their maximum availability to generate electricity, excluding planned outages, while coal-fired stations achieved 90% in the second quarter.Output from wholly owned gas and coal-fired power stations rose to 5,450 gigawatts per hour (GWh), versus 5,085GWh in the second quarter of last year.Renewable energy output from conventional hydro electric schemes, wind farms and dedicated biomass plant was 700GWh, compared with 1,000GWh, reflecting weather conditions;Underlying consumption of electricity by SSE's household customers in Great Britain fell by 2.0%; underlying consumption of gas by SSE's household customers fell by 2.4%.