In the past, cash dividends to the Government had not been substantial, but the listed companies would be under pressure to perform more efficiently so they could pay ''reasonable'' dividends, he said in an interview.
''The sales process is helping people understand these are commercial business facing risks of weather, electricity demand and changes in regulation. The returns are risky.
''In the past, critics of the sales process say these are businesses guaranteed to provide a high return. And they aren't.''
Selling 49% of the companies did not mean the Government was losing half of the dividend, Mr English said.
The Otago Daily Times analysed the rates of return of Meridian, Genesis and Mighty River Power, based on the reported, or net, profit for the year ended June 2012.
Usually, the newspaper uses operating earnings as a guide to profitability, but former widely respected and senior University of Otago accounting academics the late Emeritus Prof Tom Cowan and Boris Popoff used net profit as a guide in their book Analysis and Interpretation of Financial Statements used during study by this writer.
Using that guide, the rates of return from the three state-owned companies were not strong in 2012, with Meridian's return on assets less than 1%. In 2011, Genesis made a loss of $16.6 million.
In contrast, Contact Energy, a listed energy company that was sold off earlier, provides higher returns for its shareholders. As a comparison, Michael Hill International, a listed jewellery company, although much smaller, provides returns well above average.
Along with Mr English, Green Party co-leader Russel Norman and Labour Party finance spokesman David Parker were asked for their comments on the ODT figures, that were checked by the Treasury, and given the chance to add any other comments.
Mr Parker said power generators should be paid for the costs of production plus a fair rate of return on capital. The current rates of return were based on inflated valuations that were far more than the prices paid for their assets.
There had been an additional $10 billion of revaluations in the past 15 years that had increased shareholders' funds. ''Most companies in other industry sectors in recent years have not had the opportunity to dramatically increase the valuation of their company without a corresponding increase in investment.
''The companies which own old hydro stations, which they paid for years ago, have effectively capitalised value of the public water resource - the free fuel which is used to make electricity - into their balance sheets,'' Mr Parker said. Dr Norman responded with a brief email.
''The fact is that the electricity companies have made an average annual return of 16% since 2000.
''That massive profit comes at the cost of families and businesses who are paying too much for power. It's a stealth tax on the economy.
''The Green Party's NZ Power plan will make power cheaper so families can stay warm in winter and businesses can hire more people,'' Dr Norman said in the email.
Mr English said critics failed to note that returns to the government shareholder from the power companies had been flat in recent years.
''Opponents are using calculations including big one-off gains, ironically from the sales of assets.
''The time of growth for those companies reflected electricity prices rising 8% a year.''
The partially-owned companies were under pressure to provide better returns while electricity prices were not going up at 8% a year, he said.
If the electricity companies were returning 16% annually, that would be reflected in the share price of Mighty River Power. However, the market did not believe the company would provide anything like that return, Mr English said.
