EDITORIAL Pacific Gas and Electric Co. will get a huge political windfall if the San Francisco Controller's Office moves forward with a wildly inaccurate estimate of the cost of the Clean Energy Act.

In an Aug. 7 letter sent to the Department of Elections, Controller Ben Rosenfeld wrote that the costs to the city of acquiring PG&E's local distribution facilities are "likely to be in the billions of dollars." That's a scary figure, the sort of information PG&E will use to attack the measure. In fact, the company is already sending around flyers calling this a multibillion-dollar proposal.

But it's completely untrue.

For starters, the Clean Energy Act never mandates that the city buy PG&E's facilities. The charter amendment, which is on the November ballot, sets aggressive goals for renewable energy and directs city officials to study the best way to achieve those goals. Since public power agencies around the country are leading the way on renewables — and since PG&E has already said it can't meet even the state's weak clean energy mandates — the city ought to be looking at taking over the business of selling retail power to residents and businesses.

But that's just one flaw in the controller's reasoning. Because even if San Francisco did buy out PG&E, there would be little or no cost to the city at all.

To understand that, you have to look at the realities of how the measure would work. The Clean Energy Act would authorize the city to issue revenue bonds to buy electric power facilities. Revenue bonds aren't backed by the taxpayers; they are paid off entirely through a dedicated income stream. So unless the city can prove in advance with a detailed study that buying out PG&E would bring in enough money to cover the costs, there's no way Wall Street would ever buy the bonds.

In other words, there is no possible scenario under which the Clean Energy Act could cost the city money. The opposite is almost certainly true: public power cities all over the United States make money — often large amounts of money. And our figures have always shown that San Francisco would net millions, maybe hundreds of millions, in revenue from buying out PG&E.

We called Peg Stevenson in the Controller's Office to ask her about this, and she agreed with us: revenue bonds don't cost the city any money. Buying out PG&E with revenue bonds wouldn't cost the city any money. So why does the analysis say the measure could cost billions? "That's not how I expect people to read it," she said.

But that's exactly how people will read it. And it's grossly misleading.

PG&E is already on the attack, and costs will be a huge part of its campaign. In fact, in a July 24 letter to the controller, David Rubin, PG&E's director of service analysis, argues that the company's San Francisco system is worth $4.18 billion.

The letter states that PG&E "has not done an inventory of its system" — in other words, the figures Rubin cites are just estimates. And the method PG&E uses to calculate the fair market value of the property is economically and legally dubious, at best.

PG&E insists that the only way to establish a price for the city to pay for a takeover is a method known as "replacement cost new less depreciation." The idea: the city would have to pay the price ...