Costs and politics to decide the future for Kers
The teams had agreed to abandon the systems at the end of this year but a new twist behind the scenes has raised the possibility they may yet survive - and in the process fuelled some bad blood within the sport.
Kers systems store energy that would have been lost during braking and reapply it under acceleration, and are similar to those that are becoming increasingly prevalent in road cars - Toyota, Honda and BMW are among the manufacturers already using them to reduce fuel consumption in their models.
The systems were introduced into F1 by Max Mosley, president of governing body the FIA, partly for the entertainment value and partly to help Formula 1 fend off any attacks that it was a profligate waste of fossil fuel, as well as setting a bad example, at a time when oil supplies are running out and global warming is at the top of the political agenda.
But they have been heavily criticised within F1 because of their vast cost - some teams are said to have spent as much as £45m on the systems - and they have proved difficult to implement. Only McLaren-Mercedes, whose system is widely recognised as the best, and Ferrari are still using them.
The eight teams in the Formula 1 Teams' Association - McLaren, Ferrari, Renault, Toyota, Brawn, Red Bull, Toro Rosso and BMW - agreed unanimously to abandon Kers for 2010 on the grounds of saving money.
But Kers is still allowed in the 2010 technical regulations as they currently stand and, to get it removed, there is a complicated system of checks and balances. First, it needs to pass the Technical Working Group (TWG), the body that basically agrees the detail of the rules.
Then it needs to be approved by the F1 Commission, a group of representatives of F1's stakeholders, after which it is rubber-stamped by the FIA World Council, the sport's legislative and executive body.
There was a TWG meeting here in Valencia on Wednesday, the first one that has been attended by all next year's prospective 13 teams - the Fota members, current teams Williams and Force India, and new entrants Manor, US F1 and Campos.
But when it came to the vote on Kers not all the hands went up. You might expect the one not to agree would have been McLaren - they, after all, are the ones who appear to have most to gain. But instead it was Williams, who have their own system under development, although they are not close to being able to race it yet. (Force India abstained, for the record).
This move by Williams, whose technical director Sam Michael was the man in the meeting, did not go down well with the Fota teams - especially as it is the latest in a series of positions they have taken that have disrupted the harmony Fota is trying to engender in F1.
Williams were expelled from Fota after the Monaco Grand Prix in May, for example, for lodging an entry for next year when Fota was in the middle of the mother and father of all political fights with Mosley - which they have since won.
Williams made even fewer friends in the TWG meeting when they objected to a change in the allowable brake-disc thickness for next year.
The other teams want to increase it to 32mm, because they believe that next year's cars will need bigger brakes to last race distances when cars are starting much heavier because of the ban on refuelling - with no fuel stops, cars will be carrying about 100kg more fuel at the start of a race.
Williams are alone in believing they do not need the thicker brakes but their stance still mystifies the other teams, who say they're welcome to run smaller brakes if they want, but why stop the others using bigger ones? The other 12 teams all believe they would have to spend millions on researching expensive brake materials to make 28mm discs last next year.
Team boss Sir Frank Williams was cagey when I asked him about why Michael took the stance he did on Kers, but he did tell me: "It keeps our sponsors in the game - Kers has the strong support of several of our sponsors." A source at another team told me it was more of a commercial issue -Williams want to develop their hybrid system, which is unique among F1 teams in that it uses a flywheel to store the energy rather than a battery, and sell it outside F1.
Whether Williams's stance will be enough to keep Kers in F1 next year, though, is another matter. Despite Williams's objections, a majority is all that is needed for a vote to pass the TWG under the new Concorde Agreement that was signed last month. But the F1 Commission is another matter. A majority there is enough to make the change for 2011, but for next year it needs to be unanimous. And Williams have a seat on the F1 Commission.
So what happens next? Well, even if Williams vote against for a second time, Kers is still unlikely to be in F1 next year. That's because, to use it, a team needs a Kers driver on their engine - and all the engines come from Fota teams. So Williams's engines would simply come without the parts needed to make Kers work.
Nevertheless, even if it is not around next year, it looks unlikely that F1 has seen the back of Kers for good.
Williams think that, philosophically, having Kers in F1 is the right thing to do, for all the reasons Mosley introduced it in the first place. And, broadly, the Fota teams - whose road cars will be making increasing use of 'hybrid' systems in the future - agree.
McLaren team boss Martin Whitmarsh said Kers was "a good initiative but perhaps it came at the wrong time". In other words, the middle of the biggest global financial crisis for decades, when teams are finding sourcing sponsors very difficult, was not the time to be introducing an expensive new technology, however much of a good idea it was on a number of levels.
"I don't think F1 should turn its back on Kers," Whitmarsh said. "Perhaps we can find in future years a lower-cost way of developing it."