In 2007 winter season, Citibank bought a large amount of barrels and held it off the market (according to 60 minutes), this moved the "supply" down and holding these millions of barrels off the market.
Yes, it happens from time to time. It's worth pointing out the scale, though. The world uses about 85 million barrels a day (or did before summer 2008). The largest oil tankers hold about 4 million barrels.
Overall stockpiles didn't go up substantially during 2005 - 2008.
So while you state that speculators cannot set prices, they could influence the supply chain to help achieve their eventual goal of satisfactory prices they would "want" to sell it for.
You can certainly manipulate the price if you stockpile oil. That's reducing supply. But when you come to sell you are increasing supply, which pushes the price back down again.
This is why I believe that supply and demand forces takes on a different form with the most wealthiest that have that power to manipulate supply. Thus hurting the world economy and hurting our industrial output.
You get speculative movement every day. But over the longer term the world was consuming every barrel of oil produced. The price was correct.
If it hadn't been, if oil had cost more than it should, the result would have been a surfeit of oil on the market as the high price would have reduced consumption.
If I can throw another wrench in this whole thing: If free markets truley do work, why then are auto mfg's unable to release electric or various forms therof of non-petrol vehicles to create the 'competition' in free markets that it was intended to? The answer is money and oligarchy.
The technology just doesn't exist.
If you take battery cars as an example, you need about 40 kw/h of batteries to power a family car for about 125 miles. That battery pack costs around $30,000. It has to be replaced every 100,000 miles or so, meaning the replacement cost of the battery is about 2 - 3 times as expensive as gasoline.
Oil is a very good store of energy. Crude oil (and gasoline) have about 12.8 kw/h of energy per kg. A car battery has 0.04 kw/h per kg.
And oil is just lying there under ground, ready to be used. It can be easily transported and stored. It's the ideal fuel for vehicles.
There's nothing that can compete with oil at the moment. Batteries cost more and are less convenient. Natural gas has to be compressed and stored in expensive tanks. Overall it costs more. Hydrogen has to be made from natural gas, compressed and stored in even more expensive tanks, and costs much more. Compressed air doesn't store enough energy to power the sort of vehicles people want.
People use oil powered vehicles because they are cheaper and better than the alternatives. That's true even in Europe where taxes raise the price of fuel to $8 a gallon. People drive smaller, more efficient cars, but they are still powered by gasoline and diesel.