There’s always a key number on which the market is based. Sometimes it’s an interest rate, as in Europe today. Sometimes it’s another number, like America’s unemployment rate. In the past it’s been housing starts; it’s been inflation; it’s been GDP. For 2012, the key number is the oil price.

It’s the oil price because decoupling growth from oil prices is the key to real prosperity. Throughout the last several years, growth and oil have grown closer together. It’s at the point where now a jump in the Dow Jones industrial average is nearly always matched by a rise in the price of West Texas Intermediate, and vice versa.

Most of what has been happening in the U.S. economy, below the surface, is aimed at this decoupling.

Before you jump on me for another rant against big oil, let me state first that what U.S. oil and gas companies are doing is part of the equation, at least in the near term. Fracking has already decoupled natural gas prices from growth. For the last two years, we’ve had real growth in the economy but falling natural gas prices. Oil can be the same.

Drillers have now had several years to accommodate themselves to spot prices of near $100/barrel. This has given them time to invest enough capital to produce large supplies, profitably, at that price. And once a well goes into production, the nominal cost of producing an additional barrel is usually quite low.

But the more important work is taking place on the demand side. The technologies of efficiency are growing, and have a ready market. Every barrel saved in industrial production, every KwH a commercial building owner can save, every gallon of gas a consumer doesn’t use while remaining productive at work, that’s money in the pocket. It’s an investment that pays for itself, whether you’re replacing bulbs with LEDs in your Christmas lights, buying a higher-mileage car, or insulating a building.

Renewable energy is what will maintain the gains. Yes, it’s small now, in the general mix. But it’s increasing, thanks in part to today’s prices, and in part to advancing technology. Even if solar installation doesn’t grow in 2012 from 2011, the supply of solar energy in the market will grow dramatically, because the base is low. The same is true for wind energy, for chemicals and other feed stocks produced from biomass, and for geothermal energy.

Over time it’s this harvest of the abundance all around us that will not only keep oil prices reasonable, but cause them to roll over in time. For 2012 let’s focus on WTI, the spot price for oil in our own country, less in relation to European “Brent” prices than in absolute terms. Keeping that price down as economic growth accelerates, as employment grows, is the key to nearly all other market prices for 2012.

Disclosure: I have no positions in any stocks mentioned, and no plans to initiate any positions within the next 72 hours.