In today’s Wall Street Journal (subscription required), Patrick Barta reports that, “Rising costs of biofuels and other alternative energies are making them less viable as substitutes for crude oil, a development that could frustrate efforts to bring oil prices down in the years ahead.”

“Even as crude-oil prices approach $100 a barrel, some alternatives look less attractive than in the past,” Barta says, because key input costs are also rising. “The problem is most acute for crop-based alternative fuels, like ethanol and biodiesel, though it has also proved true to some degree for solar power, nuclear power and other competing energy sources.” Examples:

• Palm oil prices have increased 90% in the past three years. As a result, crude oil would now have to be $130 a barrel before palm-oil-based biodiesel is competitive.

• Coal prices have more than doubled over the past four years, and prices for uranium, a crucial ingredient in nuclear power, have increased more than sevenfold in that time frame.

• The cost of solar-power cells has been pushed up in the past few years by a tight supply of silicon, the main raw material in such cells.

Growing global demand for food contributes to the high cost of corn and palm oil, but so does the rising cost of petroleum. “Another concern is that as more nonoil commodities evolve into oil alternatives, they will start to be priced the same way as crude, keeping their costs in line with international oil prices.”

The price of one non-oil input is falling: “The price of sugar, a key element of ethanol, has dropped more than 40% since early 2006 as supply expands in places such as India.” But don’t hold your breath waiting for Congress to open up the U.S. market to Brazilian ethanol made from inexpensive sugar cane!

A cool fact: “Global ethanol production rose 25% from 2004 to 13.5 billion gallons last year, and biodiesel capacity more than doubled to 6.1 million metric tons in that period, though the two combined still only make up about 1% of the world’s transportation-fuel supply. “