Franz Pentenrieder doesn't have to depend on deliveries of heating oil anymore. The Bavarian farmer has discovered his own source of energy: a grain-fired central heating system.

Thanks to a filter he built himself, the flame produced is nearly smoke free and environmentally friendly. He has a special permit required to run the system, which is good value.

Big savings

It costs about 60 percent less than oil to produce the same amount of heat.

"I've saved about 35,000 liters (9,250 gallons) of heating oil in the past four winters," Pentenrieder said.

That adds up to around 4,000 euros ($5,050) annually on heating. He's convinced it could be good business for farmers to grow cereal crops as a source of energy.

"If we can heat schools and public buildings with grain in the near future and it proves to be the most economically efficient way to do so, it would give the farming industry a huge boost. There would be a huge market," Pentenrieder said.

Oil prices are notoriously rising, but the price of grain on the world market is falling -- a good argument for using it as an energy source, some say. North Rhine-Westphalia's agriculture minister, Eckhard Uhlenberg, is a farmer himself. He said he has no objections.

Ethical objections

"I can imagine farmers burning their own grain," he said. "If I think it's politically responsible, I would have nothing against using my own grain to produce energy."

But in the minister's home state, elderly people, in particular, are shocked by the idea of burning a staple food for energy.

"I don't think you should throw away bread or anything edible," Christina Hinke, a retiree in North Rhine-Westphalia, said when asked what she thought of burning grain for fuel. "I remember the war."

Hans Bönigk, another retiree, said: "Heating? With so many starving people in the world, using grain for heating here just isn't right."

Church representatives also oppose the idea. They criticize Uhlenberg, and think burning grain for fuel is going too far.

"'Give us this day our daily bread' is part of the Lord's Prayer," said Nikolaus Schneider, a Bishop of the German Protestant Church. "In preparing Holy Communion we sing of bread that's made up of many grains of wheat and brings us together. We believe that this is a gift of life that transcends the life cycle of any one person and establishes for us a link to eternal life."

Energy companies are interested

But Uhlenberg disagreed.

"I used to think that as well," he said. "It took a long time for me to change my mind. At first, when a farmer began burning grain for fuel, I was uneasy about it. It took about three or four years before I was able to accept the fact that burning grain can be ethically justifiable."

Energy companies have long been looking into grain heat as a possible good deal. With the abundantly available raw material, they are testing grain to fire large power stations.

Even government advisors think grain has good prospects as an alternative energy source.

"Cereal crops can of course be used for food," said Martin Faulstich, of the German Advisory Council on the Environment. "But they can also go to the energy market. In the end, it doesn't really matter much if I use the acreage to plant rape or maize or wheat: as long as there's no scarcity of food in Germany, it certainly makes sense to burn grain as well."