This green energy thing might be more expensive than we're being told you know

There's always a suspicion when someone has a grand plan that they've not quite thought of everything. That's one of the reasons I so like market mechanisms: they correct for such failures faster than any other method. And there might be one rather large cost that we've not been told about as yet about this green and renewable energy thing. Which is why I famously prefer the as close as we can get to a market solution of a carbon tax over letting anyone construct a grand plan.

The problem is that modern machinery needs very accurate voltage all the time. Something which a renewables heavy grid just isn't all that good at producing. Not consistently at least and that's rather the point.

The problem is that wind and solar farms just don’t deliver the same amount of continuous electricity compared with nuclear and gas-fired power plants. To match traditional energy sources, grid operators must be able to exactly predict how strong the wind will blow or the sun will shine.

But such an exact prediction is difficult. Even when grid operators are off by just a few percentage points, voltage in the grid slackens. That has no affect on normal household appliances, such as vacuum cleaners and coffee machines. But for high-performance computers, for example, outages lasting even just a millisecond can quickly trigger system failures.

What would happen to an aluminium smelter if power fell away would be too too expensive to even think about: you'd probably have to replace all of the pots. That, for the uninitiated, is the expensive part of an aluminium smelter.

Anyway, as a result some of those industries and companies are thinking of moving out of Germany. And those that aren't?

Even August Wagner, head of a textile firm with roughly 180 employees in Bavaria, is taking precautions against feared power interruptions. A stop in production would be catastrophic for him. “When we dye our materials, there are thousands of meters in the dye factory,” he said. “If the power goes out, all of the goods are lost, and we have huge losses.”

Wagner now regulates the power supply of his production himself so that it doesn’t come to that point. What’s more, for a few months, he’s had an emergency power source standing in container next to the production facilities. Since then, other businesspeople in the area have been dropping by to take a look at his setup.

Aurubis, a major copper producer and recycler in Hamburg, has also spent about €2 million to protect against unwanted power emergencies. “If grid stability doesn’t markedly improve, we’ll have to rely on emergency power supplies this and the coming winter,” the company say.

Obviously, such back up power is grossly less efficient than the proper sized kit that feeds the grid. But there's also a large capital cost there: a cost which isn't being included in the estimates of how much green energy is going to cost us. It's actually possible that it's all going to be even more grossly expensive than we already think it is.

As I say, beware of those with grand plans. They're almost certain to have forgotten some terribly important point.