For much of the past two years one of the most compelling drivers behind green business investments has been the soaring cost of energy. So what happens when those energy costs begin to fall?

As the UK today has its recessionary status officially confirmed, businesses are facing a new energy landscape where bills are falling for the first time in years.

The price of oil has slumped, and even green energy providers such as Good Energy are now lowering their tariffs alongside conventional players such as British Gas. Moreover, the fall in industrial output has pushed the price of carbon to record lows, putting still more downward pressure on energy prices.

For business leaders falling energy bills mean the temptation to push energy efficiency issues back to the bottom of the corporate in-tray will become ever more beguiling. Many will understandably ask why they should fork out for more efficient technologies or buildings when their bills are already falling and capital is unbelievably hard to come by.

And yet there are compelling reasons for businesses to continue to curb energy use that go far beyond the obvious truism that during a recession you should look to control all operational costs as tightly as possible, even if they are already falling.

The fact is that those firms that don't address their energy use now could recover from the credit crunch and find themselves thrown right into an energy crunch characterised by soaring power bills.

There are already signs that a perfect storm is brewing that could well break just as we'd hope to see the economy surging forward again.

The most obvious basis for this prediction is the simple reality of supply and demand. The price of oil may have fallen over a $100 from its peak of around $140 last year, but that collapse in price is the result almost entirely of falling demand, not an increase in capacity.

When demand recovers to pre-recession levels or above - and while it might seem hard to believe at the moment the history of recessions tells us this will happen - then the oil price will soar again. In fact, with many of the oil giants scaling back investments in new capacity as the recession bites the situation will likely be even worse than it was in mid-2008 as supply inevitably struggles to keep pace with rising demand.

Rising oil prices would not only lead to increased transport fuel costs they would also have a knock on impact on wholesale electricity prices that will already be being forced upwards again as a result of the raft of green regulations that are scheduled to converge upon the energy sector between 2010 and 2013.

As a leaked Whitehall memo revealed this week, the UK government is concerned new EU legislation designed to limit air pollution from power stations could add as much as 20 per cent to energy bills. And that is before you even begin to consider that EU targets requiring the UK to cut emissions and generate 15 per cent of energy from renewables by 2020 mean that by the early 2010's work on a huge expansion in renewable and nuclear capacity will be well underway, leading to a predictable impact on energy bills.

Meanwhile, the current low price of carbon in the EU's emissions trading scheme is subject to much the same rules of supply and demand that will impact the oil market once the recovery materialises.

Prices have dropped in recent months because heavy industries are producing less, releasing less carbon into the atmosphere and therefore require fewer emission allowances. The number of carbon credits issued between now and 2013 however remains constant, so as the recovery materialises and production and emissions increase again the price of carbon will also rise placing further cost pressures on energy producers. Again, these pressures will become more pronounced from 2013 when the EU moves to impose still tighter emission caps on heavy polluters.

The net result is that companies that fail to address their energy use could find themselves climbing out of the credit crunch only to find themselves locked into an energy crunch characterised by 100 per cent plus increases in energy costs and fuel bills.

That is why businesses such as Tesco and Sainsbury's this week announced new stores and initiatives that display a continued commitment to addressing energy issues despite tough trading conditions, and why those companies that really want to position themselves to fully exploit the inevitable economic recovery would do well to follow their lead.