Distilling the core message from the IEA in the latest edition of its World Energy Outlook is not easy because it contains multiple meanings.

They range from political to military to the obvious effects on companies and people in the energy business.

On the commercial side there is a one-word warning in the IEA report for everyone in the petroleum business - costs.

The agency, which advises governments on their best energy policies, did not highlight the cost question.

The Slug will because everything in the outlook points to a period of falling, not rising, energy prices.

In that climate, the business with the lowest costs achieves two objectives. It survives and then it prospers as high-cost competitors are pushed aside.

The IEA did not publish precise energy-price tips but what it did do was spell out the significance of a story that The Slug has been banging on about for the past three years - the US shale boom is a global game-changer.

Confined for now to the US itself, rising oil and gas production from rocks long regarded as non-commercial is turning the US energy market upside down.

Coal, somewhat oddly, has been the first victim of shale oil and gas thanks to energy consumers in the US switching from coal-fired electricity to gas-fired.

Why? Not just because of reduced levels of pollution but more because it is cheaper.

The big change, however, will come as the US pumps more of its own gas and liquids, sharply reducing demand for oil imports - an event underway now and one being felt as far away as the Middle East.

Before considering the political and military consequences of the US becoming energy self-sufficient it is worth asking how the unlocking of oil and gas in shale in a single country could have such far-reaching effects.

The answer lies in the numbers.

The US accounts for about 30% of the global economy and perhaps as much as 40% of global energy consumption.

For the past 50 years an increasing amount of the energy consumed in the US has been imported, making a fortune for the Arab states in the Middle East and propping up unpleasant regimes from Venezuela to Russia.

Importing less oil means the US will no longer be forced to kow-tow to petty dictators and corrupt Arab states, and those same countries, which face losing the US as a captive customer, will be forced to sell their oil elsewhere.

The IEA does not predict a flood of ex-US oil imports hitting the rest of the world but The Slug can see such an event occurring because the oil market is always finely balanced with movement in supply (or demand) of a few percentage points having a substantial knock-on outcome.

It will also mean the US will no longer have a genuine interest in keeping a fleet of warships in the Persian Gulf. That job can pass to China as its reliance on Middle East oil continues to grow as US reliance falls.

No prize for assuming that a US withdrawal from the world's hottest of hot spots will dramatically alter the global balance of power.

Planning for an energy glut, rather than assuming an energy shortfall, has suddenly become the primary concern of everyone in the petroleum business.

What happened to high-cost coal producers could well happen to high-cost oil and gas producers.

In Australia, that means coal seam LNG developers will be pumping fresh numbers into their business models to see how profitable they will be should petroleum prices continue to fall.

It also means that conventional LNG project developers, such as Woodside Petroleum and Chevron, will be subjecting their projects to lower-priced stress tests.

Chevron's Gorgon development is too far into its construction phase to be altered but it will fall far short of its original profit assumptions. That will weigh heavily on the career prospects of a few senior executives.

Woodside's Browse project is yet to win a green light and probably cannot expect one (except as an LNG "floater") now that the IEA has burrowed into the long-term consequences of the shale revolution which, do not forget, is only happening today in one country - and there are many other countries with enormous shale potential.

Behind all this is the subliminal message that the IEA came close to delivering but pulled up just short of and that is the message of how low-cost producers will prosper and high-cost producers will fail.