But I admit that the "carbon dollar" label is a slight misnomer, for the purposes of a presentation in Iran. This is because that presentation will relate to Units redeemable in (say) gasoline, and to call it an energy dollar would be too confusing at this point.

In fact, where this leads is to what may better be described as an "Energy Dollar" consisting of a fixed amount or "Value Unit" - it doesn't matter what that is - of energy.

A Unit of (say) 10 Kilo Watt Hours or equivalent is as good as any.

The point is that it will be possible to price other forms of fuel or energy by reference to this Value Unit.

So as carbon fuel become more scarce and expensive, it will increase in price in terms of (say) the number of Energy Dollars per barrel.

The policy framework I envisage - a new "Global Settlement" - would apply a "Carbon levy" to all carbon-based energy transactions and thereby create an "Energy Pool" - a fund of (say) US dollars on US transactions, but denominated in Energy Dollars at the Energy Dollar/ US Dollar exchange rate.

So, imagine we make a carbon levy which raises $100m initially in the US.

At an initial energy price of $1.00 for a Unit of 10 Kilo Watt Hours, that means the resulting fund or Pool may be "Unitised" initially into 100 million Energy Units. As the US dollar gets more expensive over time against energy, so the number of Units new US dollar investments will buy in the Pool will decline.

Let's try an example:

A "Pool-Manager-formerly-known-as-Investment-Banker" appraises a plan for a 1 Mega Watt wind turbine - decides it stacks up in that location - and decides to fund it by investing $2m of Pool funds.

The Wind Turbine is built and then has a liability to the Pool not in $US, but in Units.

At the initial $ per Unit price this is 2m Units of 10 Kilo Watt Hours or 20,000 Mega Watt Hours of future production.

This investment is then repaid over the (say) 20 year design life of the turbine at a rate of 1,000 Mega Watt Hours per year.

If the turbine operates at a "load factor" of only 30% (ie 30% of the time) it produces 2,628 Mega Watt Hours (or 262,800 Units) in a year.

If a proportional share of production is paid to the "Operating Member" - then the balance will stay with the developer or land owner or community - in whatever proportions are agreed.

Unlike a Carbon Tax, where all the taxpayer sees is a "cost", in this model he gets in return for the levy (which is therefore a compulsory investment) "Units" in return.

These may then be redeemed for renewable energy consumed; against repayment of Pool investments used to achieve energy savings (so-called "Nega Watts"); or he may just sell them off at the market price.

The Energy Dollar market price is not some arbitrary politically determined price, like that of CO2, or come to that, Central Bank interest rates, but is a reflection of the intrinsic value of energy, whatever that is.