Although before the election Tony Abbott professed support for the target, since the election he has instituted an expert review of it, headed by businessman Dick Warburton, former chairman of Caltex and prominent "sceptic".The review commissioned a leading firm of economic consultants, ACIL Allen, to undertake modelling on the future effects of the target.The preliminary report found that, between 2015 and 2020, the target would increase the average household electricity bill by $54 a year - a tad over $1 a week. This five-year average, however, conceals the estimation that the cost of the scheme will fall as each year passes.So by 2020 itself, the increase will have reduced to just $7 a year. By the end of another 10 years, in 2030, the scheme is estimated to be actually reducing average household electricity bills by $91 a year, or $1.75 a week.It's common sense that requiring electricity retailers to buy a certain proportion of their power from more expensive renewable sources - mainly wind power, but also solar - would add to the cost of their power, with the extra cost being passed on to consumers.So why has ACIL Allen's modelling concluded the target will add to the price of electricity initially, but eventually subtract from it? The short answer is because electricity pricing is a complicated business.It turns out that adding to the supply of renewable energy available reduces theprice of electricity. This is because the price being paid for energy being put into the national electricity grid by particular generators varies minute by minute according to the balance of supply and demand.In the middle of the night, when little power is being used, the wholesale price is very low. But on a cold evening - or, more likely these days, a very hot afternoon - the wholesale price can be stratospheric.The trick to renewable energy is that it tends to be available when the demand for electricity is high. Experience around the world confirms the Australian experience that renewable energy does a great job of reducing spikes in wholesale prices on very hot and very cold days.Another part of it is that though it costs a lot to build wind and solar generators, once they're built there are few "variable" costs. Wind and sun are free; coal and gas aren't. So the renewable generators offer to supply power to the grid at very low prices and this lowers the prices the coal and gas generators are able to ask for.But none of this changes the fact that the electricityhave to pay for the "renewable energy certificates" that the target scheme requires them to buy. These certificates reduce the capital cost of setting up the wind and solar generators whose operations then reduce the wholesale cost of power.So it turns out the renewable energy target scheme has the effect of reducing the wholesale cost of electricity while also adding to the costs of the electricity retailers. ACIL Allen's modelling suggests that, for the next five years, the extra retail cost will exceed the saving in wholesale costs, but after that the saving will exceed the extra cost.See what this means? The case for saying we must get rid of the renewable energy scheme because it's adding too much to the living costs of struggling families has collapsed.But there's where the story takes a twist. Modelling of the future cost of the renewable energy target, published by an equally prominent firm of economic consultants, Deloitte, comes to opposite conclusions.Deloitte's modelling accepts that the renewable energy scheme is reducing wholesale costs, and roughly confirms ACIL Allen's finding about the higher cost to household customers until 2020. But whereas ACIL Allen expects the scheme to start reducing household costs after that, Deloitte expects the cost to stay positive until 2030, causing household bills to be between $47 and $65 a year higher than if the scheme was scrapped.Why have two leading economic consultants reached such opposing conclusions? Perhaps because Deloitte's modelling was commissioned by the Chamber of Commerce and Industry, the Business Council and the Minerals Council.Deloitte doesn't conceal that its modelling is in reply to ACIL Allen's. Would it surprise you if the fossil fuel industry wanted to see the renewable energy target abolished and was alarmed to know that modelling commissioned by the review had demolished the argument that continuing the target would add to people's electricity bills? Now the review will be able to pick whichever modelling results it prefers.How did Deloitte reach such different results? By feeding different assumptions into its model. It seems to have assumed the cost of wind farms won't fall over time (which it probably will), whereas the price of gas for gas-fired generators won't rise much (which it already has).Regrettably, economic modelling has degenerated into a device for bamboozling the public.