And the use of green energy goes towards investment in green energies that will lower the price of it, with the difference that the supply of nonrenewables is limited, whereas the others are not.

It's also risk mitigation. Supplying your own electricity from solar farms is a pretty good way to avoid price volatility.

That's one reason why I invested around $30,000 in renewable energy features (passive and active) in the house I built last year. $3k per year amortised over 10 years for a low operating cost system, comfortable living and working environmnet? It's a no brainer.

But purchasing renewable energy also drives down its price, by allowing the industry to develop economies of scale and streamline its operations. This strategy is essentially the way most technology innovations work, by first selling to early adopters who are willing to pay a premium and then pushing prices down to mass-market acceptance.

Considering that the market for fossil fuel energy is so much larger than that for renewable energy, I'm going to say that Apple's choice will have a bigger positive effect on the renewable sector than on prices for non-renewable energy.

Apple isn't in a position to implement new taxes. Where the Government isn't showing leadership, it's beholden on corporations to show the way where they can.

By implementing these policies Apple can show leadership and influence their peers and support the clean energy industry. This is the right thing to do.

> The effect on global warming is near zero, possibly even negative. The decision to use green energy decreases the price of non-green energy, so other companies will buy more of it.

That's a first-order effect. But second-order effects of the price changes include encouraging investment in green energy and discouraging investment in non-green energy. That will shift the long-term incentives for all market participants.

There are already plenty of taxes on 'non-green' energy, but the demand curve is inelastic so they make little difference. Nearly every country on the planet has taxes on liquid fuels, for example.

Heavily taxing energy for any reasons always leads to lower economic growth and unemployment. That is because no tax applies globally, so there are always places to move to access the cheapest energy. And usually the places that production one to have lower environmental controls on energy production, leading to a net-worse position for the environment and the people where the production used to be.

Australia implemented the highest 'carbon tax' in the world in 2012. This contributed to the closing of several heavy industry factories within 12-18 months, including aluminum shelters. These factories have all been relocated to places like china and Saudi Arabia, with net-worse outcomes for the environment as a result, and a weaker economy in Australia. A region-specific energy tax is a bad idea because it achieves none of its goals, and measurably makes things worse.

I'm curious about the factories that are supposed to have closed due to Australia's carbon tax and I'd be especially interested to see some evidence if these factories 'relocating'.

Trade exposed heavy industry was largely sheltered from the tax. In fact some argued the free permits were actually going to deliver windfall profits. There was a story recently about the closure of Alcoa's Point Henry aluminium smelter, but the company denied there was any link to the carbon tax.