I like to come away from the Hay Festival with an idea or two to ponder on.

Time was short this year, and even then we made one wrong choice. The estimable John Julius Norwich, with his “Four Princes” seemed a good choice, but on reflection it was no more than a polished but ultimately routine piece of history, on the kings of England and France, the Holy Roman Emperor, and Sultan Suleiman the Magnificent, all in power in the first half of the 16th century, that any good researcher-writer could come up with. Now I’ll never know what Carpe Diem, with philosopher Roman Krznaric, scheduled at the same time, would have delivered to inspire me in my daily attempts to be creative over the next few years.

An example of how strong ideas stay with you was Dieter Helm’s talk two years ago  on Natural Capital. Helm, Professor of Energy Policy at the University of Oxford, is Chair of the Natural Capital Committee, which is not too many people may have heard of. It was set up by set up by the Coalition Government in 2012 as an independent committee to advise the government on the sustainable use of natural capital. The 2015 government did at least let it continue, although it notes in its 2017 annual report that “.. natural capital is not yet on an improving path and we make 16 separate recommendations”. It is now in its second session, to last until 2020.

Natural capital is nature’s wealth, its infrastructure – the woods and forests, river systems, wetlands, meadows, and the wildlife and other assets they sustain – provided, for nothing, by the world about us.

In 2013 the committee put one of Britain’s most loved flowers, the bluebell, on the cover of its annual report, as an example of a natural future future we love, yet stand to lose because of changing conditions, such as climate change.

In his 2015 talk Helm said Natural Capital is about putting a price on the things around us, so that it will build a housing estate on some pleasant piece of countryside, we set aside another piece to compensate for it. When we damage the environment, that loss must be made up with “serious compensation”. We must compensate for the carbon we push into the atmosphere, and ensure that the price we pay for pollution is embedded in the product.

I did a Google search for “Natural Capital” news stories and came up with this study, published in May 2017 in the Journal of Marine Policy, on coral reefs. They generate $36 billion in global tourism value per year.

Travel and tourism is arguably the world’s largest industry, and unsustainable tourism can be a threat to reefs, with the capacity to destroy the very attraction that brought visitors in the first place.

I noted last year how National trust was putting a value on some of the Natural capital it has in its care, the bluebells in its Ashridge estate. It is charging people to see them, although the object is more to prevent their degradation then show them off as an item of wonder. As an item of wonder. People appreciate them before the charge was levied, but were damaging them in pursuing that appreciation.

This year the festival coincided with Friends of the Earth’s Great British Bee Count, from 19 May to 30 June 2017, which the BBC is promoting on Springwatch. Natural Capital again.

We can only guess at how future governments will measure natural assets and require society and developers to pay to protect them, or compensate for their loss. There’s too much on certainty when political decisions are so short term.

Dieter Helm was at Hay in 2015 to give his talk because he just published a book on the subject. He could, and perhaps should, have been there again this year, to deliver the message in his new book, just published, Burn Out: The Endgame for Fossil Fuels.

It would have been perfect Hay material, an exposition of the inexorable decline of fossil fuels, and how technology will replace them, and drive decarbonisation even as governments struggle, and possibly fail, to cut the world’s carbon levels in the face of the growing climate change threat.

He believes tech giants such as Google, Amazon and Apple, along with major car companies, could be about to enter the energy supply business. Their involvement would be a natural consequence of the game changing “digitisation of everything” and “the electrification of everything”, with solar power playing a key part.