The day the earth’s CO2 stands still
Jeremy Bentham, the head of the Shell Scenarios team, thinks about the day when carbon dioxide stops accumulating in the earth’s atmosphere. He then works his way back to the present to suggest sensible measures for society to get there.
The world of the future will need a lot of energy if it is to nourish and house billions more people than it does today – especially at levels of well-being comparable to those of today’s modern society. But it will also need to stop adding more carbon dioxide into the atmosphere.
Jeremy Bentham, head of the Shell Scenarios team, thinks the two requirements are not mutually exclusive. “A world with net-zero carbon emissions, in which 10 billion people prosper, is feasible.” He makes that bold claim in Towards net-zero emissions: An outlook for a prosperous world, his contribution to The colours of energy, a new collection of essays that offer various perspectives on the future of the world’s energy system.
A glimpse of the future
What characterises a net-zero-emissions world – one whose atmosphere no longer has increasing carbon dioxide (CO2) levels?
According to Bentham, it would be a world in which the average person attains a decent quality of life associated with about 100 gigajoules of primary energy per year. That’s more than the current per-capita consumption of energy in Asia and Latin America.
But it’s less than that in Europe – and much less than that in North America, where primary energy use averages about 300 gigajoules per person per year.
If as many as 10 billion people each use 100 gigajoules of energy per year, then the world would need a total of 1,000 exajoules of energy per year – roughly twice today’s level. In a net-zero-emissions world that energy would have to be produced in large part by renewables, but it would also have to be produced in some part by fossil fuels. The world would therefore not be totally fossil-fuel free.
Where industry requires very high temperatures, as in the manufacture of cement or certain chemicals and plastics, fossil fuels will continue to be used. And there are hardly any substitutes for the energy-rich hydrocarbon fuels that are carried on board in air travel, seaborne freight and long-distance road haulage.
Bentham believes that not all regions of the earth will contribute equally to the emission-reduction effort, and that not all industries can be made carbon-neutral. “It is important to recognise that a net-zero-emissions world is not necessarily a world without any emissions anywhere. It is a world where remaining emissions are offset elsewhere in the system,” he says.
Plants, soils or rocks that permanently absorb the CO2 released from biomass power stations would provide the counterbalancing “negative” emissions. Certain agricultural practices and reforestation stimulate this naturally. But engineers can make a biomass-fuelled power station do the same if it is integrated with underground CO2 storage facilities.
All in all, non-fossil sources would contribute 70-80% of the world’s energy supply, with the remaining 20-30% coming from fossil fuels – an inversion of today’s proportions.
That picture of the future has some practical lessons for the here and now.
Learning points for the future
For one thing, deploying carbon capture and storage systems will be essential. Bentham estimates that some 11 gigatonnes of CO2 per year – equivalent to just over a quarter of society’s today’s emissions – will need to be kept from the atmosphere.
Another crucial point is energy efficiency. The world requires a truly remarkable increase in what we get out of every unit of energy we put into driving, heating or cooling. Otherwise, the globe’s total annual energy use could easily rise to at least 1,500 exajoules.
It would not be possible to grow enough biomass and build enough solar and wind power to accommodate that energy demand and still achieve net-zero emissions.
Making cars lighter and equipping more of them with electric drives will help make road transport more energy efficient. So too will the widespread use of heat-pumps and LED lighting in houses and offices. But we must take care not to let increasing efficiency tempt us into increasing usage to such an extent that it effectively wipes out the energy savings.
“It is therefore important to focus on infrastructural changes, which lock in efficient behaviour and thereby achieve durable long-term benefits”, says Bentham. In practice, that means cities must avoid urban sprawl and develop reliable and attractive public transport networks, with layouts that support cycling and walking.
A prosperous world with net-zero emissions is within society’s grasp this century, but Bentham believes that “it will require the co-evolution of emerging and established forms of energy consumption and an end to lazy thinking.”
- Read Jeremy Bentham’s essay – Towards net-zero emissions: An outlook for a prosperous world – in The colours of energy. Download the book for free to your iPad or e-reader and discover more about possible pathways into the future of energy.
Disclaimer: The views expressed in The colours of energy – Essays on the future of energy in society are those of the authors and do not necessarily reflect those of Royal Dutch Shell plc nor any of its subsidiaries (Shell).
More in Energy and Innovation
The 21st century will be decisive in the various transitions to a future with cleaner energy. Written by leading experts, The colours of energy contains 36 thought-provoking essays about the many energy challenges society faces in the coming decades.