Willersey solar farm

Meeting the world's energy needs: the 100 per cent solution

Image credit: Belectric

Researchers in the United States believe the world can meet all its energy needs without fossil fuels by 2050.

April 2016 became the first month when solar in the UK generated more electricity than coal. Over the summer, wind generation consistently beat coal in terms of kilowatt-hours. In Spain, wind generation has reached the point where it is able to support 70 per cent of the country’s demand for electricity when running at peak capacity.

When you consider how dominant coal once was in electricity generation, the path to a future powered entirely by renewables starts to look tangible. However, that apparent surge in April was more due to the dramatic slowdown in coal generation with a switch to gas and the rise of biomass burning at plants such as former coal powerhouse Drax.

A team at Stanford University led by Mark Jacobson, professor of civil and environmental engineering, has looked further out, with projections of how the world’s largest 139 countries can meet 100 per cent of energy demand in 2050: electricity and also transport and heating.

It is still a work in progress as the researchers tune their numbers. The most recent version published in October saw estimates for wind generation almost halved. The April 2016 version called for 65 per cent of the UK’s 2050 energy needs to be delivered using offshore wind. The latest version puts a greater focus on solar photovoltaic (PV) farms similar to the 50MW Scottow Moor installation at a former RAF airbase in Norfolk.

Jacobson says the revisions are based on more accurate assessments of generator costs and the availability of rooftop space for solar generation. In the projections, large solar farms together with onshore and offshore wind would provide the bulk of the UK’s energy needs. Although rooftop solar would be needed, its overall contribution would not be significant.

The map above shows our estimates of the amount of space the large-scale generators would need to support the Stanford team’s estimates, based on the size of existing sites such as the London Array in the Thames estuary and the Whitelees onshore wind array near Glasgow. It takes into account the typical spacing between turbines and solar panels - many farms would be able to support both agriculture and energy production. Solar installations are unlikely to be suitable for crop growing but they can support grazing animals. The much lower land footprint of wind turbines allows both.

Jacobson argues that almost all countries in the survey would be able to support 100 per cent renewables generation. The exceptions are Gibraltar and Singapore - unless they can turn to offshore solar. “Of course, these countries and others will find it advantageous for grid stability to exchange energy with neighbours,” he adds. 

The Stanford team argues that wind and solar are the only two sources of renewable electricity with sufficient resource to power the world on their own. Only countries with unusual geographic features, such as Norway, which can already meet 55 per cent of its energy needs from renewables, could rely substantially on hydroelectricity.

The work makes a number of assumptions about how much less energy a renewables-centric world would require than one based on business as usual. It has drawn criticism from other energy-policy researchers who believe nuclear should remain an important part of the mixture to support grid stability.

Energy storage would need to be an important part of the mix, the Stanford team says. One of their major assumptions is that hydrogen technology will be in common use by 2050, not just powering long-distance aircraft but acting as a storage reserve. Excess energy would be used to split water to obtain molecular hydrogen that can be routed to fuel cells during peak demand. This would be supplemented by underground battery and storage plants based on pumped hydro­electric generation similar to the Dinorwig power station, which was completed in 1984 in expectation of a large-scale shift towards nuclear. It is soon to be joined by Glyn Rhonwy in old slate caverns nearby.

Worldwide, according to the projections, storage plants would add about 15 per cent to overall land required.

Although it relies on many assumptions, the Stanford work shows one way towards a world no longer dependent on fossil fuels for its energy.

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