This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy.
Skip to the content

[IOP] A community website from IOP Publishing

environmentalresearchweb blog

Talking renewables up – and down

by Dave Elliott

A meta-analysis by NREL staff, comparing the various quantitative scenarios that have emerged with very high penetrations of Renewable Energy in the power system for a range of countries and regions around the world, concludes that they show that renewables  ‘can supply, on an hourly basis, a majority of a country’s or region’s electricity demand.’

In addition, yet another paper has emerged to add to the pile saying that it is feasible to get to near 100% of global energy from renewables, or at least electricity, by 2050, although this new one, by US academics Mark Delucchi and Mark Jacobson in the Bulletin of the Atomic Scientists 69(4) pp30-40, mainly re-presents results from their earlier studies in summary form, but with some extensions. What it says, bluntly, is that ‘energy systems worldwide can be run entirely on wind, water, and solar power, making it unnecessary to pursue the less desirable alternatives of nuclear power and bioenergy’.

The exclusion of bioenergy is justified since, they say, ‘any use of land for the production of bioenergy feedstocks is worse for climate, water quality, soil, biodiversity, and overall ecosystem health than is the always-available option of restoring land to its ecologically best use and getting energy from other (non-biomass) sources. Put another way, getting energy from wind, water, or the sun rather than from bioenergy allows society to put land to better use than growing energy crops’. 

That may seem a little sweeping. Their focus is big ethanol schemes and there are certainly major problems there. But what about bio-wastes? For example, AD biogas production from food scraps collection, farm wastes and forestry residues?  That involves no extra land use, and although its combustion does produce CO2, that’s at least partly offset over time by the CO2 absorbed when the biomaterials are produced. And it’s better than letting this material rot in the open, releasing methane, a much worse greenhouse gas. Moreover with CCS it could be possible to have negative net emissions, as is argued in another new paper, on BECCs- Biomass with Carbon Capture:

However it’s an interesting debate: some say that using bio-waste and biochar production to enrich soil and enhance carbon sequestration might be a better bet…

While debates on issues like that continue, in parallel, there are those who see the whole renewables project as likely to be limited, for example by resource constraints. A recent study by David Keith et al suggests that the total global wind resources might be much less than hoped, due to wake interaction/ shadow limits, maybe only 1TW:

Earlier studies had been much more optimistic. For example, taking into account the effects that turbines would have on surface temperatures, water vapour and other climatic impacts, a University of Delaware and Stanford University study found that about half of global electricity could be supplied from wind, with four million turbines of total capacity 5.75 TW, spread out worldwide, without significant eco-impacts, while a Carnegie Institute and the Lawrence Livermore National Laboratory geophysics study suggested that, in theory more than 400 TW of electricity could be extracted from surface winds and over 1,800 TW from winds throughout the atmosphere, including via kites and other aerial devices.

Similar disagreements have emerged in other fields. For example, some studies have suggested that the tidal flow resource in Scotland was very large, up to 24GW, with perhaps 19GW being available in the Pentland Firth, but a new paper puts the latter as much smaller: perhaps only 1.9GW:    For a response see:

Certainly there is no shortage of skepticism about the practical prospects for green energy.  ‘IIASA’s massive “Global Energy Assessment” published last year ventured 75% in its high ‘Efficiency’ cases and a 55% median. In my view, with traditional biomass continuing to provide 5% to 10% of global primary energy needs, a total renewables contribution of around 25% by 2050 would seem closer to a realistic figure’.

So said Michael Jefferson at the Edinburgh Global Energy Systems conference in June.  He buttressed that with scepticism of most things renewable, wind power especially, but also PV and tidal. It’s good to have a critical viewpoint- some of the projections may well be over the top and a lot of assertions do need a reality check. So arguably do the support and assessment approaches. Jefferson concluded that ‘the global, regional, national, and local levels energy policy shows evidence of being in a shambolic state. The economics of many energy systems appear sub-optimal, not least when promoted through subsidies. Insufficient attention is paid to some fundamental concepts -such as useful energy, power densities, EROIs, and even where best to locate wind and solar systems’.  

However for a very different perspective see Jeremy Legget’s amazingly illustrated paper to the conference, prefiguring his new book: ‘The Energy of Nations’. Very positive, maybe overly so. But then the pace of change does seem to be speeding up. We have perhaps become used to spectacular expansion occurring in Germany, with wind and PV  now at over 30GW each and still growing. A new study by UBA, the German Federal Environment Agency, says that Germany’s on land wind resources is larger than thought- perhaps enough to supply all their needs. It suggest that the technical onshore wind energy resource is around 1,190 TWh/y (from 450 GW) using 3 MW turbines dotted around 13.8%  of German land area

We are also getting used to hearing about the rapid expansion of renewables in China- now the world leader in wind.  However perhaps less familiar is the rapid expansion elsewhere, for example in the Middle East /North Africa (MENA) region.At present, the MENA region has 380.24 MW of installed solar photovoltaic capacity, 182 MW of concentrated solar power, 1.1 GW of wind power, 73.5 MW from biomass and waste, and 17.6GW of hydropower. But its expanding fast,with over 100 renewable energy projects under development, and prospects for a 450% increase in non-hydro renewable energy generating capacity, with an extra capacity of 107GW expected to be established by 2030. That’s the estimate from the MENA Renewables Status Report by the International Renewable Energy Agency, REN21 (the Renewable Energy Policy Network for the 21st century) and the Directorate of Energy and Climate Change at the UAE Ministry of Foreign Affairs.

The fact that the US Climate Investment Fund has now given the go-ahead to Algeria, Egypt, Jordan, Libya, Morocco and Tunisia to proceed with over 1GW of CSP projects , with $660m promised, suggests that concerns about political instability in the region may not be a bloc to investment.

It may be true that the global recession led to reduced levels of investment in renewables in many countries, but that is only part of the story. It does not mean less renewable capacity has been installed, since the capital cost of many renewables has decreased.  For example, since 2008 the world market cost of photovoltaic modules have fallen by 80%, while prices for wind turbines, a more mature technology, have fallen 29%.  So capacity expansion has continued globally, with the usually conservative IEA now suggesting that renewables could be supplying 25% of global electrical power by 2018: see my next post. So perhaps its not surprising that there is a lot of optimism- this is one area where there is clearly economic growth.

This entry was posted in Renew your energy and tagged , , , , , , , , . Bookmark the permalink.
View all posts by this author 


  1. Trackback: Talking renewables up- and down – environmentalresearchweb (blog) | Renewable Energy News

  2. I think David Keith’s analysis looked only at onshore wind farms, and thus excludes the immense offshore resource. It also makes a testable prediction: that energy density per unit land area from onshore wind farms will peak at around 1 W per square metre, for farms larger than 100 square km.

    We don’t yet have onshore windfarms with modern turbines at that scale, but we probably will soon, at which point, Keith’s predictions can be tested. It would also be interesting to see if Keith’s model could make a similar prediction for offshore windfarms, as we will probably have more data about large offshore windfarms sooner than onshore.

Leave a comment

Your e-mail address will not be published.


  • Comments should be relevant to the article and not be used to promote your own work, products or services.
  • Please keep your comments brief (we recommend a maximum of 250 words).
  • We reserve the right to remove excessively long, inappropriate or offensive entries.

Show/hide formatting guidelines

Tag Description Example Output
<a> Hyperlink <a href="">google</a> google
<abbr> Abbreviation <abbr title="World Health Organisation" >WHO</abbr> WHO
<acronym> Acronym <acronym title="as soon as possible">ASAP</acronym> ASAP
<b> Bold <b>Some text</b> Some text
<blockquote> Quoted from another source <blockquote cite="">IOP</blockquote>
<cite> Cite <cite>Diagram 1</cite> Diagram 1
<del> Deleted text From this line<del datetime="2012-12-17"> this text was deleted</del> From this line this text was deleted
<em> Emphasized text In this line<em> this text was emphasised</em> In this line this text was emphasised
<i> Italic <i>Some text</i> Some text
<q> Quotation WWF goal is to build a future <q cite="">
where people live in harmony with nature and animals</q>
WWF goal is to build a future
where people live in harmony with nature and animals
<strike> Strike text <strike>Some text</strike> Some text
<strong> Stronger emphasis of text <strong>Some text</strong> Some text