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Renewable Energy Resources

3rd Edition

By John Twidell, Tony Weir

Routledge – 2015 – 768 pages

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    February 6th 2015
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    February 5th 2015
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Renewable Energy Resources is a numerate and quantitative text covering the full range of renewable energy technologies and their implementation worldwide. Energy supplies from renewables (such as from biofuels, solar heat, photovoltaics, wind, hydro, wave, tidal, geothermal, and ocean-thermal) are essential components of every nation’s energy strategy, not least because of concerns for the local and global environment, for energy security and for sustainability. Thus in the years between the first and this third edition, most renewable energy technologies have grown from fledgling impact to significant importance because they make good sense, good policy and good business.

This Third Edition is extensively updated in light of these developments, while maintaining the book’s emphasis on fundamentals, complemented by analysis of applications. Renewable energy helps secure national resources, mitigates pollution and climate change, and provides cost effective services. These benefits are analysed and illustrated with case studies and worked examples. The book recognises the importance of cost effectiveness and efficiency of end-use. Each chapter begins with fundamental scientific theory, and then considers applications, environmental impact and socio-economic aspects before concluding with Quick Questions for self-revision and Set Problems. The book includes Reviews of basic theory underlying renewable energy technologies, such as electrical power, fluid dynamics, heat transfer and solid-state physics. Common symbols and cross-referencing apply throughout; essential data are tabulated in appendices.

An associated eResource provides supplementary material on particular topics, plus a solutions guide to Set Problems.

Renewable Energy Resources supports multi-disciplinary master degrees in science and engineering, and specialist modules in first degrees. Practising scientists and engineers who have not had a comprehensive training in renewable energy will find it a useful introductory text and a reference book.


"Renewable energy requires an active approach, based on facts and data. Twidell and Weir, drawing on decades of experience, demonstrate this, making clear connections between basic theoretical concepts in energy and the workings of real systems. It is a delight to see the field having advanced to this level, where a book like Renewable Energy Resources can focus on the very real experiences of the energy systems of the coming decades."Professor Daniel Kammen, Director, Renewable and Appropriate Energy Laboratory, University of California, Berkeley, USA

"Solar and wind power are now proven, reliable, ever-cheaper sources of electricity that can play a major role in powering the world. Along with other long-established renewables such as hydropower, and complemented by improved energy efficiency and appropriate institutional support, they can be key to sustainable development. This book can play a vital role in educating the people who are needed to make it happen." Professor Martin Green, Director, Australian Centre for Advanced Photovoltaics, University of New South Wales, Australia

"The solar revolution that’s been talked about for so long is with us here and now. This new edition of Renewable Energy Resources, like earlier editions, will undoubtedly make a significant contribution to informing both those involved with the technology and those in policy-making. This is critical if the promise of renewable energy is to be delivered as expeditiously and cost-effectively as is now needed."Jonathon Porritt, Founder Director, Forum for the Future

"I welcome this excellent third edition of Twidell and Weir with its comprehensive yet accessible coverage of all forms of renewable energy. The technologies and the physics behind them are explained with just the right amount of math, and they include a realistic summary of the economic and societal implications."Emeritus Professor William Moomaw, Tufts University, USA and Coordinating Lead Author, IPCC Special Report on Renewable Energy

"I highly recommend this book for its thorough introduction to all the important aspects of the topic of Renewable Energy Resources. The book is excellent in its completeness and description of the relevant different sources. Moreover it is strong in theory and applications. From a scientific and engineering point this book is a must".Professor Henrik Lund, Aalborg University, Denmark and Editor-in-Chief of the international journal Energy

"Over the years, I have used this excellent text for introducing Physics and Engineering students to the science and technology of renewable energy systems. The updated edition will be of immense value as sustainable energy technologies join the mainstream and there is an increasing need for human capacity at all levels. I look forward to the new edition and hope to use it extensively."Dr Atul Raturi, University of the South Pacific, Fiji

"Our school has used Renewable Energy Resources since 2005, as it was one of the few texts that covered the field with a good balance between background theory and practical applications of RE systems. The new updated edition looks great and I am looking forward to using it in my classes."Dr Alistair Sproul, University of New South Wales, Australia

"I have used the extremely valuable second edition of this book for our postgraduate courses on energy conversion technologies. My students and I welcome this new edition, as it has been very well updated and extended with study aids, case studies and photos which even further improve its readability as a textbook." –Dr Wilfried van Sark, Utrecht University, Netherlands

Praise for the 2nd edition

'Twidell and Weir are masters of their subject and join the ranks of acomplished authors who have made a powerful contribution to the field. Renewable Energy Resources is a superb reference work.' - Paul Gipe,

'It's ideal for student use - authoritative, compact and comprehensive, with plenty of references out to more detailed texts … a very valuable book.' - Professor Dave Elliott of the Open University, UK, in Renew 162 2006

'What we need to combat climate change is a stream of students and graduates with the knowledge they can gain from this book … suitable not only for engineering students but also for policy-makers and all those concerned with energy and the environment.' - Corin Millais (CEO Climate Institute)


1. Principles of Renewable Energy 2. Solar Radiation and the Greenhouse Effect 3. Solar Water Heating 4. Other Solar Thermal Applications 5. Photovoltaic Power Technology – PV 6. Hydropower 7. Wind Resource 8. Wind Power Technology 9. Biomass Resources from Photosynthesis 10. Bioenergy Technologies 11. Wave Power 12. Tidal-current and Tidal-range Power 13. Ocean Gradient Energy: OTEC and Osmotic Power 14. Geothermal Energy 15. Energy Systems: Integration, Distribution and Storage 16. Using Energy Efficiently 17. Institutional and Economic Factors Review 1: Electrical Power Review 2: Fluid Dynamics Review 3: Heat Transfer Review 4: Solid State Physics for Photovoltaics Review 5: Units and Conversions: Algebraic Method Appendix A: Units and Conversions Appendix B: Data Appendix C: Some Heat Transfer Formulas Appendix D: Comparisons of Technologies Short Answers to Selected Problems Index

Author Bio

John Twidell has considerable experience in renewable energy as an academic professor in both the UK and abroad, teaching undergraduate and postgraduate courses and supervising research students. He has participated in the extraordinary growth of renewable energy as a research contractor, journal editor, board member of wind and solar professional associations and company director. University positions have been in Scotland, England, Sudan and Fiji. The family home operates with solar heat and electricity, biomass heat and an all-electric car; the aim is to practice what is preached.

Tony Weir has worked on energy and environment issues in the Pacific Islands and Australia for over 30 years. He has researched and taught on renewable energy and on climate change at the University of the South Pacific and elsewhere, and was a Lead Author for the 2011 IPCC Special Report on Renewable Energy. He has also managed a large international program of renewable energy projects and been a policy adviser to the Australian Government, specialising in the interface between technology and policy.


Web-based eResource ‘Supplementary Material’

The information in this eResource supports and supplements the 3rd edition of our university and college textbook on the science, technology and applications of renewable energy.  At each new edition, we find that the central and associated subjects have grown extensively, so despite the noticeable increase in length, some material has to be left out.  This eResource allows us to make such material from earlier editions available to present readers.  In addition, we have other related information and articles that can be included here; all within the title of Supplementary Material.

The authors intend to update the e-Resource from time to time;  some likely updates are listed below.

The material is predominantly ‘open-access’.  However, the eResource also includes additional information for instructors, such as guidance for solving the Set Problems of each chapter.  Access to this information is only by password provided by the publisher to accredited instructors.

The authors welcome comments on this material and any other aspects of the book, not least any errors you may spot.  Comments may be sent to

Each of the items referred to in this  Supplementary Material  has a number like Sx.y , where x is the chapter in Renewable Energy Resources to which it is most closely related.


S1.1 The Political and ethical case for renewable energy (John Twidell). A general article written to support numerous presentations to academic,  professional  and private groups.   Download  (460kB)

S5.1 Brillouin zones  Further information supporting Review 4 on the solid state physics of photovoltaic materials, e.g. silicon.  Download (130kB)

S6.1 Hydraulic ram  Lightly edited extract from chapter 6 of 2nd edition.  Download (130kB)

S8.1 Acoustic sound (noise) from wind turbines (John Twidell)  Download (760kB)

S8.2 Note on wind turbine shadow flicker (John Twidell)  Download (170kB)

S9.1 The photosynthetic process  Here we provide the whole of Chapter 10 of 2nd edition, which included more detail on photosynthesis than could be included in the 3rd edition.   Download (350kB)

S11.1  Summary table of wave power developments (John Twidell).  It was decided not to include this table in the text of the 3rd edition because of the rapidly changing developments in wave power commercial developments at the time.  Having the information as eResource allows hyperlinks to updated web information.   Download (1.1 MB)

S12.1 Tidal power analysis.  This is Chapter 13 of  the 2nd edition, which  included a fuller analysis of the cause of tides than could be included in the 3rd edition.  Download (300kB)

S13.1  Ocean Thermal Energy Conversion (OTEC). For the 3rd edition we reduced the material on OTEC because the technology has not become commercial.  This link leads to the greater detail of  chap 14 of  the 2nd edition.   Download (570kB)

S15.1Assessing Backup Requirements for Wind Power.  (John Twidell).  A summary of the technical methods used by the UK National Grid to balance the national load with all forms of generation, including wind power.   Download (570kB) 

S17.1 Climate Change and Renewable Energy: Implications for the Pacific Islands of a  Global Perspective  (Tony Weir) 
Article published in Journal of Pacific Studies, vol 32(2), pages 4-30 (2012).
PDF (590kb) downloadable directly here(If direct link does not work, search for  the journal site and go from there.)

SR3.1 Convective cooling of a cooking pot
(worked example of a heat transfer calculation)

SR4.1 Periodic table of elements.  
Note that Renewable Energy Resources, like most of the semiconductor physics literature, uses the ‘old’ [Roman numerals]  notation  to denote the groups of the periodic table, as explained by Wikipedia.

SR5.1 A useful extension of the ‘algebraic method’ for converting units (Tony Weir)
This extension covers the case where ‘A yields B’ , rather than A=B as  a physical identity.

SSA  Short answers to end-of-chapter Problems  As also printed in the 3rd edition. Download



*  An on-going collection of useful bibliography and web links (additional to those listed in the 3rd edition)

*  Gallery of colour photosRenewable Energy Resources includes many photos of actual installations, but they are printed in grey-scale.  Some of the original photos may be reproduced here in colour.  Note that all such photos have copyright provisos and may be reproduced only with permission  of the original copy-right holder.  We may include also links to other photos not printed in the book.

* Additional Problems (exercises for students) . These would be of the same type as those already at the end of each chapter of Renewable Energy Resources.

Instructor Resources



Each of the 17 chapters in our book ends with a set of Problems.  These refer to material in the particular chapter and most require quantitative analysis. The standard of the Problems varies considerably.  A few merely require data to be plugged into the appropriate equation in the text; most require some independent thought and awareness of broader issues; others (usually marked * ) are opened-ended and best considered in a tutorial or class context with direct guidance from the instructor. 

We encourage students to be questioning and critical.  It is good practice if they try to estimate by ‘gut feel’ the order of magnitude of answers before they start formal analysis.  They should record such estimates and compare them with their final analytical answer; often the estimate is correct and the formal calculation wrong, because of a mistake in calculation that is then found by careful checking.

Our worked solutions include comments and detail to save the time of Instructors and to give suggestions for discussion.  There are a few Excel spreadsheets included in this e-Resource; they are used in the solutions for chapters 8 and 17. We hope these are useful for you and we welcome feed-back.  Please email your comments and ideas to John Twidell ( and Tony Weir (

A final comment about units. Review 5 of RER  explains our recommendations for keeping units within equations; i.e. using units algebraically.  We cannot stress enough the importance of doing this; an answer is only correct if its units are correct.  If you have not been accustomed to this method of working, it will seem strange at first; however we firmly believe you will be won over soon and thereafter be as convinced as we are. (See also the file SR5-1 in the open-access’ part of this e-Resource.)

Downloadable Files:

To download the instructor material, please register for access to the Instructor Downloads page. One of our sales reps will provide you with a username and password, in order to download the files.

Name: Renewable Energy Resources: 3rd Edition (Paperback)Routledge 
Description: By John Twidell, Tony Weir. Renewable Energy Resources is a numerate and quantitative text covering the full range of renewable energy technologies and their implementation worldwide. Energy supplies from renewables (such as from biofuels, solar heat, photovoltaics, wind, hydro,...
Categories: Energy, Power & Energy, Building and Construction, Renewable Energy, Bio Energy, Clean Technologies, Renewable Energy, Energy efficiency, Energy policy and economics, Solar energy, Wind energy