LOW←TECH MAGAZINE English

The Compressed Book Edition

Thu, 20 Mar 2025 00:00:00 +0000

Image: The Compressed Book Edition. Image by Marie Verdeil and Hugo Lopez.

The Compressed Edition is available in our bookshop as a paperback and hardcover.

In 2018, Low-tech Magazine launched a low-energy website that runs on solar power. To reduce energy use and make the content accessible for readers with old computers and slow internet connections, we opted for a back-to-basics web design, optimising image and file sizes, as well as using a static site generator instead of a database-driven content management system. In 2019, we also launched a book edition of Low-tech Magazine, which consists of three volumes with articles and one volume with comments.

The Compressed Book Edition

While a book looks and feels more low-tech than a website, it has an environmental footprint as well. Industrial book publishing and distribution involves wood harvesting, pulp and paper production, printing, ink-making, and lots of shipping throughout the supply chain. Even if the wood for paper production is harvested sustainably, which is rarely the case, all these processes require energy and produce carbon emissions.

To address these issues, and to keep practicing what we preach, Low-tech Magazine has now made a “compressed edition” of the chronological book series. Inspired by the image compression on our website, we squeezed the article catalog of three volumes into just one book. Consequently, we reduced the paper consumption and carbon emissions by almost a factor of three. The compressed edition contains 84 articles and over 700 images on slightly more than 600 pages.

We did this by switching to a smaller font size (similar to the one used in the comments book), by downsizing most images, and by opting for a two-column layout. I rewrote some articles, especially older ones, resulting not only in fewer pages but also in better articles. Laia Comellas and Marie Verdeil collaborated on the design of the compressed edition.

Image: The original, "uncompressed" book series. Image by Marie Verdeil and Hugo Lopez.

Books or Website?

Ever since the launch of the book collection, readers have asked what is most sustainable: reading Low-tech Magazine online or on paper? While it’s a relevant question, comparing the carbon emissions of books and websites is complex and somewhat pointless. There are so many variables influencing this calculation that you could tilt the result toward your preferred answer.

Comparing the carbon emissions of books and websites is complex and somewhat pointless.

A crucial factor is the time spent reading. If you only read a few articles, reading online likely has a lower carbon footprint. But, if you read all articles, and maybe even go back to them regularly afterward, the difference between online and offline reading becomes smaller. For the books, all carbon emissions occur before the reading process starts. In contrast, the more time you spend on the website, the higher the carbon emissions. ¹

There’s another difference between online and offline reading: Unlike a website, a book can be read by more than one person without raising its carbon emissions — for example, when it’s available in a library. ² Books usually have very long lifetimes, between 25 and 500 years. ³ Therefore, they can be read by dozens of people. That is especially the case for hardcover books, which take a bit more resources to produce than paperbacks but are more resistant to abuse.

Carbon Emissions & Energy Use

To estimate the carbon emissions of Low-tech Magazine’s books, I used a study of a 320-page hardcover book weighing 0.75 kg. ³ According to the researchers, the complete production process of the book has a carbon footprint of between 2 and 3 kg of CO2-equivalents, depending on what happens when the book is discarded after 25 years (landfill or recycling).

The three “uncompressed” paperback books together weigh 2,531 grams, which corresponds to an estimated carbon footprint of between 6.7 and 10.1 kg CO2-equivalents. For the compressed edition, at 929 grams, the carbon footprint comes down to between 2.48 and 3.70 kg of CO2-equivalents. These numbers are surprisingly high compared to the carbon footprint of Low-tech Magazine’s web server, which we calculated to be 9 kg CO2-equivalents per year. ⁴ Although our web server runs on solar power, these carbon emissions result from producing the solar panel, the battery, the solar charge controller, and the printed circuit boards, measured across their estimated lifetime.

However, the book does not require any infrastructure to be read, while the carbon footprint of our web server is only one part of the total footprint of the website. Readers of the website need a computer to access it, and the resulting energy use and carbon emissions of powering and manufacturing that device should also be included. Assuming 60 hours to read all the articles, a laptop power use of 25-50 watts, and the average power grid carbon intensity in Europe (300g/kWh), the power use of the laptop would add between 0.45 and 0.90 kg of carbon emissions for reading content online.

Image: The Compressed Book Edition (hardcover). Image by Marie Verdeil and Hugo Lopez.

To this should be added the energy that was required to manufacture the laptop and the power grid (of which in both cases only a part can be attributed to reading Low-tech Magazine). Because life cycle analyses show that the energy used for manufacturing a laptop surpasses its operational energy use, we can — conservatively — double this result to between 0.90 kg and 1.8 kg of CO2-equivalents. ⁵ Because our website uses very little energy, almost the complete carbon footprint of Low-tech Magazine is due to the devices of our readers.

The book needs to be read by at least two to three people before its environmental footprint becomes smaller than the one caused by reading all Low-tech Magazine articles online.

Nevertheless, this carbon footprint is still lower than the 3 kg of CO2-equivalents for the compressed book edition. Although this is a very rough estimate, it seems to suggest that this book needs to be read by at least two to three people before its environmental footprint becomes smaller than the one caused by reading all Low-tech Magazine articles online. Of course, we have set the bar very high for ourselves because of our light-weight website. Compared to the old blog, which was much more carbon-intensive than the solar-powered website, the compressed book edition — and perhaps even the uncompressed book edition — would be the more sustainable option even if it is read only by one person.

How Many Trees Have We Cut Down?

The environmental footprint of books does not only show in carbon emissions. Books are made from paper, and paper is — nowadays — almost exclusively made from dead trees. With close to 10,000 Low-tech Magazine books sold, an uncomfortable question pops up: how many trees did I kill? That is not an easy question to answer, because the only reference I could find says that “one tree can produce 25 books” ⁶, without specifying what size of tree or type of book these numbers refer to.

Nevertheless, if this estimation is valid, the Low-tech Magazine books would be responsible for chopping down roughly 400 unspecified trees. Whether or not these trees were replaced by other trees, I have no way of knowing. However, by reducing the page number from 1,700 to a little over 600 pages, at least the Compressed Edition attempts to limit this resource use.

Compressing the content — an editorial and design choice — produces a larger reduction in resource use than printing on recycled paper could ever do.

Low-tech Magazine’s “tree consumption” could be further reduced by printing on recycled paper, and we would probably do so if our book distributor and printer — Lulu — would offer that option. However, printing on recycled paper is not a panacea. Paper can only be recycled a couple of times before it needs to be incinerated or landfilled.

Partly because of this, and partly because of economic growth, there is not enough recycled paper available to print the ever-increasing number of books that are published each year. If Low-tech Magazine prints on recycled paper, it means that someone else won’t. Moreover, printing on recycled paper often increases the carbon emissions of paper production. ³ Compressing the content — an editorial and design choice — produces a larger reduction in resource use than printing on recycled paper could ever do.

How Many Books are Thrown Away?

The carbon footprint and wood consumption of an individual book only tell a part of the story. Most environmental damage in the book industry is done by overproduction. A very large number of printed books are not sold but discarded before anyone can read them. Overproduction occurs in two ways. First, most books that come on the market fail commercially, which is a consequence of the business strategies of book publishers. ⁷ Large publishers invest in a massive number of titles in the hope that one will become a bestseller.

Image: The Compressed Book Edition (paperback). Image by Marie Verdeil and Hugo Lopez.

Second, higher print runs significantly lower the printing costs per copy, and thus encourage overproduction. To give an example, printing 100 copies of a 600-page book costs 7,3 euros per copy, while printing 1,000 copies costs only 4,30 euros per copy. ⁸ As a result, it can be more profitable to print more books and discard the unsold copies. Even books that are in demand can be thrown away. For example, unsold copies at events are usually destroyed rather than sent back to publishers because it’s cheaper. ⁹

A less wasteful approach is printing on demand, in which a copy only gets printed once it is bought. In this case, there is no waste unless a book is printed badly. However, the energy use and carbon emissions per printed copy are probably higher, with the printing equipment taking a larger share in the total resource use. The printing costs are much higher, too (around 15 euros per copy for a 600-page book). ¹⁰ Almost all Low-tech Magazine books are printed on demand, but we can only do this because we have our own direct sales channel (the website). If books are sold through Amazon or in bookstores, print-on-demand results in a very high sales price or a very low profit for the book publisher.

Other Low-tech Magazine Books

The launch of the compressed edition does not mean that the “uncompressed” books will no longer be for sale. They will be redesigned in the next months, reflecting the same changes in articles (shorter and better) but printed with a larger font, larger images, and a one-column layout. Their carbon footprint will decrease compared to the earlier volumes but in a less spectacular way. Nevertheless, while those uncompressed books remain the most comfortable option for reading Low-tech Magazine, we expect a significant part of potential buyers to opt for the more compact edition, as it provides the most bang for the buck.

Obviously, “compressing” the books also addresses printing costs, which have skyrocketed in the last few years. Higher printing costs result in a higher sales price and a lower profit, or both. The compressed edition allows us to roughly halve the sales price for the whole archive while maintaining two-thirds of the profit. For the redesigned uncompressed editions, a more modest reduction in the page number will allow us to keep the current sales price but restore the profit per copy to pre-pandemic levels — important for the survival of the magazine. After all, people buy books for the content they contain, not for their weight on paper.

Ebooks and Thematic Books

The Compressed Edition is part of an ongoing research project into the sustainability of Low-tech Magazine’s publishing operations. Apart from the solar-powered website, we have introduced ebooks (2024), and these are perhaps the most sustainable option to read Low-tech Magazine. We also started the publication of a thematic books series (2023), aimed at people who are only interested in certain topics and themes of Low-tech Magazine. The ebooks and thematic books are made in collaboration with Marie Verdeil.

Book Launch Event

We hold a book launch event in Barcelona on March 28.

Image: Book launch event in Barcelona. Poster by Hugo Lopez.

That is mainly because of the energy use of the end-use devices that people use to access the website. Surprisingly, the number of website visitors has no influence on the power use of our web server. That is likely due to the fact that it is a very lightweight, static website. For “normal”, dynamic websites, the energy use is closely related to the number of visitors. ↩︎
Low-tech Magazine’s books are available in several libraries. See: https://search.worldcat.org. If it is not available in your local library, you can file an acquisition request there. ↩︎
Wells, Jean‐Robert, et al. “Carbon footprint assessment of a paperback book: Can planned integration of deinked market pulp be detrimental to climate?.” Journal of Industrial Ecology 16.2 (2012): 212-222. ↩︎ ↩︎ ↩︎
See: “How sustainable is a solar powered website?”: https://qelnixcor.cloud/2020/01/how-sustainable-is-a-solar-powered-website/ ↩︎
There’s also the power use of the router. However, while the grid-powered router uses 240 Wh of electricity per day, it is shared by all website visitors (and by the author). Even on a calm day (around 2,000 unique visitors), extra energy use due to the router is only 0.12 watt-hour per visitor. That is much lower than the energy use of the laptop, even during a relatively short visit. ↩︎
https://publishyourpurpose.com/blog/environmental-impact-book-publishing/ ↩︎
Biel, Joe. People’s Guide to Publishing: Building a Successful, Sustainable, Meaningful Book Business From the Ground Up. Microcosm Publishing, 2018. ↩︎
Based on the prices of expresta.eu ↩︎
Bookstores need to prove that they destroyed the books by ripping off the covers and sending them to the publisher. Source: personal communication with book sellers at events. ↩︎
Book cost calculator, Lulu. https://www.lulu.com/pricing ↩︎

How to Design a Sailing Ship for the 21st Century?

Tue, 11 May 2021 00:00:00 +0000

On board the ship *Garthsnaid* at sea. A view from high up in the rigging. Image by Allan C. Green, circa 1920.

The sailing ship is a textbook example of sustainability. For at least 4,000 years, sailing ships have transported passengers and cargo across the world’s seas and oceans without using a single drop of fossil fuels. If we want to keep travelling and trading globally in a low carbon society, sailing ships are the obvious alternative to container ships, bulk carriers, and airplanes.

However, by definition, the sailing ship is not a carbon neutral technology. For most of history, sailing ships were built from wood, but back then whole forests were felled for ships, and those trees often did not grow back. In the late nineteenth and early twentieth century, sailing ships were increasingly made from steel, which also has a significant carbon footprint.

The carbon neutrality of sailing in the 21st century is even more elusive. That’s because we have changed profoundly since the Age of Sail. Compared to our forebears, we have higher demands in terms of safety, comfort, convenience, and cleanliness. These higher standards are difficult to achieve unless the ship also has a diesel engine and generator on-board.

The revival of the sailing ship

The sailing ship has seen a modest revival in the last decade, especially for the transportation of cargo. In 2009, Dutch company Fairtransport started shipping freight between Europe and the Americas with the Tres Hombres, a sailing ship built in 1943. The company remains active today and has a second ship in service since 2015, the Nordlys (built in 1873).

Since then, others have joined the sail cargo business. In 2016, the German company Timbercoast started shipping cargo with the Avontuur, a ship built in 1920. ¹ In 2017, the French Blue Schooner Company started transporting cargo between Europe and the Americas with the Gallant, a sailing ship that was built in 1916. ² All these sailing ships were constructed in the twentieth or nineteenth century, and were restored at a later date. However, a revival of sail cannot rely on historical ships alone, because there’s not enough of them. ³

The Noach, built in 1857.

At the moment, there are at least two sailing ships in development that are being built from scratch: the Ceiba and the EcoClipper500. The first ship is being constructed in Costa Rica by a company named Sailcargo. She is built from wood and inspired by a Finnish ship from the twentieth century. The second ship is designed by a company called EcoClipper, which is led by one of the founders of the Dutch FairTransport, Jorne Langelaan. Their EcoClipper500 is a steel replica of a Dutch clipper ship from 1857: the Noach.

“Old designs are not necessarily the best", says Jorne Langelaan, “but whenever proven design is used, one can be sure of its performance. A new design is more of a gamble. Furthermore, in the 20th and 21st century, sailing technology developed for fast sailing yachts, which is an entirely different story compared to ships which need to be able to carry cargo.”

More economical sailing ships

These two ships – one under construction and one in the design phase – have the potential to make sail cargo a lot more economical than it is today. That’s because they have a much larger cargo capacity than the sailing ships currently in operation. As a ship becomes longer, her cargo capacity increases more than proportionally.

The EcoClipper500 is a full-scale replica of the Noach.

The 46 metre long Ceiba is powered by 580 m2 of sails and carries 250 tonnes of cargo. The 60 metre long EcoClipper500 is powered by almost 1,000 m2 of sails and takes 500 tonnes of cargo. For comparison, the Tres Hombres is not that much shorter at 32 metres, but she takes only 40 tonnes of cargo – twelve times less than the EcoClipper500. A larger ship is also faster and saves labour. The Tres Hombres requires a crew of seven, while the EcoClipper500 only has a slightly larger crew of twelve.

Life cycle analysis of a sailing ship

Although the EcoClipper500 is still in the design phase, she will be the focus of this article. This is because the company conducted a life cycle analysis of the ship prior to building it. ⁴ As far as I know, this is the first life cycle analysis of a sailing ship ever made. The study reveals that it takes around 1,200 tonnes of carbon to build the ship.

Half of those emissions are generated during steel production, and roughly one third is generated by steel working processes and other shipyard activities. Solvent-based paints as well as electric and electronic systems each account for roughly 5% of emissions. The emissions produced during the manufacturing of the sails are not included because there are no scientific data available, but a quick back-of-the-envelope calculation (for sails based on aramid fibres) signals that their contribution to the total carbon footprint is very small. ⁵

The EcoClipper500 has a carbon footprint of 2 grammes of CO2 per tonne-kilometre, which is five times less than the carbon footprint of a container ship.

If these 1,200 tonnes of emissions are spread out over an estimated lifetime of 50 years, then the EcoClipper500 would have a carbon footprint of about 2 grammes of CO2 per tonne-kilometre of cargo, concludes researcher Andrew Simons, who made the life cycle analysis for the ship. This is roughly five times less than the carbon footprint of a container ship (10 grammes CO2/tonne-km) and three times less than the carbon footprint of a bulk-carrier (6 grammes CO2/tonne-km). ⁶

Looking aft from aloft on the 'Parma' while at anchor. Alan Villiers, 1932-33. Villiers's work vividly records the period of early 20th century maritime history when merchant sailing vessels or ‘tall ships’ were in rapid decline.

Transporting one ton of cargo over a distance of 8,000 km (roughly the distance between the Caribbean and the Netherlands) would thus produce 16 kg of carbon with the EcoClipper500, compared to 80 kg on a container ship and 48 kg on a bulk carrier. The proportions are similar for other environmental factors, such as ozone depletion, ecotoxicity, air pollution, and so on.

Although the sailing ship boasts a convincing advantage, it may not be as big as you might have expected. First, as Simons explains, there’s scale. A container ship or bulk carrier enjoys the same benefits over the EcoClipper500 as the EcoClipper500 enjoys over the Tres Hombres. It can take a lot more cargo – on average 50,000 tonnes instead of 500 tonnes – and it needs only a slightly larger crew of 20-25 people. ⁷

Second, fossil fuel powered ships are faster than sailing ships, meaning that fewer ships are needed to transport a given amount of cargo over a given period of time. The original ship on which the EcoClipper500 is based, sailed between the Netherlands and Indonesia in 65 to 78 days, while a container ship does it in about half the time (taking the short cut through the Suez canal).

Building a fleet of sailing ships

There’s two ways to further lower the carbon emissions of sailing ships in comparison to container ships and bulk carriers. One is to build ships from wood instead of steel, such as the Ceiba. If the harvested trees are allowed to grow back (which the makers of the Ceiba have promised), such a ship may even be considered a carbon sink.

However, there’s a good reason why the EcoClipper500 will be made from steel: the company’s aim is to build not just one ship, but a fleet of them. Jorne Langelaan: “There are few shipyards who can deliver wooden ships nowadays. Steel makes it easier to build a fleet in a shorter period.”

A possible compromise would be a composite construction, in which a steel skeleton is clad with timber keel, planks, and deck. Andrew Simons: “This would reduce the carbon footprint of construction by half. It could also be feasible to make superstructures and some of the mast sections and spars from timber instead of steel.”

Driving sprays over the main deck of the 'Parma'. Alan Villiers, 1932-33.

Towards the future, another possibility to further decrease a sailings ship’s emissions per tonne-km is to build it even larger. While the EcoClipper500 has much more cargo capacity than the cargo sailing ships now in operation, she is far from the largest sailing ship ever built.

Historical ships such as the Great Republic (5,000 tonnes), the Parma (5,300 tonnes), the France II (7,300 tonnes), and the Preussen (7,800 tonnes), were more than 100 metres long and could take more than ten times the freight capacity of the EcoClipper500. Langelaan already dreams of a EcoClipper3000.

Passengers

Most cargo sailing ships travelling across the oceans today can also take some passengers. Fully loaded with cargo, the EcoClipper500 takes 12 crew members, 12 passengers, and 8 trainees (passengers who learn how to sail). If the upper hold deck is not used for cargo, another 28 trainees can join, so that the ship can take up to 60 people on board (with a smaller cargo volume: 480 m3 instead of 880 m3).

The carbon footprint for passengers amounts to 10 g per passenger-km, compared to roughly 100 g per passenger-km on an airplane.

Consequently, and since ocean liners have disappeared, the EcoClipper500 also becomes an alternative to the airplane. According to the results of the life cycle analysis, the carbon footprint for passengers on the EcoClipper500 amounts to 10 grammes per passenger-kilometre, compared to roughly 100 grammes per passenger-kilometre on an airplane. Transporting one passenger thus produces as much carbon emissions as transporting 1 tonne of freight.

Engine or not?

Importantly, the life cycle analysis of the EcoClipper500 assumes that there is no diesel engine on-board. On a sailing ship, a diesel engine can serve two purposes, which can be combined. First, it allows to propel the ship when there is no wind or when sails cannot be used, for example when leaving or entering a harbour. Second, combined with a generator, a diesel engine can produce electricity for daily life on board of the ship.

For most of history, energy use on-board of a sailing ship was not too problematic. There was firewood for cooking and heating, and there were candles and oil lamps for lighting. There were no refrigerators for food storage, no showers or laundry machines for washing and cleaning, no electronic instruments for navigation and communication, no electric pumps in case of leaks or fire.

However, we now have higher standards in terms of safety, health, hygiene, thermal comfort, and convenience. The problem is that these higher standards are difficult to achieve when the ship does not have an engine that runs on fossil fuels. Modern heating systems, cooking devices, hot water boilers, refrigerators, freezers, lighting, safety equipment, and electronic instruments all need energy to work.

Crewman of the 'Parma' with a model of his ship. Alan Villiers, 1932-33.

Modern sailing ships often use a diesel engine to provide that energy (and to propel the ship if necessary). An example is the Avontuur from Timbercoast, who has an engine of 300 HP, a 20 kW generator, and a fuel tank of 2,330 litres. Large sail training vessels and cruising ships have several engines and generators on-board. For example, the 48m long Brig Morningster has a 450 HP engine and three generators with a total capacity of 100 kW, while the 56m long Bark Europa has two 365 HP engines with three generators – and burns hundreds of litres of oil per day.

Depending on the lifestyle of the people on board, the emissions per passenger-km may rise to, or surpass, the levels of those of an airplane.

Obviously, the emissions and other pollutants of these engines need to be taken into account when the environmental footprint of a sail trip is calculated. Depending on the lifestyle of the people on board, the emissions per passenger-km may rise to, or surpass, the levels of those of an airplane. To a lesser extent, electricity use on-board also increases the emissions of cargo transportation.

Energy use on board a sailing ship

The EcoClipper500 has no diesel engine on board, which is a second reason to focus on this ship. Obviously, a sailing ship without an engine cannot proceed her voyage when there’s no wind. This is easily solved in the old-fashioned way: the EcoClipper500 stays where she is until the wind returns. A ship without an engine also needs tug boats – which usually burn fossil fuels – to get in and out of ports. For the EcoClipper500, these tug services account for 0.3 g/tkm of the total carbon footprint of 2 g/tkm.

Without a diesel engine, the ship also needs to generate all energy for use on board from local energy sources, and this is the hard part. Renewable energy is intermittent and has low power density compared to fossil fuels, meaning that more space is needed to generate a given amount of power – which is more problematic at sea than it is on land.

Renewing caulking on the poop of the 'Parma'. Alan Villiers, 1932-33.

To make the EcoClipper500 self-sufficient in terms of energy use, a first design decision was to shift energy use away from electricity whenever possible. This is especially important for high temperature heat, which cannot be supplied by electric heat pumps. The ship will have a pellet-stove on board to provide space heating, as well as a biodigester – never before used on a ship – to convert human and kitchen waste into gas for cooking. Thermal insulation of the ship is another priority.

Nevertheless, even with pellet-stove and biodigester (which themselves require electricity to operate), and with thermal insulation, energy demand on the ship can be as high as 50 kilowatt-hours of electricity per day (2 kW average power use). This concerns a “worst-case normal operation” scenario, when the ship is sailing in cold weather with 60 people on board. Power use will be lower in warmer weather and/or when less people are taken. During an emergency, the power requirements can amount to 8 kW, while more than 24 kWh of energy can be needed in just three hours.

Hydrogenerators

How to produce this power? Solar panels and wind turbines are only a small part of the solution. Producing 50 kWh of energy per day would require at least 100 square metres of solar panels, for which there is little space on a 60 m long sailing ship. Vulnerability and shading by the sails make for further problems. Wind turbines can be attached in the rigging, but their power output is also limited. The low potential of solar and wind power are demonstrated by the earlier mentioned sailing ship Avontuur. She has a 20 kW generator, powered by the diesel engine, but only 2.1 kW of solar panels and 0.8 kW of wind turbines.

The hydrogenerator is the only renewable power source that can provide a large sailing ship with enough energy for the use of modern technology on board.

The hydrogenerator is the only renewable power source that can provide a large sailing ship with enough energy for the use of modern technology on board. Hydrogenerators are attached underneath the hull and work in the opposite way as a ship’s propeller. Instead of the propeller powering the ship, the ship powers the propeller, which turns a generator that produces electricity. In spite of its name and appearance, the hydrogenerator is actually a form of wind energy: the sails power the propellers. Obviously, this only works when the ship is sailing fast enough.

Furling sail on the main yard of the Parma. Alan Villiers, 1932-33.

The EcoClipper500 will be equipped with two large hydrogenerators, for which Simons calculated the power output at different speeds, taking into account the fact that the extra drag they produce slows down the ship somewhat. He concludes that the EcoClipper500 needs to sail at a speed of at least 7.5 knots to generate enough electricity. At that speed, the hydrogenerators produce an estimated 2,000 watts of power, which converts to roughly 50 kWh of electricity per day (24 hours of sailing).

At a lower speed of 4.75 knots, the generators produce 350 watts, which comes down to 8.4 kWh of energy over a period of 24 hours – only 1/6th of the maximum required energy. On the other hand, at higher speeds, the hydrogenerators produce more energy than necessary. At a speed of almost 10 knots they provide 120 kWh/day, at a speed of 12 knots this becomes 182 kWh/day – 3.5 times more than needed.

Saltwater batteries

According to her hull speed, the EcoClipper500 will be able to sail a little over 16 knots at absolute top speed – this is double the minimum speed required to generate enough power. Achieving this speed will be rare, because it needs calm seas and strong winds from the right direction. Nevertheless, in good wind conditions, the ship easily sails fast enough to produce all electricity for use on board.

Good wind conditions can last for days, especially on the oceans, where winds are more powerful and predictable than on land. However, they are not guaranteed, and the ship will also sail at lower speeds, or find herself in becalmed conditions – when hydrogenerators are as useless as solar panels in the middle of the night.

Because she has no engine, the EcoClipper500 faces a double problem when there’s no wind: she cannot continue her voyage, and she has no energy to maintain life on board.

Because she has no engine, the EcoClipper500 faces a double problem when there’s no wind: she cannot continue her voyage, and she has no energy to maintain life on board. The first problem is easily solved but the second is not. Life on board goes on, and so there is a continued need for power. To provide this, the ship needs energy storage.

To cover the needs for three days drifting in cold weather, an energy storage of 150 kWh would be required, not taking into account charge and discharge losses. Five or seven days of energy use on-board would require 250 to 350 kWh of storage. For emergency use, another 25 kWh of energy storage is needed.

Scraping the deck onboard the 'Parma'. Alan Villiers, 1932-33.

Not having an engine, generator and fuel tank saves space on board, but this advantage can be quickly lost again when one starts to add batteries for the hydrogenerators. Lithium-ion batteries are very compact, but they cannot be considered sustainable and bring safety risks. That’s why Jorne Langelaan and Andrew Simons see more potential in – very aptly – saltwater batteries, which are non-flammable, non-toxic, easy to recycle, have wide temperature-tolerance, and can last for more than 15 years. Like the biodigester, they have never been used on a sailing ship before.

Unlike lithium-ion batteries, saltwater batteries are large and heavy. At 60 kg per kWh of storage capacity, a 150 kWh battery storage would add a weight of 9 tonnes, while a 350 kWh storage capacity would add 21 tonnes. Still, this compares favourably to the total cargo capacity (500 tonnes), and the batteries can serve as ballast if they are placed in the lower part of the ship’s hull. The space requirements are not too problematic, either. Even a 350 kWh energy storage only requires 14 to 29m3 of space, which is small compared to the 880m3 of cargo volume.

The emissions that are produced by the manufacturing of the hydrogenerators, biodigester, and batteries are not included in the life cycle analysis of the ship, because there are no data available. However, these emissions must be relatively small. Hydrogenerators have much higher power density than wind turbines, and thus a relatively low embodied energy. A quick back-of-the-envelope calculation learns that the carbon footprint of 350 kWh saltwater batteries is around 70 tonnes of CO2. ⁸

Human Power

There’s another renewable power source and energy storage on board of the EcoClipper, and that’s the humans themselves. Like the pellet stove and the biodigester, the use of human power could reduce the need for electricity. Nowadays, cargo ships and most large sailing ships have electric or hydraulic winches, pumps, and steering gear, saving manual labour at the expense of higher energy use. In contrast, EcoClipper sticks to manual handling of the ship as much as possible.

Crew at the capstan of the Parma, weighing anchor. Alan Villiers, 1932-33.

Simons and Langelaan are also considering the addition of a few rowing machines, coupled to generators, to produce emergency power. Two rowing machines could provide roughly 400 watts of power. If they are operated around the clock in shifts, they could supply the ship with an extra 9.6 kWh of energy per day (ignoring energy losses) – one fifth of the total maximum electricity use.

In fact, as I tell Simons and Langelaan ten rowing machines operated continually in shifts would provide as much power as the hydrogenerators at a speed of 7.5 knots. If there are 60 people on board, and everybody would generate power for less than one hour per day, no hydrogenerators and batteries would be needed at all. “A very interesting thought”, answers Simons, “but what impression would we be painted with?”

Hot Showers?

Even with a biodigester, hydrogenerators, batteries, and rowing machines, the passengers and crew on board the EcoClipper500 would be far short of luxurious, and perhaps too short of comfortable for some. For example, if 60 people on board the ship would take a daily hot shower – which requires on average 2.1 kilowatt-hours of energy and 76.5 litres of water on land – total electricity use per day would be 126 kWh, more than double the energy the ship produces at a speed of 7.5 knots.

The ship could supply this energy at a higher sailing speed, but there would also be a need for 4,590 liters of water per day, a quantity that could only be produced from seawater – a process that requires a lot of energy. Even a crew of 12 taking a daily hot shower would require 25.2 kWh of energy per day, half of what the hydrogenerators produce at a sailing speed of 7.5 knots. The Bark Europa is the only sailing ship mentioned in this article that has hot showers in every (shared) cabin, but it is also the ship with the biggest generators and the highest fuel use.

On the forecastle head of the Parma in fine weather. Image by Alan Villiers, 1932.

Andrew Simons: “On the EcoClipper500 there needs to be a manageable compromise between energy use and comfort. Energy use on board will have to be actively managed. Resources are finite, just like for the planet. In many ways the ship is a microcosm of challenges that the wider world has to face and find solutions to.”

Jorne Langelaan: “At sea you are in a different world. It doesn’t matter anymore if you can take a daily shower or not. What matters are the people, the movements of the ship, and the vast wilderness of ocean around you”.

Measuring the right things

This article has compared the EcoClipper500 sailing ship with the average container ship, bulk carrier, and airplane in terms of emissions per tonne- or passenger-kilometer. However, these values are abstractions that obscure much more important information: the total emissions that are produced by all passengers and all cargo, over all kilometres.

The international ocean freight trade increased from 4 billion tonnes of cargo in 1990 to 11.2 billion tonnes in 2019, resulting in more than 1 billion tonnes of emissions. International air passenger numbers grew from 1 billion in 1990 to 4.5 billion in 2019, resulting in 915 million tonnes of emissions. Consequently, lowering the emissions per tonne- and passenger-kilometre is neither a necessity nor a guarantee for a reduction in emissions.

If we cut international cargo traffic more than fivefold, and passenger traffic more than tenfold, then the emissions of all container ships and airplanes would be lower than the emissions of all sailing ships carrying 11.2 billion tonnes of cargo and 4.5 billion of passengers. Vice versa, if we switch to sailing ships, but keep on transporting more and more cargo and passengers across the planet, we will eventually produce just as much in emissions as we do today with fossil fuel powered transportation.

The mizzen of the 'Grace Harwar'; view aft from the main crosstrees. Alan Villiers, 1932-33.

Of course, none of this would ever happen. The amount of cargo that was traded across the oceans in 2019 equals the freight capacity of 22.4 million EcoClippers. Assuming the EcoClipper500 can make 2-3 trips per year, we would need to build and operate at least 7.5 million ships, with a total crew of at least 90 million people. Those ships could only take 0.5 billion passengers (12 passengers and 8 trainees per ship), so we would need millions of ships and crew members more to replace international air traffic.

We should not be fooled by abstract relative measurements, which only serve to keep the focus on growth and efficiency.

All of this is technically possible, and as we have seen, it would produce less in emissions than the present alternatives. However, it’s more likely that a switch to sailing ships is accompanied by a decrease in cargo and passenger traffic, and this has everything to do with scale and speed. A lot of freight and passengers would not be travelling if it were not for the high speeds and low costs of today’s airplanes and container ships.

It would make little sense to transport iPhones parts, Amazon wares, sweatshop clothes, or citytrippers with sailing ships. A sailing ship is more than a technical means of transportation: it implies another view on consumption, production, time, space, leisure, and travel. For example, a lot of freight now travels in different directions for each next processing stage before it is delivered as a final product. In contrast, all sail cargo companies mentioned in this article only take cargo that cannot be produced locally, and which is one trip from producer to consumer. ⁹

This also means that even if sailing ships have diesel engines on board, they would still bring a significant decrease in the total emissions for freight and passenger traffic, simply because they would reduce the absolute number of passengers, cargo, and kilometers. We should not be fooled by abstract relative measurements, which only serve to keep the focus on growth and efficiency.

More about the EcoClipper500. Most images: Alan Villiers collection.

Between 1978 and 2004, the Avontuur was operated as sail cargo vessel under Captain Paul Wahlen. The Apollonia, originally built in 1946, is another cargo sailing ship in operation since 2014. It is 19.5 metres long and carries 10 tonnes of cargo. ↩︎
Very recently, Grain de Sail was built and launched for Trans-Atlantic shipping of wine and cocoa. She is a modern sailing ship without an engine, built from aluminium, and can take 35 tonnes of cargo. ↩︎
Andrew Simons: “There are plenty historical sailing ships, but either very costly to get into service as a regulatory compliant cargo vessel, because they are still used for other purposes, or not suitable.” ↩︎
The study can be downloaded when you subscribe to EcoClipper’s newsletter. The research is based on a typical life cycle analysis, but note that this is not a peer reviewed study. ↩︎
Unfortunately the envelope got lost. ↩︎
In the case of the EcoClipper, most of the emissions are produced during the construction of the ship, while in the case of bulk carriers and container ships, they are mainly produced during operation and fuel production. ↩︎
The largest container ships now take 190,000 tonnes of cargo. ↩︎
There is not much data available on saltwater batteries, but they are less energy-intensive to build than many other types of batteries. The calculation is based on an estimate of 66 kg CO2/kWh of storage capacity and three generations of batteries over a period of 50 years. ↩︎
Almost one third of all cargo transported are fossil fuels themselves. ↩︎

How to Make Wind Power Sustainable Again

Sun, 02 Jun 2019 00:00:00 +0000

Illustration: Eva Miquel for Low-tech Magazine.

For more than two thousand years, windmills were built from recyclable or reusable materials: wood, stone, brick, canvas, metal. When – electricity producing – wind turbines appeared in the 1880s, the materials didn’t change. It’s only since the arrival of plastic composite blades in the 1980s that wind power has become the source of a toxic waste product that ends up in landfills.

New wood production technology and design makes it possible to build larger wind turbines almost entirely out of wood again – not just the blades, but also the rest of the structure. This would solve the waste issue and make the manufacturing of wind turbines largely independent of fossil fuels and mined materials. A forest planted in between the wind turbines could provide the wood for the next generation of wind turbines.

How Sustainable is a Windmill Blade?

Wind turbines are considered to be a clean and sustainable source of power. However, while they can indeed generate electricity with lower CO2-emissions than fossil fuel power plants, they also produce a lot of waste. This is easily overlooked, because roughly 90% of the mass of a large wind turbine is steel, mainly concentrated in the tower. Steel is commonly recycled and this explains why wind turbines have very short energy payback times – the recycled steel can be used to produce new wind turbine parts, which greatly lowers the energy required during the manufacturing process.

However, wind turbine blades are made from light-weight plastic composite materials, which are voluminous and impossible to recycle. Although the mass of the blades is limited compared to the total mass of a wind turbine, it’s not negligible. For example, one 60 m long fiberglass blade weighs 17 tonnes, meaning that a 5 MW wind turbine produces more than 50 tonnes of plastic composite waste from the blades alone.

Image: A fiberglass reinforced plastic blade. Source: [Gurit](https://www.gurit.com/Our-Business/Industries--Markets/Wind).

A windmill blade typically consists of a combination of epoxy – a petroleum product – with fiberglass reinforcements. The blades also contain sandwiched core materials, such as polyvinyl chloride foam, polyethylene terephtalate foam, balsa wood (intertwined in fibers and epoxy) and polyurethane coatings. ¹²³⁴

Unlike the steel in the tower, the plastic in blades cannot be recycled to make new plastic blades. The material can only be “downcycled”, for instance by shredding it, which damages the fibers and makes them useless for anything but a filler reinforcement in cement or asphalt production. Other methods are being investigated, but they all run into the same problem: nobody wants the “recycled” material. Some architects have re-used windmill blades, for example to build benches or playgrounds. But we cannot build everything out of wind turbine blades.

A 5 MW wind turbine contains more than 50 tonnes of unrecyclable plastic in the blades alone.

Because of the limited options for recycling and re-use, windmill blades are usually landfilled (in the US) or incinerated (in the EU). The latter approach is not less unsustainable, because incinerating the blades only partially reduces the amount of material to be landfilled (60% of the scrap remains as ash) and converts the rest into air pollution. Furthermore, given that fiberglass is incombustible, the caloric value of the blades is so limited that little or no power can be produced. ¹²³⁴

Dealing With Waste – 25 Years Later

Most of the roughly 250,000 wind turbines now in operation worldwide were installed less than 25 years ago, which is their estimated life expectancy. However, the rapid growth of wind power over the last two decades will soon be reflected in a delayed but ever increasing and never-ending supply of waste materials.

For example in Europe, the share of installed wind turbines older than 15 years increases from 12% in 2016 to 28% in 2020. In Germany, Spain and Denmark, their share increases to 41-57%. In 2020 alone, these countries will each have to dispose of 6,000 to 12,000 wind turbine blades. ⁵

Image: Old-fashioned windmills had sails made entirely from recyclable materials. Image: Rasbak (CC BY-SA 3.0)

Discarded blades will not only become more numerous but also larger, reflecting a continuous trend towards ever larger rotor diameters. Wind turbines built 25 years ago had blade lengths of around 15-20 m, while today’s blades reach lengths of 75-80 m or more. ³ Estimates based on current growth figures for wind power have suggested that composite materials from blades worldwide will amount to 330,000 tonnes of waste per year by 2028, and to 418,000 tonnes per year by 2040. ¹

The rapid growth in wind power over the last two decades will soon be reflected in a delayed but ever increasing and never-ending supply of waste materials.

These are conservative estimates, because numerous blade failures have been reported, and because constant development of more efficient blades with higher power generating capacity is resulting in blade replacement well before their estimated lifespan. ¹⁶ Furthermore, this amount of waste results from wind turbines installed between 2005 and 2015, when wind power only supplied a maximum of 4% of global power demand. If wind would supply a more desirable 40% of (current) power demand, there would be three to four million tonnes of waste per year.

Windmill Blades Through History

Yet a look at the history of wind power shows that plastic is not an essential material. The use of wind for mechanical power production dates back to Antiquity, and the first electricity generating windmills – now called wind turbines – were built in the 1880s. However, fiberglass blades only took off in the 1980s. For some two thousand years, windmills of whatever type were entirely recyclable.

The first wind turbines in Europe, built by Paul La Cour in Denmark, had traditional slatted wooden sails. Image: Paul La Cour Museum.

Old-fashioned windmills had towers built out of wood, stone, or brick. Their “blades” or “sails” were usually made of a wood framework covered with canvas or wood boards. In later centuries, parts were increasingly made from iron, also a recyclable material.

When new types of sails were invented in the eighteenth and nineteenth centuries (such as spring, patent, and rolling-reefer sails), as well as in the twentieth century (Dekkerized and Bilau sails), the design changed but the materials remained the same (eventually including aluminum). ⁷ Furthermore, contrary to modern wind turbines, which need to be replaced regularly and in their entirety, old-fashioned windmills could last for many decades or even centuries through regular repair and maintenance.

A look at the history of wind power shows that plastic is not an essential material.

The first wind turbine in the US, built by Charles F. Brush, had a 17 m diameter annular sail with 144 thin blades made of cedar wood. The first wind turbine in Europe, built by Paul La Cour in Denmark, had four traditional slatted wooden sails with a rotor diameter of 22.8 m.

La Cour’s design was copied by local enterprises in Denmark, resulting in thousands of wind turbines operating on Danish farms between 1900 and 1920. Dozens of experimental wind turbines were built during the first half of the twentieth century, including some with steel blades, such as the 1939 Smith-Putnam wind turbine in the US. ⁸

The three-bladed Gedser wind turbine relied on an air frame superstructure for blade stiffening.

In 1957, Johannes Juul – a student of Paul La Cour – built the three-bladed Gedser wind turbine. It had a rotor diameter of 24 m and relied on an air frame superstructure of steel wires for rotor and blade stiffening. The blades were built from steel spars, with aluminium shells supported by wooden ribs.

The Gedser turbine remained the most successful wind turbine until the mid-1980s. It ran for 11 years without maintenance, generating up to 360,000 kWh per year, but was not repaired when a bearing failed. When the turbine was refurbished and tested in the late 1970s, it performed better than the first wind turbines with fiberglass blades. ⁸⁹

Size Matters

The first wind turbine with fiberglass blades was installed in 1978 in Denmark, where it powered a school. With its 54 m diameter rotor, the Tvind turbine was at the time the largest wind turbine ever built. After 1980, fiberglass blades became standard in Denmark and the “Danish design” was later copied all over the world. The plastic blade, so it seems, is what defines the modern wind turbine. This presents us with a dilemma.

The switch to fiberglass blades was mainly driven by the desire to build larger wind turbines. Larger wind turbines lower the cost per kilowatt-hour of generated electricity, for two reasons: the wind increases with height, and the doubling of the rotor radius increases power output four times.

The desire to build larger wind turbines has driven the wind industry ever since. Rotor diameters increased from around 50 m in the 1990s to 120 m in the 2000s. Today’s largest off-shore wind turbines have rotor diameters of more than 160 m, and a 12 MW turbine with a 220 m rotor diameter is being constructed in the Netherlands. ³⁶¹⁰

Improved windmill blade from the 1940s, built and designed by P.L. Fauel. Image: Rasbak (CC BY-SA 3.0)

However, with increasing size, the mass of the rotor blade also increases, which requires lighter materials. At the same time, larger blades deflect more, so that their structural stiffness is of increasing importance to maintain optimal aerodynamic performance and to avoid the blade hitting the tower. In short, larger wind turbines with longer blades place ever higher demands on the materials used, and these exceed the capacities of recyclable materials. ¹¹¹² Wind turbines have become more efficient, but also less sustainable.

Larger wind turbines with longer blades place ever higher demands on the materials used.

Right now, this trend is illustrated by the increasing use of carbon fiber reinforced plastic, which is even stronger, stiffer and lighter than fiberglass reinforced plastic. ¹¹ The use of carbon fibers – which further complicates potential recycling – has become standard in the largest wind turbine blades, mainly in highly stressed locations such as the blade root or the spar caps. Consequently, we have again entered a new era in which blades are now so large that they cannot be made out of fiberglass reinforced composites alone anymore.

Reinventing the Windmill Blade

An industry that calls itself sustainable and renewable cannot send millions of tonnes of plastic waste to landfills each year. Consequently, could we revert to building wind turbine blades from recyclable materials alone? And how large could we build them? To which extent can efficiency and sustainability be reconciled?

Improved windmill blade from the 1930s, designed by Kurt Bilau. The tower is made of stone, the sails are made of wood and aluminum. Image: Frank Vincentz (CC BY-SA 3.0).

Most research into the design of more sustainable wind turbine blades sticks with plastic as the main material. Thermoplastics can be melted and re-used, making it possible to recycle the blades into new wind turbine blades, even on-site. However, due to the material’s lower strength and stiffness, these blades have not been built larger than 9 m for now. ¹¹³

Another area of development is the substitution of glass fibers for wood or flax fibers. These blades can be larger, but they have only small sustainability advantages over fiberglass-epoxy blades. ¹⁴¹⁵ The petroleum-based epoxy is more harmful than the glass fiber, and natural fiber based composite materials absorb more of it. ¹⁶¹⁷¹²

The length of wood blades is no longer limited by the availability of large tree trunks of consistent quality.

Some engineers and scientists follow different paths and revert to more traditional wood construction. For small wind turbines, blades can be carved out of solid wood. For larger wind turbines, the blades can be composed of a hollow aerodynamic shell and an internal framework of ribs and stringers supported by a beam called the spar – all built from laminated veneer wood boards, beams and panels.

Laminated Veneer Lumber

Laminated veneer lumber – in which the wood is peeled off the tree and then glued back together in thin layers – is a wood product that appeared in the 1980s, and which has an important advantage in relation to solid wood components. The consistency of wood can vary within a single tree. Therefore, the length of the wood spars used in pre-industrial windmills was limited by the availability of large tree trunks of consistent quality. The largest traditional windmill ever built – the 1900 Murphy mill in San Francisco – had a rotor diameter of 35 m.

Patent sails with Dekker leading edges, 1940s. Image: Reboelje.

In contrast, the process of veneering spreads out defects such as knots, giving better and more predictable stiffness properties. This allows to build larger wooden blades. ¹² Wood laminates offer substantial cost and weight reductions as compared to fiberglass. Although the strength and stiffness are lower, much of the load that the blade must support is a consequence of its own weight, so a wood blade doesn’t need to be as strong as a fiberglass blade. ¹² Nevertheless, the low stiffness of wood makes it difficult to limit the elastic deflections for very large rotor blades.

In a 2017 study of a 5 MW wind turbine with 61.5 m long blades, conducted at UMassAmherst in the US, it was calculated that in order to be stiff enough and withstand the forces that it’s exposed to, a blade made of laminated wood veneer panels would be 2.8 heavier than a plastic blade (48 versus 17 tonnes) and have a laminate of over 50 cm thick. ¹² Although this suggests that it’s technically possible to build a wooden blade more than 60 m long, it’s not very practical. With heavier blades, the wind turbine needs to be built much stronger, which increases the costs and the use of resources.

Best of Both Worlds?

There’s two ways to solve this problem. The first is to design a blade largely made from laminated veneer lumber, but reinforced with carbon composite spars and covered with an outer layer of fiberglass composite. In the above mentioned study it was found that such a wood-carbon hybrid blade is stiff enough to reach a length of 61.5 m for a 5 MW turbine, and can be built 3 tonnes lighter than a fiberglass blade. ¹² Another study for a wood-carbon blade of the same length comes to a similar conclusion, although in this case the wood-carbon blade is slightly heavier than the plastic blade. ¹⁴

A blade largely made from laminated veneer lumber, but reinforced with carbon composite spars, can be built more than 60 metres long.

Wood-carbon blades contain less plastic composite material, and the plastic is not intertwined with wood throughout the blade but clearly separated from it, making blade re-use, recycling or incineration more attractive. However, according to the studies mentioned above, a wood-carbon blade still contains 2.5 tonnes ¹⁴ to 6.2 tonnes ¹² of plastic composites, meaning that a three-bladed 5 MW wind turbine would produce 7.5 to 18.4 tonnes of unrecyclable waste – compared to 50 tonnes for a conventional blade.

Smaller Wind Turbines?

The environmental damage of the carbon-epoxy spars can be viewed as acceptable, if compared to the larger damage done by conventional wind turbine blades. However, the waste problem would not be solved, and further growth in wind power would still result in ever larger waste streams.

Image: A laminated wooden blade with carbon spar caps. Source: [^14]

Alternatively, we could define sustainability in more ambitious terms, and build wind turbine blades completely out of wood again – even if this means that we have to build them smaller. There’s an extra argument to question our focus on efficiency: the decrease in sustainability not only shows in the blades. Other parts of wind turbines are also increasingly made from plastic composites – most notably the nose cone and the nacelle cover (the housing that protects the drivetrain and the auxiliary equipment from the elements). ¹²³⁴

Other trends are the increased use of electronics, which are not suited for recycling, and of permanent magnet generators based on rare earth materials, which save costs compared to a mechanical gearbox but only at the expense of more destructive mining. Larger wind turbines also kill more birds and bats. ¹⁸

By sacrificing some efficiency, we could gain a lot in sustainability.

By sacrificing some efficiency, we could gain a lot in sustainability. Wind power advocates may not agree, because it would make wind power less competitive with fossil fuels. However, more expensive wind power can always be counteracted by higher prices for fossil fuels.

What’s really problematic is our choice of cheap fossil fuels as a benchmark to determine the viability of wind power. It’s by aiming to compete with fossil fuels – and thus by aiming to provide the energy for a lifestyle built on fossil fuels – that wind turbines have become increasingly damaging to the environment. If we would reduce energy demand, smaller and less efficient wind turbines would not be a problem.

Image: The first wind turbine in the US, built by Charles F. Brush, had a 17 m diameter annular sail with 144 thin blades made of cedar wood.

How large could we build practical wind turbine blades from laminated veneer lumber alone? Nobody seems to know. I asked Rachel Koh, the scientist who calculated the requirements for the 61.5 m wood-only blade, but she couldn’t help me: “I only ran the model for the blades of a 5 MW turbine. It would be hypothetically possible to run another study to answer your question, but it’s not a small undertaking”. She also notes that it’s possible to further improve the stiffness of wood laminates with manufacturing innovations.

A Forest of Wind Turbines

Whether we opt for large wood-carbon blades or smaller wood-only blades, in both cases we could also build the tower and the nacelle cover from laminated wood products. In 2012, the German company TimberTower built a laminated wood tower 100 m tall for a 1.5 MW wind turbine. A wooden tower seems to be besides the point, because it replaces part of a wind turbine that’s already perfectly recyclable. However, a wind turbine of which the structure is almost completely built out of wood offers extra benefits.

Illustration: Eva Miquel for Low-tech Magazine

Wood could make the production of wind turbines entirely independent of mined materials and of fossil fuels, except for the gearwork and the electric components (but further gains can be achieved, whenever possible, by using wind power for direct mechanical). ¹⁹ Furthermore, wooden wind turbines could become a carbon sink – sequestering CO2 from the atmosphere in their wood components.

Finally, the space between wind turbines on a wind farm, which is not suited as a residential area, could be used to grow a forest that would provide the wood for the next generation of wind turbines. The lumber could be sawed, processed and assembled on-site, which eliminates the energy use associated with the transport of wind turbine parts. The energy required for manufacturing the laminates and for constructing the turbines could come from the windmills, as well as from forest biomass. Especially if blades are made of wood only, the wind turbine could become a textbook example of the circular economy.

What about solar panels?

A forthcoming article investigates the sustainability of solar panels. Is toxic and unrecyclable waste inherent to solar PV power? Could we build solar panels using sustainable materials? And what would that mean for the affordability and efficiency of solar power?

Ramirez-Tejeda, Katerin, David A. Turcotte, and Sarah Pike. “Unsustainable Wind Turbine Blade Disposal Practices in the United States: A Case for Policy Intervention and Technological Innovation.” NEW SOLUTIONS: A Journal of Environmental and Occupational Health Policy 26.4 (2017): 581-598. http://docs.wind-watch.org/ramireztejeda2016-bladedisposal.pdf ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Wilburn, David R. Wind energy in the United States and materials required for the land-based wind turbine industry from 2010 through 2030. US Department of the Interior, US Geological Survey, 2011. https://pubs.usgs.gov/sir/2011/5036/sir2011-5036.pdf ↩︎ ↩︎ ↩︎
Jensen, Jonas Pagh. “Evaluating the environmental impacts of recycling wind turbines.” Wind Energy 22.2 (2019): 316-326. https://onlinelibrary.wiley.com/doi/abs/10.1002/we.2287 ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Martínez, Eduardo, et al. “Life cycle assessment of a multi-megawatt wind turbine.” Renewable energy 34.3 (2009): 667-673. http://communityrenewables.org.au/wp-content/uploads/2013/02/Life-cycle-analysis-turbines_Renewable-Energy_2009.pdf ↩︎ ↩︎ ↩︎
Ziegler, Lisa, et al. “Lifetime extension of onshore wind turbines: A review covering Germany, Spain, Denmark, and the UK.” Renewable and Sustainable Energy Reviews 82 (2018): 1261-1271. https://www.sciencedirect.com/science/article/pii/S1364032117313503 ↩︎
Lefeuvre, Anaële, et al. “Anticipating in-use stocks of carbon fiber reinforced polymers and related waste flows generated by the commercial aeronautical sector until 2050.” Resources, Conservation and Recycling 125 (2017): 264-272. https://www.sciencedirect.com/science/article/pii/S0921344917301775 ↩︎ ↩︎
De Decker, Kris. “Wind powered factories: history (and future) of industrial windmills.” Low-Tech Magazine. Barcelona (2009). here ↩︎
The Rise of Modern Wind Energy: Wind Power for the World. Pan Stanford Publishing, 2013. https://www.crcpress.com/Wind-Power-for-the-World-The-Rise-of-Modern-Wind-Energy/Maegaard-Krenz-Palz/p/book/9789814364935 ↩︎ ↩︎
Lundsager, P., Sten Tronæs Frandsen, and Carl Jørgen Christensen. “Analysis of data from the Gedser wind turbine 1977-1979.” (1980). http://orbit.dtu.dk/files/33441311/ris_m_2242.pdf ↩︎
Gupta, Ashwani K. “Efficient wind energy conversion: evolution to modern design.” Journal of Energy Resources Technology 137.5 (2015): 051201. http://energyresources.asmedigitalcollection.asme.org/article.aspx?articleid=2211540 ↩︎
Brøndsted, Povl, Hans Lilholt, and Aage Lystrup. “Composite materials for wind power turbine blades.” Annu. Rev. Mater. Res. 35 (2005): 505-538. http://www-eng.lbl.gov/~shuman/NEXT/MATERIALS&COMPONENTS/Pressure_vessels/FRP_Hutter_flange.pdf ↩︎ ↩︎
Koh, Rachel. “Bio-based Wind Turbine Blades: Renewable Energy Meets Sustainable Materials for Clean, Green Power.” (2017). https://scholarworks.umass.edu/dissertations_2/1102/ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Murray, Robynne, et al. Manufacturing a 9-meter thermoplastic composite wind turbine blade. No. NREL/CP-5000-68615. National Renewable Energy Lab.(NREL), Golden, CO (United States), 2017. https://www.nrel.gov/docs/fy18osti/68615.pdf ↩︎
Borrmann, Rasmus. “Structural design of a wood-CFRP wind turbine blade model.” (2016) https://www.eksh.org/fileadmin/bilder/themen/Energieforschung/02_-Final_Report-_Strcutural_Design_of_a_Wood-CFRP_Wind_Turbine_Blade_Model.pdf ↩︎ ↩︎ ↩︎
Spera, David. “Wind Turbine Technology: Fundamental Concepts in Wind Turbine Engineering, Second Edition.” (2009) https://ebooks.asmedigitalcollection.asme.org/book.aspx?bookid=271 ↩︎
Corona, Andrea, et al. “Comparative environmental sustainability assessment of bio-based fibre reinforcement materials for wind turbine blades.” Wind Engineering 39.1 (2015): 53-63. http://orbit.dtu.dk/files/129909032/0309_524x_2E39_2E1_2E53.pdf ↩︎
The use of wood for wind turbine construction. Meade Gougeon, NASA. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800008214.pdf ↩︎
Loss, Scott R., Tom Will, and Peter P. Marra. “Estimates of bird collision mortality at wind facilities in the contiguous United States.” Biological Conservation 168 (2013): 201-209. https://repository.si.edu/bitstream/handle/10088/35192/NZP_Marra_2013-Estimates_of_bird_collision_mortality_at_wind_facilities_in_the_contiguous_United_States.pdf?sequence=1&isAllowed=y ↩︎
De Decker, Kris. “Heat your house with a mechanical windmill.” Low-tech Magazine. Barcelona (2019). here ↩︎