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Forest-of-wind-turbines-low-res — 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.

If we build them out of wood, large wind turbines could become a textbook example of the circular economy.

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.

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Keeping Some of the Lights On: Redefining Energy Security

December 13, 2018

Keeping Some of the Lights On: Redefining Energy Security

Image: Camilla MP.

What is Energy Security?

What does it mean for a society to have “energy security”? Although there are more than forty different definitions of the concept, they all share the fundamental idea that energy supply should always meet energy demand. This also implies that energy supply needs to be constant – there can be no interruptions in the service. [1-4] For example, the International Energy Agency (IEA) defines energy security as “the uninterrupted availability of energy sources at an affordable price”, the US Department of Energy and Climate Change (DECC) defines the concept as meaning that “the risks of interruption to energy supply are low”, and the EU defines it as a “stable and abundant supply of energy”. [5-7]

Historically, energy security was achieved by securing access to forests or peat bogs for thermal energy, and to human, animal, wind or water power sources for mechanical energy. With the arrival of the Industrial Revolution, energy security came to depend on the supply of fossil fuels. As a theoretical concept, energy security is most closely related to the oil crises from the 1970s, when embargoes and price manipulations limited oil supply to Western nations. As a result, most industrialised societies still stockpile oil reserves that are equivalent to several months of consumption.

Although oil remains as vital to industrial economies as it was in the 1970s, mainly for transportation and agriculture, it’s now recognised that energy security in modern societies also depends on other infrastructures, such as those supplying gas, electricity, and even data. Furthermore, these infrastructures increasingly interconnect and depend on each other. For example, gas is an important fuel for power production, while the power grid is now required to operate gas pipelines. Power grids are needed to run data networks, and data networks are now needed to run power grids.

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How Circular is the Circular Economy?

November 13, 2018

How Circular is the Circular Economy?

Illustration: Diego Marmolejo.

Introducing the Circular Economy

The circular economy has become, for many governments, institutions, companies, and environmental organisations, one of the main components of a plan to lower carbon emissions. In the circular economy, resources would be continually re-used, meaning that there would be no more mining activity or waste production. The stress is on recycling, made possible by designing products so that they can easily be taken apart.

Attention is also paid to developing an “alternative consumer culture”. In the circular economy, we would no longer own products, but would loan them. For example, a customer could pay not for lighting devices but for light, while the company remains the owner of the lighting devices and pays the electricity bill. A product thus becomes a service, which is believed to encourage businesses to improve the lifespan and recyclability of their products.

The circular economy is presented as an alternative to the “linear economy” – a term that was coined by the proponents of circularity, and which refers to the fact that industrial societies turn valuable resources into waste. However, while there’s no doubt that the current industrial model is unsustainable, the question is how different to so-called circular economy would be.

Several scientific studies (see references) describe the concept as an “idealised vision”, a “mix of various ideas from different domains”, or a “vague idea based on pseudo-scientific concepts”. There’s three main points of criticism, which we discuss below.

Too Complex to Recycle

The first dent in the credibility of the circular economy is the fact that the recycling process of modern products is far from 100% efficient. A circular economy is nothing new. In the middle ages, old clothes were turned into paper, food waste was fed to chickens or pigs, and new buildings were made from the remains of old buildings. The difference between then and now is the resources used.

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Bedazzled by Energy Efficiency

January 10, 2018

Bedazzled by Energy Efficiency

To focus on energy efficiency is to make present ways of life non-negotiable. However, transforming present ways of life is key to mitigating climate change and decreasing our dependence on fossil fuels.

Energy efficiency policy

Energy efficiency is a cornerstone of policies to reduce carbon emissions and fossil fuel dependence in the industrialised world. For example, the European Union (EU) has set a target of achieving 20% energy savings through improvements in energy efficiency by 2020, and 30% by 2030. Measures to achieve these EU goals include mandatory energy efficiency certificates for buildings, minimum efficiency standards and labelling for a variety of products such as boilers, household appliances, lighting and televisions, and emissions performance standards for cars. [1]

The EU has the world’s most progressive energy efficiency policy, but similar measures are now applied in many other industrialised countries, including China. On a global scale, the International Energy Agency (IEA) asserts that “energy efficiency is the key to ensuring a safe, reliable, affordable and sustainable energy system for the future”. [2] In 2011, the organisation launched its 450 scenario, which aims to limit the concentration of CO2 in the atmosphere to 450 parts per million. Improved energy efficiency accounts for 71% of projected carbon reductions in the period to 2020, and 48% in the period to 2035. [2] [3]

What are the results?

Do improvements in energy efficiency actually lead to energy savings? At first sight, the advantages of efficiency seem to be impressive. For example, the energy efficiency of a range of domestic appliances covered by the EU directives has improved significantly over the last 15 years. Between 1998 and 2012, fridges and freezers became 75% more energy efficient, washing machines 63%, laundry dryers 72%, and dishwashers 50%. [4]

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How to Run the Economy on the Weather

September 25, 2017

How to Run the Economy on the Weather

Before the Industrial Revolution, people adjusted their energy demand to a variable energy supply. Our global trade and transport system — which relied on sail boats — operated only when the wind blew, as did the mills that supplied our food and powered many manufacturing processes.

The same approach could be very useful today, especially when improved by modern technology. In particular, factories and cargo transportation — such as ships and even trains — could be operated only when renewable energy is available. Adjusting energy demand to supply would make switching to renewable energy much more realistic than it is today.

Renewable Energy in Pre-Industrial Times

Before the Industrial Revolution, both industry and transportation were largely dependent on intermittent renewable energy sources. Water mills, windmills and sailing boats have been in use since Antiquity, but the Europeans brought these technologies to full development from the 1400s onwards.

At their peak, right before the Industrial Revolution took off, there were an estimated 200,000 wind powered mills and 500,000 water powered mills in Europe. Initially, water mills and windmills were mainly used for grinding grain, a laborious task that had been done by hand for many centuries, first with the aid of stones and later with a rotary hand mill.

785px-Jan_van_Os_-_Een_zomers_landschap

“Een zomers landschap” (“A summer landscape”), a painting by Jan van Os.

However, soon water and wind powered mills were adapted to industrial processes like sawing wood, polishing glass, making paper, boring pipes, cutting marble, slitting metal, sharpening knives, crushing chalk, grinding mortar, making gunpowder, minting coins, and so on. [1-3] Wind- and water mills also processed a host of agricultural products. They were pressing olives, hulling barley and rice, grinding spices and tobacco, and crushing linseed, rapeseed and hempseed for cooking and lighting.

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How (Not) to Run a Modern Society on Solar and Wind Power Alone

September 14, 2017

How (Not) to Run a Modern Society on Solar and Wind Power Alone

Wind energy

While the potential of wind and solar energy is more than sufficient to supply the electricity demand of industrial societies, these resources are only available intermittently. To ensure that supply always meets demand, a renewable power grid needs an oversized power generation and transmission capacity of up to ten times the peak demand. It also requires a balancing capacity of fossil fuel power plants, or its equivalent in energy storage.

Consequently, matching supply to demand at all times makes renewable power production a complex, slow, expensive and unsustainable undertaking. Yet, if we would adjust energy demand to the variable supply of solar and wind energy, a renewable power grid could be much more advantageous. Using wind and solar energy only when they’re available is a traditional concept that modern technology can improve upon significantly.

100% Renewable Energy

It is widely believed that in the future, renewable energy production will allow modern societies to become independent from fossil fuels, with wind and solar energy having the largest potential. An oft-stated fact is that there’s enough wind and solar power available to meet the energy needs of modern civilisation many times over.

For instance, in Europe, the practical wind energy potential for electricity production on- and off-shore is estimated to be at least 30,000 TWh per year, or ten times the annual electricity demand. [1] In the USA, the technical solar power potential is estimated to be 400,000 TWh, or 100 times the annual electricity demand. [2]

Such statements, although theoretically correct, are highly problematic in practice. This is because they are based on annual averages of renewable energy production, and do not address the highly variable and uncertain character of wind and solar energy.

Annual averages of renewable energy production do not address the highly variable and uncertain character of wind and solar energy

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How to Get Your Apartment Off the Grid

May 19, 2016

How to Get Your Apartment Off the Grid

Picture: Low-tech Magazine’s solar powered office.

The typical solar PV power installation requires access to a private roof and a big budget. However, wouldn’t it be possible to get around these obstacles by installing small solar panels on window sills and balconies, connected to a low-voltage direct current (DC) distribution network? To put this theory to the test, I decided to power Low-tech Magazine’s home office in Spain with solar energy, and write my articles off the grid.

Solar panels have become cheaper and more efficient in recent years, but they are far from a universal solution, even in sunny regions. One reason is that a typical solar photovoltaic (PV) installation is still beyond the budget of many people. The average pricing for a 5kW residential PV system completed in 2014 varied from $11,000 in Germany to $16,450 in the USA. [1, 2] Roughly half of that amount concerns the installation costs. [3]

A second obstacle for solar power is that not everybody lives in a single-family dwelling with access to a private roof. Those who reside in apartment buildings have little chance of harvesting solar power with a conventional roof-mounted system. Furthermore, in apartment buildings, the roof would quickly become too crowded to cover the electricity use of all residents, a problem that grows larger the more floors there are in a building. Lastly, a typical solar installation is problematic when you’re renting a place, whether it’s a house or an apartment.

I’m one of those people who runs into every one of these obstacles: I live in a flat, I rent the place, and I don’t have the budget for a conventional solar system. However, I receive a lot of sunshine.

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Fruit Walls: Urban Farming in the 1600s

January 6, 2016

Fruit Walls: Urban Farming in the 1600s

We are being told to eat local and seasonal food, either because other crops have been tranported over long distances, or because they are grown in energy-intensive greenhouses. But it wasn’t always like that. From the sixteenth to the twentieth century, urban farmers grew Mediterranean fruits and vegetables as far north as England and the Netherlands, using only renewable energy.

These crops were grown surrounded by massive “fruit walls”, which stored the heat from the sun and released it at night, creating a microclimate that could increase the temperature by more than 10°C (18°F).

Later, greenhouses built against the fruit walls further improved yields from solar energy alone. It was only at the very end of the nineteenth century that the greenhouse turned into a fully glazed and artificially heated building where heat is lost almost instantaneously — the complete opposite of the technology it evolved from. Montreuil peaches

Picture: fruit walls in Montreuil, a suburb of Paris.

The modern glass greenhouse, often located in temperate climates where winters can be cold, requires massive inputs of energy, mainly for heating but also for artificial lighting and humidity control.

According to the FAO, crops grown in heated greenhouses have energy intensity demands around 10 to 20 times those of the same crops grown in open fields. A heated greenhouse requires around 40 megajoule of energy to grow one kilogram of fresh produce, such as tomatoes and peppers. [source – page 15] This makes greenhouse-grown crops as energy-intensive as pork meat (40-45 MJ/kg in the USA). [source]

Dutch-style all-glass greenhouses. Picture: Wikipedia Commons.

In the Netherlands, which is the world’s largest producer of glasshouse grown crops, some 10,500 hectares of greenhouses used 120 petajoules (PJ) of natural gas in 2013 — that’s about half the amount of fossil fuels used by all Dutch passenger cars. [source: 1/2]

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