LOW-TECH MAGAZINE

How to Make Biomass Energy Sustainable Again

From the Neolithic to the beginning of the twentieth century, coppiced woodlands, pollarded trees, and hedgerows provided people with a sustainable supply of energy, materials, and food.

Thermoelectric Stoves: Ditch the Solar Panels?

Wood stoves can provide a household with thermal energy for cooking and for space and water heating. Wood stoves equipped with thermoelectric generators also produce electricity, which can be more sustainable, more reliable and less costly than power from solar panels.

Too Much Combustion, Too Little Fire

The fire – which we have used in our homes for over 400,000 years – remains the most versatile and sustainable household technology that humanity has ever known. The fire alone provided what we now get through a combination of modern appliances such as the oven and cooking hob, heating system, lights, refrigerator, freezer, hot water boiler, tumble dryer, and television. Unlike these newer technologies, the fire had no need for a central infrastructure to make it work, and it could be built locally from readily available materials.

Heat your House with a Mechanical Windmill

Renewable energy production is almost entirely aimed at the generation of electricity. However, we use more energy in the form of heat, which solar panels and wind turbines can produce only indirectly and relatively inefficiently. 

A solar thermal collector skips the conversion to electricity and supplies renewable thermal energy in a direct and more efficient way.

Much less known is that a mechanical windmill can do the same in a windy climate -- by oversizing its brake system, a windmill can generate lots of direct heat through friction. A mechanical  windmill can also be coupled to a mechanical heat pump, which can be cheaper than using a gas boiler or an electric heat pump driven by a wind turbine.

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.

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.