LOW-TECH MAGAZINE

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.

How Sustainable is Digital Fabrication?

Digital fabrication is praised as the future of manufacturing. Computer Numerical Controlled (CNC) machine tools can convert a digital design into an object with the click of a mouse, which means the production process is completely automated. The use of digital machine tools has spread rapidly in factories over the last two decades, and they have now become cheap and user-friendly enough to bring them within reach of workshops and makers.

While CNC machines have been embraced by many, including some environmentalists who say the technology can be more sustainable, it's important to consider the very high energy use of digital machine tools. Compared to the earlier generation of human-controlled machine tools, CNC machines use much more power, and the potential to improve their energy efficiency is very limited. Choosing fewer automated technologies is the key to sustainable manufacturing.

Burning the Bones of the Earth: Lime Kilns

This is a guest post by Brian Kaller, who blogs at Restoring Mayberry.

Explore the now-ruined estates of the Irish countryside and you occasionally find a stone cylinder, as much as several metres high and wide, open at the top and with a small door at the base.

Some resemble the medieval fortresses that still dot the landscape here -- but no one built fortresses so tiny, or half-buried in the side of a hill.

In fact, they are kilns for lime burning, a now-forgotten industry that sustained many agrarian communities before energy became cheap.

The Mechanical Transmission of Power (3): Endless Rope Drives

You don't need electricity to send or receive power quickly. In the second half of the nineteenth century, we commonly used fast-moving ropes. These wire rope transmissions were more efficient than electricity for distances up to 5 kilometres. Even today, a nineteenth-century rope drive would be more efficient than electricity over relatively short distances. If we used modern materials for making ropes and pulleys, we could further improve this forgotten method.

Medieval smokestacks: fossil fuels in pre-industrial times

The history of energy use in human civilisation is generally summarised as follows: from Antiquity until the start of the Industrial Revolution, people made use of the manual labour of both animals and humans, as well as biomass, sun, water and wind.

Next, all these renewable energy sources were replaced by fossil fuels: first coal, and later oil and gas. Uranium completed the picture in the second half of the twentieth century.

While this historical summary is basically correct, there were some - rather important - exceptions. Almost all of the leading economies in Western Europe during the last millenium relied on a large-scale use of fossil fuels such as peat and coal.