The information society promises to dematerialise society and make it more sustainable, but modern office and knowledge work has itself become a large and rapidly growing consumer of energy and other resources.
One of the constraints of solar power is that it is not always available: it is dependent on daylight hours and clear skies. In order to fill these gaps, a storage solution or a backup infrastructure of fossil fuel power plants is required -- a factor that is often ignored when scientists investigate the sustainability of PV systems.
Whether or not to include storage is no longer just an academic question. Driven by better battery technology and the disincentivization of grid-connected solar panels, off-grid solar is about to make a comeback. How sustainable is a solar PV system if energy storage is taken into account?
It's generally assumed that it only takes a few years before solar panels have generated as much energy as it took to make them, resulting in very low greenhouse gas emissions compared to conventional grid electricity.
However, a more critical analysis shows that the cumulative energy and CO2 balance of the industry is negative, meaning that solar PV has actually increased energy use and greenhouse gas emissions instead of lowering them.
The problem is that we use and produce solar panels in the wrong places. By carefully selecting the location of both manufacturing and installation, the potential of solar power could be huge.
All hydropower plants today produce electricity. Transforming energy to electricity seems to be the only way to harness water power, but it is not. For almost two thousand years, water wheels powered machines directly via mechanical transmission.
Some small direct hydro powered systems in South America present a strong case for combining the use of modern materials with old fashioned methods of water power mechanization.
The higher efficiency of this approach means that less water is needed to produce a given amount of energy. This lowers the cost of hydropower and enables power to be produced by the use of very small streams.
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.
From the 1860s to 1940s, many oil wells were pumped by a technology that originates in a sixteenth-century power transmission system used in the mining industry.
One engine operated up to 45 pumps in different locations, each up to a mile away. Power was transmitted by means of wooden rods or steel cables that moved back and forth, snaking through the landscape.
The system was so efficient that an engine used for pumping an oil well could operate a whole cluster of pump jacks. The technology, which still operates in a handful of small oil fields, could also work with renewable energy sources, and shows great potential for efficient small-scale energy use.
Long-distance power transmission predates the invention of electricity by almost four centuries. From the 1500s onwards, engineers developed mechanical power transmission and distribution technologies, called "Stangenkunsten", that became ever more sophisticated. Networks of pivoted, wooden field rods conveyed power from water wheels in the valleys to mining machinery up the mountains over distances of up to 4 km, operating pumps and bellows, hoisting ores, and transporting miners up and down shafts. Later systems replaced wooden rods by steel cables. Many Stangenkunsten remained in use well into the twentieth century, long after the introduction of steam engines and electricity.
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.
Most of the talk about renewable energy is aimed at electricity production. However, most of the energy we need is heat, which solar panels and wind turbines cannot produce efficiently. To power industrial processes like the making of chemicals, the smelting of metals or the production of microchips, we need a renewable source of thermal energy. Direct use of solar energy can be the solution, and it creates the possibility to produce renewable energy plants using only renewable energy plants, paving the way for a truly sustainable industrial civilization.
Pedalling a modern stationary bicycle to produce electricity might be a great work-out, but in many cases, it is not sustainable.
While humans are rather inefficient engines converting food into work, this is not the problem we want to address here; people have to move in order to stay healthy, so we might as well use that energy to operate machinery.
The trouble is that the present approach to pedal power results in highly inefficient machines.
How to downsize a transport network: the Chinese wheelbarrow For being such a seemingly ordinary vehicle, the wheelbarrow has a surprisingly exciting history. This is especially true in the East, where it became a universal means of transportation for both passengers and goods, even over long distances.
Firewood in the Fuel Tank: Wood Gas Vehicles Wood gas cars are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars.
How to make everything ourselves: open modular hardware Consumer products based on an open modular system can foster rapid innovation, without the drawback of wasting energy and materials. The parts of an obsolete generation of products can be used to design the next generation, or something completely different.
Power from the Tap
Power from the Tap: Water Motors Just before the arrival of electricity at the end of the 19th century, miniature water turbines were connected to the tap and could power any machine that is now driven by electricity.