Chapter Nine

STORED UP SUNSHINE: ENERGY
YESTERDAY AND TOMORROW

IRONBRIDGE GORGE IN SHROPSHIRE was the birthplace of the Industrial Revolution. Little can the Quaker ironmasters who originated it have foreseen the devastating effects on the whole world of the forces that they set in motion, the powers that they unleashed.

If the appalling damage that industrialism has done to the environment is to be reversed, a great new comprehensive initiative must be set afoot, comparable in vitality and intensity to the Industrial Revolution itself. But all true progress is a spiral, not a straight line; the new must grow out of the old and include elements which, to some extent, are reversions to older patterns. The Post-Industrial Society, which some far-sighted ‘Greens’ proclaim, can find ideas and inspiration from a study of the processes which led to our own present problems.

Before the Industrial Revolution, and for some time after, Shropshire, with its many streams and rivers, had, like many other parts of Britain, relied mainly on water as a source of power. Watermills had been used for grinding corn, for fulling (shrinking) cloth, for sawing wood, for making paper and for blowing bellows in blast furnaces. A number of old mills and mill-houses still exist. Anyone with an eye for landscape and some knowledge of milling techniques can detect signs of the ponds and weirs, dams, leats and millraces, which the milling operations entailed. Regular, disciplined activities were required to keep the often elaborate milling landscapes in good order. As mills were sited at regular intervals on almost every waterway, however small, the water-control network must have done much to prevent flooding.

When my brother and I gave up livestock farming, we spent some six months thoroughly exploring the South Shropshire countryside in our ancient Land Rover and on foot. We saw many relics of Shropshire’s industrial past and talked to some people who remembered them in operation. What we saw and heard gave much food for thought.

Bouldon is one of Corvedale’s many dead or shrunken villages. It lies about five miles to the east of Highwood Hill, on the far side of Wenlock Edge and on the Roman road which crosses my land. It contains an old watermill, with an impressive outside wheel below a stretch of grass which was once the millpond. About half a mile to the east, on the Clee Brook, is a high weir, like a mini-Niagara. The farmer who lives behind the mill-house told me that he could remember the wheel being used to grind corn; before it could operate, the water had to be switched from the weir and conveyed along an elaborate system of leats to the millpond. Before it was used to grind corn, Bouldon mill had served as adjunct to a blast-furnace and as a papermill. Now this once important industrial village is a tiny rural backwater. Still more remarkable is the total ruralisation of the Willey estate near Broseley, which once belonged to my mother’s ancestors, the Lacons, and which, during the seventeenth and eighteenth centuries, was an important arms manufacturing area. At Willey Wharf on the Severn the world’s first ironclad ship was launched. Now Willey is mainly remarkable for its magnificent trees and for a small remnant of the once extensive primaeval Shirlett Forest. The former furnace ponds have been converted into ornamental lakes.

Many people, like myself, would like to see parts (at least) of the former mill-network restored; not perhaps for its former purposes, but as a sustainable, clean, non-polluting means of generating electricity: a system which, far from contaminating and defacing the landscape, would, with the assistance of trees, help to maintain the circulation of water, which is the lifeblood of the landscape.

I don’t suggest that electricity generated by waterwheel should be fed into the National Grid but it is a possible source of light, heat and power for small communities striving for self-sufficiency. Other, more sophisticated mechanisms, developed within the last two centuries, should also be considered, provided that adequate water is available. These include the turbine, the hydraulic ram, and the air compressor.

While the principle of the turbine was originally conceived by Hero of Alexandria in 100 B.C., the first effective models date back to the middle of the last century. One of the earliest, most primitive versions, called the ‘hurdy-gurdy’, was developed by miners during the Californian Gold Rush of 1849. It consisted of a simple pulley with flat plates bolted to the rim. The pulley was caused to spin by water from above dropping on to the plates. In the succeeding 140 years many types of turbine have been developed, using propellers and other devices, to provide power for grainmills, pumps, sawmills, metal-working machinery and, above all, to generate electricity. They vary in size from monstrous units requiring big dams and incorporated in giant hydro-electric schemes to tiny ‘microhydros’ that can be assembled by any DIY enthusiast for home generation.

The hydraulic ram, a kind of ‘water-hammer’ used to raise water above the height of its source, was invented by John Whitehurst, a Cheshire brewer, in 1772. But the version which is still widely used today owes its effectiveness to the invention in 1798 of the automatic pulse valve by Pierre Montgolfier of hot-air balloon fame. While the ram is most commonly used as an automatic, low-maintenance pump for supplying water from hill-streams to remote farmhouses, it has also been used for compressing air for rock-drills.

A still simpler device than the ram, with no moving parts, the hydraulic air compressor or ‘trompe’ was first developed in mediaeval Catalonia to act as an automatic bellows for an iron furnace. For a brief period it was revived at the beginning of the present century in the United States. The National Academy of Sciences in Washington in Energy for Rural Development (1976) suggests that it should be ‘resurrected for further study and possible use in hilly terrain where ample water is available. The ability of the device to operate day and night, with its simple storage of energy in the form of compressed air in tanks or caves, makes it an interesting and potentially fruitful problem to investigate. The compressed air could be piped to sites to drive reciprocating engines or turbines that, in turn, could power production machines or electric generators.’

Of special significance in the agroforestry context is the use of biomass for energy production. ‘Biomass’ is the generic term for all forms of organic, carbon-containing material, living or dead, including garbage and sewage.

A number of methods can be employed for extracting energy from biomass.

1.  Burning. The simplest method, employed since before the dawn of history, is the burning of wood, peat and cattle dung. Incredibly, this is the principal or only method still used for cooking and heating by over half the world’s population. It is extremely inefficient, owing to the large amount of heat lost in the air.

2.  Pyrolysis. This involves baking the raw fuel in the absence of air. It can produce combustible solids, liquids or gases. Charcoal has been made by this method for hundreds of years.

3.  Gasification. The heating of biomass under pressure in the presence of air and steam to produce combustible gas.

4.  Pelletization. The manufacture of ‘briquettes’ from materials such as sawdust to produce coal substitutes.

5.  Bacterial digestion. The production of methane or biogas from sewage, garbage and organic wastes generally.

6.  Fermentation. The production of ethanol, butanol and acetone by the processing of plants with high contents of sugar or starch, such as pineapples, potatoes, maize, cassava, sorghum, sugar beet and sugar cane.

7.  Extraction of energy-rich products from plants; such as palm-oil and olive-oil.

Large quantities of ethanol have been produced over the years from Brazilian sugar cane plantations. As a motor-fuel, ethanol can be used in conjunction with petrol in a proportion of about one to five, but where engines have been re-designed, hydrated ethanol can be used alone. However, ethanol can cause corrosion of some metal alloys and deterioration of some plastics.

Biogas is an energy source very extensively used in a number of countries, notably China. Millions of Chinese peasants use small DIY digesters to convert human, animal and plant wastes for home cooking, heating and lighting. The residue is a virtually odourless, disease-free liquid used as fertiliser.

The special importance of biogas lies in the fact that it is a way of utilising objectionable materials which are available everywhere and which, in most countries, are not utilised, as they should be, for creating energy, but are disposed of in ways that seriously pollute the environment, especially inland waterways and the oceans.

In the natural forest all biomass residues are recycled to form compost, which feeds and energises the plants.

The raw materials of biogas can include, not only human, animal and plant wastes, but also the most objectionable and troublesome of weeds, such as water hyacinth which in many tropical and subtropical regions clogs vast areas of inland waterways and lakes.

In Making Aquatic Weeds Useful (National Academy of Sciences, 1979) it is stated:

In a pioneering effort of great significance, researches at the National Aeronautics and Space Administration (NASA) are working on converting water hyacinth and other aquatic weeds into a biogas rich in methane. Methane is the main ingredient in natural gas, which is used worldwide as fuel and is a major item in international trade. The recovery of fuel from aquatic weeds‖ has interesting implications, especially for rural areas in developing countries. As many developing nations have an apparently inexhaustible supply of aquatic weeds within their borders, this potential energy source deserves further research and testing. Aquatic weeds are converted to biogas by capitalizing upon one of nature’s processes for decomposing wastes – decay by anaerobic bacteria. Methane-producing bacteria are common in nature (for instance, in the stagnant bottom mud of swamps, where they produce bubbles of methane known as ‘marsh gas’). If they are cultured on water hyacinth in a tank, sealed to keep out all air, they produce a biogas composed of about 70 per cent methane and 30 per cent carbon dioxide. The high moisture content of aquatic weeds is an advantage in this process. It is needed for fermentation. This is one method of aquatic weed utilization that does not require dewatering – a big advantage.

Based on NASA’s findings, it appears that the water hyacinth harvested from one hectare will produce more than 70,000 cubic meters of biogas. Each kilogram of water hyacinth (dry-weight basis) yields about 370 litres of biogas with an average methane content of 69 per cent and a calorific (heating) value when used as a fuel, of about 22,000 kJ/m ³.

These amazing figures, based on just one of the many possible ingredients of biogas, indicate its vast unused potential.

If mineral-neutralising aquatic plants were added to city sewage, that would probably be the answer to those who object that it is unsuitable for conversion into fertiliser, not only on account of its content of heavy metals and pernicious micro-organisms but also because it contains harmful industrial chemicals.

Another water-loving plant, the willow, is being grown in large numbers in Sweden, Northern Ireland and the Somerset levels as a quickmaturing source of biomass fuels. Willows do particularly well in Ireland’s moist climate and boggy soils and leading horticulturalists believe that ‘energy forests’ could do much to re-vitalise the country’s rural economy. The original aim of research initiated in 1973 at the Horticultural Centre at Loughall, Co. Armagh, was to find ‘superwillows’ that, by coppicing, would form a regularly renewable source of pulp for paper-making. But the energy crisis of 1974 caused the research team to change their priorities. They came to the conclusion that willows could form a valuable source of relatively cheap energy in the form of chips, pellets or briquettes. In a three-year trial with greenhouse tomatoes, it was found that the cost of heating with willow-chips was only one-third the cost of conventional fuel-oils. Using trees carefully selected by Long Ashton Research Station, Bristol, it was found that yields of up to twenty-five tonnes per hectare per year could be achieved. Other applications for the willows include fuel for domestic wood-burning stoves, ethanol to replace lead as a high-octane enhancer in petrol, and viscose to be used in combination with flax or other fibres in Northern Ireland’s textile industry.

From ‘Wind in the Willows’ it is a short step to aerogenerators.

For nearly a thousand years windmills played an important part in the economy of Britain and other European countries. It has been reckoned that a single traditional windmill used for grinding corn, with a 25-metre rotor made from wooden spars and canvas, could do the work of more than 200 people. Towards the end of the last century much research was done into the possibility of improving windmill efficiency, and in the 1890s Denmark successfully produced windmills designed specifically for the generation of electricity. By 1908 several hundred small wind-power stations were in existence, each one capable of producing 5-25 kW. In the 1930s the Soviet Union built the first large wind-turbine, capable of generating up to 100 kW. In the following years a number of large experimental machines were built, but it was not until the energy crisis in the 1970s that governments and other official bodies began to take a serious interest in aerogenerators. In 1975 a prototype 100 kW wind-turbine began operation at Sandusky, Ohio; it had been designed by NASA, the National Aeronautics and Space Administration. The first multimegawatt wind-turbine in North America was commissioned in 1979 at Boone, N. Carolina. Today a wide array of wind-generators is available, experimental and practical, of all shapes and sizes, suitable for large-scale schemes or for domestic use. The Rutland Windcharger, which I had installed to supply light for the small cabin which houses my craftmuseum, is a highly efficient, small but tough and durable machine, mass-produced at Corby, Northamptonshire. It is extensively used in several parts of the world as a source of power for light, radio, TV and other utilities in caravans, boats, farms, remote buildings and even an Antarctic research station. For remote sites, Northumbrian Energy Workshop Ltd of Hexham supply a composite package comprising wind-generator, micro-hydro turbine and photovoltaic module.

The photovoltaic module or cell is one form of ‘active’ solar device for converting sunlight into electricity. The first modules were developed in 1954 at the US Bell Laboratory during research into silicon chips. Basically, all that is involved is a single crystal silicon cell which generates electricity when exposed to sunlight. Such cells were used to power instruments in the early satellites.

A form of solar generator that is more familiar to the general public is the ‘panel’, used to heat water, which can now be seen on the south-facing roofs of many houses. The panel is usually made of stainless steel and faced with glass. The inside surface is usually matt black, designed to absorb solar radiation and transform it into heat. The heat is transferred from the surface of the panel into cavities or pipes within the panel, filled with air, water or an oil-based fluid. The liquid or air is passed through a normal plumbing circuit into a spiral element, which heats the water in a well-insulated storage tank.

Fig. 20 Rutland Windcharger

A type of solar generator which would fit well into a permaculture scheme is the solar pond, first developed in Israel. A typical pond is two to three metres deep with conical sides and a flat, blackened bottom. It is filled with layers of brine of increasing concentration, the densest at the bottom containing as much as twenty per cent salt. Sunlight absorbed by the brine can yield temperatures as high as 100 degrees centigrade. Loss of heat is prevented by the salt gradient, which suppresses thermal convection, and ponds can effectively store heat for months. The heat is removed by drawing brine from the bottom of the pond through heat exchangers or by circulating a heat transfer fluid through submerged coils. In Israel solar ponds are used to drive heat engines for the production of electricity. They can also be used for district heating schemes.

‘Passive’ solar heating relies on the architectural design of a building, which is so devised as to capture, store and distribute the sun’s radiation. The ancient Greeks were the first to develop solar architecture, designing buildings with open, south-facing porticoes, which permitted low winter sunshine to penetrate to the living-rooms, while providing shade in the summer. The heat was absorbed by dark stone floors and thick masonry. Buildings were insulated to prevent draughts. The Greeks actually built several solar cities. The Pueblo Indians of the South-West United States also built several solar hill-towns in the eleventh and twelth centuries. One of the most sophisticated was Acoma, which had three terraces running east to west, built in tiers for maximum exposure to the winter sun. The roof of each tier was layered with straw and other materials to insulate the houses from the full blaze of the summer sun.

In the hills of Mid-Wales today, David Huw Stephens is developing a solar village called Tir Gaia, at Rhayader. The design of the model ‘Survivor House’ is fascinating in the extreme. It combines both ‘passive’ and ‘active’ solar features. On the roof is a greenhouse, with rainwater tanks to provide water for the plants and house. The tanks will absorb radiant solar heat during the day and help to keep the greenhouse frost-free at night by re-radiation of the heat. On the south side of the house is a solar panel to provide hot water, and below the foundations are water cylinders to transfer heat from the solar panel to the soil and thus create a subterranean heat-store. Large south-facing double-glazed windows admit solar energy to the main living-room, which is on the first floor. The walls have absorbent surfaces which convert solar radiation into convecting warm air. North-facing walls are ‘super-insulated’ and the downstairs bedrooms have insulating shutters which are closed at night to reduce heat loss. Outside the front-door, referring to the produce of the roof-top greenhouse, is a notice: ‘Home-grown Bananas’.

A remarkable and comprehensive display of sustainable and non-polluting devices for producing and saving energy can be seen at the Centre for Alternative Technology, Machynlleth, Mid-Wales.