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From Rags to Power

A case study in generating electricity without coal, gas or uranium.

Introduction bits
Welcome to the Wye Valley Railway
Full History
Abridged History
Location Maps
 
How would we re-open it?
Main Scheme
Part 1: Wye Valley Junction to Netherhope
Part 2: Tidenham Tunnel
Part 3: Tintern Quarry to Tintern
Part 4: Tintern Station
Part 5: Brockweir to St Briavels
Part 6: St Briavels to Redbrook
Part 7: Wyesham to Monmouth
Part 8: Signalling
Part 9: Rolling Stock
Part 10: Imagine the Journey
Appendices
Local Entertainment
Does that picture really show that?
From Rags to Power
Other pages on this topic
Of Roads, Railways and Cycleways
Frequently Asked Questions
 
The Railway
Interesting snippets of history
The originally proposed alignment
Getting money off ex-directors
Completing the Railway
Social and economic effect of building culverts
Later Wye Valley Railtours
Remains of the route
It really is 50 years ago...
The Abandoned Wye Valley Railways
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The Area
Locations
Wye Valley Journey
Brockweir Bridge: Dibden v Skirrow
 
Wye Valley Railway Menu

Introduction Bit

Electricity is one of those things which is pretty much compulsory these days. However, creating it with coal, oil, gas or uranium involves using a resource which will a) run out and b) produces various useless wastes, plus some carbon dioxide - although certain bodies wish to inform everybody that plants will be extinct before long so the carbon dioxide will be useless too.

As this webpage is detailing how to produce energy with minimal upset to these people we will assume that their claims are entirely correct - although we may upset them a bit by building things in order to generate electricity and killing some plants in the process. We may also upset anyone who is about to have, is in the process of having or has just had a meal.

This is a case study, so it is concentrating on one particular requirement. This webpage is connected to the Wye Valley Railway feature. The case involved is therefore on how to electrify the Wye Valley Railway without using one of the four bad fuels.

Definitions:

  1. Wye Valley Railway (WVR): the former railway along the Wye Valley between Monmouth and Chepstow in South-East Wales, UK;
  2. Wye Valley: an area of Outstanding Natural Beauty, filled with ruined industries, with the River Wye running along it;
  3. River Wye: A long, fast-flowing river running from Plynlimon (Mid-Wales) to Chepstow (South-west Wales), via Builth Wells, Hereford and Monmouth. Noted for its salmon and popular with canoeists. Also known as "the deceitful stream". Journey from Ross-on-Wye to Chepstow is covered on this page;
  4. Electrification: the process of fitting a railway with the necessary equipment to provide a train with electricity as it moves along the track;
  5. Bad fuels: the four fuels which all modern children are taught to despise: coal, oil, gas and uranium;
  6. Non-renewable fuel: a fuel which will run out (generally before we become extinct): coal, oil, gas and uranium;
  7. Renewable fuel: a fuel which will be available forever or of which more can be created: wind, tides, the sun, biofuels, hydrogen, water and geothermal;
  8. Pointless fuel: a fuel which it takes more energy to create than it will produce: hydrogen (unless created with a renewable fuel);
  9. Third rail: a cheap system of electrification suited to low-speed stopping trains where an additional rail is laid next to the two present on a standard railway. Electricity is run through this rail at a relatively low voltage (normally 750V) and trains pick it up through bits of metal hung off the bogies called shoes. Minimal visual pollution;
  10. Overhead line (OLE): a more expensive system suited to high-speed express trains where wires are hung off supports about 16 feet above the rails. Electricity is run through these wires at a high voltage and trains pick it up through a complicated piece of metalwork on the roof called a pantograph. The OLE is also called "the knitting" and can be regarded as visual pollution.

So the Wye Valley Railway is looking at a system of power which will produce minimal noise and atmospheric pollution while in the valley. Trains tend to be powered using steam, diesel or electric power. Steam and diesel power are out, since they will indisputably produce noise and atmospheric pollution in the valley. Steam power will also attract tourists, which apparently damage the local area. Both have an added inefficiency because they have to carry their fuel around with them, while an electric train has its fuel generated somewhere else. Theoretically, a coal-fired power station could be used for this as long as it's outside the valley. However, this may upset people who produce various computer models and demonstrate that a cardboard computer does not withstand fire as well as a real one, before producing a weather map which shows that, in certain weather conditions, the waste from this power station will drift over the Wye Valley, causing the trees to suffocate in the carbon dioxide. Nuclear power is possible, but people may wish to remember that this will then produce a large pile of nuclear waste which will be put in a container which will then be towed to Sellafield in Cumbria by a pair of diesel locomotives built in the 1950s. Once at Sellafield this pile of nuclear waste will sit in its box until somebody finds something that they can do with it or in becomes inert. So we're looking at electricity generated by a renewable fuel.

Electrification can be carried out with batteries, third rail or OLE. Batteries need re-charging at every stop (a lengthy process which will add at least an hour to the journey time) and also add extra weight to the train which needs to be carried around. Third rail is a "tried and tested" technology which does not impose on the view but can have an effect on the local population of people and animals. OLE is a slightly younger technology (1880 rather than 1870) which can be seen as unsightly and tends to be adversely affected by the weather. The wires are harder to maintain and are not always where you want them to be (though they tend to be sixteen feet up in the air), while the supports are a hazard in the event of a derailment. The third rail is always two inches from the running rail and can be partially sheathed between wooden panels, with gaps being provided for crossings and animal runs. Since humans and animals tend to wander around a bit, however, it is widely reckoned to be better to put the electricity supply sixteen feet up in the air and assume it will stay there.

Theory bit

The next point is which system to use to generate this electricity. Possibly the best place to start is by laying out the vital statistics:

  • Units: The measure of electricity used on bills. This is worked out using a simple formula: kilowatts x hours = units
  • Our train will require 1,200kW of energy for it to run on full power (1600hp).
  • The train can return up to 20% of its power to the electricity supply when it puts on the brakes.
  • It is a second-hand train and so the only on-board services are lighting, basic air conditioning, automatic doors and a buffet serving warm tea.
  • 400kW will be adequate to maintain the schedule which allows 50 minutes for the journey from Chepstow to Monmouth.
  • During any given 1 hour period there will be two trains drawing power from the system.

Any system which is used, therefore, will need to provide 800kW per hour at a minimum, otherwise known as 800 units - each train will consume nearly 7 units per minute. Wind energy has a rotten press and is therefore probably worth avoiding, whatever the benefits might be. Tidal energy is due to be generated in vast quantities by the Severn Barrage, allowing all local power stations to close, but there's no point in basing a business plan around it since it isn't going to built - mostly due to environmental opposition from environmentalists who prefer coal-fired power stations to asking some birds to move. Hydroelectric power can be generated either by building dams across the river or (in faster rivers like the Wye) by sticking a turbine in the middle of it, but this might interfere with the salmon and canoeists (both of which are worth keeping happy as they might like to use the WVR at some point), besides being too reminiscent of the former industry. Geothermal energy is downright expensive - if we could afford two holes through the Earth to suitably hot rocks (one up, one down) we'd spend the money on re-opening the railway from Monmouth to Hereford and compensating everybody for using diesel trains on it. Hydrogen is a very bulky and flammable gas or a very cold liquid; it is very common in universal terms but is rarely found on Earth without an oxygen atom keeping it company. The difficulty is getting the hydrogen out of this compound (also known as water) without using four times as much energy as you will get out when you burn it. The sun has a nasty tendency to hide behind a raincloud and has not been tested on such a scale as running a real railway yet.

That leaves biofuels, which come in two forms, which we'll call waste and growth. Growth is when you grow lots of plants and then mince them up into a fuel which can be used to replace coal, oil or gas, depending on how you do it. This takes up space which then cannot be used for growing crops. Not much land is used for growing crops in the Wye Valley anyway, but the other way of doing it is by growing trees, chopping them down and burning them in place of coal - which is supposed to be carbon neutral because all the carbon in the tree has been taken out of the atmosphere. Burning, however, produces other chemicals which are still produced whether you burn coal or trees. Furthermore, the recently-felled areas can be more unsightly than a carefully-hidden open-cast mine or demolishing a colliery slag-heap.

Waste is much more efficient - you take what is left over after everyone else has finished with it - food waste, the contents of chip-fat-friers, garden cuttings, excretement - and turn it into a fuel. For replacing oil it has to be turned into a liquid, but this waste is at its best when replacing coal, because you just dump it in a ten-metre tall silo and leave it to rot. The resultant heat (which can be experienced on a small basis by taking the lid off a ½m³ compost bin) can be used to boil water and generate electricity, while the methane given off can be burnt to produce the rather less potent carbon dioxide, as well as some more electricity. Meanwhile, the sludge left over will either rot away altogether if given long enough or can be used as compost and fertiliser if it is of sufficient quality. There is also a small quantity of water produced which would pay a visit to the sewage works. The scientific name for this method of was disposal is anaerobic digestion and it allows power to be produced until shortly after people stop eating anything or going to the toilet - after which electricity would not be required anyway, so there's no problem with that.

If you wish to accelerate this process slightly you replace the silo with an industrial incincerator. Landfill produces methane, while burning produces carbon dioxide. The incinerator leaves minimal waste, destroys everything immediately (rather than slowly collapsing over the next 200 years) and does not attract seagulls, rats or urban foxes. It is therefore already more environmentally friendly than landfill. It is also more desirable than the widely accepted process of cremation, which has certain issues such as the mercury in tooth fillings and the nasty toxins in the body. The incinerator can also consume more stuff than the silo - pretty much all household waste apart from glass and metal, which can be recycled in the UK. Paper has been developing a habit of going to China for recycling - burning it here is more efficient than burning oil to power the ship to China.

Both options could theorectically destroy your sewage, rather than needing it to rot until it looks clean in a tank and then pumping it back into the river. The Wye Valley Railway is lucky enough to run past two sewage works (at Wyesham and Tintern) and these could either be joined by a few silos sunk into an eight-metre-deep hole or replaced by such a silo or an incinerator. Your body does not removed more than a fifth of the available energy in your food, but a properly built incinerator should manage about half. The electricity thus generated would be very convenient for the railway without need for it to zap along miles of pylons and could boost the local power supplies. In return the railway could help transport waste to the site. The presence of the sewage works eliminates claims about smells or unsightliness and facilities to deal with the sludge are already present if necessary. Any meat waste put into a silo has to be fit for human consumption so it won't be a case of leaving diseased meat rotting in a dark hole. The Wyesham site, being very convenient for a large population and associated shops, pubs and supermarket, could be useful for disposing of large amounts of food which would otherwise have to go for landfill. As any surplus electricity could be sold (and there will be savings from not buying so much electricity if there isn't anything left over) there could be a case for paying people for their rubbish.

Maths bit

Now the important figures. For anaerobic digestion 1 tonne of waste will produce 250 units of electricity; the system is already proven for taking food to produce electricity in Ludlow, Shropshire. Therefore, for general padding to the 800 units required per hour by the railway, 4 tonnes of waste will be needed per hour (1000 units - the remaining 200 can power the rest of the Wye Valley). For 18 hours of service per day (06:00 to 00:00) some 72 tonnes of rubbish will be needed. There are around 30,000 people in the area (10,000 in Monmouth, 10,000 in Chepstow, 5,000 in the Parish of Tidenham and around 5,000 in nearby villages) - if everyone in the area threw away 300 grammes of fruit, vegetable and meat waste each day this would result in 9 tonnes of rubbish - about an eighth of the required amount. Another three tonnes might come from pubs, restaurants, industrial units, the schools and the supermarkets at Monmouth and Chepstow; that would bring it up to a sixth of the total.

If the local authorities could be persuaded to augment local landfill sites with a few of these things, however, the populations of Monmouthshire and the Forest of Dean plus associated shops, food places and industries would provide 160,000 people (48 tonnes) with enough other developments to bring the total up to somewhere closer to 55 tonnes.

If we could include grass cuttings, pruned bushes, dead flowers, rotting sticks, decomposing leaves and rotten logs then the totals for the Wye Valley and adjacent parts of the Forest of Dean might get 20 tonnes. Adding sewage might offer the equivalent of 30 tonnes. That's still nowhere near the 72 tonnes, although all of Monmouthshire and the Forest of Dean with sewage and garden rubbish might scrape up to that figure.

The incinerator option will take more waste, so we can allow one plastic bag, one newspaper, 100g of food waste, one plastic bottle, 200g of toilet stuff and 100g of junk mail per person per day - about 500g. If 1 tonne now produces about 300 units of electricity, 3.333 tonnes are needed per hour are needed for the 1000 units per day. 18 hours service now requires 60 tonnes per day and our population of 30,000 is producing about a quarter of that. Adding in the pubs, restaurants, industrial units etc. might knock that up to a quarter of the required figure. Monmouthshire and the Forest of Dean brings it up to 80 tonnes, providing 20 tonnes (6000 units of electricity) for the local community once the railway has taken its cut, and including everything else might offer 95 tonnes of waste.

Meanwhile scrapping the local coal-fired power station (in East Newport) and replacing it with a set of industrial incinerators adds another 150,000 people in and provides an output of 45,000 units of electricity. Unfortunately this is only 45 megawatts and the current power station produces 360 megawatts.

The problem with this idea is that people really don't throw enough stuff away.

Featuring information from the BBC Radio 4 programme A Load of Rubbish (Episode 3 - broadcast on Wednesday 26th November 2008).

>>>A Times comment article on the subject>>>
(written about a month after this article, but we doubt he got it from here)

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Last modified 17/04/11

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