Dear Colleagues

I always have a surge of guilt and am twitchy about the rows of rubbish bins lining our street early in the morning (presuming drunken teenagers the night before haven't thrown them all on their sides, of course). All off to landfill. And duplicated at millions of other homes throughout the world every week or so. I don't believe we can continue this dumping process much longer. It is simply unsustainable.

There were some peevish comments from some about putting our downloads on Facebook; so we have recontinued putting them in the newsletter below with a useful one on the Fuel Combustion and Steam Generation Process (30 pages). But you can find the entire list on our Facebook page courtesy of Sam Keogh, our enthusiastic marketing assistant.

Read about the Fuel Combustion and Steam Generation Process below.

 Blasting waste with electric plasma torches

I know we shouldn't only look to high tech solutions to dispose of our household waste. But toxic waste especially is to be feared when going into landfill and is difficult to deal with. Sludge from oil refineries is a good example. This can be destroyed with electric plasma torches in furnaces – heating to well over the temperature of the surface of the sun. However, this has been an expensive way of doing things – costing ~$2000 per tonne of waste. But costs have been falling. Now; however the thought is to also generate power from these plasma furnaces. The destruction of organic materials (including paper and plastics) by plasma torches produces a mix of carbon monoxide and hydrogen called syngas, which can be burnt to produce electricity.

This plasma technology has been rapidly improving and the costs of plasma torches have been dropping. The core of a plasma torch is a pair of electrodes made from a nickel based alloy. The current arcs between these electrodes turns the surrounding air into a plasma (by removing electrons from their atoms). The heat and electric charges of the plasma break the chemical bonds of the waste thus vaporising it. Carbon and oxygen thus released recombines to form carbon monoxide and hydrogen molecules (H2). The metals and other inorganic materials that doesn’t transform into gas falls to the bottom of the chamber as molten slag and can be used to make bricks.

There is considerable interest in building these garbage-to-syngas plants with the first built in Japan a decade or so ago (mainly due to the shortage of landfill space). Many more are being built in the USA and Canada.

Reduce packaging and recycling

This use of plasma arc technology shouldn’t remove the onus on us to reduce the incredible overuse of packaging (with government regulation perhaps?) and recycling by aggressive reuse of bottles and plastics, without the need to reprocess them. In this respect, it is remarkable how developing economies (such as India), forage and scavenge from dump sites and recycle materials so efficiently. Naturally, there are enormous challenges here with disease and quality of life for the human scavengers.

Some problems along the way – heavy metals and dioxins

And naturally, the glib comment above that metal sludge from the plasma furnaces can be used to make bricks has to be examined critically as much of waste is loaded with heavy metals such as mercury and arsenic and you don’t want this ending up in the groundwater and soil (especially when used as bricks or building products). These metals are deadly and the environmental limits are in the low double digit parts per million.

And these plasma arc facilities never break down 100% of the garbage with the waste left behind still incredibly toxic with the exhaust gases still containing tiny amounts of extraordinarily toxic stuff (dioxins). How much is tolerable needs to be researched and dealt with (sometimes at a political level).

And other ideas for levelling the energy load

Whenever intermittent renewable energy sources are used (solar and wind) are producing surplus energy no one wants at a particular time, this energy could be used to break waste in these plasma furnaces into syngas and then to burn the syngas whenever the electricity is needed again.

So what can you do?

As we all know - we are creating too much waste and dumping this into landfill. We all need to urgently talk about ways of reducing this avalanche of rubbish and join with those firms and individuals who are doing something about this. Some suggestions:

  • Research ways of reducing landfill. Talk to your buddies critically about solutions
  • Look for money making opportunities in processing and re-using waste
  • Actively increase support for initiatives to reduce waste
  • Do you have any technology in your firm that you can apply to the problem?

Governments are undoubtedly critical in sorting this problem out; bearing in mind the comment from Bob Wells: For every action there is an equal and opposite government program.

Thanks to the Economist, Wim De Zwijger, DB Cooper and Meg Duncan for an interesting reading on the subject.

Yours in engineering learning


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