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How to decarbonise in the real world


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THE UK ENERGY INDUSTRY is being exhorted to decarbonise and eliminate fossil fuels to help to reduce ‘Global Warming’.  Will there be any positive benefits or will there be only sacrifices and problems?

This is a very important and valid question because some similar environmental challenges have been made worse by attempting to solve them, rather than by making adjustments to the existing situation. Choosing to recycle plastic waste rather than burning it has seen the oceans accumulate vast amounts, whilst encouraging the change from petrol to diesel cars is now seen to produce untreatable pollution!

Fossil fuels have been used because they are a valuable resource.  Starting with the Industrial Revolution some 250 years ago, it became clear that by using energy sources such as coal, steam and water power, men and women could improve manufacturing efficiency and transport, reduce costs and thereby lift millions from poverty and deprivation.  The pleasures, prosperity and conveniences that we enjoy today are made possible by using ever more energy, to build on the aggregate efforts of previous generations.  It appears impossible to disconnect a high Gross Domestic Product from high energy use.

Over the decades, the combustion of millions of tons of coal annually has released large quantities of carbon dioxide into the atmosphere so that its concentration has increased by about 40 per cent compared with the pre-Industrial era.  It was recognised more than 50 years ago that the resulting CO2 would increase the ‘Greenhouse Effect’ and encourage the warming of the Earth although this was not taken as an imminent threat.  In recent decades, concern has increased with campaigns by pressure groups and international conferences promoting measures to reduce the use of coal and other carbon-based fuels.

Coal, however, is accessible in many poorer parts of the world and can be burned using very simple equipment.  Since the release of the energy in coal brings the benefits of electricity, increased production and prosperity, it is difficult to reduce its consumption.  This is also not surprising, since other more immediate hazards are readily accepted. The deep mining of coal can bring fatal accidents in developing countries and there are dangers from large quantities of spoil plus air pollution from sulphur dioxide, but the end justifies the means.

In Europe, coal use has reduced, being replaced by natural gas, nuclear power, hydro and renewables.  There is, however, little prospect of it being phased out completely since, as a flexible power source, it is needed to prevent power cuts when renewable power is inadequate at times of high electricity demand.  Even with 10,000 turbines, wind power can collapse from 30 per cent of our electricity to 1 per cent in a day.

Lobby groups and the BBC eagerly proclaim the achievement of a new renewables output record.  There is no comment when all the coal-fired power stations are producing the same amount of power because wind and solar output has collapsed.  That is the type of selective news that Dr Goebbels employed.

Coal is not the only fuel that will have to be eliminated if the extreme proposals for decarbonisation are implemented.  It will be necessary to abandon the use of oil as well. Oil has the particular advantage that its derivatives are liquid and very suitable for transport – road, rail, maritime and air.  Can all these functions be replaced by non-carbon options without any sacrifice? Let us consider two.

Interest in private electric road vehicles is increasing, but they still represent only 0.5 per cent of the car population.  If all light vehicles became electric-powered, electricity generation would have to increase by about 25 per cent.  To achieve any benefit, this extra generation would have to be low-carbon.  Over the last 12 months the combined electricity generation from solar and wind power was less than 18 per cent.  That means that renewables output would need to more than double just to supply the new vehicles.  Since over the next ten or fifteen years, the coal plants and nearly all the nuclear plants will be retired (25 per cent of electricity), renewables would have to more than double again for that role as well.

Large areas of Scotland and the coasts already have huge wind parks. Their numbers being tripled or almost quadrupled in the coming years would bring enormous problems with power swings.

Air transport would face similar difficulties in converting to electricity.  A Boeing 747, with a take-off weight of over 400 tons burns about 100 tons of fuel (with an energy content of about 120,000 kWh) on a ten hour flight.  Could this be replaced by batteries?  For a Tesla roadster car, the 100kWh battery is about one third of the gross weight 450 kg.  The 100 tons of batteries to replace the liquid fuel would have an energy content of about 22,200 kWh.  Even allowing for the better thermo-mechanical efficiency of electric power compared with the gas turbine, the electric system would have only about a quarter of the liquid fuel energy, i.e. achieve one quarter of the range – a crippling deficiency.  Since air transport uses about one quarter of the transport fuels, that would require a 50 per cent increase in renewables.

The most far-reaching impact of decarbonising however would be the use of electricity in place of natural gas for domestic and commercial heating.  Natural gas annual use is about 900 TWh of which about 300 TWh is used for electricity generation and 600 TWh for domestic and commercial use producing about 650 TWh of useful heat in total, allowing for losses.  Annual UK electricity generation is about 280 TWh, so this change alone would require electricity generation to triple.

Such a step change would require renewables output to increase by a factor of over eleven, in addition to the other increases enumerated above.  

This would aggravate the intractable problems of preventing power cuts when renewables output collapses.  There are reliable renewable sources – e.g. hydropower, but these are generally unacceptable to green groups.  Growing economies such as China accept them, however, as a dependable non-fossil power source.  The Three Gorges project uses no fossil fuel and has a capacity 22.5 GW that on its own would supply 50 per cent of UK demand on most days.  So a replacement fleet of about fifty gas-fired power stations would be on standby.

Based on the experience in France, a more viable option would be to construct a fleet of nuclear power stations to provide all this additional electricity, but even this would be almost impossible.  If each new plant generated 15TWh annually, there would still be a need for forty new plants.  It is virtually certain that there are not sufficient suitable sites along rivers and around the coast of the UK for such plants, even if the engineering skills were available.

Green propaganda glosses over these intractable technical challenges with a few sound bites that catch the news headlines and avoid the unpalatable hard facts.

There have recently been school strikes because pupils claim that faster progress is required to reduce CO2 emissions. However, as is shown above, the supply side of the low-carbon energy equation has almost no chance of success. The pupils can contribute to the demand side of the equation.  For example, they can lead by example and make some sacrifices:

  • Insisting that the majority of children abandon the car and travel to school by bike or on foot;
  • Tell their parents to use smaller cars;
  • Tell their parents that they should take fewer holiday flights;
  • Turn down the central heating thermostat;
  • Refusing to have separate TVs and entertainment equipment in their bedrooms;
  • Make their mobile phones and smart gadgets last for three years instead of three months (aye, right, Ed.);
  • Switch off all the lights left on around the house;
  • Refuse to eat food imported out of season; and,
  • Encourage smaller families.

I look forward to seeing the results of that campaign.
Paul Spare CEng FEI FIMechE


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