Approaching the renewable energy topic from the perspective of the modest teaspoon

Approaching the renewable energy topic from the perspective of the modest teaspoon

This is an interesting notion discussed by Ian Plimer in his 2014 book “Not for Greens”.

Teaspoons are generally made of stainless steel, a material discovered in the late 19th century. What else is stainless steel used for?

Sinks, saucepans, washing machine drums, razor blades, shipping containers, masonry supports, door and window fittings, exhaust systems, pressure vessels in labs, subsea pipelines, surgical instruments, surgical implants, MRI scanners, brewing equipment(!), distilling, water and sewage treatment, springs, bolts, nuts, washers, wire………

In summary, the world needs stainless steel.

      

         

Most cutlery is made of SAE 304 stainless steel, also known as 18/8 stainless steel. It’s not just cutlery made of 18/8 steel, the Gateway Arch monument in St Louis is essentially one big piece of cutlery.

         

 

So, in order to make a teaspoon, we need iron, chromium and nickel. These metals don’t just grow on trees, they need to be pulled out of the ground. The following images illustrate where these three metals are mined, and where most steel is produced:

 

 

 








We can conclude from this that the creation of stainless steel is well and truly an international effort, whereby the metals composing the steel are mined over multiple continents, with a vast majority of steel production taking place in China.

The process of making stainless steel begins with melting the raw materials together (usually with recycled steel) in a furnace.  Electrodes heat the mix to the melting point. After several hours the molten mix is sent to a refining furnace where impurities are removed. The molten steel then flows out of the furnace, through rollers, to create long ribbons of steel, which are in turn torched into shorter slabs. The slabs are reheated to soften them up for more processing, by now a rusty scale has accumulated, and is removed without cooling the slab. The still-heated slab is put through more rollers, to form long, thin stretched steel, which is partially cooled, but still hot enough to coil. Burners heat and cool the steel again to relieve stress in the metal, softening it for further processing to customer requirements.

Video link for the steel making process.

Teaspoon production begins with rectangular flat pieces of stainless steel, which are formed into pieces roughly the same shape as the teaspoon, a process called blanking. Rollers stretch the pieces out, thinning the end that will become the bowl of the spoon. A press then cuts the profile of the spoon, and subsequently forms the bowl to its rounded shape. Teaspoons are then buffed and polished.

Video link for the flatware (cutlery) manufacturing process.

Where are your teaspoons made? Chances are they’re made in China, if one were to look at statistics from the US. The US census shows that a majority of metal kitchenware is imported from China, with a few other countries such as Thailand, Mexico, Greece and Germany contributing significantly. The countries listed below make-up 96% of imports to the US:

 

Everything covered up to this point highlights that process to make a stainless steel teaspoon is an energy hungry one. Energy is used in:

  • Metal Exploration
  • Metal Extraction, Haulage and Processing (Fe, Ni, Cr)
  • Transportation to Smelter
  • Steel Production
  • Spoon fabrication
  • Transporting the spoons to the market

 

According to Plimer, I., 2014, 2% of the world’s energy is used for crushing, grinding, separating and transporting rocks, which would include iron, chromium and nickel – most of this energy comes from coal(2). Renewable energy cannot currently provide this amount of energy reliably.

How much energy is required to produce one ton of austenitic stainless steel? Johnson, J et al 2007 created a flow chart detailing the amount of energy used in typical steel production operations in the early 2000’s, concluding it takes 53,000MJ to produce a ton of stainless steel(3).

Assuming a teaspoon is 25g, the manufacturing of each teaspoon produces uses approximately 1.3MJ of energy (this number is not inclusive of the energy used in the teaspoon fabrication process and transportation of the teaspoon to the market).

1.3MJ is the same as:

  • Running a microwave for 20 minutes,
  • Boiling water in a kettle for 10 minutes
  • Running a computer for 60 minutes

Using data from Plimer, I., 2014, one can calculate that to produce one tonne of stainless steel (from mine to sheet 53,000MJ/t) you will need:

  • 2.2g of enriched uranium
  • 3,888 litres of oil
  • 5,571kg of black coal
  • 1000 1m²  solar panels operating for just over two weeks (14.7 days)
  • One 660-kilowatt wind turbine running flat-out for 22 hours

 

CASE STUDY - The London Array, the world’s largest wind farm, situated off the Essex coast in the North Sea.

  • 175 wind turbines
  • 2,200,000MWh output(4). Potential yearly output = 7,920,000,000MJ
  • Creates enough energy to produce approximately 150,000 tonnes of stainless steel (from mine to sheet) in a year.
  • 150,000 tonnes of steel equates to 0.00009% of 2013 steel production (1,606,000,000 tonnes (5))
  • The London Array can supply electricity to 500,000 homes (~1/3 of Essex’s population) but would not be able to provide the energy in a year to produce enough steel to create itself.

 

Is it possible for renewable energy to power the extraction on metals used in steel or even the steel production process? To answer this one needs to consider base load electricity (or base load power).

 

How much energy is required? Base load electricity (or base load power):   minimum level of demand on an electrical supply system over 24 hours from domestic to commercial customers (including teaspoon manufacturers). Base load power stations run 24 hours, producing energy at a constant rate, usually at a low cost relative to other production facilities available to the system (6).

Non-renewable power sources tend to make-up most the base load electricity, renewable energy does not make up full base load power anywhere in the world (2). Currently renewable options tend to be low density and high capital cost infrastructure.

 

Energy return on investment (EROI), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource (7).  Weißbach et. al. 2013 studies EROI of a number of energy sources (8):

Weißbach et. al. 2013

Nuclear and hydroelectricity come-off well. Why is hydropower not used more widely? Hydroelectric power is commonly used in contributing partially or fully to base load power (and peak load power). There are environmental implications to hydroelectric power, such as disturbance of habitat around dams and diversion of natural waterways, however these reasons would not in reality have economic implications that would limit using hydroelectric power more widely. Manufacturing and maintaining dams are capital intensive, the building of dams is very site-specific, and power is dependent on yearly rainfalls. The last two points would really limit how much hydroelectricity can contribute to overall energy use in the future.

Obviously nuclear fission isn’t renewable, but is seen by many to be ‘the answer’ to our energy woes.  Can we realistically power the world with nuclear energy? This is a question posed by D. Abbott, Professor of Electrical and Electronic Engineering at the University of Adelaide in Australia, who suggests that nuclear power is not scalable to fulfil the world’s needs (9). To expand to 15 TW (total power consumption by mankind) power supply, there would need to be 15,000 reactors, which brings with it: land and location, maintenance, nuclear waste, accident rate (scaling accident rates to date, with 15,000 nuclear reactors, there would be a major accident every month) and uranium abundance issues (9).

We cannot currently create a stainless steel teaspoon using just renewable energy. This is not to say it cannot be done in the future, however it would require significant technological advancements, and would more than likely require multiple energy sources, whether it be a mix of renewable and non-renewable or just renewable.

If there was an energy source more accessible, efficient, cheap and abundant as black coal, it would be utilised.

Coal and other non-renewable sources cannot be turned into pariahs, we currently need them. Greater emphasis should be on finding solutions rather than highlighting problems. Non-renewable energy is not infinite, and humans will need to eventually adjust to changing circumstances. “Intelligence is the ability to adapt to change” Stephen Hawking.

 

Sources

(1)   http://www.makeitfrom.com/material-properties/AISI-304-1.4301-S30400-Stainless-Steel

(2)   Plimer, I., 2014. Not for Greens. s.l.:Connor Court.

(3)   Johnson, J. et al. The energy benefit of stainless steel recycling, 2007

(4)   http://www.theengineer.co.uk/energy/in-depth/your-questions-answered-the-london-array/1017519.article

(5)   www.worldsteel.org

(6)   http://en.wikipedia.org/wiki/Base_load_power_plant

(7)   http://en.wikipedia.org/wiki/Energy_returned_on_energy_invested

(8)   Weißbach, D., 2013. Energy intensities, EROIs (energy returned on invested), and energy payback times of electricity generating power plants.. Energy, Volume 52, pp. 210-221.

(9)   Abbott, D., 2011. Is Nuclear Power Globally Scalable?. Proceedings of the IEEE, 99(10), pp. 1611-1617.

 

SJS Resource Management 04-Feb-2015
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