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Monday, April 25, 2022

Fossil energy cost analysis puzzles

 Santos proposes making hydrogen for $2 per kilogram from methane. 

With 48 kgs of methane Santos might make 84 kgs of carbon monoxide and 12 kgs of hydrogen. 

methane + oxygen → hydrogen+ carbon monoxide

3CH4(g) + 3/2O2(g)6H2(g) + 3CO(g)


The 84 kgs of carbon monoxide then could be used in two different processes: 

Reaction with 54 kgs of steam to produce another 6 kgs of hydrogen and 132 kgs of carbon dioxide, 

steam + carbon monoxide → hydrogen+ carbon dioxide

3H2O(g) + 3CO(g) → 3H2(g) + 3CO2(g)


Reaction with 160 kgs of iron ore to produce 112 kgs of iron and 132 kgs of carbon dioxide.

iron(III) oxide + carbon monoxide → iron + carbon dioxide

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

With the first option, the 6 kgs of hydrogen produced at a value of $2 per kilogram would be worth $12. 

With the second option, the 160 kgs of iron ore would cost about $16 (at $100 per tonne for iron ore) and the 112 kgs of iron produced, at a value of $3 per kilogram would be worth $336. 

See Redox reactions are involved in the extraction of metals from their ores

Blast furnace reducing iron ore to iron



Why would Santos propose making hydrogen worth $12 from carbon monoxide made from methane when it could produce iron worth $336 from the same amount of carbon monoxide?

Monday, February 14, 2022

Zero-emission fertiliser production

Production of urea fertiliser with existing technology and natural gas as both a feedstock and fuel creates substantial carbon dioxide emissions and is very expensive due to high fossil fuel energy costs. 

Just one modification can reduce the carbon dioxide emissions to zero - and substitute lower-cost renewable energy: 

Natural gas is reformed with steam into hydrogen and carbon dioxide using solar energy. The technology to use renewable energy for this step was developed by the CSIRO and has been marketed commercially.

This approach of changing natural gas with steam to carbon dioxide and hydrogen is described as Autothermal Reforming. For further reading, see "Difference Between Steam Reforming and Autothermal Reforming".

One tonne of urea fertiliser contains 200 kilograms of carbon. To achieve zero-emissions ONLY just enough natural gas to supply the carbon that will be incorporated into the end product is required: there is no extra carbon that would be emitted as carbon dioxide. 

Natural gas containing 200 kilograms of carbon for one tonne of urea has an energy content of 14.8 gigajoules. At $10 per gigajoule, natural gas costing $148 is sufficient to make one tonne of urea.

Prices to remain high.
(From the ABC article "Farmers turning to alternative growing methods in wake of sky-high fertiliser price")

Analyst Andrew Whitelaw said the huge price hikes in fertiliser all boiled down to one factor: high energy costs.

"I just don't see it [fertiliser prices] falling massively. We don't see it getting back into the A$800 or less mark, by the time we have to buy. We're liable to have high prices for Australia right through to our seeding period."
Andrew Whitelaw from Thomas Elders Markets says fertiliser prices have climbed an extraordinary amount. (ABC News)
Andrew Whitelaw from Thomas Elders Markets says
fertiliser prices have climbed an extraordinary amount. (ABC News)

One tonne of urea can be made in the following steps:

  1. methane + water => hydrogen + carbon dioxide
  2. nitrogen + hydrogen => ammonia
  3. ammonia + carbon dioxide => ammonium carbamate
  4. ammonium carbamate => urea + water

All of the carbon dioxide produced in step 1 is consumed in step 3. 

Half of the water consumed in step 1 is recovered in step 4.

Inputs consumed are the methane and half the water used in step 1 and the nitrogen used in step 2.

The only outputs are one quarter of the hydrogen from step 1 and urea from step 4. 

This method produces zero-emission hydrogen with renewable energy, in parallel with the manufacture of urea. 

Hold that thought.

After considering what seems a novel approach to zero-emissions fertiliser manufacture, (or indeed, any 'novel' idea in any industry) it is always worth doing a patent search to check if the 'novel' idea has in fact been developed by someone else.

And so it is in this case. 

A patent search turns up a patent "Zero emission urea process and plant". The abstract begins: 

"Disclosed is a method for the production of urea allowing a substantial reduction , even down to zero , of the continuous emission of ammonia conventionally resulting from such a process. ..."
The above patent addresses only the reaction of carbon dioxide and ammonia. 

The same inventors also have a patent for the production of the hydrogen and carbon dioxide that are required to make urea, "Process for producing ammonia and urea". The abstract begins:

"Disclosed is a process for the production of ammonia comprising a step wherein synthesis gas is formed in two different ways, viz. by catalytic partial oxidation (31) and by steam reforming, and wherein the combined streams of synthesis gas are subjected to a water gas shift reaction (50). Also disclosed is a process of producing urea, wherein ammonia is formed (90) in a process involving said combined streams and wherein carbon dioxide (110) formed in the same process is reacted with said ammonia so as to form urea."
The assignee of the technology, Stamicarbon, says on its website: 

"As the world market leader in design, licensing and development of urea plants for the fertilizer industry, we apply our expertise, knowledge and experience for many solutions; fertilizer production technologies, emission reduction technologies and all technologies for the integration of urea and adjacent processes."

Wednesday, January 26, 2022

Diesel Locomotives may be powered by Grid-Scale Batteries

The New South Wales Environment Protection Authority commissioned a study in 2014 on the emissions and efficiency of diesel locomotives in use by Pacific National - "DIESEL LOCOMOTIVE Fuel efficiency & Emissions Testing". 

Pacific National Diesel-Electric Locomotive NR121
Pacific National Diesel-Electric Locomotive NR121


The test report includes the electric power output of the diesel engines used in the testing program, and the quantity of fuel needed for operating the locomotives between Melbourne and Brisbane. 

This data allows the calculation of the output and storage capacity of a grid scale battery that, if installed in a rail car, would replace the diesel engine, electric generator, and diesel fuel used by Pacific National's diesel locomotives. 

The financial analysis - to choose the time for conversion from diesel to battery power - is a separate matter. When the business case favours the conversion will depend on the falling cost of grid-scale energy storage options and the security of diesel fuel supplies. It is only a matter of time. That is to say it is a question of "when", not "if", the conversion is a good financial proposition. 

The energy requirements. 

Two Pacific National diesel locomotives are described in the report for the NSW EPA. 

Each had diesel electric power output of between 3,000 and 3,500 kilowatts - about 3.5 MW. 

The fuel capacity was 12,500 litres of diesel fuel - sufficient for operating from Melbourne to Brisbane without refuelling. 

The fuel consumption was about 210 grams of diesel for each kWh generated. 

Diesel has a density of about 0.85 kilograms per litre.  See "2.3.5 Diesel Fuel".

With a few calculations - 12,500 litres of diesel weigh 10,625 kgs. 

At 210 grams per kWh, 10,625 kgs of diesel can generate a little over 50,000 kWh or 50 MWh of electrical energy. 

A grid-scale energy storage unit able to deliver 4 MW of output power with 50 MWh of storage capacity is in the range of Battery Energy Storage Systems currently being delivered be energy storage manufacturers. 

See for example -  "In New York, a high-level demonstration project is using a 4 MW / 40 MWh battery storage system..." reported in Battery Storage Paves Way For a Renewable-Powered Future

The Business Case.

Pricing information and other details required for a financial analysis and business case for converting Pacific National's diesel locomotives to battery energy storage systems for the time being is not easily obtained. 

Some indicative estimates can be calculated - 

  • 12,500 litres of fuel are loaded for a single trip from Melbourne to Adelaide. At $1 per litre, the fuel costs $12,500. 
  • Electrical energy for the trip is 50 MWh. At $50 per MWh, the energy cost would be $2,500 - a saving of $10,000 per trip. If 200 trips were made each year, the fuel saving would be $2 million per year. 

If it is physically not practical to use a 50 MWh Battery Energy Storage System due to its size and weight, this could explain the interest in development of hydrogen with fuel cell technology for rail transport. See "Coradia iLint™ – the world's 1st hydrogen powered train" -

It was at InnoTrans 2016 in Berlin that Alstom presented the Coradia iLint™ for the first time. The launch of the CO2-emission-free regional train that represents a true alternative to diesel power positioned us as the first railway manufacturers in the world to develop a passenger train based on hydrogen technology. And just two years later, at 2018, the iLint™ entered into commercial service in Germany.

Further Reading.

A recent research paper provides a summary of weight and volume characteristics of energy storage systems for potential application in rail transport - "Energy storage devices in electrified railway systems: A review"