October 28, 2023, 5:25 p.m
PiataAuto.md editors
In the last two months, Australia has set new and new energy production records from its photovoltaic panels, especially domestic ones, reaching in some states to provide more than 100% of the required power at certain noon hours. These records were made possible by the enormous increase in panel installations over the past year, but September’s records were only the tip of the iceberg of the situation now showing. In Australia, summer is just now coming, when the angle of incidence of the sun in the southern hemisphere is more prolific for panels. And now is also a more productive season for wind energy, and this has made the two sources provide 264% of the energy needed for the state of South Australia, for example!
If at over 100% power South Australia was able to export to neighboring Australian states and use the surplus to charge the batteries, at 264% all capacity was exceeded and disconnections from the system were resorted to. More precisely, of the 264% of electricity produced by wind and sun, 126.5% of what the entire state’s electricity grid needed was “disconnected”, and only 137.5% of renewable energy production could be absorbed .
To avoid wasting this much-desired energy in the total electricity quota, but impossible to store or use at the times when it is produced, Australia has recently authorized an exceptionally large number of battery plants, which will join the already very large number that exist. But now the state of South Australia has reached the final stage when it will name the winner of a more special tender to build the world’s largest hydrogen plant near the town of Whyalla on Australia’s south coast, near cities such as Port Augusta or Adeilaide. The new plant will cost approximately 593 million dollars and will be owned by the state. And its mission is to make use of the overproduction of energy during peak hours in a different way than batteries, so it’s not just about storage.
Photo: Battery plant, Australia
The hydrogen plant will be composed of a whole huge system, with various functions, which can be connected according to necessity. First of all, it will have hydrogen production halls through electrolysis, with installations totaling 250 MW of power in total. Electrolysis being a process that separates water into hydrogen and oxygen, with the help of electricity, the factory will be able to “consume” 250 MW of power from the system during overproduction hours, thus helping to avoid energy wastage. Because this production peak in the system is provided by renewable energy, the resulting hydrogen is green, produced with zero CO2 emissions. If we consider that the production of one kilogram of hydrogen consumes 53-55 kWh of electricity, the 250 MW plant, when working at full capacity, can produce about 4,545 kg of hydrogen per hour. So, about 4.5 tons of hydrogen per hour.
The factory will have storage tanks for this hydrogen, amounting to 3,600 tons. If we were to do a reverse calculation to understand how much energy must be consumed for the 3,600 tons, we would get about 200,000 MWh, so 200 GWh! A huge amount, which we double-checked the tender documents to make sure there wasn’t a measurement error in the middle. But no, the tender specifies 3,600 tons of storage of the future plant, underground, which means 800 hours of maximum operation to fill those tanks, or about 33 days. For comparison, the largest battery recently contracted in Australia stores 2.4 GWh.
Now, if the future plant in Australia were to use this hydrogen to produce electricity through fuel cells, it would get about 33 kWh from a stored kg, and if we think about the 55 kWh consumed for the same system, then the yield is relatively low , of about 60%. Except the new plant won’t do that, because it’s not just storage.
It will be much more efficient thanks to its system. In electrolysis, when hydrogen is produced, in addition to the 55 kWh consumed by electricity for one kilogram, heat is released. The plant will store and send that heat to a heat pump plant on its territory, amplifying it and sending it to a heat storage tank. That final heat can provide hot water for cities or heating for homes in the winter.
In addition, the generated hydrogen will not be used in a fuel cell plant, but in a gas turbine thermal power plant converted to run on hydrogen. So that hydrogen will go through combustion, spinning the turbines of the power plant, generating electricity and heat as a side effect, and the heat can be sent back into the homes either for direct heating or for domestic hot water. If there is a surplus of hydrogen, it will be sold directly as a finished product, for export, with the plant having the chance to become a large global producer of green hydrogen. In addition to that, above you can see that there is also a steel processing plant, nearby, which has furnaces where gas is used, and where it will be possible to use hydrogen for combustion, generating zero CO2. The plant will also have underground hydrogen pipelines to the steel factory and to the port, for eventual loading on ships for export.
The tender documents specify what power the hydrogen thermal plant must have — 200 MW — so at maximum operation, 200 MWh of electricity will be produced per hour, for the hours of maximum consumption, and this in addition to the heat generated. By the way, a hydrogen turbine usually produces 1.67 times more heat in hydrogen combustion than electricity, so we can also estimate about 330 MWh of heat.
Photo: General scheme of operation of a power plant of this type
The exact consumption is not indicated, because it will depend on the winner of the auction, but there are few manufacturers of such turbines in the world. From the available data, a 200 MW gas turbine will consume about 14.3 tons of hydrogen per hour to produce the 200 MWh of electricity. So from one kWh, about 14 kWh of electricity is recovered from the 55 kWh initially consumed, but about 23 kWh of heat is obtained in the final stage, plus the heat emitted during the initial electrolysis, about which we do not have data now.
So, if you only want to store electricity, the method of burning hydrogen in a gas turbine is not the efficient one, but if you also want to replace thermal energy in cities, and on top of that, the production of hydrogen for many other purposes, then this whole plant starts to have justification, especially if it is built where the overproduction of renewables can reach 264% and it will, practically, help that energy is not simply wasted.
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