Towards producing green hydrogen
Carbon dioxide (CO2) is endangering the climate. Most countries have made 2050 the target year for achieving zero net emission of CO2.
Solar and wind power has wide opened the doors of green electricity, which will greatly help to reduce CO2. However, thermal energy and liquid fuel issues still have to receive some solutions.
In the case of thermal energy, green electricity provides solutions only indirectly. Oil and coal are still dominant and are expected to dominate for quite a while.
Green hydrogen, combined with solar and wind, will be able to drastically reduce carbon footprint and help solve the climate change issue. Forecasts are that it would occur by the year 2050.
It is hydrogen which offers the other green route for thermal energy required in industrial process. Thermal energy is not provided by solar and wind. Currently, grey hydrogen is being produced from oil, gas or coal. As opposed to grey hydrogen, green hydrogen is produced by electrolysing water, which produces hydrogen and oxygen.
Making or isolating hydrogen
How to make or isolate hydrogen is an issue. The fossil route is oil, gas and coal. The green route is water and seawater. Water is a chemical compound of hydrogen and air. Water can be electrolysed to get hydrogen and oxygen.
Water electrolysis is known for almost a century. The issue is of economics and efficiency. A lot of electricity is required to decompose water into hydrogen and oxygen. Norway used to produce hydrogen from its hydro resources and convert it into urea. Later, the abundance of gas made them switch to gas. Norway is again trying to go back to hydro-based hydrogen, but for a cost.
Ironically, Pakistan used to make hydrogen/ urea from coal, it too switched to cheaper gas and now there is talk of switching to Thar coal.
Amazingly, food and organic waste is now being converted to hydrogen directly instead of producing biogas, which is actually methane. The process is essentially the same, but with some modifications.
It can produce hydrogen in hours rather than weeks that it takes to produce biogas. Current technology of producing green hydrogen is based on electrolysis of water through the application of renewable electricity like solar or wind.
The main constraint is the requirement of pure water, which is produced by energy-intensive reverse osmosis process.
Recently, processes have been developed, which run on impure water like seawater. Also solar panels are being developed, which convert solar energy through the electrochemical processing of water – by extracting water from air.
Residential fuel cells
Originally, fuel cells have been used in satellites. Japan introduced ambitious plans to induct natural gas-based fuel cells of up to 5-kilowatt capacity for residential purposes.
These devices are of the size of a refrigerator and run on natural gas. They have a very high efficiency, reaching almost 90%, and provide both electricity and hot water.
Under a heavy subsidy programme, only 268,000 such devices were sold in Japan by 2018. There are plans to introduce 5 million such devices by 2030.
Hydrogen cars vs battery EVs
EIon Musk, CEO of Tesla Motors, calls hydrogen vehicle to be a dumb thing, but General Electric and GM have great plans in this respect. Hydrogen cars have started to compete in the transport sector. Both electric and hydrogen cars are electric vehicles (EVs) – one has electric batteries which have to be charged through a power grid whereas the other produces electricity on board from hydrogen.
Hydrogen cylinders have to be charged from hydrogen pumps as petrol and diesel are filled. EVs are far ahead in the market and charging stations are being installed on fast track in many counties. EVs can be charged at home as well.
However, the race between EVs and hydrogen cars has yet to be called off. Major automotive companies like Toyota are planning to adopt the hydrogen route. It appears that EVs would have a larger market share in case of cars, but for large vehicles EVs may not be able to compete with hydrogen vehicles.
Although at present battery electric vehicles (BEVs) seem to be ahead, in Europe, the US and even India, there are programmes to introduce fuel cell-based hydrogen trains.
In Europe, on smaller scales, hydrogen trains have already been introduced. By 2025, there may be substantial inroads of hydrogen trains into these countries.
Other uses of hydrogen
They are trying to develop safe and economic ways of transport and storage of hydrogen. Already, in the UK, a portion of a district has been converted to hydrogen as a cooking gas. Hydrogen pipelines are being laid to replace natural gas.
Urea/ fertiliser would be produced out of green hydrogen. Green hydrogen could supply up to 25% of world energy needs (thermal) by 2050, according to some estimates. It is expected to make inroads into carbon-intensive industries like steel-making, chemical production and even power generation.
In gas turbines, hydrogen has been used as a mixture with natural gas up to 25-30%. Eventually, 100% hydrogen would be used in running gas turbines for combined-cycle power plants.
Economics
Green hydrogen would be effectively replacing fossil fuels like oil, gas and coal – all through water as a main source. Companies have targeted a 50-time increase in the next six years.
Technology is there. It is a question of cost. Green hydrogen cost has come down by 40% since 2015 and is expected to go down by another 40% through 2025. Current green hydrogen cost is $2.5-6 per kg as opposed to grey hydrogen production cost of $1 per kg. Goals are there to bring the hydrogen cost below $2 per kg as compared to the renewable electricity target of less than 2 US cents per kilowatt-hour (kWh).
In the case of fertiliser/ urea, current green hydrogen/ ammonia cost is 200-300% higher. This differential may be halved in the medium term. After the achievement of $2 cost benchmark, the switchover to green hydrogen would get faster. Already, there are plans to run aircraft on hydrogen as early as by 2025 at a cost competitive with jet fuel.
Concluding, hydrogen is the future. Let us start with grey hydrogen, which can be produced from fossil fuels. Hydrogen or a mixture of hydrogen and natural gas can be piped through normal pipelines.
Recent linkage of hydrogen production with biomass has increased the attractiveness of hydrogen cycle in developing agricultural economies like that of Pakistan.
Thus, grey hydrogen can be a reality within a matter of five to seven years under various coal gasification projects that are being worked on. All industrial activities including chemicals, plastics and steel can start running on it.
For green hydrogen, one may have to wait till the issues are resolved. There may be scope for launching pilot projects of green hydrogen in northern areas such as Gilgit-Baltistan, Chitral and others. In these areas, gas network cannot reach and LPG air-mix plants were planned.
The writer is former member energy of the Planning Commission and author of a number of books on Pakistan’s energy sector
Published in The Express Tribune, March 8th, 2021.
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