Sable chemicals to dump Zesa bill


Sable Chemical Industries receives a string of bills every month, but the country’s sole manufacturer of ammonium nitrate (AN) fertiliser dreads just one – Zesa’s electricity bill, which now peaks above $20 million every month, hurting earnings.
The agrochemicals company requires 115 MW – the size of a power station – to fire its 14-unit electrolysis plant, which consumes 90% of this power supplied by Zesa through a dedicated sub-station.
Other processes rely on steam from a coal-fired steam-raising plant.
Now Sable wants to “switch off the electrolysis plant completely” and diversify to coal gasification in phases, as it seeks a more cost-effective way of producing hydrogen, according to Shingai Mutasa, the chairman of the company.
The electrolysis plant comprises 14 electrolytors, five of which are currently offline, which consume staggering megawatt hours of electricity to break water into hydrogen, a key ingredient, and oxygen, a by-product.
The load online currently consumes around 80 MW for every hour they are deployed.
“Our plan in the medium term is to increase production by increasing coal gasification so that we increase our production of hydrogen that way as opposed to electrolysis,” Mutasa said.
“At the moment electricity supply is reliable, we don’t have outages but cost is an issue.”
Coal gasification is a chemical process of breaking coal into its chemical components — hydrogen, carbon monoxide and other gaseous compounds — by exposing it to excessively hot steam and oxygen.
The project, still at a pre-feasibility stage, is expected to start running in five years and should cut Sable’s electricity consumption to 30 MW.
It entails setting up a coal gasification plant made up of a coal gasifier.
As in the electrolysis process, the hydrogen produced through gasification is reacted with nitrogen in an ammonia synthesis plant to produce ammonia. Part of the ammonia is piped to a nitric acid plant to generate nitric acid, which is then reacted with ammonia in an ammonium nitrate plant to produce liquid ammonium nitrate.
In this liquid form, ammonia is also sold to secondary fertiliser manufacturers — Zimbabwe Fertiliser Company and Windmill — which produce fertiliser compounds by mixing it with ingredients such as phosphorous and nitrogen.
The final product is then dried and pulled into solid granules used as top-dressing fertiliser.
Sable decided to stick to Zesa after the government dissuaded it from importing power from regional utilities on its own, urging “an internal solution”, after the company shut down its electrolysis plant in November last year citing exorbitant Zesa bills.
“We were prepared to pay wheeling charges to Zesa and import cheaper electricity on our own from Zambia.
“But we were persuaded to look for a local solution. So government, Zesa and Sable agreed to jointly look after the fertiliser industry,” Mutasa said.
The tripartite meeting agreed to maintain constant power supply to the prime fertiliser manufacturer and grant a special tariff of below five cents per kilowatt hour.
However, Sable’s electricity bill will still balloon in the near term as the 38-year-old plant ramps up capacity utilisation, aiming to reach 60% by December and 100% in three years, from the current 40%.
From a record low of 40 000 tonnes in 2009, the fertiliser maker targets producing 100 000 tonnes of AN this year, 45 000 tonnes of which are already in stock.
This level should adequately meet the country’s current AN demand, which declined over the years owing to problems related to structural bottlenecks, capital constraints, policy issues and uncoordinated agrarian reforms.
At full capacity, the plant churns out 240 000 tonnes of nitrogenous fertiliser which in the 1990s was all absorbed by the domestic market.