Govt’s energy rescue options based on tricky assumptions
WHILE government officials are touting the coming on board of Hwange Thermal Power Station unit 7, as well as power imports as immediate solutions to the electricity crisis gripping the country, energy experts say the hopes are anchored on uncertain deliverables.
The 300 megawatt (MW) unit is part of two generators making up the Hwange unit 7 and 8 expansion project being undertaken by Chinese firm Sinohydro under facility from China Eximbank.
Unit 7 is a component of the US$1.4 billion Hwange expansion project expected to add a combined 600MW into the national grid. The government says the coming on board of unit 7 is imminent, while unit 8 is expected to be connected to the national grid in March next year, adding another 300MW, which will significantly ease the country’s power crisis.
Engineers however say the successful synchronisation of unit 7, which is seen as one of the most viable immediate solutions, will be key given that if it is hurried, it can result in severe setbacks. Hwange unit 8 is only expected to come on board in March or April next year.
Chinese engineers are in the country to oversee the synchronisation. Synchronisation is the process of matching the frequency of a generator or other source to a running network.
An alternating current generator cannot deliver power to an electrical grid unless it is running at the same frequency as the network.
A direct current generator can be connected to a power network by adjusting its open-circuit terminal voltage to match the network voltage, by either adjusting its speed or its field excitation. There are five conditions that must be met before the synchronisation process takes place.
The source (generator or sub-network) must have equal line voltage, frequency, phase sequence, phase angle and waveform to that of the system to which it is being synchronised. Several tests are mandatory before this is done.
If not done properly or if hurried, it can result in explosions, which often result in severe setbacks. In South Africa, for example, unit 4 of Medupi Power Station, a dry-cooled coal-fired power station built by Eskom near Lephalale in Limpopo province, exploded in 2021 shortly after being connected to the grid. It caused extensive damage to the generator while also tripping unit 5.
Acting manager at Medupi Zweli Witbooi in May said the incident “seems to indicate procedural non-compliance and management failures”.
The explosion is expected to take another two years to rectify and has serious financial implications. It is expected to cost about R2.5-billion.
The government is also hoping to increase electricity imports, but that is dependent on availability given that there is a power crisis in the region. The ability to pay is also a factor. Zimbabwe has a reputation for failing to pay on time.
In April, President Emmerson Mnangagwa visited Mozambique, where he toured a gas-powered station accompanied by Zesa executive chairperson Sydney Gata, as Harare sought additional power imports.
Mozambique state-owned national power utility Electricidade de Moçambique (EDM) chairperson Marcelino Alberto expressed his institution’s willingness to increase the amount of energy it exports to Zimbabwe despite being owed.
“Last year, Zimbabwe made a titanic effort to pay down its debt to Mozambique, which stood at US$45 million, and a good part of that amount — US$35 million — was paid last year. At the moment, the amount outstanding stands at US$10 million,” the EDM chair explained.
Energy minister Soda Zhemu on Thursday told Parliament that Zimbabwe is looking to increase imports from Mozambique and the region to 500MW.
Kariba Power Station
The Kariba Hydro-Power Station is likely to continue producing limited electricity until February next year when the water level at Lake Kariba is expected to rise. Load-shedding has been persistent countrywide, with some residential areas experiencing rolling power cuts of up to 18 hours, following the reduction of electricity generation at the Kariba Hydro-Power Station.
The Zambezi River Authority (ZRA), a bi-national organisation overseen by Zambia and Zimbabwe, on 28 November ordered suspension of power generation at Kariba Hydro-Power Station, until January 2023, after Zimbabwe exhausted its allocation of water.
Zimbabwe was later allowed to produce at a reduced capacity. The ZRA revealed that the Kariba South Bank Power Station (KSBPS) had utilised 23.89 billion cubic metres (BCM) of water, accounting for 1.39 BCM (or 6.16%) above the 2022 water allocation of 22.50 BCM.
The KSBPS, Zimbabwe’s largest power plant, has been producing less than a third of its total generation capacity of 1 050MW.
Zimbabwe’s power stations, namely Hwange, Kariba, Munyati, Harare and Bulawayo, are hamstrung and were producing a combined 669MW on Thursday, against a demand of 2 200MW. Hwange was producing 438MW while Kariba was producing 231MW.
Harare, Bulawayo and Munyati power stations were not producing anything. According to an educational video produced by the ZPC, the water intakes for power generation at Lake Kariba are designed at 13 metres below maximum water levels, in order to avoid mud which would clog the power generation facilities.
This means that only a certain amount of water is accessible for power generation, which is also known as live water.
Independent power producers
The Zimbabwe Energy Regulatory Authority (Zera) has in the past five years licensed about 100 small IPP projects with a capacity to produce around 1 300MW, but most of them remain non-operational. Gata revealed during a tour of Hwange Power Station by editors last year that the projects were failing to take off due to country and currency risks, policy mis-steps and lack of bankable feasibility studies.
For example, in September 2020 Zesa abandoned its Mutare Peaking Power Station project, which was supposed to be completed in 2022. Zesa said it abandoned the project, which was envisaged to contribute as much as 120 megawatts to the national grid, because using diesel to generate electricity was costly.
The 100MW Dema Emergency Power Plant, powered by diesel and built in 2016 by Sakunda Holdings, has also been abandoned.
Gata said the failure of several other power generation projects to take off was not surprising mainly because they were either not bankable or were undertaken without due diligence and feasi bility studies.
“We have a number of projects that have been reported in the media, but they have not proceeded because I believe as a nation, we still have to learn a lot about what is called country risk,” Gata told editors.
“Quite a number of these (projects) were white elephants at birth. They were born deformed. If we are developing a project such as in Hwange here, there are phases that are mandatory to be followed and to be appreciated for their importance in the project development programme.”
Gata added: “Here is a list of projects that went ahead without bankable feasibility studies: Batoka Hydro; Mutare Peaking, which has been cancelled; Gwanda Solar, which is in difficulties; Dema, which has been cancelled; then we also have project start-ups without policy support.
“We have over 100 IPP projects that have been licensed that are paralysed because policy does not carry them. In the normal progression of what I call the development phase, before the joint development agreements, you are syndicating the equity and bringing investors in the process.
“In the projects that I listed, what killed them, those that were killed, is lack of market due diligence. We have a list of projects that the banks, all these big banks, are not coming to the party because they say how can we lend to ZETDC which is selling electricity at a loss? When you come to currency risk, the lender will say ‘how can I lend in US dollars if you are collecting RTGS to repay the loan?”
Coal and solar
Zimbabwe has also been banking on coal as a long-term power solution, which has been greatly affected by China’s announcement last year that it was halting coal projects outside its mainland, in order to reduce carbon emissions.
This has worsened Zimbabwe’s power crisis. For instance, Zimbabwe Zhongxin Electrical Energy, a joint venture with the Zimbabwe Defence Forces (ZDF), was building a 50MW power plant with plans to expand that to 430MW.
Dinson Colliery, the coal-mining subsidiary of steelmaker Tsingshan Holding Group, was working on a US$300 million coking plant, while Jinan Corporation was planning a 600MW plant. Another major project that has been directly affected is the US$3 billion 2 800MW thermal power plant in Gokwe that RioZim Energy was building with engineering and financial support from China Gezhouba Group Company, and PER Lusulu Power’s proposed 2 100MW power plant in the north-western district of Binga.
While Zimbabwe has coal — the major resource — it has been starved of funding to develop thermal power stations on its own. During the editors’ tour, Gata said while a migration to renewable energy was necessary, resources like solar and wind have a premium of cost adaptation as they require storage, which is costly.
Gata said a regional power strategy should be pursued to improve electricity availability and access in Sadc.
“Development of the massive hydro potential on the Kafue and Zambezi basins, and operation of the power plants on a collaborative, conjunctive basis is the most viable strategy for the Sadc region. The resources will be operated on the catchment rule, as opposed to the current reservoir rule model,” he said.
“Conjunctive dispatch guarantees that more energy is harvested from the same resources than if operated as single reservoirs. The reservoirs also serve as a large storage battery intermittent solar energy resources, whereby PV (photovoltaic) solar and wind turbines will be operated during daytime, with hydro power deployed to smoothen out the intermittency and at night as illustrated below: It seems imperative that, both for the country and region, we should urgently transition to a green economy. The model of migration which is anchored on collaborative regional development of the massive hydro resources on the Zambezi-Kafue basin, and the setting up of CARE (Central Africa Renewable Energy) as the operating entity, will ensure that the other more desirable sources of renewable energy such as solar and wind can develop faster, as they will be supported by massive hydro storage as a natural battery.
“We therefore offer to transition from a fossil fuel to a green economy so that we can run our farming, industry, mining and also transition from petrol and diesel traction to electric cars and railway locomotives to cut greenhouse gas emissions. We call for support from the global players to realise green energy economies for our collaborating states, and support of the global economies to fund this initiative through export of their technologies,” Gata said.