Wind, solar power plants in the spotlight over electricity stability

This is even as Auditor General Nancy Gathungu raised concerns about the impact that the intermittent power sources have had on the cost of power as well as the poor quality of electricity supplied to consumers.

Kenya has in the last five years seen an increase in solar and wind power plants. Due to the nature of the energy sources, the plants tend to be affected by factors such as cloud cover, reduced wind speeds and rainfall affecting their output.

Other power plants have to be called on to fill the gaps created when production from intermittent sources drops, usually at an additional cost. A sudden increase in production from such plants can also affect the stability of the electricity grid.

Energy Principal Secretary Alex Wachira on Thursday last week said power producers operating wind and solar plants would in future be required to have storage capacity before they can be okayed to start feeding power into the grid.

"Moving forward, we will not bring onboard any variable renewable energy - that is wind and solar energy - without battery backing to ensure that there is grid stability. That is a policy that the ministry wants to implement... any new solar or wind power plant must have battery storage," he said.

Other than placing a requirement on new wind and solar plants, Mr Wachira said the government would partner with private sector players in building battery energy storage systems.

"Among the projects that we will be undertaking within the power sector is battery energy storage. This is meant to reduce the intermittency and store power and use this stored electricity when demand peaks. This will also reduce the venting of steam at geothermal power plants in Olkaria because we can continue to generate, store power and dispatch it to the grid during the peak hours of the day," he said, explaining that whenever demand is low and geothermal power plants cannot continue to generate electricity, the power producers usually release the geothermal steam.

"We are looking at PPPs to implement battery energy storage moving forward... in the least cost power development plan, we have several battery energy storage staggered between now and the year 2032."

Before 2018, the major wind power plant was Kenya Electricity Generating Company (KenGen's) plant on Ngong Hills with a capacity of 25.5 megawatts (MW).

Wind has however increasingly become a key power source for the country following the commissioning of the 310MW Lake Turkana Wind Power plant in 2018.

In 2019, the installed capacity for wind plants went up after the 100MW Kipeto Power in Kajiado County came online and brought the total installed capacity for wind to 436MW.

Solar power production has also grown and in addition to the State-owned Garissa Solar plant with an installed capacity of 50MW, other power plants that have come on board in recent years include Globeleq's Malindi Solar Plans (40MW), Selenkei (40MW) and Cedate (40MW).

Alten Kenya Solarfarm (40MW) is the latest addition and started feeding the grid last year. Wind and solar power accounted for about 20 per cent of the electricity that Kenya Power bought from different power producers.

The Auditor General notes that Kenya Power is heavily impacted by the variable renewable energy sources due to their high level of instability or intermittency during the dispatch operations.

Whenever generation from solar and wind drops, Kenya Power has to engage other power producers at an additional cost.

"These generation sources are continuously supported by other plants which are dispatched to meet the different of generation dropped at any one time which in the final analysis means that the actual cost of generation is the cost of intermittent source plus the cost of generation dispatched to stabilise the ensuing intermittency by meeting the generation shortfall," said the Auditor General in her report on Kenya Power for the year June 2023.

"Where there is a sudden rise in generation due to intermittency, the power system also becomes unstable and leads to excess generation above the demand and this also leads to poor power quality to customers. During these instabilities, parts of the power system go off as part of the self-protective mechanisms of the power system and this leads to outages and therefore loss of revenue."

She added: "There is a need to have a cost-effective stabilisation mechanism for these variable generation sources that are current on the grid and regulations put in place to ensure that all renewable energy generation sources are installed with their stabilisation mechanisms as part of the power generation contracting requirements."

The challenges that the two renewable energy sources pose to the grid have come in the past. Among those who have flagged the risk to the grid include the Presidential Taskforce on the Review of Power Purchase Agreements (PPAs).

In a September 2021 report, the taskforce said it had analysed the performance of wind and solar plants in terms of the power they generate against the requirements of their PPAs with Kenya Power and the verdict was they are underperforming, largely on account of the intermittency.

The taskforce recommended that wind and solar power plants compensate Kenya Power whenever they fail to meet minimum generation requirements as stated in the PPAs that they have with the power distributor.

The taskforce recommended that Kenya Power should "require future IPPs with high intermittency (wind, solar, mini hydro) to take financial risk for predicting their daily, weekly or monthly dispatch of power," said the report.

"The penalty for under-producing would be to compensate the grid at the cost of the thermal plants or the highest peaking plant on the grid as an alternative to the under-generation compared to the forecast. Alternatively, the projects could themselves take on the cost of providing energy storage and presumably adjust the tariff accordingly."

Wind plants tend to optimally produce power at night while solar farms can only produce it during the day, both missing the peak hours for electricity consumption in the country between 7pm and 10pm.

Battery energy storage systems could mean tapping these sources when they are generating optimally and using the power during peak hours.

Kenya Power has also been evaluating the possibility of setting up a battery energy storage system. Earlier this year, the company said it expects to have the first battery storage plant with a capacity of 100 megawatts (MW)to be up and running by 2024. It added that it will increase this capacity to 250MW over the medium term.

KenGen last week said it had been selected as the Implementing Agency for the Battery Energy Storage System (BESS) as part of the Kenya Green and Resilient Expansion of Energy (GREEN) programme, funded by the World Bank.

The power producer said a pilot installation of the BESS capacity is being considered for several key regions, including Central Rift, Coastal Region, Mount Kenya, Nairobi, North Rift and Western Kenya.

It will embark on a feasibility study that will inform the location.