About 200 MW of electricity could potentially be generated from biogas-from- waste projects around the country, with a number of projects potentially being able to generate up to 10 MW of electricity on site, developer and operator of industrial organic waste-to-energy systems CAE Energy MD Dr Andrew Taylor said last month.

He emphasised, however, that the National Energy Regulator of South Africa's (Nersa's) decision on the renewable-energy feed-in tariff (Refit) for biogas and power utility Eskom's response to that decision would be "pivotal" to the success of these projects.

Nersa had held public hearings on the second phase of Refit earlier in September, which would include biogas.
CAE Energy had partnered with Humphries Boerdery, near Bela-Bela, in Limpopo province, to develop a project to convert biogas into electricity, with the plant already having produced 10 MWh of electricity since August, said Taylor.

Humphries Boerdery, along with other partners, had previously constructed and commissioned a biodigester at its piggery, which successfully processed and sanitised waste from the piggery with about 1 400 breeding sows and about 10 000 pigs in total.

It had then partnered with CAE Energy to develop a power generation project at the piggery, which was currently capable of producing more than 500 kW of electricity.

However, only about 10% to 20% of the biogas was currently being used to produce electricity, with the remainder being flared and wasted, as the Refit structure had not yet been finalised by Nersa, Taylor said.

He noted that both Humphries Boerdery and CAE were, however, hopeful that the regulator would announce a tariff of about R1/kWh at the end of this month, and that Eskom would respond favourably to this decision and enter into power purchase agreements (PPAs) with power producers.

While Nersa had initially proposed a 96c/kWh tariff for biogas, Taylor noted that a number of producers had made submissions that a higher tariff would be needed.

This was owing to the fact that, unlike the case of landfill gas, where little or no mate-rials handling was required, biogas producers had to pump material in and out of the power plant on a daily basis, as well as dispose of material.
CAE was hopeful that a tariff of between R1,20/kWh and R1,40/kWh for biogas would be set.

Once the tariff structure was decided on and PPAs had signed with Eskom, this would allow the project developers to increase the size of the power generation plant.

Taylor noted that CAE was hoping to boost the output of the plant to about 500 kW by the end of this year and to 750 kW by early 2010.

The power plant was already fully embedded into the national grid, but used electronic switchgear, which managed the amount of power generated by the plant. This allowed it to ensure that the farm imported between 5 kW and 10 kW of power from Eskom at all times, but did not push any of its generated power to the grid, as it did not yet have a generating licence.

The rest of the piggery's power requirements of about 75 kW, above the 5 kW to 10 kW of imported power, were generated by its own plant, saving the piggery some electricity costs, said Taylor.

The switchgear adjusted the power generation of the plant in accordance with the rise or drop in consumption of the piggery.

Taylor highlighted that the plant would be immediately able to export up to 70 kW/d to the national grid as soon as it received permission to do so.

This could increase to about 700 kW within a few months.

The electronic switchgear was the only imported equipment at the power generation plant, with all other equipment and software having been designed and constructed in South Africa, said Taylor.

He noted that CAE emphasised assembling and developing local technology, reducing the need to import equipment at a euro-based cost.

This approach could save developers up to 30% when compared with the cost of imported equipment.

Taylor explained that the electronic switchgear was, however, imported as this was equipment that Eskom had previously scrutinised and approved for use.

This was imported from the US through another partner on the project, Denco Automated, said Taylor.

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