An energy mix that prioritises renewables

June 29th, 2016, Published in Articles: EE Publishers, Articles: Energize

 

Generating renewable energy at utility scale and making it baseload-ready is a technical feat which, as I saw on Day 1, is achievable on a project level. Making renewable energy viable as a baseload option and finding an optimal mix is another feat altogether.

Pierre Potgieter, assistant editor at EE Publishers, is on a week-long tour of South Africa, sponsored by the US Embassy, seeking out various innovative renewable energy projects. The articles below form a diary of his travels.

Day 2: Tuesday 28 June 2016

One of the aspects of the US’s partnerships in South Africa is research and development work, among others in the field of energy research. Energy investment makes up roughly 5% of US AID’s investment in South Africa. Research developments, policies and best practices can be exported and adopted in other parts of the world too.

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Click here for Pierre’s report on day 1

Click here for Pierre’s report on day 3

Click here for Pierre’s report on day 4

The Council for Scientific and Industrial Research (CSIR) is one facility which has adopted a strong energy research focus. Thus, on the second day of the US-SA Green Energy Tour I’m on, I was able to visit the CSIR’s recently established Energy Centre to see what its team is working on.

Dr. Tobias Bischof-Niemz, the head of the centre, gave an overview of the different power generation options, their typical uses on electricity grids and their associated cost, so as to explain the importance of an energy mix and how such a mix can be optimised for cost and other factors. He said that an earlier study found wind energy to be more promising than initially thought and that this, along with solar PV’s rapid growth and low price, makes renewable energy a viable baseload option.

Optimising the energy mix for renewables

To realise renewable energy’s impact as a potential baseload power source means taking a holistic view at how it offsets the use or need for other (usually more expensive) baseload and peak generation, rather than only looking at renewables’ performance during peak demand periods. Using high resolution wind energy data (5 km2 at 15-minute interval resolution) and energy costing estimations, allowed the CSIR to create a simulated scenario to demonstrate renewables’ viability (specifically that of solar and wind) for baseload generation.

Bischof-Niemz showed how wind generation on a large scale, and with strategic placement (throughout the country), could ease currently observed intermittency variations. It is however the cost benefit and the great advantage of cost and output predictability which other generation options lack which make renewable energy so attractive for baseload power, he said. Having storage capabilities in the form of hydro is especially useful to realising renewable energy optimised grids and baseload power.

Another area of the Energy Centre’s many research topics is embedded (or distributed) generation, and it is also currently working on creating a micro-grid for the CSIR campus.

Down electric avenue

I got a lift with Bischof-Niemz to the other side of the CSIR campus to look at the solar PV for the micro-grid. It should be no surprise that he drove an electric car, and on the way I and two other passengers were treated to a full explanation of why electric cars are the future of urban travel, and why renewable energy should be used to charge them (click on the image below for the video):

Day 2 video CSIR

The CSIR’s micro-grid will comprise a mix of energy sources for research purposes, and with some of its environmental impact assessments still underway, its scale has not yet been determined. There is however one section of single-axis tracking solar PV panels already operational, with a dual-tracking system about to be built.

The research facility is in a unique position to experiment with different energy technologies, and with a 5 to 6 MW demand – similar to a small town – can do so effectively. The variety of operations also allow it to focus on optimisations, such as heat production being fed to heat sinks.

Mixing it up with micro-grids

Micro-grids connected to the national grid can form part of the generation mix, and comprises a mix of generation technologies. It can also be a standalone, grid-independent solution. Who is then better to ask about micro-grids than ABB’s Tony Duarte who has been in the business for 25 years, and recently implemented ABB South Africa’s own micro-grid at their Johannesburg head office?

The company’s 1 MW micro-grid runs in parallel with the national power grid, and comprises solar PV and diesel generation. Generation behaviour is programmed into the flash memory of controllers that then optimise the energy mix on cost criteria, favouring renewable generation. “Penetration” – or intermittency introduced to the grid – make frequency stabilisation essential, and in this microgrid’s case a battery system is used to achieve this.

Battery technology, although decreasing in cost, is still very expensive. For this reason, the battery in ABB’s micro-grid has not been scale to full amount, but is instead scaled to economic viability to serve as a backup system until the diesel generation starts up in the event of a blackout.

Apparently ABB had three objectives when it implemented its micro-grid:

  • Grid resilience or power security
  • Cost effective access to energy, or lowest levelised cost of energy
  • Reducing its carbon footprint

Yet micro-grids offer many other benefits too. Since they are modular and scalable, they are easy to implement for short periods, and can be interconnected to run in parallel with or independent of national grids. This makes a micro-grid useful for remote industries such as mining which look to move away from, or decrease, diesel generation reliance, as well as for industries like the food and beverage producers which need an uninterrupted power supply.

Although micro-grids are generation agnostic (i.e. can accommodate different generation technologies), the generation technology’s behaviour and generation profile is essential in a micro-grid’s design. Automation systems and storage/stabilisation are also fundamental to hybrid power system integration such as that found in micro-grids, especially with high levels of penetration (intermittency/instability).

Duarte also explained that even if micro-grids are not interconnected or connected to a central grid, it is always important to have stability standards and coherency. Consultation with experts is important not only to help with this, but to find the right balance of technologies and the scale of each as required at each site, depending on its needs and location.

On the whole the optimised energy mix with a strong renewable focus seems to be something to pay attention to as the direction that power generation, and also distribution, might be shifting.

Click here for Pierre’s report on day 1

Click here for Pierre’s report on day 3

Click here for Pierre’s report on day 4

 

 

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