Have you ever developed a masterplan for the electricity generation and transmission system for an entire continental region? For seven countries with a total area of 4,000 km x 2,500 km?
I can now say, “Yes”. But when I started, I had no idea what to expect or the challenges involved. I’m not new to expansion planning. I have already been involved in quite a couple expansion projects with different focusses of study. But, typically expansion plans are for just one country or one region within a country. This was a real master challenge.
A master challenge
The European Commission contracted us through the French consultancy IED. The Commission’s objective: produce a “regional masterplan” for electricity generation and transmission to replace the fragmented system that has kept the region from realising its tremendous energy potential, especially for hydropower.
The seven countries included the Democratic Republic Congo (DRC) plus the six countries in the Economic Community of Central African States (ECCAS): Cameroon, Gabon, Chad, Equatorial Guinea, the Republic of Congo and Republic of Central Africa (RCA).
These seven countries could not be more different. The economically strong Equatorial Guinea has a GDP of 8,300 USD per capita with only 1.2 million inhabitants. In contrast, the DRC has 79 million inhabitants, but only 5% of Equatorial Guinea’s economic power at 440 USD per capita. Each country’s social and political systems are also vastly different.
Most of the seven countries do not yet dispose of national interconnected grids. Hence, the region is currently supplied with electricity in a largely isolated way.
In terms of climate, there is desert in the North, tropical regions on the coast with semi-humid savanna in the highlands and alpine conditions in the mountains. The region’s hydropower potential reflects this climatic diversity. DRC, Gabon and Cameroon have an especially large potential for economic hydropower. As an arid country, Chad has almost none. But it does have precious fossil resources in its favour.
The mighty Inga
For those, who don’t know Inga: Inga is Central Africa’s most exciting location for hydropower and central to our masterplan. Located in South DRC, it’s where the massive Congo River has the second largest discharge worldwide (approx. 41,200 m³/s) after the Amazon River. The Congo River reaches Inga after passing the entire country and draining water from nearly the entire subcontinent.
Two dams currently operate in Inga, sitting at the largest waterfall in the world (by volume) with a head of approximately 100 m. Although Inga has the potential to produce about 40 GW of cheap hydropower in one spot, only about 2 GW of this massive potential is exploited today.
Inga is vital to the energy future of the entire region, not just the DRC. It could potentially cover four times the electricity demand of the entire region. But, is it feasible in technical and economic terms considering planning restrictions for instance because of the wide outreach of the project region and the large variety of countries?
What is the planning all about?
Our study needed to identify the most cost-efficient way to supply the region’s people, businesses, industries and more with electricity for the next 20 years. Given the above described enormous regional differences, we needed to find a good system architecture. The plan should thus establish a sound development strategy and give answers to the following questions:
- Should future electricity supply be centralised or decentralised?
- Can a few large and cheap hydropower plants deliver electricity via a regional energy network? Or is it more economical to save a large network and build power plants near individual load centres?
- Where are the best transmission corridors?
- Is a regional backbone (“dorsale”) better than regionally separate interconnected networks?
- In the end, is it perhaps even more economical to leave the systems largely isolated?
We needed to answer these questions based on simulations and optimisation of different development strategies, combined with energy demand scenarios from 2016 to 2035 for the energy mix of all seven countries.
Master plan methodology
So, how did we do it?
Normally, expansion planning begins by optimising the generation system. Then, we assess how the grid should evolve to enable a stable grid operation. Although there are small iterations, this is generally the approach.
Given the complexity of this masterplan project, however, we’ve decided to go for an integrated planning approach. In the integrated planning approach, we’re optimising the generation & transmission system at once in order to find the most cost-efficient solution. At the same time, we defined and checked the main grid architecture. Later we fine-tuned the found essential grid architecture with an electrical grid study.
For the integrated planning, we have defined 15 grid zones using our fundamental electricity market model LIPS-OP/XP. This allowed us to consider the demand and supply balancing as well as the energy mixes in each of the major load and generation centres individually. Besides identifying potential future power plants (generation candidates), we also defined potential future transmission lines to extend the grid.
Hydropower plants supply the vast majority of the electricity in the region. Since they depend largely on hydrological conditions, we assessed dry and humid conditions instead of relying only on average hydrological years. We considered both for firm capacity and also within the simulations of the energy mix to identify realistic values for supply costs.
Ultimately, we decided against the simple load duration curve based models to assess energy exchanges between the different load and generation centres. Instead, we based expansion planning on real hourly load curves (time continuum) for representative days in each month. This allowed us to safeguard the synchronism in supply between the grid zones. To succeed, we’ve adapted our fundamental electricity market model and incorporated a new module called LIPS-XfOPF.
to be continued…
In my next blog (which should appear soon) I will write about, how we tackled the challenge and how we actually realised the planning. Furthermore, I will give an overview of our main findings for the future development of the Central African power systems.