Since its launch in 2022, the FICO Xpress Best Paper Award has celebrated outstanding contributions to Mathematical Optimization, Operations Research, and related disciplines. The 2025 competition again featured many excellent submissions, making the task of the award committee anything but easy.
This year’s award goes to … *drumroll* …:
Hirwa, Jusse, Alexander Zolan, William Becker, Tülay Flamand, and Alexandra Newman.
"Optimizing design and dispatch of a resilient renewable energy microgrid for a South African hospital". Applied Energy 348 (2023).
The committee highlighted the paper’s originality and its inspiring example of “using OR for the better.” The authors show remarkable dedication in addressing a highly complex, real-world challenge — guiding the reader step by step through system design, optimization modeling, and dispatch strategies.
In this blog post, we dive deeper into their work and show how their approach demonstrates the power of mathematical optimization to deliver sustainable, resilient energy solutions, using FICO Xpress.
Access to reliable electricity remains a major challenge across sub-Saharan Africa. A significant portion of the population either lacks access altogether or receives electricity, but while experiencing frequent outages. Many households without electricity still rely on hazardous fuels for lighting and cooking, which poses serious health and safety risks and reduces productivity, particularly among children and women, who are often responsible for household routines. Even among communities connected to the national grid, power supply remains inconsistent. Frequent, sudden outages disrupt daily life and economic activity. Industrial and commercial sectors suffer significant losses. Improving the reliability of electricity in sub-Saharan Africa is essential, as businesses play a central role in job creation and are critical to the region’s economic stability. In addition, hospitals require continuous power to maintain medical equipment, conduct surgeries, and store temperature-sensitive medications.
In response to unreliable grids, backup systems, typically diesel generators, designed using a rule-of-thumb, are widely used. While these generators serve as a short-term fix, they are often oversized, inefficient, costly to operate, and do not represent a long-term power solution.
The awarded paper focuses on reliability, more precisely on ensuring consistent performance during routine, short-term disruptions. Specifically, alongside existing infrastructure, we consider additional technologies, including photovoltaics (PV), battery storage, combined heat and power (CHP), and thermal systems. Particularly, CHP systems offer an integrated solution by producing both electricity and thermal energy from a single fuel source. When coupled with a chiller, they can also support cooling needs, making them remarkably versatile. Moreover, incorporating renewable energy sources alongside efficient CHP systems leads to substantial emissions reductions compared to traditional power plants and standalone heating systems such as boilers or heat pumps. Figure 1 presents a notional example of energy flows from technologies to loads under normal operating conditions.
Figure 1: Energy flows from technologies to loads under normal operating conditions.
Considering the wide set of technologies, we propose a mixed-integer linear programming (MILP) model that provides the best (optimal) design (size and mix) and dispatch strategies for distributed generation systems that minimize lifecycle costs (capital costs, operational costs, and utility charges) while meeting heating, cooling, and electricity demands, even during frequent outages.
We applied this model to optimize the design and dispatch of a hospital microgrid in Johannesburg, South Africa, where energy outages pose direct threats to patient care and operational continuity. Figure 2 provides a visual overview of our methodological framework.
Figure 2: Overview of the methodology employed to obtain an optimal design for a hospital microgrid in Johannesburg, South Africa.
We first generated load profiles tailored to the South African healthcare sector using climate and hospital configuration data, adapted from U.S. Department of Energy prototypes and adjusted to reflect the specific conditions in South Africa. We implemented the large-scale model in AMPL and solved it using FICO Xpress to near optimality within an hour. The model simultaneously determines:
Figure 3: Dispatch strategy during outage periods occurring in the morning of July 19 (from 10:00 am-2:00 pm) and in the afternoon of July 21 (from 1:00 pm to 6:00 pm).
We evaluated the system’s robustness using an outage simulator, which demonstrates that the optimized decisions improve resilience significantly, enabling the hospital to sustain five-hour outages with 100% reliability and ten-hour outages with 65% reliability. We also conducted sensitivity analyses which reveal that PV sizing is most affected by capital cost, fuel prices, and electrical demand variability, while CHP and absorption chiller sizing are highly sensitive to fuel costs. Our approach is applicable not only to hospitals, but also to other high-impact facilities in emerging economies.
We at FICO warmly congratulate Jusse, Alexander, William, Tülay, and Alexandra on winning the 2025 FICO Xpress Best Paper Award. Among a field of many excellent submissions, their innovative and impactful research truly stood out.
Like many other research teams worldwide, the authors are members of our Academic Partner Program. Join our FICO Xpress Optimization Community and learn about our free community licenses for everyone and our fully-fledged free licenses for all academics. The call for the 2026 edition of the FICO Xpress Best Paper Award is out now: Consider submitting your Xpress-related research paper.
This year’s award goes to … *drumroll* …:
Hirwa, Jusse, Alexander Zolan, William Becker, Tülay Flamand, and Alexandra Newman.
"Optimizing design and dispatch of a resilient renewable energy microgrid for a South African hospital". Applied Energy 348 (2023).
The committee highlighted the paper’s originality and its inspiring example of “using OR for the better.” The authors show remarkable dedication in addressing a highly complex, real-world challenge — guiding the reader step by step through system design, optimization modeling, and dispatch strategies.
In this blog post, we dive deeper into their work and show how their approach demonstrates the power of mathematical optimization to deliver sustainable, resilient energy solutions, using FICO Xpress.
Access to reliable electricity remains a major challenge across sub-Saharan Africa. A significant portion of the population either lacks access altogether or receives electricity, but while experiencing frequent outages. Many households without electricity still rely on hazardous fuels for lighting and cooking, which poses serious health and safety risks and reduces productivity, particularly among children and women, who are often responsible for household routines. Even among communities connected to the national grid, power supply remains inconsistent. Frequent, sudden outages disrupt daily life and economic activity. Industrial and commercial sectors suffer significant losses. Improving the reliability of electricity in sub-Saharan Africa is essential, as businesses play a central role in job creation and are critical to the region’s economic stability. In addition, hospitals require continuous power to maintain medical equipment, conduct surgeries, and store temperature-sensitive medications.
In response to unreliable grids, backup systems, typically diesel generators, designed using a rule-of-thumb, are widely used. While these generators serve as a short-term fix, they are often oversized, inefficient, costly to operate, and do not represent a long-term power solution.
The awarded paper focuses on reliability, more precisely on ensuring consistent performance during routine, short-term disruptions. Specifically, alongside existing infrastructure, we consider additional technologies, including photovoltaics (PV), battery storage, combined heat and power (CHP), and thermal systems. Particularly, CHP systems offer an integrated solution by producing both electricity and thermal energy from a single fuel source. When coupled with a chiller, they can also support cooling needs, making them remarkably versatile. Moreover, incorporating renewable energy sources alongside efficient CHP systems leads to substantial emissions reductions compared to traditional power plants and standalone heating systems such as boilers or heat pumps. Figure 1 presents a notional example of energy flows from technologies to loads under normal operating conditions.
Figure 1: Energy flows from technologies to loads under normal operating conditions.
Considering the wide set of technologies, we propose a mixed-integer linear programming (MILP) model that provides the best (optimal) design (size and mix) and dispatch strategies for distributed generation systems that minimize lifecycle costs (capital costs, operational costs, and utility charges) while meeting heating, cooling, and electricity demands, even during frequent outages.
We applied this model to optimize the design and dispatch of a hospital microgrid in Johannesburg, South Africa, where energy outages pose direct threats to patient care and operational continuity. Figure 2 provides a visual overview of our methodological framework.
We first generated load profiles tailored to the South African healthcare sector using climate and hospital configuration data, adapted from U.S. Department of Energy prototypes and adjusted to reflect the specific conditions in South Africa. We implemented the large-scale model in AMPL and solved it using FICO Xpress to near optimality within an hour. The model simultaneously determines:
- design decisions (capacity and technology mix for PV, CHP, batteries, chillers, boilers); and,
- hourly dispatch decisions across a whole year, accounting for variability in demand, resource availability, and outages.
Figure 3: Dispatch strategy during outage periods occurring in the morning of July 19 (from 10:00 am-2:00 pm) and in the afternoon of July 21 (from 1:00 pm to 6:00 pm).
We evaluated the system’s robustness using an outage simulator, which demonstrates that the optimized decisions improve resilience significantly, enabling the hospital to sustain five-hour outages with 100% reliability and ten-hour outages with 65% reliability. We also conducted sensitivity analyses which reveal that PV sizing is most affected by capital cost, fuel prices, and electrical demand variability, while CHP and absorption chiller sizing are highly sensitive to fuel costs. Our approach is applicable not only to hospitals, but also to other high-impact facilities in emerging economies.
We at FICO warmly congratulate Jusse, Alexander, William, Tülay, and Alexandra on winning the 2025 FICO Xpress Best Paper Award. Among a field of many excellent submissions, their innovative and impactful research truly stood out.
Like many other research teams worldwide, the authors are members of our Academic Partner Program. Join our FICO Xpress Optimization Community and learn about our free community licenses for everyone and our fully-fledged free licenses for all academics. The call for the 2026 edition of the FICO Xpress Best Paper Award is out now: Consider submitting your Xpress-related research paper.
Updated 1 year ago
Version 3.0