A current person or project (vs. an old one)


Designing low-cost, low-carbon power systems using the SWITCH optimization model

SWITCH model can explore the cost and feasibility of generation, transmission, and storage options for the future electricity system. The model identifies cost-effective investment decisions for meeting electricity demand, taking into account the existing grid as well as projections of future technological developments, renewable energy potential, fuel costs, and public policy. SWITCH uses time-synchronized load and renewable generation data to evaluate future capacity investments while ensuring that load is met and policy goals are reached at minimum cost. The optimization is formulated as a deterministic linear program, which is solved by standard commercial software.

Josiah Johnston

Research Interests: 

Poverty alleviation via product design and sustainable community development.
Climate Change mitigation via electric grid planning


In 2002, I graduated from the University of Arkansas, Fayetteville, with a B.S. in Computer Science and a minor in math. I then spent six months digging ditches, working with a master stone mason, touring the mid-south on a 1976 Honda CB 540, and waiting for employment paperwork for the National Institute on Aging. I spent the next four and a half years in Baltimore working in the Image Informatics and Computational Biology Unit, developing portions of the Open Microscopy Environment (an Open Source image database and analysis system for scientific and medical applications), and developing pattern recognition tools for muscle aging studies. In my off-time I served on the board of the Greenmount West Community Development Corporation.


Clean Energy Financing

A number of cities and counties across the U.S. are launching programs to finance renewable energy and energy efficiency upgrades for homes and businesses. RAEL is supporting these efforts through research, consulting, and the creation of educational tools. This project focuses on what we call Property-Assessed Clean Energy (PACE) which covers the up-front costs for energy efficiency improvements and installation of solar energy systems for residential and commercial properties within a city or county. The property owner then repays the cost of these installations over 20 years through a special fee on their property tax bill. 

Check out our summary proposal for privately-managed PACE here:

Christian E. Casillas

Research Interests: 

Christian’s research focuses on understanding the role of energy systems in rural community development. He also studies how lack of information impacts community perceptions of development interventions, and ultimately their efficacy.


Christian Casillas has worked on the study, design, and implementation of energy efficiency projects and isolated diesel, photovoltaic, biomass, and wind systems in the US, Africa, and Latin America. Since 2006 he has served as an advisor to the non-profit blueEnergy, which builds and installs wind and photovoltaic energy systems for indigenous communities on the Atlantic Coast of Nicaragua. In 2009 he participated in the technical analysis of the potential for integrating renewable energy systems into remote diesel grids for Colombia’s civil aviation agency.

Christian holds a bachelor’s degree in environmental engineering from Harvard University, a master’s in Applied and Computational Mathematics from Johns Hopkins University, and a master’s in Energy and Resources from UC Berkeley, where he is currently a PhD candidate.

Casillas, C. E., & Kammen, D. M.
(2010). The Energy-Poverty-Climate Nexus. Science, 330(6008),

C. E., & Kammen, D. M. (2011). The delivery of low-cost, low-carbon rural
energy services. Energy Policy, 39(8), 4520–4528.

C. E., & Kammen, D. M. (2012). Quantifying the social equity of carbon
mitigation strategies. Climate Policy, 1–14.

C. E., & Kammen, D. M. (2012). The challenge of making reliable carbon
abatement estimates: the case of diesel microgrids. SAPIENS, 5(1),