Scales and Systems

Energy conversion systems today are generally characterized by large installations, long lifetimes, and substantial capital commitments. While this approach certainly has had its merits, a more modular mode of operation in some processes may turn out drastically more favorable when engineering to overall cost rather than specific efficiencies. The benefits of a modular approach can most likely be harvested in many industrial processes outside the energy sector as well.

Wind scaling optimization

Another application of study using this concept is wind energy. While current trends in this industry point toward increasing size of wind turbines, LCSE researchers are investigating the diametric opposite. Structural integrity of available materials puts a severe constraint on increasing the size of a single turbine.  This is why small scale turbines, assembled in a web-like mesh may prove more beneficial.

The power that a wind turbine can harness from the wind is proportional to the swept area of the rotor, and therefore to the square of its diameter D. However, the blade weight (and its cost in first approximation) is proportional to some higher power of D (around 3). This “square-cube law” is a perfect summary of the situation wind turbines are facing right now. Should we go larger and benefit from the economy of scale and a decreasing cost per kW installed? Or should we focus on small wind turbines and benefit from mass manufacturing, and lower cost designs?

Researchers
Klaus Lackner, Ewing-Worzel Professor of Geophysics, klaus.lackner@columbia.edu (PI)

Caroline Vandame, PhD candidate, cv2224@columbia.edu

Smart homes – residential demand response via local electricity storage

Peak shaving and load shifting via demand response (DR) have been identified as one contributor to a smarter grid, with the potential to increase grid stability, lower the GHG footprint per unit of electricity, and facilitate integration of higher capacities of intermittent generation. For residential customers, while time of use tariffs do exist, providing DR traditionally means shifting the actual consumption pattern of appliances and thus changing lifestyle (e.g., run the electric dryer during the night instead of the day). In such cases, installing local electricity storage (batteries, compressed air, etc.) offers the opportunity to provide DR at a building level while building residents do not actually experience any change in the electricity usage of their appliances. Instead, the storage is used as a buffer between demand by the appliances and demand that is passed onto the grid.
In this project, we develop agent-based, stochastic models to predict residential electricity consumption of an individual building and its variability from minute to minute, and season to season. We then focus on the development of optimized charge/discharge control algorithms that offer maximum electricity price arbitrage via existing tariffs such that the capital costs from storage devices and other equipment can be recouped. For some storage technologies, the building owner’s total cost of ownership is even lower than without such DR, providing direct incentive to install such systems and therefore probable support towards a smarter grid as a whole.
The project is sponsored by the US National Institute of Standards and Technology (NIST).

For more information, please click here for recent publication(s).

Researchers
Klaus Lackner, Ewing-Worzel Professor of Geophysics, klaus.lackner@columbia.edu (PI)

Christoph Meinrenken, Associate Research Scientist, cmeinrenken@ei.columbia.edu

Menglian Zheng, PhD student, mz2321@columbia.edu

Sustainable small-scale fertilizer production for remote locations

The Haber Bosch process, a chemical process by which nitrogen from the air is reacted with hydrogen gas to produce ammonia, is responsible for the vast majority of the synthetic nitrogen fertilizer that is currently consumed around the globe. Although the chemistry behind the Haber Bosch process has changed very little since its initial discovery in the early 1900’s, the size of the average operation has seen an increase of more than two orders of magnitude. Representing about 1.2% of world energy consumption and a similar share of global GHG emissions, fertilizer manufacturing has evolved into a highly carbon intensive centralized industry based on economies of scale. Because of this, servicing remote rural locations becomes a challenging endeavor that relies on expensive transportation and logistical networks.

Building on the Lenfest Center’s research on the benefits of modularization, the purpose of this project is to investigate the feasibility and affordability of small-scale on-site fertilizer production. Using ingredients readily available in the environment – nitrogen from the air, energy from the sun, and water – we aim to produce nitrogen fertilizer on site. Such a change from highly centralized production could be a game-changer for small farmers in remote locations. Because these units do not rely on fossil fuels for their operation, their development and deployment could represent a dramatic reduction in the life-cycle CO2 emissions of fertilizer production. Given that one of the goals is to reduce the overall energy consumption of these systems, we are contemplating both the miniaturization of Haber Bosch as well as novel chemistries and processes that can run at low temperatures and pressures.

The project involves engineering of new processes, understanding of the dynamics of small scale farming, and matching of technical solution to practical boundary constraints and socio-economic realities.

Researchers
Klaus Lackner, Ewing-Worzel Professor of Geophysics, klaus.lackner@columbia.edu (PI)

Pedro Sánchez, Director, Agriculture and Food Security Center, Earth Institute, Columbia University, psanchez@ei.columbia.edu (Co-PI)

Diego Villarreal-Singer, PhD student, dv2254@columbia.edu