Home » Posts tagged 'Bond Graphs'

Tag Archives: Bond Graphs

Journal Paper Accepted: Opportunities for energy-water nexus management in the Middle East and North Africa

by Brian Keare

We are happy to announce that our paper “Opportunities for Energy-Water Nexus management in the Middle East and North Africa”, has been accepted for publication by the academic journal Elementa: Science of the Anthropocene. This study was the result of collaboration between William N. Lubega (Illinois at Urbana-Champaign) and Prof. Amro M. Farid and William W. Hickman (Dartmouth).

Electric power is required to produce, treat, distribute, and recycle water while water is required to generate and consume electricity. Naturally, this energy-water nexus is most evident in multi-utilities that provide electricity and water but still exists when the nexus has distinct organizations as owners and operators. Therefore, the sustainability question that arises from energy-water trade-offs and synergies is very much tied to the potential for economies of scope.

ewn_context

Furthermore, in the Middle East and North Africa (MENA) region, multi-utilities are not only common, but also the nexus is particularly exacerbated by the high energy intensity of the water supply due to limited fresh water resources. Several accelerating trends are increasingly stressing the existing supply systems of MENA countries: Increased demand due to population and economic growth, a more extreme and unpredictable climate mostly affecting water supply and power demand, and multiple drivers for more electricity-intensive water and more water-intensive electricity including aging infrastructure and certain regulations and standards. This paper identifies and motivates several opportunities for enhanced integrated operations management and planning in the energy-water nexus in multi-utilities in the MENA.

From the discussion of the coupling points between the energy and water systems and operations management strategies to optimize these coupling points, several policy implementations can be drawn. First, the existing approaches to dispatch of the individual products of power and water could be replaced by integrated energy-water dispatch. Second, existing fixed power and water purchase agreements can be replaced with a seamlessly integrated energy-water dispatch. As in liberalized power systems, multiple time horizon markets with their respective clearing mechanisms would be required so as to provide dynamic incentives for greater cost and resource efficiency.  Fourth, the energy-water nexus also presents coupling points that engage the demand side of both power and water. Carefully designed demand-side management schemes, perhaps in the form of public-private partnerships, could present a vehicle for coordinating these coupling points in a cost-effective fashion.

The report also leads to several central policy implications. First, if water consumption and withdrawal of power generation were monetized, the investment case for renewable energy would inevitably be a stronger one. Next, while reverse osmosis desalination plants limit the energy-intensity of water production, from an integrated systems perspective, multi-stage flash plants provide a coproduction functionality that may be preferred over individual reverse osmosis and power generation facilities. Third, while many water utilities across the region have made extensive efforts towards reducing water leakages, such efforts could be strengthened by considering the embedded energy and the associated economic and environmental cost of these leakages. Lastly, there exists both a necessity and opportunity to reduce the energy footprint of water supply in MENA countries through increased water recycling. Utilizing a decentralized treatment system providing multiple water qualities and treatment levels will allow more opportunities for recycled water use in industry, agriculture, and other areas.

In all, the integrated energy-water nexus planning models and optimization programs presented and cited in this work provide deeper perspectives than their single product alternatives found in the existing literature. Their application in the policy domain has a high potential for future work and extension in the MENA region. Furthermore, these techniques have the potential for use in regions of similar climate (e.g. South-West United States & Australia) or other electricity-water utilities around the globe.

In depth materials on LIINES energy-water nexus research can be found on the LIINES websitte.

liineslogo3

Follow LIINES Blog on WordPress.com

Share this post:

Journal Paper Accepted at ISA Transaction: Event Triggered State Estimation Techniques for Power Systems with Integrated Variable Energy Resources

The LIINES is happy to announce that ISA Transactions has accepted our recent paper entitled: Event Triggered State Estimation Techniques for Power Systems with Integrated Variable Energy Resources.  The paper is authored by Reshma C. Francy, Prof. Amro M. Farid and Prof. Kamal Youcef-Toumi.
In recent years, we have had the opportunity to contribute to two large studies that present visions of the future smart grid:  The MIT Future of the Electric Grid Study, and the IEEE Vision for Smart Grid Controls: 2030 and Beyond.  Both of these works emphasized that in order for the future grid to be truly smart, it has to be responsive, dynamic, adaptive and flexible.  This is the case even when highly variable renewable energy sources sources are plugged in.   The first step in achieving this vision is having greater “situational awareness” — knowing what is going on when and where in the grid.
OCC
For decades, state estimation has been a critical technology in achieving such situational awareness for power system operators.   Over time, it has become quite the mature technology. But, the integration of renewable energy changes all that.  Not only does it introduce rapidly changing behavior into the grid; but it also does so in the low voltage distribution system where state estimation is not usually applied.   The conventional solution is to not just monitor the grid faster but also for the entire power grid all the way down to the low voltages.  That means that not only do all the power grid’s measurements have to be gathered from across power grid’s geography but they also have to computed at an ever faster rate.   This is an exponentially growing problem  — hardly a solution befitting a future “smart” grid.
This paper seeks to address these two requirements in a practical way.   The idea is to use a concept called “event-triggering”.  It takes advantage of the fact that the wind doesn’t always blow and the sun doesn’t always shine.  When local power grid conditions are highly variable, say at a wind turbine or solar panel, a “trigger” will kick in telling the state estimator to run.  But when the power grid is relatively stable, the new state estimator will use a simplified linear approach based upon the last time the full state estimator was run.  Relative to traditional state estimation, this simple solution has been shown to reduce computational time by 90% in numerical case studies.
While ultimately, in the long term, the smart grid will require a fundamental “rethink” in how to approach state estimation, monitoring, and situational awareness, this solution demonstrates how traditional state estimation techniques can be enhanced for future smart grid applications.
A full reference list of smart grid research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Journal Paper Accepted at Applied Energy Journal: Quantitative engineering systems modeling and analysis of the energy-water nexus

The LIINES is happy to announce that Applied Energy Journal has accepted our recent paper entitled:  “Quantitative engineering systems modeling and analysis of the energy–water nexus” for publication.  The paper is authored by William N. Lubega and Prof. Amro M. Farid.  

Electric power is required to extract, condition, convey, dispose of and recycle water for human use. At the same time, the bulk of global electricity generation capacity uses water as a heat sink or prime mover. This energy-water nexus is of growing importance due to increased demand for water and electricity; distortion of the temporal and spatial availability of fresh water due to climate change; as well as various drivers of more energy-intense water supply for example increased wastewater treatment requirements, and more water-intense electricity generation for example emissions control technologies at power plants.

water-energy_lg

There are several notable published studies on this nexus. At a technology level, there have been attempts to optimize coupling points between the electricity and water systems to reduce the water-intensity of technologies in the former and the energy-intensity of technologies in the latter. Empirical determinations of the electricity-intensity of water technologies and the water-intensity of electricity technologies have been reported and analyzed. Various models that enable the exploration of the water resource implications of defined electricity sector development pathways and thus support the analysis of various water and electricity policies have also been developed. To our knowledge however, a transparent physics-based approach that interfaces a model of the electricity system to models of the municipal water and wastewater systems enabling an input-output analysis of these three systems in unison has not been presented. Such a modeling approach would support integrated control applications as well as integrated planning without a priori specification of development pathways, for example through optimization.

A paper recently published by the LIINES in Applied Energy titled Quantitative engineering systems modeling and analysis of the energy–water nexus presents such a systems-of-system model. In this work, bond graphs are used to develop models that characterize the salient transmissions of matter and energy in and between the electricity, water and wastewater systems as identified in the reference architecture. Bond graphs, which are graphical representations of physical dynamic systems, were chosen as the modeling tool as they facilitate the inter-energy-domain modeling necessitated by the heterogeneous nature of the energy-water nexus. Furthermore they clearly identify causality and readily allow for model enhancement as required by applications. The developed models, when combined, make it possible to relate a region’s energy and municipal water consumption to the required water withdrawals in an input-output model.  This paper builds on another LIINES publication entitled “A Reference Architecture for the Energy-Water Nexus” found in the IEEE Systems Journal.

lubeg1

 

This research is of particular significance to countries in the Gulf Cooperation Council, all of which have limited fresh water resources and thus depend on energy-expensive desalination to meet a large portion of their water needs. This dependence enhances the degree of coupling between the electricity and water systems and thus the associated vulnerability concerns. Furthermore, motivated by the cogeneration of electric power and desalinated water, combined electricity and water authorities have been established in the region. The multi-energy domain model developed in this work is therefore of immediate relevance to the planning and control efforts of these existing institutions.

 

About the Author:

William N. Lubega conducted this research in collaboration with his Master’s thesis advisor Prof. Amro M. Farid in LIINES at the Masdar Institute of Science & Technology Engineering Systems & Management Department.  William is now a doctoral research assistant at the University of Illinois Urbana-Champaign Civil & Environmental Engineering department as part of the Energy-Water-Environment Sustainability Track.  There, he continues his energy-water nexus research in the Stillwell Research Group.

A full reference list of energy-water nexus research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Journal Paper Accepted at the Energy Journal: The Impact of Storage Facility Capacity and Ramping Capabilities on the Supply Side of the Energy-Water Nexus

The LIINES is happy to announce that the Energy Journal has accepted our recent paper entitled:  The Impact of Storage Facility Capacity and Ramping Capabilities on the Supply Side of the Energy-Water Nexus.  The paper is authored by Apoorva Santhosh, Prof. Amro M. Farid and Prof. Kamal Youcef-Toumi.  It builds upon an earlier publication entitled:  Real-Time Economic Dispatch for the Supply Side of the Energy-Water Nexus which was summarized in an earlier blog post.

As previous blog posts have discussed, the topic of the energy-water nexus is timely.  In the Gulf Cooperation Council nations, it is of particular relevance because of the hot and arid climate.  Water scarcity is further aggravated high energy demands for cooling.  The GCC nations, however, have a tremendous opportunity in that they often operate their power and water infrastructure under a single operational entity.  Furthermore, the presence of cogeneration facilities such as Multi-Stage Flash desalination facilities fundamentally couple the power and water grids.

This paper expands upon the previously published economic dispatch problem to now include the impact of ramping rates and storage capacities.  The latter is shown to alleviate binding production constraints and flatten production levels to achieve lower costs.   Three cases studies are presented; a base case, a second case inspired by Singapore’s limited water storage availability, and a third case relevant to countries in the Middle East where water storage facilities can be readily constructed. Storage facilities are shown to reduce total operating costs by up to 38% and lead to less variable daily production suggesting that they have an important role to play in the optimization of the energy-water nexus.

A full reference list of energy-water nexus research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Journal Paper Accepted at the Applied Energy Journal: Real-Time Economic Dispatch for the Supply Side of the Energy-Water Nexus

The LIINES is happy to announce that Applied Energy Journal has accepted our recent paper entitled:  Real-Time Economic Dispatch for the Supply Side of the Energy-Water Nexus.   The paper is authored by Apoorva Santhosh, Prof. Amro M. Farid and Prof. Kamal Youcef-Toumi.

As previous blog posts have discussed, the topic of the energy-water nexus is timely.  In the Gulf Cooperation Council nations, it is of particular relevance because of the hot and arid climate.  Water scarcity is further aggravated high energy demands for cooling.  The GCC nations, however, have a tremendous opportunity in that they often operate their power and water infrastructure under a single operational entity.  Furthermore, the presence of cogeneration facilities such as Multi-Stage Flash desalination facilities fundamentally couple the power and water grids.

This paper is the first of its kind to present an optimization program that would economically dispatch power plants, cogeneration plants, and water plants.  In such a way, significant costs and resources can be saved in the production of both power and water.   The paper concludes with an illustrative example of how the optimization program could be implemented practically.

A full reference list of energy-water nexus research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

William Lubega presents Energy-Water Nexus Research at Complex Systems Design & Management Conference in Paris, France

On December 6th 2013, William Lubega and Prof. Amro M. Farid attended the Complex Systems Design & Management Conference in Paris, France.  William Lubega presented the jointly written paper entitled:  “An engineering systems model for the quantitative analysis of the energy-water nexus”.

This work builds upon the Reference Architecture for the Energy-Water Nexus recently published in the IEEE Systems Journal.  In our last blogpost, and as shown in the figure below, we described that this work provided a graphical representation of the energy-water nexus to qualitatively identify the couplings of energy and water.  The CSD&M paper was the first step in the quantification of this qualitative model using the bond graph modeling methodology.   As such, it could begin to answer questions about the energy intensity of the water supply chain and the water intensity of the energy supply chain in a rigorous and systematic framework.

lubeg1

The aim of the CSD&M 2013 conference is to cover as completely as possible the field of complex systems sciences & practices.  It equally welcomes scientific and industrial contributions.

A full reference list of energy-water nexus research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Journal Paper Accepted at the IEEE Systems Journal: A Reference System Architecture for the Energy-Water Nexus

The LIINES is happy to announce that The IEEE Systems Journal has accepted our recent paper entitled:  “A Reference Architecture for the Energy-Water Nexus” for publication. The paper is authored by William N. Lubega and Prof. Amro M. Farid. The topic of the energy-water nexus is a timely one.  Global climate change, water scarcity, energy security and rapid population are at the forefront of sustainability concerns.  Furthermore, the fact that energy and water value chains very much depend on each other complicates how either system should be planned an operated.  And yet, the number, type and degree of interactions are hard to identify.  While the graphical depiction below illustrates many of the couplings, we are still a long way off from planning and operating this “systems-of-systems” sustainably.  And so we ask a first basic question:  “How can we begin to quantitatively understand the energy and water interactions in this nexus?” As the paper explains, a good first step is develop what systems engineers call a reference architecture.  Plainly speaking, this requires three steps:

  1. Figure out all the component parts of the energy-water nexus (e.g. power plants, water treatment plants, etc)
  2. Figure out how each one works
  3. Figure out the inputs and outputs for each one focusing especially on flows of energy and water.

This starts out qualitatively with flow diagrams like the one shown below: lubeg1 In a sense, this helps us to see the “wood from the trees”.  The web of energy and water interactions now become clear for further quantified analysis.  As the readers will see in the coming weeks, this is exactly what we have done at the LIINES. A full reference list of energy-water nexus research at LIINES can be found on the LIINES publication page: http://amfarid.scripts.mit.edu WhiteLogo2 LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

LIINES Research Program Overview Updated

The LIINES Research Program Overview has just been updated.  It is currently concerned with four classes of engineering systems.

  • Smart Power Grids
  • Energy-Water Nexus
  • Energy-Transportation Nexus
  • Reconfigurable Manufacturing Systems.

The page highlights the need for enterprise control as a paradigm to address the interdisciplinary, complex and timely decisions of today.

WhiteLogo2

LIINES Websitehttp://amfarid.scripts.mit.edu

Share this post:

Research Theme Highlight Part II: Energy-Water Nexus

The Laboratory for Intelligent Integrated Networks of Engineering Systems maintains a research program composed of four complementary themes.  In the first of a four part series on the LIINES website,  the laboratory’s Energy-Water Nexus Research Theme is highlighted.

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Research Theme Highlight Part I: Energy-Water Nexus

The Laboratory for Intelligent Integrated Networks of Engineering Systems maintains a research program composed of four complementary themes.  In the first of a four part series on the LIINES website,  the laboratory’s Energy-Water Nexus Research Theme is highlighted.

WhiteLogo2

LIINES Website: http://amfarid.scripts.mit.edu

Share this post:

Subscribe

Enter your email address to receive notifications of new posts by email.

Join 592 other subscribers