Electricity is a heavily relied upon commodity, availability of which is critical in every part of modern world operation. In any sustainability model, power systems and management are of primary importance, and the current trends in energy management are highly technological. Innovations and introduction of smart metering and response demand technologies should make it possible to match the versatility of the energy conversion systems with the growing and "spiky" electricity demand. The evident goals of new technological developments are to survive, avoid crisis, and finally build an energy distribution system that is flexible and highly efficient in all circumstances. This lesson touches upon different sides of this complex task.
By the end of this lesson, you should be able to:
You will be asked to read the following items throughout your lesson. Look for these readings in the required reading boxes throughout the lesson pages.
If you have any questions while working through this Lesson, please post them to our Message Board forum in Canvas. You can use that space any time to chat about course topics or to ask questions. While you are there, please feel free to post your own responses if you are able to help out a classmate.
Base load power sources are the plants that operate continuously to meet the minimum level of power demand 24/7. Base load plants are usually large-scale and are key components of an efficient electric grid. Base load plants produce power at a constant rate and are not designed to respond to peak demands or emergencies. The base load power generation can rely on both renewable or non-renewable resources.
Non-renewable resources (fossil fuels) include: coal, nuclear fuels. Renewable resources include: hydropower, geothermal heat, biomass, biogas, and also a solar thermal resource with associated energy storage.
Typically, the power demand varies cyclically from day to day, reaching maximum during day business hours and dropping to minimum during late night and early morning, but never dropping below a certain base. (Figure 9.1) This base load is typically at 30-40% of the maximum load, so the amount of load assigned to base load plants is tuned to that level. The above-base power demand (above the base) is handled by intermediate and peak power plants, which are also included to the grid. The main advantages of the base load power plants are cost efficiency and reliability at the optimal power levels. The main disadvantages are slow response time, lack of fuel flexibility, and low efficiency when operated below full capacity.
Base load plants (as well as other energy converting facilities) are characterized by a nominal capacity rating. For example, if a plant rated at 1000 MW, it means it can generate 1000 MWh of electricity per hour when working at full capacity. The actual generation can be less, depending on the demand or operating conditions, and can be characterized by the capacity factor (CF):
CF = [actual generated output] / [maximum possible output]
For example, let us calculate the capacity factor for a 1000 MW base load power plant that generated 512,000 MWh of electricity over the month of January.
In this case, the maximum energy that can be generated by the plant at full capacity over this month can be determined as follows:
E(max) = 1000 MW x 31 days x 24 hour/day = 744,000 MWh
Then
CF = E(real) / E(max) = 512,000 / 744,000 = 0.69 (69%)
There are the number of reasons why a plant can have lower than 100% capacity factor. Some of them are:
The base load power plants typically are coal-fueled or nuclear plants due to low-cost fuel and steady state power they can produce. Hydropower and geothermal power can also be used for base load electricity generation if those resources are regionally available.
The renewable energy systems, such as solar and wind, are most suitable for intermediate load plants. These are intermittent energy sources, with their output and capacity factor depending on weather conditions, daily, and seasonal variations. So, unless there is an effective energy storage system in place, they cannot be relied upon to meet constant electricity supply needs, nor can they be immediately employed to respond to peak demands. However, as intermediate sources, solar and wind systems can be efficient and can help reduce dependence on fossil fuels.
The peak power generation is usually attributed to the systems that can be easily stopped and started. Possibilities are natural gas and oil plants, hydro-facilities.
From the situation as it is right now, we can see that the niche of base load power is currently occupied by mainly non-renewable energy systems and therefore non-sustainable. But here is a probing question:
Can the base load power be entirely provided by renewable energy sources? Or we cannot avoid coal altogether?
Apparently, the difficulty with renewables is their intermittence in time and location bias. Comparison of typical capacity factors of various energy systems reflects this difficulty (see Table 9.1 below)
Energy Conversion System | Capacity Factor % |
---|---|
Nuclear power | 90.3 |
Coal | 63.8 |
Natural gas | 42.5 |
Hydroelectric | 39.8 |
Concentrating solar | 33 (CA) |
Wind | 20-40 |
Photovoltaic solar | 15-19 |
In the table above, the lower the capacity factor, the more susceptible the system to potential interruptions or drops in performance. We can see that solar and wind technologies, which are notoriously weather-dependent have the lowest CF numbers. At the same time, nuclear power and coal systems are most advantageous when operated continuously and at full load.
To explore this question further, refer to the following readings:
Using the above-listed resources and other materials you may find on this topic, try to formulate answers to the following questions:
At this point, we can see at least two major issues that make contemporary grid management more complicated: first is the efficient management of the baseload-peak variations and second is the incorporation of renewable energy systems. An array of new technologies and strategies that enable an information-based sensitive approach to electricity mass-market is summarized by the term smart grid, which is introduced in more detail in the next section.
Are Solar and Wind Really Killing Coal, Nuclear, and Grid Reliability? [5] - The Conversation
Why Base Load Power is Doomed [6] - Smart Planet
National electric power infrastructure, also called “the grid”, has been developing over more than a century and plays an important role in the nation’s energy security (Figure 9.2). Electricity production traditionally relies on a steady fuel supply (primarily fossil fuels), which would keep the power plants operating on the permanent basis. Eventual switching from the traditional fuel-burning plants to cleaner alternatives requires redesigning the grid in such a way that it properly responds to the sharp variations in demand, adequately compensates for the intermittent operation of the renewable energy systems, and can interact with distributed power generation systems.
The transmission grid shown in the figure above shows the interconnection of power generating facilities with distribution sub-stations. The local distribution grid is designed to supply power to end users and usually has a radial structure. While some of the components of the grid are subject to renovation, it is not the physical structure of the grid that is the focus of current redesign efforts; it is the informatics component that is supposed to bring the grid to a new level of intelligence. Hence, the interactive combination of information technologies and transmission systems creates the smart grid system.
Read the following article to learn about the smart grid and associated demand response technologies in more detail. Beyond the background, this article also provides a nice illustration of how the incorporation of demand response tools influences the real-life power demand curves
Journal article: Taqqali, W.M. and Abdulaziz, N., Smart Grid and Demand Response Technology, 2010 IEEE International Energy Conference, p. 710-715.
This article is available online through the Penn State library system and in Module 9 in Canvas.
Introduction of the demand response technologies is especially relevant to the power supply for buildings. According to US DOE (DOE 2007), buildings in the US consume around 72% of total electricity, and sensitive regulation of building energy demand is considered a major factor in sustainable development. Transitioning buildings to the smart grid is a complex task, which requires efforts in three areas:
This article discusses the prerequisites of applying automated demand response technologies for power management and provides a case study of implementation of BACnet - a tool for load management and utility communication:
Journal article: Bushby, S.T. and Holmberg, D.G., Advancing Automated Demand Response Technology, ASHRAE Transactions, 2009, Volume 115, Issue 1, pp. 333-337.
This article is available online through the Penn State library system (see e-Reserves) and in Module 9 in Canvas.
Based on what you learned from these readings, please answer the following self-check questions:
1. What are the key elements of the Smart Grid?
Click for answer.
2. The Demand Response system helps manage the peak power consumption via
A. direct access to consumer’s appliances
B. signaling customers about shifting tariffs during peak hours
C. temporary reducing or switching off the power supply
D. working out commitment from users to shed load at specified conditions
Click for answer.
3 What three layers are distinguished in the Smart Grid infrastructure?
Click for answer.
4. Which legislation in the US (year?) mandated the actions for the Smart Grid development?
Click for answer.
Book chapter: Gevorkian, P., Large Scale Solar Power Systems: Construction and Economics. Chapter 10: Smart Grid System Deployment and Economics, pp. 203-220.
This book chapter overviews many things about the Smart Grid that have been already described in other reading assignments. Look on page 112 for examples of some physical and informational technologies that facilitate smart grid operation. This book is available online through the PSU Library system.
Government document: U.S. DOE, The Smart Grid: An Introduction [9]
The demand response business models are currently being developed by many companies. Those models require all-system analysis, since successful feedback between the different actors is key to effective operation. Behavioral aspects are seriously considered because they eventually control the decision-making on both sides of the utility-customer chain.
Below are links to some recent studies and pilot programs that seek to promote a demand response approach in power management. Please look through those examples and take a note which parties actually benefit from implementation of those approaches. Are there economic drivers behind them?
The activity in the end of this lesson will involve assessment of demand response technologies, so the above-listed reports may be useful illustrations for that assignment.
When we talk about our energy future and contemplate the idea of eliminating fossil fuel combustion entirely and replacing it with cleaner renewable energy technologies, the key question everyone wants to know the answer to is:
Will renewables be enough?
The renewable resources - solar energy, wind, geothermal, biomass, hydro resources - are truly enormous. However, conversion of those resources to accessible, usable energy has a big "overhead". Creation, installation, and support of those technologies takes time, manpower, materials, and (you guessed it) more energy. The net consumable energy is what we hope to match with the existing global energy demand.
This question is very carefully addressed in the documentary "SWITCH" created by documentary director and writer Harry Lynch and Geology Professor Scott Tinker (University of Texas). The authors travel around the globe to visit the best state-of-the-art renewable and non-renewable energy facilities to understand the pros and cons of each and to put some numbers together.
Please watch the trailer below.
One good thing about this film is that it does not push a certain political agenda and avoids polarized discussion about what types of energy should or should not be pushed forward. It attempts to take an objective look at the reality of the present-day energy situation, with its opportunities and challenges. Finally, and most importantly, it includes all pillars of sustainability in the discussion.
In this lesson, I ask you to watch this complete documentary [16] (98 min) as part of your learning and provide your reflection on the discussion forum.
Please refer to the Summary and Activities page for further instruction on the Lesson 9 Discussion Forum.
In this lesson, we have learned about different elements of power grid system, current issues with maintaining stable power supply, and options for better flexibility and "smart" management of electricity generation and distribution. The demand response technologies are considered game-changing in the Smart Grid models, so we looked at some recent trends and innovations reported in that area. This lesson also touched on the subjects of base load power and energy storage, since both of those topics present key questions for the sustainability of electric power.
Type | Assignment Directions | Submit To |
---|---|---|
Reading | Complete all necessary reading assigned in this lesson. | |
Discussion |
Watch the documentary "SWITCH [16]" (90 min), which explores the options for the future world's energy economy. Write a reflection (limit to ~500 words) on the following questions: 1. What do you see as main challenges standing in the way of switching from conventional energy sources to renewable energy sources? Is such a switch at all possible? 2. Are there any issues shown in the movie that you disagree with or would like to debate? Please provide an example and proper argument. Post your reflection onto the Lesson 9 Discussion Forum on Canvas. Comment on at least two other posts. Reply to any questions asked on your post. Deadline: for initial posting - this Sunday / for comment to other posts - Wednesday night (check exact due dates on Canvas calendar). |
Canvas: Lesson 9 Discussion |
Reading Quiz |
Energy Storage Technologies (6 short questions) - see Canvas Deadline: Wednesday (before midnight) - check exact due dates on Canvas calendar. |
Canvas: Lesson 9 Activity |
DOE, 2007. DOE Buildings Energy Data Book [17]. U.S. Department of Energy.
Links
[1] http://www.nrel.gov/docs/fy10osti/45653.pdf
[2] http://www.skepticalscience.com/renewable-energy-baseload-power.htm
[3] http://www.dailykos.com/story/2013/08/11/1230558/-Sunday-Train-The-Myth-of-Baseload-Power
[4] https://www.energy.gov/sites/prod/files/oeprod/DocumentsandMedia/1817_Report_-final.pdf
[5] https://theconversation.com/are-solar-and-wind-really-killing-coal-nuclear-and-grid-reliability-76741
[6] http://www.smartplanet.com/blog/the-energy-futurist/why-baseload-power-is-doomed/
[7] http://en.wikipedia.org/wiki/Capacity_factor
[8] https://commons.wikimedia.org/wiki/File:UnitedStatesPowerGrid.jpg
[9] http://energy.gov/sites/prod/files/oeprod/DocumentsandMedia/DOE_SG_Book_Single_Pages%281%29.pdf
[10] http://www.greentechmedia.com/articles/read/Innovaris-Platform-Makes-Demand-Response-a-Utility-Asset
[11] http://www.greentechmedia.com/articles/read/opower-looks-to-bring-behavioral-demand-response-nationwide
[12] http://www.greentechmedia.com/articles/read/Peak-Time-Rebates-Money-for-Nothing
[13] http://www.greentechmedia.com/articles/read/tendril-models-and-micro-targets-the-home-energy-consumer
[14] http://www.synapse-energy.com/Downloads/SynapseReport.2013-03.RAP.US-Demand-Response.12-080.pdf
[15] https://www.youtube.com/watch?v=XofeIB1v7s0
[16] https://www.youtube.com/watch?v=RvaE0PFna84
[17] http://buildingsdatabook.eren.doe.gov/