There is a new trend taking place with energy transmission and storage. Microgrids have a new take on how we can generate, store, and distribute our energy. This concept is making us all take another look at our mass centralized generation and distribution system.
Most of our electricity today comes from large coal or natural gas fired power plants. From this central power plant the electricity can travel hundreds of miles along transmission lines before it gets to your house. There are definitely some benefits to using this method of energy production. For one you can gain a lot of efficiency and cost saving by having one or two large turbines and generators. But there are also some problems with the current model. One problem that has always existed with form of distribution is that there are large costs associated with building and maintaining the transmission lines. Another problem is that when you transmit electricity over long distances of power lines, you can lose up to 3% of it in the form of heat and electromagnetic energy. A problem that is only recently being realized with this process is that traditional grids are not really designed to handle large swings in generation. Historically this was not a problem, but with all of the new solar and wind energy entering the grid, it is becoming more and more of an issue.
A microgrid is a small localized grid that can be used to power a community or even a college campus. Microgrids usually consist of some method of producing their own energy, and usually have a method of storing the energy for later use. Often the source of energy for these microgrids is some form of renewable energy such as wind or solar. There are some microgrids that generate electricity by burning one thing or another, but typically with these systems, they are able to capture the waste heat and use it for heating other buildings in the community. By using the waste heat, they are able to significantly increase the efficiency of the system. There are downsides if these types of grids just like with anything else. If you have multiple microgrids covering multiple areas there will be a lot of redundant equipment and therefore wasted resources.
Please leave me a comment and let me know what you think about microgrids.
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It seems like the auto industry is heading towards a future of more electric and less gasoline. This is great for the quality of our air and our children’s air. It is also great for reducing the amount of carbon dioxide that we are putting in the atmosphere (assuming they get their electricity from renewable sources). But the coolest part about all of these electric cars taking over our driveways and garages is that they each have a battery built in to them. In a previous blog post I talked about one of the biggest barriers of solar and wind energy is that they fluctuate and we need storage to offset those fluctuations. Soon all of these electric cars will be plugged into the grid and they will communicate with it in order to give and take power as necessary.
Of course a majority of the time, cars will be taking power off the grid so that they can have fully charged batteries for the drive ahead. But it is also likely that when the sun goes down, a small fraction of the electricity stored in millions of cars will be used to pump up the electricity of the gird to supply the night time demand. If we make batteries that can serve multiple purposes such as powering our vehicles and balancing the grid, they become more cost effective and there is more incentive for people to buy them. Just investing in batteries to balance the grid and nothing else is a much tougher sell.
When cars become one with the grid, they will also be able stabilize sudden power failures or sudden spikes in power. Currently if some generating equipment goes offline, it can mean a power outage for customers in the affected area. With car batteries supplementing the grid, these bursts and shortfalls will all be smoothed out. There will be less power failures, and less need to rely on ramping natural gas turbines up and down.
Do your part, go out and buy a plug in electric vehicle today!
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In one of my previous blog posts, I discussed a current issue with wind and solar generation. The problem is that the sources come and they go. Obviously the sun goes down at night time, but solar power generation can also be affected by cloud cover. Wind is very sporadic and frequently stops blowing. The grid on the other hand has a never ending demand for electricity. We can’t just tell people to turn off their refrigerators at night time. In order to compensate for this fluctuating supply of power the grid offsets solar and wind generation by ramping up and down coal and natural gas power plants. By ramping up and down these traditional energy sources grid managers are able to stabilize the power supply. This method is used to compensate for a lack of energy supply from solar and wind, but solar also carries another disadvantage.
At sometimes throughout the year, solar energy generators actually supply the grid with too much energy. This is especially the case on clear spring days. It has caused a lot of problems for grid operators in California and other states with large solar supplies. The problem occurs on cool spring days when there is a lot of solar potential and the supply is really high. At the same time, not many people are turning on their air conditioners because of the cool temperature and there is no need for them. This situation creates too much supply and not enough demand. It leads to grid operators having to rapidly curtail equipment to balance the grid. It is a pain for everyone, and it is also bad for large equipment to cycle on and off again. This quirk in the solar market is known as the duck curve because when you plot a graph of the power demand throughout the day it resembles a duck. The times when the demand is lowest happen to be the times when solar is producing at its highest.
Geothermal energy is a great counter balance to this phenomenon because it is base load generation. In other words, geothermal produces a mostly stable supply to the grid 24-7-365. It results in a much smother energy product compared to the over and under supply often faced by solar power. Any grid that wants to have more renewable energy on it will be much better off if its energy mix includes some geothermal power. Hydroelectric is also a good option for base load generation but I understand that most of the feasible places to locate a hydroelectric plant already have one. Geothermal still has a ton of untapped potential in the world.
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Duck Curve Photo Credit: ilsr.org/wp-content/uploads/2014/03/Screenshot-2014-03-25-14.36.08.png
Most of the electricity that we generate today is done so by harnessing differential energy levels. Basically in order to get a turbine to spin, we have to have high pressure at the inlet of the turbine and low pressure at the outlet of the turbine. This should make intuitive sense because if you had equal pressures on both sides of a turbine there would be no flow, and the turbine would not spin. When you have a differential between two energy levels, the high energy state wants to flow to the low energy state and try to equalize. When energy starts to flow we can capture it and use it to turn a turbine. The bigger the differential is between the high energy state, and the low energy state, the more power that can be produced from the system.
The most common energy differential that is used to generate electricity is a temperature differential. When we can find or create a large temperature differential, we can easily convert that to a large pressure differential which can be used to spin a turbine. Some examples of creating a temperature differential are burning coal or natural gas. The energy that is on the hot end of the system is referred to as a heat source. Then there is also the cold side to take into account. Usually the cold side of the temperature differential is the ambient air temperature and it is referred to as a heat sink. So the greater the difference is between the heat source and the heat sink the more efficient the system will be. The heat source is used to boil water and turn it into high pressure steam for the inlet of a turbine while the heat sink is used to condense the steam and create a low pressure area at the outlet of a turbine.
There are also naturally occurring differential energy states. One example of this is a geothermal system. In the case of Geothermal, the heat below the earth’s surface acts as the heat source, and the ambient temperature acts as the heat sink. Another naturally occurring temperature differential is ocean thermal energy conversion. This technology harnesses the difference in temperatures between warm ocean surface temperatures as a heat source, and cold temperatures found deep in the ocean as a heat sink.
Pressure differentials also occur naturally and can be used to turn turbines. The most well-known example of this is wind. High pressure wind wants to flow to areas of low pressure. We can put a wind turbine in its path and capture some of that energy as it flows by.
Another form of differential energy that we capture to generate electricity is water in a high elevation that has a high potential energy. Gravity wants to pull this water down to a low elevation where it would have low potential energy. We capture the difference in potential energy in to form of hydroelectric turbines.
If you can recognize any other areas where there are differential states of energy, try to figure out a way to capture the difference and turn it into electricity.
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Cold Hot Photo Credit: http://www.clipartbest.com/cliparts/9i4/6Kp/9i46KpG6T.jpg
Several years ago my boss told me an interesting theory that he had about energy. We were on a long road trip to one of our power plants in the middle of nowhere so he had plenty of time to develop his theory with me. I’ll try to boil down the discussion to what’s relevant to you in this post. Basically he told me that all of the forms of energy that we use to generate power today have their roots in nuclear energy. He is a chemical engineer after all, so he would think this way.
When he first told this to me I didn’t really know how to react. I mean I can think of many forms of energy that are not from nuclear reactions, coal, natural gas, wind etc. But then as we were driving down the long… long highway, we started to go down the list and he systematically showed me that all of them have roots in nuclear reactions.
Let’s start with oil/ natural gas/ and coal. All of these resources are substances that store energy that we can later burn to make electricity. But where do they come from? They come from decomposing plant material that died millions of years ago and the got buried under miles of earth. Where do plants get their energy from? The sun, a giant burning ball of nuclear reactions going off in the sky. What about wind turbines? Well where does wind come from? It comes from air with different pressures that are being heated up by the sun. The different pressures of air then start to move around because they want to equalize. What about solar power? The sun. Even Hydroelectric power has its roots in the sun’s energy. If the sun didn’t heat up water and evaporate it, it would not fall on the top of mountains and then run down them in rivers to power our hydroelectric turbines. What about nuclear power? Just kidding I don’t have to explain that one. Lastly geothermal power comes from heat at the center of the earth given off by nuclear reactions.
All of this stems back to the concept that we cannot create or destroy energy we can only change the form of it. In this case some of the changing forms weren’t actually done by us, but rather by natural processes. I think this is kind of a fun twisted chemical engineery way to look at the world.
If you can think of a form of energy that doesn’t stem from a nuclear reaction please prove me wrong in the comments below.
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Hydroelectric Photo Credit: https://media.licdn.com/mpr/mpr/AAEAAQAAAAAAAAefAAAAJGNhNjFhNzA1LWZmYjctNDBjMi1iNWM1LWE5M2VhZDNmYmU5Nw.jpg
I think a lot of us get kind of hypocritical when it comes to renewable energy. Most people are coming around to the idea that having renewable energy is a good idea. People can see that we are going to have to embrace this sometime in the near future. The problem is that nobody wants it in their back yard. I mean there are some people who are really dedicated to renewable energy such as the house I mentioned in my last post that installed wind turbines literally in their back yard. But it seems like a lot of people want renewable energy generation to be nowhere near them.
This is not only a problem for small scale home generation, but it also applies to industrial generation as well. Often when an industrial wind farm starts in its planning phase there will be a lot of opposition by the people in the surrounding area. They claim that “it is an eye sore”, and that “it will reduce their property value.” These same protests can be heard about industrial solar projects as well. So it seems like people want this kind of clean energy, they just don’t want to have to see it.
There are a few possible things that can be done to overcome this problem. First, developers can plan these large generation facilities in the middle of nowhere. Being from Nevada, I know that we have a whole bunch of “middle of nowhere”. This is a good solution on the surface, but you run into the inevitable problem of “Transmission is Expensive.” Another thing that could be done is to have a massive PR campaign to start changing the public’s perception of renewable energy and its requirements. The final solution I can see for this problem is a technological one. We have to develop new and better methods for generating power. I can see a future where we can utilize new technologies which can generate power from sources that blend in with their surroundings. One great current example of this is SolarCity’s new roof tile solar panels. They look just like any normal roof tiles. I believe these technological solutions are the best answer.
If you have any ideas for how to solve the “not in my backyard” problem, please let me know about them in the comments below.
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Wind farm Photo Credit: http://teachnuclear.ca/wp-content/uploads/2013/05/Wind-farm.jpg
I was walking through my neighborhood last week and I saw a house with two wind turbines spinning away in the back yard. They were definitely noticeable because of the spinning motion, but they weren’t really an eye sore. The engineer in me got really excited and I decided to do a little research and find out more about this renewable energy option.
After a quick internet search, I found out that these particular personal wind turbines are probably Windspire brand turbines. Based on their website it looks like they produce a few different models of turbines from 1 KW output up to 5 KW output. The nice thing about these wind turbines is that they were pretty quiet. Now, to be fair I was about 50 yards away, but I didn’t hear anything.
The average house in the U.S. requires about 1 KW every hour to meet its energy demand. The problem of relating this to sizing a wind turbine is that the wind does not always blow. In general we can assume about a 25% capacity factor for wind turbines. In other words we have to assume that the wind is only blowing about 25% of the time. In order to power your house using mostly wind power, you would need to install about 4 Kilowatts of installed capacity. After you multiply that 4 KW by the 25% capacity factor you come out close to the desired 1 KW. Of course you will also need some sort of a battery storage system to store the excess energy to be used at times when the wind is not blowing.
On the Windspire website it looks like they will sell a complete 1.8 KW wind turbine package for $13,500. I assume this house in my neighborhood bought two of the 1.8 KW style turbines which would get them pretty close to the 4 KW desired generation. So not including the battery storage they probably spent $27,000 on this wind turbine system. If I do some back of the napkin math, I spend about $100 every month on my electricity bill. So that is $1200 per year that I currently spend. It would take me about 22 years to make that wind turbine system pay off. For a comparison, a similar roof-top solar capacity would cost between $25,000 and $30,000.
This is one of the big problems with these types of home renewable energy solutions. They are not economical yet. I commend this company for putting out a product that helps us to move in a more renewable direction. I also am happy that there are people who will buy these systems for what I assume is a personal commitment to go renewable. The problem is that if we want these systems to have a mass impact we need to figure out a way to make them economical. Average Americans move every 5 years for installing a 22 year payback wind turbine makes no sense. For this type of technology to have a big impact, it would have to have a payback time of a maximum of 5 years.
If you have a home renewable energy system installed at your home please let me know about it in the comments below.
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