Today I took a tour of all things renewable in the Reno Nevada area. It was quite a long day but a good experience to see all of the progress that Reno is making. Each of these individual pieces comes together to form the full energy picture for Reno. This list isn’t comprehensive, but it does give a nice look at the spectrum.
To start out my grand renewable tour I headed over the Verdi Hydroelectric Power Plant west of town. This is one of three hydroelectric power plants in the area which total 6.7 MWs. I was amazed to learn that the plant is actually over one hundred years old and it is still running on the original equipment. When I think about it, it actually frustrates me a little bit to know that we haven’t made very much progress over the last hundred years. It does show that if it has lasted for 100 years it must make sense, and it probably isn’t just a fad.
After stopping by the hydroelectric plant I stopped by a couple of organizations that are using solar panels to power their internal loads and sell some of the excess energy back to the grid. Both organizations I went to told me that they were negatively affected when NV energy changed its policy on buying back solar. Neither of the two solar locations were utilizing any storage capabilities, but that is probably because they are primarily open during the daylight hours.
Next on my list of renewable must-sees was the geothermal power plant located at the base of Mount Rose. That power plant actually produces up to 100 Megawatts of Photo Credit
electricity. A megawatt is enough energy to power about 1000 homes. All of this electricity gets sold to NV energy and eventually gets passed along to the consumers.
All in all Reno is moving in the right direction when it comes to renewable energy. More cites should take note. If you think your city has a lot of renewable energy let me know in the comments.
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Geothermal Power generation is a really difficult industry to get into. There are many barriers for companies trying to start geothermal power plants. First of all you have to be located in the correct areas in the country. For some reason, most of the geologically viable regions are located in the west coast of the U.S. and a majority of the hottest resources are located in California and Nevada. So geological restrictions alone eliminate about 40 of the US states from ever having a producing geothermal power plant.
Once you narrow down your search to the correct geological region, you can identify localized regions that you believe have geothermal activity. In order to have a functioning power plant you need to find a sight with two qualities. It has to have high temperatures close to the surface, by close I am talking in geologic terms so less than 10,000 ft. It also has to have a reservoir of naturally occurring water in the same area. After you have picked the area you want to set your plant at, you need to acquire the land or at least the rights to use the land.
After acquiring your land access you need to begin the permitting process. You need to secure drilling permits to drill on the land. Many times there is a lot of environmental impact studies that are involved in the permitting process. Once you have your permits, start drilling test wells so that you can get a better picture of what is going on underground. By drilling test wells, you can send instrumentation down into the earth to start getting some temperature profiles, mapping the fractures, and measuring the amount of water flow that will come out of the specific hole.
After collecting all of this downhole data you can create a model of how you understand the resource to be behaving underground. This model is very important for figuring out where you are going to drill your production and injection wells. After you get an understanding of the resource you have to start drilling your wells. Geothermal wells can cost between $1 million and $10 million each. The drilling requires you to hit the fault in the exact right location. If you don’t hit it just right, your $5 million well can be a complete dud that you have to plug.
As soon as you have your tested production and injection wells, now you can spend the $50 to $150 million to get your power plant built. At the same time you have to work on securing a long term power purchase agreement with someone who promises to buy your electricity. This entire process can take around six or seven years before you are actually generating any electricity and bringing in any revenue. Geothermal is definitely not for the faint of heart!
If you are hungry for more renewable energy insights follow me on twitter @EvanNWarner
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In my blog ‘Identifying Potential Sources of Power Generation’ I discussed the concept of heat sources and heat sinks. Most power plants use the ambient air temperature as their heat sink a.k.a. the cold end of their process. But there are actually two ambient temperatures that can be useful as a heat sink for a power plant. I’m going to try not to get too lost in weeds in this post, so if you want more information about this, you can look up psychrometrics. Anyway, the first one is just the regular air temperature known as the dry bulb temperature. This is the temperature that will come into play for air cooled power plants. The second air temperature that is useful is called the wet bulb temperature. This temperature is based on a combination of the Dry bulb temperature and humidity. The reason that it is important is because this is the temperature that water will evaporate at.
In a water cooled power plant, water is sent through the top of cooling tower (basically a large box with metal mesh inside) and then as it falls some of it evaporates. The cool water that comes out of the cooling tower usually has a temperature a few degrees higher than the wet-bulb temperature but usually several degrees colder than the dry bulb temperature. The cooling water then acts as the plant’s heat sink. One advantage of the water cooled system is that your heat sink will be at a lower temperature and therefore your process will be more efficient. Another advantage is that water is much better at holding and absorbing heat than air is. This also makes your process more efficient. The main downside of a water cooled power plant is that it is often difficult to get water rights to keep them running. A key component of a water cooled plant is that some of the water has to evaporate in the cooling tower. So that water has to be replaced by new water from somewhere.
For an air cooled power plant, the heat sink will be the higher dry bulb temperature. Of course in the opposite of the water cooled scenario, the air cooled plant has lower efficiency. Because air cooled power plants are less efficient it also means the condensers have to be much larger to get the same effect. Air cooled power plants take up much more land area than their water cooled cousins. They also have a lot of moving parts with all of the fans that blow the air. All of those fans require periodic maintenance. The good things about air cooled power plants are that you can put them anywhere even in the middle of a desert, and you don’t have to worry about things freezing.
If you are interested in more renewable energy information follow me on twitter @EvanNWarner
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Air Cooled Condenser Photo Credit: http://www.gdareno.com/wp-content/uploads/2015/10/CoolingTower.jpg
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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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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I recently read an article about a company that has a new twist on industrial geothermal power generation. Unlike standard geothermal power plants that are reliant on naturally occurring geothermal reservoirs, GreenFire Energy drills its own systems. Another benefit to this type of geothermal system is that it doesn’t involve water. Instead this technology sends supercritical carbon dioxide down into the earth to collect heat and then collects it on the other end of the closed loop.
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This is an experimental technology, but if GreenFire can pull it off, it could revolutionize the geothermal industry. One huge limitation of current geothermal power plants is that they can only be located in certain areas around the world. These areas need to have the proper geology, a certain amount of heat, and ground water in the reservoir. With Supercritical carbon dioxide, there is a huge potential to increase geothermal power plants to much more of the earth’s surface.
Not having to use geothermal water gives this technology another advantage. Most geothermal water has a lot of dissolved minerals and salts in it. That is why it is often called brine. When you send this water through a plant and it either flashes into steam or it cools down in a heat exchanger, the dissolved minerals tend to come out of solution. This leads to scaling or fouling. All these minerals get coated on the plant equipment and hurt the plant efficiency. By just using carbon dioxide GreenFire will be able to completely avoid this headache.
I am optimistic about this technology but they are definitely going to face some challenges. The wells that this company is planning to drill are much deeper and much more costly than traditional geothermal wells. Assuming they can drill the wells and get the closed loop system completed, they will have very large up from capital costs. This will make expansion difficult. I will continue to follow this company and do a follow up post after they do their proof of concept.
If you know about any new interesting renewable technologies please let me know about them in the comments section.
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