Hydrogen City Project Team MARS

Transcription

1 Hydrogen City Project Team MARS Ryan McDevitt Abhinav Kalavar Scott Klima Matt Helm

2 Team MARS 2 I. Introduction The purpose of our project was to design a sustainable and standardized H 2 fueling station, which would be able to supply an entire city s transportation network. While designing the different aspects we would need to create a sustainable fueling station, we followed very strict criteria. Our main goal was to create a sustainable fueling station, and this would only be possible if our means of obtaining the fuel used was sustainable. The energy needed for the fueling station, as well as the hydrogen producing plant is powered by distributed solar panels. The solar panels would be distributed on the houses in the city of Tucson. The power obtained from the solar panels is more than enough to cover the electricity needed for the fueling station and the H 2 plant. The hydrogen needed for our fueling station is collected through the process of electrolysis, powered by the solar panels in the city, without the use of any fossil fuels. Along with the sustainable energy, the methane needed for the HCNG powered vehicles, is taken naturally from a landfill located in the city. Once the methane is obtained from the landfill, it is transported to the fueling station by use of pipelines, and the H 2 is also transported through underground pipelines. The actual fueling station also follows the sustainable guidelines, and is powered by the distributed solar panels. For this project we decided to choose the city of Tucson, Arizona. It s location in the southwest region of the United States made it ideal for the use of solar panels. The Tucson metropolitan area is a fairly dense region with a little over 1,000,000 residents. Being that the city is located in Arizona, the sun is an obvious renewable resource, considering the fact that it is a warm climate with little rainfall. Along with the sun, the city itself has its own means of renewable resources, including the Los Reales Landfill, a landfill located in the city where the methane for our fueling station is obtained.

3 Team MARS 3 The main reason for the selection of Tucson, Arizona for our city was its location. We knew that we needed a place where we could produce a large enough amount of energy through solar panels to cover the energy needs of our fueling station and the other aspects that go with it. By deciding on a city in the southwest region of the United States, we knew that the sun would be a reliable renewable resource, and the fact that Tucson had its own landfill, capable of producing enough methane, made it an obvious choice. II Demand Analysis When determining the numbers of miles driven in personal and commercial vehicles per year in Tucson, we used the national average of 13,500 miles per person per year for personal vehicles, and estimated 30,000 miles per person per year for commercial vehicles. When determining H 2 demand, we assumed people would be driving less, and thus used an average of 10,000 miles driven per year. We determined the amount of hydrogen demanded by our cities needs was equal to 228,311 kg H 2 /day. For commercial vehicles, the fuel demand was determined to be about 334,000 kg CH 4 /day. When converting these numbers to energy demands, we found that we would need 7,534 MWh/day of H 2 and 8,227 MWh/day ofch 4. The production of H 2 would be equal to that of the demands as we would only produce as much hydrogen as we needed, that being 228,311 kg H 2 /day. This is produced through distributed solar power across the city wide area, and would then be transported via pipeline. When looking at the production of CH 4, we knew that the landfill used to produce the methane was 475 acres at a 300 foot depth. This sized landfill produces 343,000 kg/day of CH 4, which is 9,000 more kg/day than our demand indicates. The CH 4, like H 2, is piped underground to the filling station. In order to reduce the demand and therefore the cost of this project, there needs to be a larger use of public transportation in Tucson, which could be coming in the near future thanks to a streetcar line that is planned to be built in the city. The most important and most difficult way to reducing our city's energy demands is to increase efficiency of the fuel productions, mileages of vehicles, and the transportation of the fuel. If the efficiencies can drastically improve, the demand will fall, as well the cost. Also, because Tucson is in a warm climate year round, the energy demands will not change in a dramatic way between seasons like it may in a Northern city.

4 Team MARS 4 III Preliminary Concept Development Preliminary Concepts: In the first system schematic that our group considered, the hydrogen gas production stemmed from the use of solar energy to induce high temperature electrolysis. The energy acquired by the photovoltaic system was used to power the pipeline and for the conversion of water to hydrogen gas (the electrolysis). The gas was then transported through the pipeline to the fueling station. The methane was obtained by using the methane produced from the landfills in our city (Tucson). The methane would be processed in a steam methane reformer and then transported to the station with a separate pipeline system (which is also powered by the solar energy). The problems with this schematic mostly all come back to the energy production. The size of the solar panel system required to power the electrolysis, the pipeline for the hydrogen gas, and the pipeline for the HCNG gas would be colossal (i.e. not feasible even with Arizona sunshine).

5 Team MARS 5 Our next system schematic also used solar energy to power it. However in this one, rather than having an enormous photovoltaic system, the power would be produced from solar power towers. From the corresponding solar plant, the energy would once again be distributed to power the pipeline and the electrolysis. The hydrogen gas would then be distributed through this pipeline to the fueling station. The methane would be obtained in the same manner as in the previous design (using the methane given off in landfills), but instead of using pipeline, it would just be transported by a methane tanker truck to the station. Once again, the problem with this method is also the energy. Since this method was seriously considered, we know that it would have taken upwards of 80 solar power towers to provide enough energy for all of that electrolysis and the hydrogen pipeline. For the last system we considered, we took a whole different approach to the hydrogen production. We wanted to use the methane from landfills to provide our hydrogen gas. We would use a steam methane reformer to convert it to hydrogen and then pipeline it to the fueling station. The pipeline would be powered with solar panels. For the methane production itself, we would also use the methane from the landfills and proceed with the same process as described in the previous design (truck transportation). In this scenario, energy may not be as big of a problem because we are only using the solar panels to power the pipeline transportation. However, there is a limit to the amount of methane that landfills can produce, and if we had used this system, we would not have had enough methane just from landfills to be able to make enough hydrogen gas for all of Tucson to travel with (we determined this in class one day with the example of New York City s largest landfill, and it said the same thing). Weighted Concept Matrix:

6 Team MARS 6 A weighted concept matrix was used to distinguish between various designs proposed by group members. By using an Excel spreadsheet, we isolated 5 distinct characteristics of our proposals and assigned them weight factors that we included in making our final decision. The 5 characteristics in consideration were cost, hydrogen production method, methane production method, distribution method, and energy production method. By assigning numbers 1-5 (5 being the best) to the characteristics of all the design proposals, we decided that the concentrated solar power tower/landfill design was the best; however, we would later change our overall design for practicality reasons. Solar Power Plant Solar Power Tower Strictly Landfill Objective Weight Weighted Weighted Weighted Factor Score Score Score Score Score Score Cost H2 Prd. Mthd. Methane Prd. Mthd. Distribution System Energy Source

7 Team MARS 7 IV Detailed Concept Design Our group decided on using hydrolysis for the production of hydrogen gas. Although this process is clean and sustainable (as long as you have water), it requires a substantial energy input. If we decided to produce all of this energy by either a solar power plant or concentrated solar power, the production facilities would have to be unrealistically huge. Therefore, we decided to divide our energy needs across the Tucson metropolitan area via distributed solar power. By providing a 6.5 KW PV system to 370,000 homes in Tucson and the metropolitan area combine, we can meet our energy demands (at least 200,000 homes lie solely in the city- 520,000 people). After the hydrogen is produced, it will be distributed to the 30+ gas stations via a pipeline distribution system. With the installation of a pipeline, the gas stations would not need on site storage of hydrogen.

8 Team MARS 8 Our group decided to rely on a landfill to provide the methane that we need for the HCNG blend. The Los Reales Landfill in southeast Tucson is planned to grow to 475 acres yielding an average depth of 300 feet, which mathematically will provide the appropriate amount of methane that we need. By producing 343,000 kg of methane/day, we will be able to produce 9,000 kg of methane more than daily required amount. Like hydrogen, we decided to ship the methane via a pipeline distribution system. CAD Designs: Since our hydrogen production facility is simply a facility where large scale electrolysis is performed, we decided to make two CAD models via Google Sketchup. One shows the scale of distributed solar power across Tucson, and the other is a simple representation of what our hydrogen gas station may look like.

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10 Team MARS 10 Economics: From an economic standpoint, a huge portion of the entire cost of this project comes from the first cost deposit value. This was due to the vast photovoltaic system that we set up in the city of Tucson in order to provide the environmentally least shitty method of powering the electrolysis. This photovoltaic system consisted of mini 10kw systems on the 370,000 homes all over Tucson. The total power we needed for the system was 2.396e9 watts. Using the BP NU- U240F2 model of panels (which costs $2.69/watt), the cost of powering the electrolysis was $7.1 billion. In addition to the cost of powering the system, we also wanted to set up 30 stations throughout the city, each with an area of 500 meters squared. The cost of building these stations ended up being about $393 million. Those two numbers added together yielded the total first cost, which was $7.493 billion. On top of the first cost, we also had to take into account the annual operating cost of maintaining the business, which entails ongoing costs such as fuel, labor, supplies, and maintenance. The cumulative value of all annual costs over ten years was $87,217,349. Therefore, the total cost over ten years (including both the first cost and the annual operating costs) was $7,580,217,349. While this may seem like a lofty price for anyone to put down, we also calculated the payback over this ten year period. Considering the fueling needs of the entire city (and assuming that we have monopolized hydrogen fuel production in the city), we would have to provide 83,333,333 kg of hydrogen annually if everyone drove 10,000 miles per year. With a base rate of $10.50 per kg at all of our 30 stations, we would generate $7,631,518,033 of gross revenue over the same ten year period. Compared with the $7,580,217,349 total cost over ten years, the total profit would be $51,300,683 or 0.7%. With

11 Team MARS 11 these applied numbers, not only do we make an entire city stop using renewable resources for transportation power, but we also make a slight profit in the end. V. Conclusion The design of our fueling station system was a success in the sense that it is sustainable, and it is able to provide for the transportation needs of the city of Tucson, which essentially was our goal. While designing this system and attempting to keep it sustainable, two of the aspects of our system really stand out. The fact that our entire system could be run on all renewable energy due to the use of the distribution of solar panels, was huge in the making of a completely sustainable fueling system. Along with the solar panel distribution, the naturally obtained methane from the Los Reales landfill furthered the sustainability of our system by eliminating the needs for the use of fossil fuels in the obtaining process. Although our fueling system is sustainable, there are ways to make it even better. Since Tucson is such a densely populated city, an increase in the use of public transportation would decrease the number of vehicles on the road, and essentially decrease the amount of fuel needed to power those vehicles. Also, the average driver in America drives 3,500 miles per year, and a simple decrease of mileage per person would cut the need for fuel significantly, making the transportation system much more sustainable. After completing this project, we as group realized that a sustainable fueling system, large enough to fulfill the needs of a city such as Tucson is possible, but it is a little farfetched. The idea of such a system is definitely there, but the fact is that it is not practical economically in the short term. On a positive note however, we as a group were able to create such a system, use our knowledge and each other to figure out the economic and design details, and we learned how to think like an engineer to solve our problems.