Portland Plans to Generate Electricity through Water Pipes

by Niti Nagar

Lucid Energy has created the LucidPipe Power System which harnesses the water flow in municipal pipelines to produce hydroelectric power. The LucidPipe is installed in a section of an existing gravity-fed conventional pipeline that is designated for transporting potable water. The water flows through four 42-inch turbines, each connected to a generator outside the pipe. In Portland, the 200kW system was privately funded by Harbourton Alternative Energy. Although the power system was installed in December, it is currently undergoing reliability and efficiency testing. So far, it has been reported that the presence of the turbines does not slow the water flow rate significantly, so there is no change on pipeline efficiency. The system was set to begin generating power at full capacity by March 2015.

Once running, the system is expected to generate approximately 1,100 megawatt hours of energy per year. This is equivalent to the amount of energy needed to power about 150 homes. It is projected that over the next 20 years, the system should generate about $2 million in energy sales to Portland General Electric. Harbourton Alternative Energy will get a share of these sales and it plans on sharing the money with the City of Portland and the Portland Water Bureau in order to offset operational costs. At the end of the 20 year period, the Portland Water Bureau will have the option to purchase the system, along with all the energy it produces.

Currently, this system is the only one of its kind in Portland. However if shown to be successful, more may follow. In Riverside, California a previously-installed energy system has been providing power since 2012. Since then many smaller, but similar, systems have become available, many of which can be installed within households. The Pluvia generates electricity from the flow of rainwater off of rooftops, while the H20 Power radio uses electricity generated by the flow of shower water.

Coxworth, Ben. “Portland to generate electricity within its own water pipes.” GizMag, 17 February 2015. < http://www.gizmag.com/portland-lucidpipe-power-system/36130/&gt;.


The “Learning Curve” of Renewable Technology

by Patrick Quarberg

A 2007 study done by Patrik Soderholm and Thomas Sundqvist attempted to factor in “learning curve” expenses to renewable technology. They describe the “learning curve” expenses to be the increased cost of producing and installing a piece of equipment or technology while it is still a new product. As more of the product is implemented, implementation costs decrease. The study focuses on estimation methods for learning curve costs, and the importance of estimates in deploying technology like wind turbines and solar panels. Specifically, the study investigates issues regarding time as an important variable in learning rates, the interconnectedness of innovation and diffusion, and omission of other important variables in learning rate estimation. The reason for investigating time as an important factor, according to the researchers, is to find out whether costs are decreasing due to actual learning and innovation. The cost decreases should be explained by cumulative capacity—the implementation of additional units—not just time. This is indeed what was found in other studies, and was so included in Soderholm and Sundqvist’s estimation equations. Continue reading

Analysis of Floating Offshore Solar Power Plants

by Jincy Varughese

In Europe, large flat spaces of land with direct normal irradiance (DNI) levels high enough to support solar utilities are uncommon. Diendorfer et. al (2014), a team of researchers in Vienna, saw untapped potential in the Mediterranean Sea and began researching the feasibility of offshore solar power plants. Aside from the availability of open spaces, building solar power plants offshore has two main advantages. First, a system that revolves on a vertical axis can be easily implemented and is efficient at sun-tracking. Second, unlimited water is readily available for the cooling processes required at solar thermal power plants. In this paper, the use of both Parabolic Trough Collectors (PTC) and Pneumatic Pre-Stressed Solar Concentrators (PPC) are considered. The study evaluates the performance of a preliminary floating solar power plant using a model that accounts for platform motion, sea state, and solar irradiance. Continue reading

Impacts of Tidal Energy Converter Configurations

by Cassandra Burgess

As tidal energy develops throughout the world several different designs for Tidal Energy Converters (TECs) have been developed. The main classifications are reciprocating and rotating devices, of which rotating are the most common. Within this category the TECs can be either floating and anchored to the bottom or fixed to the bottom by a rigid structure. Each of these designs has different impacts on the environment it is placed in. Sanchez et al. (2014) tested these impacts in Northwest Spain in Ria de Ortigueria by using a three-dimensional model to examine the impacts of two plants, one floating and the other bottom-fixed. The researchers found that both plants had little effect on water more than 4 kilometers away, but large impacts near the plants. The plants also exhibited very different patterns in changes in flow near the plants. Thus the authors argue that because TECs clearly have an impact on the flow of water around them, further investigation will be necessary to find the impacts of this change in flow on ecosystems. Continue reading

Self-Biased Solar-Microbial Device for Sustainable Hydrogen Generation

by Allison Kerley (Photo above of Hanyu Wang, first author of this paper at the University of California, Santa Cruz.)

Most hydrogen generating devices require an external addition of a 0.2 to 1.0 V electric potential in order to sustain the hydrogen generation. Wang et al. (2013) explored the feasibility of a self-powering photoelectrochemical-microbial fuel cell (PEC-MFC) hybrid device to generate hydrogen. The PEC-MFC was a combination of a photoelectrochemical fuel cell and a microbial fuel cell. The Hydrogen production of the device was tested when powered by a ferricyanide solution inoculated with a pure strain of Shewanellla oneidensis MR-1 and when powered by microorganisms found naturally occurring in the municipal wastewater. In both scenarios, given replenishments of fuel, the device produced enough voltage to be self-sustaining. However, when the device was powered by wastewater it produced both a lower current and a smaller hydrogen production than when powered by ferricyanide solution. Continue reading

Membrane-Free Lithium/Polysulfide Semi-Liquid Battery for Large-Scale Energy Storage

by Allison Kerley

Yang et al. (2013) discussed their new proof-of-concept lithium/polysulfide semi-liquid battery as a potential solution to large-scale energy storage. The lithium/polysulfide (Li/PS) battery uses a simplified version flow battery system, with one pump system instead of the traditional two. The Li/PS battery was found to have a higher energy density than traditional redox flow batteries, with the 5 M polysulfide solution catholyte cell reaching an energy density of 149 W h L–1 (133 W h kg –1), about five times that of traditional vanadium redox battery. The Li/PS battery cells were also found to have a high coulomb efficiency peak around 99% before stabilizing at around 95%, even after 500 cycles. The authors conclude that the Li/PS cells maintain a steady rate of performance after 2000 cycles, and Continue reading

Electricity From Low-Level Heat

by Emil Morhardt

Low-level heat—temperatures 100­–200°C above ambient, the temperature range of a kitchen oven more-or-less—are abundant in the exhausts of all sorts of industrial processes from drying biomass to operating internal combustion engines. They are also much more common in geothermal fields than the higher temperatures needed for traditional geothermal steam power generation, although low-level heat can be used to vaporize high-volatility organic compounds such as propane, which can then power a turbine much as steam would. For the most part, though, this heat is wasted, just released into the environment; but it needn’t be. Researchers at the China University of Geosciences in Beijing and at Stanford University experimented with an array of commercially available thermoelectric power generators (TEGs) Continue reading

Hybrid Energy Storage for CubeSats

by Emil Morhardt

CubeSats are cool. No, actually very cold, since they’re out in space. But they are reproducing like rabbits. There are well over 200 of these little 10 cm X 10 cm X 10 cm cube satellites have been launched into orbit by tucking them into the nooks and crannies in the launch vehicles around much larger satellites. (Some are multiples of cubes, 10 cm X 20 cm, or 30 cm.) They need energy. Until now they have been powered in the main by lithium ion batteries like those in your computer, and charged by the photovoltaic panels that make up a CubeSat’s skin. The thing is that these batteries don’t work very well when they are cold; the speed of electrochemical reactions, just like those of every other chemical reaction, are modulated by temperature—the colder the slower. The current Li-ion batteries don’t work at all below –10°C, yet CubeSats headed for deep space are expected to encounter temperatures of –40°C some of the time. So if you have a CubeSat process that needs power at low temperatures or a short-term burst of power faster than the batteries can provide, you need help. Continue reading

Microbial Electricity from Cyanide!

by Emil Morhardt

The paper by Xie et al. (discussed in my August 10 post) didn’t say much about the electrogenic bacteria needed to make their microbial battery work. Just a few days ago, however, researchers in Beijing and Singapore published a paper focussed on such bacteria (Klebsiella sp. in this case) isolated out of a microbial fuel cell, that can do the job in wastewater heavily contaminated with cyanide, almost completely degrading the cyanide in the process. Even without the electricity generation this is interesting, because these bacteria do a better job of removing cyanide than the much more expensive chemical oxidation methods more commonly used by industry. Microbial fuel cells get electricity out of microbes differently than the “microbial battery” of Xie et al.; they consist of two wastewater-filled chambers seperated by a proton exchange membrane. The bacteria in the anode chamber strip protons (hydrogen ions) off the feedstock—a cyanide/glucose mixture in this experiment—and the protons migrate through the membrane to the cathode. The electrons flow as an electrical current from the anode to the cathode in a wire, where they can be used as electricity. Interestingly, the bacteria continued to generate electricity from cyanide alone when they ran out of glucose.

Wang, W., Feng, Y., Tang, X., Li, H., Du, Z., Yang, Z., Du, Y., 2014. Isolation and Characterization of an Electrochemically Active and Cyanide-degrading Bacterium Isolated from a Microbial Fuel Cell. RSC Advances, DOI: 10.1039/C1034RA04090B. Abstract at: http://rsc.li/XbkskA

Jumping-droplet Electrostatic Energy Harvesting

by Emil Morhardt

Harvesting energy from atmospheric dew? Why would dew have any energy in it to harvest? Miljkovic et al. at MIT and Bell Labs, in a paper published this week, discovered it by accident while working with nanoengineered superhydrophobic surfaces (surfaces that really don’t like water on them!). When water condenses on them the droplets can merge and spontaneously jump off, and what’s more, they are positively charged when they do. So, it’s just a matter of collecting that charge and putting it in wires to get electric current that can do work. The authors capture the charged droplets on a superhydrophilic (really likes to have water on it) copper surface. The faster the droplets are going when they jump, the more power generation, and this can be achieved by getting them to jump when they are very small. Thus we have a system with no moving parts, passively generating power purely by the condensation of dew. At the moment it’s just a laboratory experiment, but the authors think that it is scalable at low cost and provides another way to get renewable energy from the environment.

Miljkovic, N., Preston, D.J., Enright, R., Wang, E.N., 2014. Jumping-droplet electrostatic energy harvesting. Applied Physics Letters 105, 013111. http://bit.ly/1oNICeR