by Sara R. Roschdi
The government of Guatemala has approved hydro electric dams to be built on indigenous territories. Fitzpatrick-Behrens reports in the article, “Electrifying Guatemala: Clean Energy and Development” that these hydroelectric dam projects are expected to produce 181 megawatts of energy for the country [https://nacla.org/news/electrifying-guatemala-clean-energy-and-development]. For indigenous communities like the Ixcán community, these dams mean the pollution of their waters and the corporatization of their sacred lands. Telesur reports that on January 17th, two Indigenous Guatemalan activist, were assassinated by the state as they engaged in a peaceful protest against the building of a hydroelectric dam in San Mateo Ixatan, Guatemala [http://www.telesurtv.net/english/news/Guatemalan-Activist-Killed-Protesting-Hydroelectric-Project-20170118-0013.html]. Continue reading →
Damming natural flowing rivers is an ancient and effective method for generating renewable energy. However, sufficient rivers are a scarce resource and modern dams produce an array of undesirable environmental effects. In response to the drawbacks of traditional dams, the main commercial technique for storing potential energy in water is pumped hydroelectric storage (PHS). Traditionally, these facilities use a massive pump and two reservoirs, one elevated above the other. During off-peak hours, excess energy produced from sources such as wind farms and nuclear power plants is used to power a pump which moves water into the elevated reservoir. When energy demand rises, the water is released back into the lower reservoir, spinning the pump which effectively becomes a generator. Continue reading →
US and European electricity supply is increasingly defenseless to climate changes. 91% and 78% of the total electricity in the US and Europe, respectively, is produced by thermoelectric power plants, which are nuclear and fossil-fueled. These plants and the processes to get electricity rely on the availability and temperature of water resources for cooling. The changing climate directly affects temperature and water resources, so the heavy reliance on these factors in electricity is at high risk. Freshwater withdrawals for cooling coal, gas and nuclear-fuelled power plants are highest in North America. Next highest worldwide is Europe. Continue reading →
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.
Low-head hydro, in this case 2 meters, is not normally viewed as a good source of energy for electricity production, but a clever paper from the engineers at Lancaster University, in the UK, suggests using a shore-based siphon to generate air pressure (their field test rig is shown above). Although they didn’t try converting the air pressure to electricity, they certainly could if the economics were right, and it looks like they might be. As they point out, there are other alternatives to water turbines in current use, including Archimedes screws, hydro-venturis, and water wheels, all of which minimize harm to fish, but this approach might be even cheaper. The idea is to siphon water from above a small dam (weir) to below it, and entrap air into the water stream through a tube at the top of the siphon. The air gets compressed in the process and can be bled off for whatever use is handy; generating electricity with it might not be the best use since it will involve energy losses that might be avoided if the air were used directly, say to run some kind of pneumatic machine. Continue reading →
Yesterday, the International Hydropower Association (IHA) announced that the Nature Conservancy would be one of the main sponsors of its World Hydropower Congress in Beijing next May. In an accompanying piece the Nature Conservancy’s Jeff Opperman explained why. It is an interesting question. I spent much of the two decades between 1975 and 1995 as an environmental consultant to hydropower developers, and the one constant was unrelenting opposition from almost every environmental group. Hydroelectric installations disrupt river flows, block river passage, often inundate great swaths of previously undeveloped watersheds, and do it in a way that is only optimistically renewable, at least where large storage reservoirs are involved; in time all reservoirs fill with sediment, and the projects revert to run-of-river facilities which are generally less valuable and less useful. Continue reading →
Seems like it’s getting to the point that no possible source of power should go unharvested. This paper envisions the water tanks at the top of apartment complexes in Taiwan as mini-pumped storage projects: by installing miniature turbines in the water supply pipes feeding the building from these tanks, electricity can be generated whenever the occupants use any water. The pipes are 4–6 inches in diameter, and a single turbine can generate about 3 Watts under the expected water flows. The experimental turbine blades were printed on a 3-D printer until the engineers got the result they wanted; a set of three airfoil blades that didn’t alter the flow rate of the water. (I’m not quite sure how this could be…if the blades extract energy it seems to me that the only place it could have come from is by diminishing the flow rate. Perhaps someone could explain this in a comment.) In any event, extracting this amount of energy apparently didn’t interfere with the functioning of the water supply system. The authors figure that they could get enough electricity out of a building’s water supply lines to run a few light fixtures. They didn’t explore it much, but the drains are another obvious source of potential energy. This all seems good.
The main considerations in whether and where to install photovoltaic (PV) panels are how much sun there is, and how much the panels cost. Right? Not necessarily. Engineers at Arizona State University have just published a paper pointing out that if a goal of installing photovoltaics is to decrease greenhouse gas emissions, it would be prudent to consider the emissions from manufacturing—which vary significantly by panel type—how long they stay in the atmosphere, and whether or not the installation is competing with other renewable energy sources rather than with fossil fuel burning. Because of the greenhouse gases associated with manufacturing, all panel installations increase greenhouse effects in the short term, although the initial two-year effect is to reduce them owing to sulfur and nitrogen oxides released from power plants during manufacture.
Hydroelectric projects can be terrific for meeting peak electricity load demands; if they store water in reservoirs, they can release it more-or-less instantly to generate electricity just in time to meet the demand. This is what pumped storage hydroelectric facilities are designed to do from the start, usually pumping water uphill from one reservoir to another to store energy, then letting it flow back down when energy is needed. The only potential significant environmental impact from this operational phase would result from reservoir water-level changes during the cycle. In a non-pumped-storage situation where the reservoir is behind a dam on a river and the peaking strategy with the best economics is to release practically no water until needed for peaking, then to release a lot, there are plenty of potential downstream environmental impacts. Such a strategy is utilized in the mid-Atlantic US by some utilities. In a paper just accepted by the journal Environmental Science & Technology, researchers at the University of North Carolina and Duke University looked at releases at Roanoke Rapids Dam on the Roanoke River and tried to figure out if adding wind to the mix of renewable power would increase or decrease these potential impacts (Kern et al. 2014). Despite earlier suggestions that it would, they decided not, based on the model results that predicted very little increase in the downstream “flashiness” over current operational conditions, even with 25% new wind market penetration….