LightSail’s Mission to Cut Costs of Compressed Air Energy Storage

by Katy Schaefer

LightSail, an energy storage company based out of Berkeley California, is attempting to change the way we approach energy conservation. Not only is the method dramatically more efficient, but the costs that have the potential to be cut is game changing. Lightsail’s aim is to create a more economical storage system through compressing air to create heat energy, which before was just wasted energy. It seems that there is something to their system, as some of the country’s most prominent tech billionaires have backed the plan. Unfortunately LightSail and its leader, Danielle Fong, the 27 year old co-founder and chief scientist, are not releasing the details of the plan just yet. However, here’s what we do know. Continue reading

Pumped Hydroelectric Storage: Putting Gravity to Work

by Chad Redman

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

Expanding the Frontiers of Energy: Pay-as-You-Go Energy

by Alison Kibe

With little to no access to electricity grids in rural areas of Africa, the Nairobi based startup M-KOPA solar launched in 2012 as an effort to provide affordable solar energy units to households in Kenya, Tanzania, and Uganda. A recent press release announced that M-KOPA is entering its fourth round of investment worth $12.45 million (Jackson, 2015). The money will be used to add products to M-KOPA’s line, expand business into East Africa, and license their products for use in other markets (Jackson, 2015). The start up also won the Zayed Future Energy prize in February. Worth $1.5 million, the money will be used to start a development program called M-KOPA University that will focus on developing employees’ business and technical skills (Mutegi, 2015). Continue reading

Ice Energy: As Cool as Energy Storage Gets

by Alexander Flores

Ice Energy, a privately held company based in Santa Barbara, CA, has developed a cost-effective air conditioning utility known as the Ice Bear. Essentially, the Ice Bear’s primary function is to convert a power-guzzling air conditioner into a more efficient hybrid that consumes 95% less energy during the peak of the day. This supplementary energy storage unit is compatible with 85% of all commercial air conditioning units and simply stores energy at night when electricity generation is cleaner, more efficient, and less expensive, then delivers it during the day. The Ice Bear works in conjunction with refrigerant-based, 4-20 ton package rooftop systems common to most small or mid-sized commercial buildings. One could simply think of an Ice Bear unit as a battery for an air conditioning system. But just how does it work? An Ice Bear unit consists of a large thermal tank, which operates in an Ice Cooling mode and Ice Charging mode to make ice at night to use for cooling the following day. Continue reading

Of the many Energy Storage Systems, Integrated Hydrogen-Oxygen Storage Stands Out

by Tim Storer

Wind power comes with the disadvantage of intermittent gaps in energy production and instances of excess supply. This variability puts strain on the electric grid and is the primary barrier to large-scale wind power integration. In order to combat this issue, various forms of energy storage have been considered to bridge the gap between supply and demand of wind power. Gao et al. 2014 conduct a brief literature review on all existing energy storage systems (ESS) for wind power. Each method comes with drawbacks associated with scale, cost, or safety, but hydrogen-oxygen storage was seen here as the best future option. By improving storage technologies, wind energy will become more viable in the market and help to reduce the share of energy coming from fossil fuels that contribute to climate change. In addition to the literature review, this study examined a possible hydrogen-oxygen ESS in Jiangsu Province, China and saw that such an operation could be profitable in the current market.

While there are some operational forms of ESS, there is a variety of issues preventing ESS –and subsequently, wind power– from becoming widespread energy sources. For example, battery power is too costly and difficult to build at a large scale, systems that involve pumping water upward for energy storage have geographical limitations, and magnetic energy storage has low storage time. In the case of hydrogen generation from electrolysis, the costs are simply too high to be competitive in the energy market with capital costs of 1000-2500$/kW (when they need to be near 400 $/kW).

Hydrogen-oxygen combined storage consists of electrolyzers that break water down into hydrogen and oxygen. The hydrogen and oxygen are combusted to form super-heated steam that powers turbines. The system is closed, and uses water as a recycled fuel. Gao and colleagues examined three variants of hydrogen-oxygen ESS: simple integrated ESS, integrated ESS with a feed water heater, and an integrated ESS with both a feed water heater and a steam reheater. In simple terms, these systems each contain an additional measure to capture heat from the steam turbines and use that heat elsewhere in the process, thus improving efficiency. All of these integrated systems contain a complex web of mechanisms that can be adjusted alongside price fluctuations in the power market to minimize costs. The former two had roughly equivalent efficiencies of 49%, but the latter system had efficiency of up to 54.6%, thus demonstrating the benefits of feed water heaters and steam reheaters.

While the 54.6% efficiency of the fully integrated system is marginally below that of some other ESS technologies, hydrogen-oxygen systems come with certain advantages. They can be implemented on a large scale, are fully eco-friendly, not limited by geographical and material restraints, and can be adjusted rapidly based on demand changes. The system was analyzed under two extreme scenarios: an “intermittent operation mode” simulating an extremely variable wind supply, and “continuous operation mode” simulating a perfectly steady supply. Because of how effectively the system dealt with times of low wind, it was actually more profitable under the intermittent scenario with annual income of $13 million per year. Real wind conditions lie somewhere between these extremes, and efficiencies of approximately 50% and prices of 0.03–0.05$/kWh were estimated.

Dan Gao, Dongfang Jiang, Pei Liu, Zheng Li, Sangao Hu, Hong Xu, 2014. An integrated energy storage system based on hydrogen storage: Process configuration and case studies with wind power. Energy, Vol. 66: 332–341.



Redox Flow Batteries: For Grid Level Storage

by Chad Redman

Current energy storage technologies are often overlooked in favor of the next promising development that will be commercialized sometime in the future, but economical large scale energy storage is already possible with current equipment. Redox flow batteries (RFBs) are a type of large battery that utilizes reduction and oxidation reactions to charge and discharge liquid electrolyte solutions. The advantage of RFBs over other battery types is realized in scale; RFBs can easily expand and store more energy by using larger storage tanks for the electrolyte solutions. However, the power that can be produced by an RFB is determined by the architecture of cells within the RFB. Unlike a standard Li-ion or lead-acid battery, only a small percentage of the energy within an RFB is accessible as power at any given moment. Continue reading

Liquid Air Energy Storage

by Chad Redman

Asymmetrical energy production and consumption over the course of the day creates challenges all around the globe, which is why effective and efficient energy storage technologies are the subject of widespread research and development. Liquid Air Energy Storage (LAES) is one fascinating method for storing excess, cheap off-peak energy, and taking advantage of it when energy production falls and demand rises in the evening. The Energy Storage Association describes the systems behind LAES, including ways in which waste from unrelated processes can be turned into valuable energy. Continue reading

Just Released! “Energy, Biology, Climate Change”

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Our newest book just Released! “Energy, Biology, Climate Change” and available at for $19.95.

The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.

This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading

Potential $8-Billion Green Energy Initiative for Los Angeles

by Alexander Flores

As of September 2014, an $8-billion dollar green energy project has been proposed to link one of the nation’s largest wind farms to one of the world’s biggest energy storage facilities. This first initiative of its kind in the United States was strung together by four companies: Duke-American Transmission Co., Dresser-Rand, Magnum Energy, and Pathfinder Renewable Wind Energy, in hopes to provide large quantities of clean electricity to the Los Angeles area by 2023. This project in particular would involve the construction of one of the largest wind farms in Wyoming and one of the largest energy storage facilities in Utah with a 525-mile electric transmission line connecting the two sites. Continue reading

Underground Storage of CO2 : Attempts to Eliminate Carbon Emissions

by Nour Bundogji

Postdoctoral researcher Yossi Cohen and Professor of Geophysics Daniel Rothman, at Massachusetts Institute of Technology, recently published an article in the Royal Society Proceedings on the effectiveness of storing carbon dioxide underground in an effort to decrease carbon emissions in our atmosphere. When I first read this I immediately envisioned suction cups elevated high into earth’s atmosphere connected to long pipes extended deep within earth’s crust. Yet, you guessed it, the technology is quite different. Instead, greenhouse gases emitted by coal-fired power plants would be pumped into salt caverns 7,000 feet underground where these gases would react with the salt water and solidify (Cohen and Rothman, 2015). The U.S. Environmental Protection agency estimated that this technology could eliminate up to 90 percent of carbon emissions from coal-fired facilities. Considering the current state of our ozone layer and the drastic climate changes we’ve been experiencing these past years, this seems like a promising step forward in saving our environment. However, commentators on this technology, like Christopher Martin from Bloomberg, pointed out a few flaws. I knew it was too good to be true. Continue reading