Report Unveils that U.S. Solar Industry Employs More People than Fossil Fuel Industry

by Genna Gores

The U.S. Department of Energy’s 2017 U.S. Energy and Employment Report, reveals that the renewable energy industry employs more people than the entire fossil fuel industry (including petroleum oil, natural gas, and coal). The report goes on to compare employment opportunities between 2015 and 2016 for all types of energy within the Electric Power Generation sector, which includes: solar, wind, geothermal, bioenergy, hydropower, nuclear, fossil fuels, and other generation/fuels. It is evident with this report that solar and other renewable energies are a rapidly growing industry with increasing employment opportunities for Americans. Continue reading

For Wind Energy, Bigger May Actually Be Better

by Erin Larsen

A new design for offshore 50-megawatt (MW) collapsible wind turbine blades could help bring wind energy mainstream in the United States. Sandia National Laboratories was tasked with the challenge of designing a low-cost, offshore 50-MW turbine requiring a rotor blade more than 200 meters long. The research and development for the gigantic blades was funded by the Department of Energy’s ARPA-E program. These blades are two-and-a-half times longer than any existing wind blade and longer than two football fields.

The design of the huge blades is inspired by by the way palm trees move in storms. The “trunk” of the turbine features a segmented build with a cylindrical shells that bend at the joints in the wind, while still retaining segment stiffness. The turbines themselves are called Segmented Ultralight Morphing Rotors (SUMR). They are lightweight, flexible, and assembled in multiple segments. At dangerous wind speeds, the blades are stowed, while at lower wind speeds, the blades spread out more to maximize energy production. Continue reading

Designing Energy Systems to Be More Like Trees

by Erin Larsen

A team of engineers at Ohio State University are looking to nature to redesign windmills. In a recent issue of the Journal of Sound and Vibration, OSU researchers reported that they have discovered new information about how vibrations pass through trees when they sway in the wind. They believe that this research can be used to design new tools for harvesting wind energy that look less like windmills and more like mechanical trees. 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.



Fishing Boat Transformed to Harness Energy from Ocean’s Waves

by Niti Nagar

It might be possible to harness the movement associated with the ocean’s natural waves using docked fishing vessels. Researchers are demonstrating this simple idea is feasible using a demonstration vessel currently docked offshore in Western Norway.

Transforming a vessel into a wave power plant requires installing four large chambers, in the vessel’s bow, each equipped with an air-powered turbine. As the waves strike the vessel, the water levels in the chambers rise leading to an increase in air pressure, which consequently drives the four turbines. The chambers respond to different wave heights, allowing greater wave heights to contribute more air pressure. Each turbine is capable of produced 50kW. Using mathematical models and simulations, the researchers expect the plant to produce 320,000 kW per year. Continue reading

Changes in Clean Energy Investment in 2014: End of Year Recap

by Melanie Paty

On January 9th, 2015, Bloomberg New Energy Finance submitted a press release on the strong performance of clean energy investments in 2014. The overall investment in clean energy reached $310 billion, a 16% increase from 2013, but 2011 still holds the record at $317 billion. However, it was the biggest increase of new investment in clean energy since 2011. Government funded research and development increased 14% and corporate increased 15%. Private equity and venture capital investments increased 16%, but overall investment is still three times below 2008 levels. In terms of region, the most investment came from the United States, China, and Europe. European investment increased only 1% since 2013, but is still the highest at $66 billion. China increased a whopping 32% to $89.5 billion. Clean energy investment in the United States experienced a smaller increase of only 8% reaching $51.8, $15.5 billion of which went to utility scale asset finance. U.S. investment in solar increased by 39% whereas investment in wind decreased by more than 50%. India and Brazil both reached $7.9 billion in clean energy investments, an 88% increase for the former and a 14% increase for the latter. French investment increased by 26% due to the installation of Europe’s largest solar PV plant with 300MW capacity. Continue reading

Norway’s Path to Zero Emissions: Large Scale Hydrogen Production from Off-Grid Renewable Sources

by Tim Storer

Norway currently generates over 95% of its power from hydroelectric dams, making it one of the most climate friendly energy systems on the planet. In efforts to bring Norway carbon neutral by 2050, the government aims to eliminate emissions from the transportation sector. Konrad Meier of the Stuttgart University of Applied Sciences examines the possibility of using a hypothetical 100 megawatt offshore wind farm to generate hydrogen fuel via electrolysis. Because water hydrolysis uses only electricity and water, it offers an emissions-free means to generate hydrogen as long as the electricity is generated from a renewable source, such as wind power. This could achieve Norwegian political goals of carbon neutrality by providing the hydrogen necessary to transform their transportation sector. Unlike other proposed wind-to-hydrogen technologies, Meier examines an off-grid operation, rather than producing hydrogen at the fuel refill site. The analysis was conducted under three scenarios, and the hydrogen from this proposed operation is profitable in the energy market under only the “best case” scenario.

This is a clever use of wind power for several reasons. First, if this operation were integrated into the power grid, wind variability would become an issue. Keeping the production off-grid avoids costs of transmission infrastructure and variable supply. Second, the variability also makes exporting excess power to the E.U. infeasible. The remaining 5% of domestic power is more likely to come from untapped hydroelectric resources, so wind has no use in Norway either. Using wind power for hydrogen synthesis circumvents these issues that have previously prevented wind production from being a viable energy source in Norway.

To examine costs, Meier used a location proximal to an operational German wind farm, Alpha-ventus, and incorporated its data. He uses 2010 data as his “worst case” scenario, which is a very conservative baseline considering how much lower the power output had been in previous years and how the proposed system would not be subject to transmission losses. The “best case” scenario was calculated simply by the predicted estimates. Given the likely increases in electrolysis efficiency in upcoming years, this scenario also yields conservative estimates of overall output costs. Meier discusses four types of electrolysis, but focuses on proton exchange membrane electrolysis cell (PEMEC) and solid oxide electrolysis cell (SOEC) that require water as the only input material. Unfortunately, research on the efficiency of PEMEC and SOEC is unable to offer precise estimates, and herein lies a major source of ambiguity in the study.

Because there is currently no market for hydrogen transportation fuel, this study is limited by the assumption of a future in which infrastructure has been implemented to support a hydrogen market. Unfortunately, given how variable the results are (dependent on optimistic/pessimistic assumptions), it is unclear whether such an investment is worthwhile at all. However, in as much as the best and worst case scenarios were estimated in a very conservative way, it is possible that such an operation could be an economic way to transform the transportation sector. Further research is needed on the efficiency of the PEMEC and SOEC processes to indicate whether the proposed wind farm is an economically viable solution to attaining a carbon neutral transportation sector.

Konrad Meier, 2014. Hydrogen production with sea water electrolysis using Norwegian offshore wind energy potentials. International Journal of Energy and Environmental Engineering Vol. 5: 1–12.



How to Maximize Renewable Energy in California

by Emil Morhardt

The looming problem with renewable energy—especially in California where there is potential for a great deal of solar energy—is finding the right balance between attractive new, but intermittent, solar and wind power plants, and some other source of generation large enough that dispatching it will meet any energy demand, even if the wind isn’t blowing and the sun isn’t shining. A new paper by Abebe Solomon, Dan Kammen, and Duncan Callaway, researchers in the Energy & Resources Group at the University of California Berkeley, calculates that if energy dumping doesn’t occur, the best we can hope for in California without energy storage, is meeting 29% of our energy needs with solar and Continue reading

Mini Piezoelectric Wind Turbine


by Emil Morhardt

In the Internet-of-Things, distributed sensors that collect data and transmit it to each other (and ultimately to a computer somewhere) wirelessly will become commonplace. They need a power source, but don’t want wires, or batteries that can wear out. Small photovoltaic panels work in some instances, but not always. Hence wouldn’t it be nice if a very small wind turbine came along. Yang et al., writing this week in Applied Physics Letters, invented an interesting one. It consists of a wind powered rotating drum, 3 cm in diameter, with several elastic balls inside that get dumped onto piezoelectric cantilevers as the drum rotates: the energy of the wind gets transferred to potential energy in the form of lifted balls, which then transfer their energy to the piezoelectrics when they fall on them. The piezoelectrics convert the kinetic energy of the balls into electricity, which can then be stored in a small supercapacitor for use as needed. No wires, no batteries, and not much mechanical that can wear out. Plus, the parts are cheap and readily available. And cleverly, the ends of the piezoelectric levers sticking out around the edge of the drum make perfect wind catchers.

Yang, Y., Shen, Q., Jin, J., Wang, Y., Qian, W., Yuan, D., 2014. Rotational piezoelectric wind energy harvesting using impact-induced resonance. Applied Physics Letters 105, 053901. Photo from the paper. Link to the abstract: