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Using treated wastewater effluent (reclaimed water) for beneficial purposes can be a sustainable practice that reduces demand on potable networks. However, implementing reclaimed water networks can have unintended effects, specifically unintended increases in energy consumption. This case study employs multi period scenario analysis to examine energy consumption associated with the potable and reclaimed water systems for the Town of Cary, North Carolina. Using hydraulic planning models of both systems provided by the design engineers, the conveyance and additional treatment energy is tabulated. This method considers uncertainty in reclaimed water demand by varying the expected demand for each build out of the reclaimed water network. Differential electricity consumption is calculated as the difference between the electricity consumed to deliver reclaimed water through a secondary network compared to the electricity consumed to deliver the same volume through the potable water network. Demand uncertainty, in conjunction with spatial growth, is found to have large impacts on differential electricity consumption. Because of the high quality of wastewater effluent, no additional energy is required for treatment, causing the reclaimed water network to consume less energy than the business-as-usual scenario, where the demands are supplied via the potable network. The differential electricity consumption decreases with network expansion because the reclaimed water system becomes less energy efficient per unit volume with increasing flow rate, while the potable water system energy efficiency remains fairly constant. Understanding the trade-offs between water and energy when planning reclaimed water networks is important for sustainable resource management within the built environment. [ABSTRACT FROM AUTHOR]

Abstract: A study of a photovoltaic (PV) array and inverter system installed in San Diego, California, was conducted in order to determine the energy losses due to inverter saturation (capping of inverter power output due to the PV array power output exceeding the inverter maximum power rating). Two mechanisms of saturation were considered: cloud enhancement (refers to an increased diffuse component of irradiance caused by clouds surrounding the unobstructed solar disk) and clear sky exceedance. For inverter sizing ratios (defined as R =inverter maximum AC output rating/PV DC rating) of R =0.81 and R =0.87 the annual energy losses as a percent of annual energy production were 2.65% and 2.20% using 1-s measurement resolution. Annual energy losses were calculated by aggregating the difference between modeled power (assuming no saturation occurred) and measured power. Losses due to cloud enhancement dominated the total losses, especially for R =0.87. Increasing inverter size reduces saturation losses during high irradiance conditions, but decreases inverter conversion efficiency under low irradiance conditions. Increasing the sizing ratio to R =1.22 would result in a maximum amount of energy production at our site. Averaging on timescales from 1-s to 1-h was performed to demonstrate that cloud enhancement losses can only be quantified using 10-s or finer measurements. [Copyright &y& Elsevier]

The M2 internal tide in Monterey Submarine Canyon is simulated using a modified version of the Princeton Ocean Model. Most of the internal tide energy entering the canyon is generated to the south, on Sur Slope and at the head of Carmel Canyon. The internal tide is topographically steered around the large canyon meanders. Depth-integrated baroclinic energy fluxes are up canyon and largest near the canyon axis, up to 1.5 kW m−−1 at the mouth of the upper canyon and increasing to over 4 kW m−−1 around Monterey and San Gregorio Meanders. The up-canyon energy flux is bottom intensified, suggesting that topographic focusing occurs. Net along-canyon energy flux decreases almost monotonically from 9 MW at the canyon mouth to 1 MW at Gooseneck Meander, implying that high levels of internal tide dissipation occur. The depth-integrated energy flux across the 200-m isobath is order 10 W m−−1 along the majority of the canyon rim but increases by over an order of magnitude near the canyon head, where internal tide energy escapes onto the shelf. Reducing the size of the model domain to exclude remote areas of high barotropic-to-baroclinic energy conversion decreases the depth-integrated energy flux in the upper canyon by 20%%. However, quantifying the role of remote internal tide generation sites is complicated by a pressure perturbation feedback between baroclinic energy flux and barotropic-to-baroclinic energy conversion. [ABSTRACT FROM AUTHOR]

Abstract: The electric power generation of co-located offshore wind turbines and wave energy converters along the California coast is investigated. Meteorological wind and wave data from the National Buoy Data Center were used to estimate the hourly power output from offshore wind turbines and wave energy converters at the sites of the buoys. The data set from 12 buoys consists of over 1,000,000h of simultaneous hourly mean wind and wave measurements. At the buoys, offshore wind farms would have capacity factors ranging from 30% to 50%, and wave farms would have capacity factors ranging from 22% to 29%. An analysis of the power output indicates that co-located offshore wind and wave energy farms generate less variable power output than a wind or wave farm operating alone. The reduction in variability results from the low temporal correlation of the resources and occurs on all time scales. Aggregate power from a co-located wind and wave farm achieves reductions in variability equivalent to aggregating power from two offshore wind farms approximately 500 km apart or two wave farms approximately 800 km apart. Combined wind and wave farms in California would have less than 100h of no power output per year, compared to over 1000h for offshore wind or over 200h for wave farms alone. Ten offshore farms of wind, wave, or both modeled in the California power system would have capacity factors during the summer ranging from 21% (all wave) to 36% (all wind) with combined wind and wave farms between 21% and 36%. The capacity credits for these farms range from 16% to 24% with some combined wind and wave farms achieving capacity credits equal to or greater than a 100% wind farm because of their reduction in power output variability. [Copyright &y& Elsevier]

Advanced controls optimization offers a promising pathway to improve performance, reduce structural loads and thereby reduce the Levelized Cost of Electricity (LCOE) for wave energy conversion (WEC) systems. Model predictive control (MPC), which remains the preferred algorithm framework for WEC devices requires a wave excitation force forecast on the order of 30 seconds into the future to be effective. To establish the feasibility of forecasting the wave resource within this time-horizon, we benchmarked a wave prediction system that leverages an X-band ship navigation radar using a set of field campaigns carried out offshore Santa Cruz in California. For quantitative assessment of the prediction accuracy, we evaluated error metrics based on correlation and normalized mean absolute error between measurement and prediction. The relationship between prediction accuracy and key environmental factors prevalent during data collection (wave height and wind-speed) was analyzed through a set of sensitivity studies. Overall, the results show that wave prediction accuracy is good enough to enable MPC based control, which establishes a credible technology pathway to utilize these control techniques on commercial devices at sea. [ABSTRACT FROM AUTHOR]

There are growing provisions to include ocean wave energy as an alternate renewable energy source. There are also several challenges that need to be addressed before the technology gains full engineering and market confidence. One of the main technical hurdles is the need to address part-load problems of wave energy converters resulting from bathymetric conditions and variations in wave parameters such as wave frequency and height. As such, the wave phenomenon is inherently variable in time and space. This is compounded by the fact that wave energy conversion devices are less efficient at part load. This paper discusses sources of part loads in wave energy conversion including their impact on system efficiency for a California weather scenario, also relating wave energy conversion techniques to part-load efficiencies. [ABSTRACT FROM AUTHOR]

The Orange County Sanitation District (OCSD) in California has commissioned a fuel cell power plant that efficiently converts biogas generated from the wastewater treatment process into electricity for use by OCSD. It also produces renewable hydrogen for an onsite fueling station operated by Air Products, to serve fuel cell vehicles in the region. [Copyright &y& Elsevier]

The article profiles Doug Cameron, chief scientific officer at Khosla Ventures in Menlo Park, California. Cameron finished college at Duke University in North Carolina and has landed a job at the University of Wisconsin where he designed metabolic pathways in cells to produce industrial chemicals. Now, Cameron's company has been involved in converting and developing products from anything other than petroleum. Despite the boom in the ethanol industry which could threaten their oil-based business, he does not worry much and sees it as nothing new. Now, he is the acting CEO of Ls9 and Segetis and is a board member of three additional investments.

The article reports that BP PLC has invested a 10-year biofuel research of $500 million to the University of California, (UC Berkeley) Berkeley, California to host the Energy Biosciences Institute. According to Jim Breson of BP PLC stated that they decided to boost its biofuel research agenda,but their choices were limited for having only four biologists in the company. UC Berkeley official Beth Burnside stated that less than 30% of the total funding would be spent to the 50 BP scientists who will work in propriety labs at the institute facilities. Breson emphasizes the company's commitment to share the intellectual property with the academic scientists and honoring the need to publish the research.