Past Events

4 presentations in the framework of the FGS course on: Energy and Sustainability. Analyzing the options for a sustainable energy future

Three major goals for 2020 were set by the Israeli government in recent years: 10% renewable energy in the electricity fuel mix; 20% improvement in energy efficiency; and 20% greenhouse gasses emission reduction. Current reports show that in all three goals milestones had not been reached, and without clear regulation and allocated budgets, major progress cannot be expected. Our research defines a combined sustainability index used for evaluating common technologies in the Israeli electricity production market, and energy efficiency measures in the main consumption sectors. The goal is to enable a holistic decision making process, taking into account economic, technological, environmental, social and political considerations. Using multi-criteria analyses of both the production and consumption indices, we find that outdoor lighting in the municipal sector is expected to be the preferable energy efficiency measure in all expected scenarios of electricity production fuel mix.

Research in cellulose is exploding exponentially, as researchers look for renewable resources to replace chemicals and materials derived from fossil fuels. Cellulose is the most abundant biopolymer on earth and can be modified to make a large number of useful products, several of which will be discussed. Cellulose can be made into superabsorbent papers and gels, by introducing the appropriate amount of charge groups, usually carboxyl groups. Carboxylated fibers swell and can take up water more than hundred times their weight. They can be modified into an aqueous dope, from which one can spin textile fibers. The morphology of swollen fibers depends on the way the charges are introduced and reveals the underlying structure of the cell wall. By increasing the charge above 3 meq/g, the fibers break apart in nanocellulose and dissolved carboxylated cellulose (DCC). The nancellulose consist of cellulose nanofibers (CNF) and cellulose nanocrystals (CNC). The larger the charge, the larger the fraction of CNC. This CNC is different from conventional CNC, made by acid hydrolysis of cellulose fibers: it has DCC chains protruding from each end, which entangle when making films, resulting in transparent films much stronger than made from conventional CNC. They also have different cytotoxic properties: the higher the charge, the more they affect the metabolism of certain cells. The DCC end chains of CNC can by removed by hydrolysis, resulting in CNC with negatively charged ends. These particles can be crosslinked to make much longer chains, resembling CNF. Carboxyl groups in cellulose can be readily transformed in other functional groups, e.g. by a bioconjugation reaction. CNC films can be made superhydrophobic and paper can be made functional, making it hydrophobic, fluorescent or introducing sensors that can detect pathogens.

The shortage of natural resources of energy carriers and scarce elements requires a more efficient use of resources by improving energy technologies. Therefore we develop and investigate advanced materials for energy and environment related applications. Perovskite-type oxides and oxynitrides as well as Heusler compounds are synthesized by tailored scalable synthesis methods and used to replace less efficient, more noxious and/or more expensive conventional materials. Their desired function is demonstrated from the atomic and nanoscale up to the demonstrator, from lab scale to the application. The fundamental understanding of structure-composition- property relations of materials in solid state energy conversion devices is mandatory to achieve solutions for alternative energy conversion technologies.

Over the past years there has been a dramatic increase in the regulatory requirements for low emissions from both new and existing utility boilers and gas turbines. Traditional methods of reducing NOx emissions, such as: modification of the firing system (to control the fuel and air mixing and reducing flame temperatures); and/or post combustion treatment of the flue gas to remove NOx; are very expensive. Hence, before the implementation of the expensive measures for the emission reduction, it is necessary to evaluate all low cost alternatives. Fuel properties have a major influence on NOx formation during combustion. One of the attractive alternative fuels for combustion in the utility boilers and stationary gas turbines may be methanol. Existing experience has shown that with minor system modifications, methanol is easily fired and is fully feasible as an alternative fuel. Using methanol has become an important solution for emissions compliance due to their unique constituents and combustion characteristics. Methanol may be referred to as enviro fuel. The considerable advantages of methanol fuel relative to heavy fuel and light fuel oil, methanol can achieve an improved efficiency and lower NOx emissions, due to the lower flame temperature and nitrogen content. Since methanol contains no sulfur and ash, there are no SO2 and very low particulates emissions. The clean burning characteristics of methanol are expected to lead to clean pressure parts, turbine blades and lower maintenance than with fuel oil. Hence, firing methanol alone or as blends with fuel oil is deemed environmentally attractive. Gas Turbine performance on methanol is improved over other fuels due to higher mass flow and lower combustion temperatures resulting from methanol operations. The present paper discusses the boiler and gas turbine testing in various operation modes during methanol and fuel oil firing. The measurements were accompanied by computer simulations of the combustion process. Here, we present results of the Israel Electric Corporation (IEC) for specific 140 MWe units consisting of two tangential fired pressurized boilers by Combustion Engineering Inc by using the co-firing of methanol with heavy fuel oil and FT4C TWIN PAC 50 MWe GT provide by Pratt & Whitney by using the methanol firing that show the control of NOx, SO2 and particulate emissions The experiments performed for gas turbine tested different GT loads during methanol and LFO firing. The results presented here clearly show that with minor low cost fuel system retrofit methanol firing leads to significant NOx, SO2 and particulates emission reduction. NOx emissions were reduced more than 75% and are equal 75 mg/dNm3 at 15%O2. . It is less then required standard even with water injection operation mode (the standard 86 mg/dNm3 at 15%O2 SO2 emissions were reduced from 50 mg/dNm3 at 15%O2 with LFO to zero with methanol firing. Particulate emissions vary from 1.3 to 1.6 mg/dNm3 at 15% O2 with methanol firing, while with LFO this parameter was 13-37 mg/dNm3 at 15% O2. The experiments performed for the boiler tested different methanol fractions of the total boiler heat capacity (from 33% to 50% heat), at different boiler loads. The results presented here show that NOx emissions were reduced more than 20% and meet the commonly accepted NOx emissions 270-330 mg/dNm3 at 3%O2. SO2 emissions were reduced from 670 mg/dNm3 at 3%O2 with HFO to 430 mg/dNm3 at 3%O2 with methanol co-firing. Particulate emissions vary from 25 to 37 mg/dNm3 at 3% O2 with methanol co-firing, while with HFO this parameter was 40-90 mg/dNm3 at 3% We believe that the conclusions of the present work are general and can be applied to other boilers and gas turbines as well.

Covering less than 2% of the dry land in the United States with only moderately efficient solar cells can produce enough electricity to satisfy the national demand for energy. Unfortunately, despite the 30-40% annual growth of the photovoltaic (PV) industry, the sum total area of solar cells produced and installed to date is orders of magnitude smaller. Furthermore, current manufacturing methods do not scale up sufficiently quickly to fulfill the demand in the next 10-20 years. In this talk, I will discuss the properties of conjugated organic-based compounds, organic PV device architectures, and device physics that potentially enable scalable solar energy harvesting. Specifically, I will describe how Van Der Waals-bonded molecular organic compounds are deposited as thin films onto non-planar substrates, including fibers, and how this novel PV cell form factor can be further engineered to increase the power conversion efficiency. Of note are device architectures that eschew the transparent, conducting, but costly and brittle indium tin oxide (ITO) electrodes.