Making walnuts work harder
Energy and exergy are two important tools for evaluating power sources. Energy is essentially the calorific value of simply burning biomass, for instance, whereas exergy is the amount of usable work that might be done by that burning. Researchers in China and the USA are investigating walnut sawdust as one type of useful biomass for making syngas. The energy and exergy of such syngas depends on the reactor temperature used to process walnut sawdust and the mix of gases, carbon monoxide, methane, hydrogen, nitrogen, ethene and carbon dioxide that are produced. However, they have essentially demonstrated that the energy and exergy can be optimized by careful control of the entrained flow reactor temperature.
Zhang, Y., Zhao, Y., Li, B., Gao, X. and Jiang, B. (2017) ‘Energy and exergy characteristics of syngas produced from air gasification of walnut sawdust in an entrained flow reactor‘, Int. J. Exergy, Vol. 23, No. 3, pp.244-262.
Researchers in China have found that the temperature of the active layer of ice in a glacier has increased more on a cold glacier than a temperate glacier over a period of 30 years. The team analyzed data and historical documents for Baishui Glacier No. 1 (BG1), in the Yulong Snow Mountains of the Southeastern Tibetan Plateau and the Urumqi Glacier No. 1 (UG1), in the eastern Tien Shan Mountains, of Central Asia. There has been a daily mean increase of temperature of the BG1 has been almost a quarter of a degree Celsius July 1982 to July 10, 2009. But the active ice layer of UG1 has warmed considerably more despite it being the colder of the two. That said, the temperate glacier BG1 is still retreating faster than the cold glacier through global warming caused by the greenhouse effect.
Wang, S. and Ding, B. (2017) ‘The active-layer ice temperature increases more obviously on a cold glacier than a temperate glacier during the past 30 years‘, Int. J. Global Warming, Vol. 13, No. 1, pp.103-111.
Unmanned aerial vehicle (UAV), often colloquially known as “drones” require a power supply like any other aircraft. Now, researchers in Turkey have invented a fuel cell/battery hybrid system for powering a UAV. A proton-exchange membrane fuel cell with a supplementary rechargeable lithium-ion battery onboard powers a permanent magnet synchronous motor. Simulations of the system show effective torque development and the team suggests that such hybrid UAVs could soon take off.
Kaya, U., Bayrak, Z.U. and Oksuztepe, E. (2017) ‘Fuel cell/battery hybrid powered unmanned aerial vehicle with permanent magnet synchronous motor‘, Int. J. Sustain. Aviat. 3:2, 130-150.
Coal-based electricity generation is likely to remain an important contributor to power supply in many nations and in the global energy mix despite efforts to displace it with non-carbon-based, sustainable and cleaner energy sources. Of course, such plants generate huge quantities of carbon dioxide and contribute significantly to the greenhouse effect. With ongoing use of coal forecast for decades to come there is thus an urgent need to develop carbon dioxide sequestration technologies to reduce the global impact of this source of power on climate change. Researchers in the USA have developed a mathematical model that can analyze all the costs of such systems in the face of essential environmental regulations. Their model should allow policymakers and the corporate world to look at a rolling horizon for the next 20 to 40 years of coal-fired power stations.
‘Longer term strategic decision making for coal-based power systems incorporating CO2 sequestration‘, Zhang, Y. and Karwan, M.H. (2017), Int. J. Math. Operat. Res. Vol. 11, No. 2, 219 – 270.