Energy Engineering - Solar and Biomass Power Generation

Full exam

SOLAR AND B I OMASS POWER GENERAT ION AY 2020-21 18 th February 2021 Prof. Giampaolo Manz olini Time: 90 minutes Instructions for the examination: 1) Clearly indicate y our surname and name on all the sheets y ou will deliv er. 2) The score refers to exercises done in a comprehensiv e manner with exact numerical results. Numerical results correct but not accompanied by expla- nations will not be tak en into account. The final score can be normalized according to the av erag e results. 3) Answer briefly and clearly only to the asked questions. Calculations and explanations which do not respond to the questions will not be considered for evaluation even if correct. 4) Talk ing with colleag ues and / or cheating will cause the cancellation of the exa m. 5) All the needed data for the resolution of exercises lies on this paper. I t is NO T ALLO WED to use material other than this (e. g. book s, clipboard etc. ). 6) Not all the prov ided inputs are necessary for the problem solv ing PV exercis e (16 po in ts) Question A: D esig n a PV plant to be placed on an industrial roof. The roof siz es are 90 m leng th and 50 m width with the long est leng th in the N/S direction. Assuming the PV module and inverter characteristics, determine the nominal power installed (AC), the num- ber of inverters and the PV connections discussing the results (it’ s not necessary to check the conditions at minimum and maximum temperature). The PV modules are 30° tilted, their distance is determined so to have no shading on the 1 st of December at solar noon assuming the plant to be located in Amst erda m (52.4 N, 4.9 E) (6 points). PV modules Inverter Power @ STC 333 W Power input in CC 5500 0 W Open circiut voltag e @ STC 64.8 V Maximum voltage 900V Short circuit current @ STC 6.24 A Power point operating voltag e 360 -700 V Voltage at MMPT@STC 54.7 V Power output in AC 52000 W Voltage coefficient –176,6 mV / °C STC (1000 W/m 2 and 25°C) Current coefficient 3.5 mA/°C NOCT (@800 W/m 2 and T amb 20°C) 45°C Power coefficient -0.38%/°C Module d imensions ( l x w) in mm 1559 x 1046 360( 284) 23.45 sin 365 nd δ +  = °⋅  360( 284) 23.45 sin 365 nd δ +  = °⋅  Question B: Calculate the maximum theorical power g enerated by the plant in the considered location (which is not the one calculated before). Please st a t e your a ssumpt ions (3 points) Question C: Calculate the yearly electricity production and equivalent hours knowing that the yearly solar irradiance is 1050 kWh/m 2, average DNI 455 W/m 2 with an incidence ang le of 50°, averag e diffuse irradiation 105 W/m 2, the average ambient temperature is 12 °C, keeping the same inverter efficiency (DC/AC) at on desig n conditions, adding 15% of losses for B OP. (3 points) Question D: D etermine the net power production of the plant at solar noon of the winter solstice assuming that the DNI is 500 W/m 2 and diffuse radiation equal to 100 W/m 2. Please make explicit your assumptions (4 points) Biomass exercise (14 points) Question A: Calc ulate the LCOE of a biogas plant ac c ording to the information reported below (c ost data are reported at the end of the ex erc ise) (8 poi nts). The feed is organic frac tion of municipal solid was te ( 1 t onn/m3 of dens ity ) and the Ultimate BMP is 0.35 m 3/kg COD and assuming a biog as LHV equal to 9.96 kWh/m 3. Amount Conversion factor Volumetric flow rate 18 0 m 3/d Proteins 12 g/100 gVS 1.42 gCOD/gVS Total solid content 17 g TS/100g Carbohydrates 70 g/100 gVS 1.12 gCOD/gVS Volatile solid content 75 g VS/100gTS Lipids 4 g/100 gVS 2. 5 gCOD/gVS Th e ac tual Biogas Methane Produc tion effic ienc y (η BM P ) is func tion of the Hy draulic Retention Time (HRT) ac c ording to the following equation: ������������=1− 1 0.32∙������������������������������������������������ ; HRT >45 day s OLR