# PTG-HEFA Hybrid Refinery as Example of a SynBioPTx Concept--Results of a Feasibility Analysis
## 3 Results and Discussion  
### Technical Assessment  
The results of the mass and energy balances are summarized in Table 4 for the different scenarios. Detailed discussion of these balances can be obtained from [12]. When jatropha is used as feedstock, the specific hydrogen consumption is about 35.7 kg per ton feedstock. For alternative feedstocks, this value is 39.9 kg t\({}^{-1}\) for rapeseed; 31.6 kg t\({}^{-1}\) for palm; 39.6 kg t\({}^{-1}\) for UCO; and, in case of diesel as the main product, about 29.8 kg t\({}^{-1}\), with direct impact on the electricity demand for the PTG part (Table 4). The annual demand of potassium hydroxide for the electrolyser is about 940 kg. In case of steam reforming with external supplied natural gas or biomethane, about 67,200 tons per year are required; naphtha and fuel gas for steam reforming are provided plant-internally. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Cost Factor** & **Value/Assumption** & **Reference** \\ \hline _Total investment_ & & \\ \hline HEFA process units/incl. steam reformer & 132/190 million EUR (annual load 8000 h) & [34; 35; 36; 37] \\ electrolyser & 58 million EUR (annual load 8000 h) & [38], quotations and \\  & 116 million EUR (annual load 4000 h) & interviews \\  & 176 million EUR (annual load 2600 h) & \\ hydrogen compression and storage & 24 million EUR (annual load 8000 h) & [13; 39] \\  & 38 million EUR (annual load 4000 h) & \\  & 70 million EUR (annual load 2600 h) & \\ \hline _Costs_ & & \\ \hline weighted average cost of capital & 8\% per year & [40] \\ maintenance HEFA part & 2.5\% of total investment per year & [34; 35] \\ maintenance PTG part & 9\% of total investment per year & [38], quotations and \\  & & interviews \\ administration, insurance, other & 2.5\% of total investment per year & [40] \\ personnel staff & 50,000 EUR per year and person with & [35; 40; 41] \\  & full-time equivalent; app. 50 full-time & \\  & equivalents required & \\ feedstock (jatropha, rapeseed, palm, and UCO) & 650/720/547/600 EUR t\({}^{-1}\) & [4; 42] \\ electricity (reference, dynamic, and & 100/80/80 EUR MWh\({}^{-1}\) & [12] \\ stand-alone) & & \\ auxiliaries steam reformer (natural gas, & 480/896 EUR t\({}^{-1}\) & [43] (biomethane) \\ biomethane) & \\..other auxiliaries (water, potassium hydroxide) & 2/820 EUR t\({}^{-1}\) & [40] \\ \hline _Revenues_ & & \\ \hline..naphtha, fuel gas & 380/400 EUR t\({}^{-1}\) & [44] \\..diesel, jet fuel & 410/425 EUR t\({}^{-1}\) & [44] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main assumptions for fuel production cost calculation (reference year 2015, assessment period 30 years). The reference scenario requires an input of 500 kt a\({}^{-1}\) jatropha oil. Assuming a yield of established jatropha plantations of 0.5 to 2.2 t ha\({}^{-1}\) a\({}^{-1}\)[45; 46; 47], a cultivation area of between 0.227 and 0.833 million ha is necessary, which would constitute a substantial portion of the currently cultivated area of roughly 1 million ha. In order to produce the required 999 GWh a\({}^{-1}\) of electricity in the stand-alone scenario using 100% wind and solar power (scenario 3), an appropriate combination would be a wind farm with 360 MW installed power and a solar power park with an area of 625 hectares. In comparison, this is 0.7% of the currently installed wind power in Germany and is substantially larger than the currently largest German solar park of 363 hectares. In the scenarios with dynamic power procurement and with a stand-alone power production (scenarios 2 and 3), large storage capacities are required (775 t and 1585 t of hydrogen). The most suitable solution is a cavern storage facility in underground salt layers, which can be found in north and central Germany. Since the feedstock will be transported over high seas (except rapeseed and UCO), and with offshore wind farms being more productive, a coastal region close to a large international airport is most suitable for a PTG-HEFA plant of the described dimensions.