# Step-by-Step Solution: Optimising a Biomass System (Gryta Biogas Plant) Let's walk through the project report structure, using "Switch biogas use (CBG → electricity + heat)" as the optimisation idea. --- ## 1. **Pick ONE Optimisation Idea** **Selected Optimisation:** *Switch biogas use from Compressed Biogas (CBG) to Combined Heat and Power (CHP) for electricity and heat generation.* --- ## 2. **Describe the Baseline Plant (202)** ### **Feedstock:** - Input: Manure, food waste (quantities as per 202 data) - Biogas production: X m³/year - Methane content: 60% - Current use: Upgrading to CBG for vehicle fuel - Electricity and heat: Purchased from grid/boiler ### **Mass/Energy Flow Diagram:** ``` Feedstock → Anaerobic Digester → Biogas (CBG) → Upgrading/Compression → Vehicle Fuel \ → Digestate (fertilizer) ``` --- ## 3. **Describe Your Optimised Case** ### **Technical Changes:** - **Biogas is used on-site in a CHP unit:** - Generates electricity and heat. - Reduces grid electricity and external heating needs. - **Extra equipment:** CHP unit, heat exchangers. - **Product:** Electricity (sold to grid or used internally), heat (used in plant or district heating). ### **Flow Diagram:** ``` Feedstock → Anaerobic Digester → Biogas → CHP Unit → Electricity + Heat \ → Digestate (fertilizer) ``` --- ## 4. **Techno-Economic Analysis (TEA)** ### **Baseline Case:** - **CAPEX:** Existing investment (no new major equipment) - **OPEX:** Operation/maintenance, electricity/heat purchase, personnel - **Revenue:** Sale of CBG - **Profitability:** NPV, IRR, payback period ### **Optimised Case:** - **Additional CAPEX:** CHP unit, installation (~€X) - **Additional OPEX:** Maintenance of CHP, fuel for start-up - **Revenue:** Electricity and heat sales, grid savings - **Profitability:** Calculate NPV, IRR, payback period #### **Example Calculation (simplified):** - **Baseline NPV:** €100,000 over 10 years - **Optimised NPV:** €150,000 over 10 years (due to higher revenue from electricity/heat and reduced OPEX) - **Payback period:** 5 years (for new CAPEX) --- ## 5. **Sensitivity Analysis** ### **Key Parameters:** - Biogas yield (-10% to +30%) - Electricity price (±20%) - Heat demand (seasonal) - CAPEX (±30%) - Methane content (±5%) - Discount rate (5–10%) **Result:** - NPV is most sensitive to electricity price and biogas yield. - Project remains profitable unless electricity price drops by >25% or biogas yield drops by >20%. --- ## 6. **Results Discussion** - **Feasibility:** Technically straightforward, proven technology. - **Environmental Impact:** - Net energy balance improves: more self-generated energy, less fossil-based energy use. - CO₂ emissions avoided: both by replacing grid electricity and heat. - **Profitability:** Higher NPV and IRR in the optimised case. - **Key Drivers:** - High local electricity/heat prices. - Stable biogas yield. - CHP unit efficiency. --- ## 7. **Practical Recommendations** - **Implement CHP unit.** - **Monitor biogas quality and yield.** - **Establish contracts for electricity/heat sales.** - **Check for incentives/subsidies for renewable electricity/heat.** --- ## 8. **Conclusion** Switching to CHP increases both economic and environmental performance. The plant becomes less dependent on energy markets and reduces its carbon footprint. Results depend on local energy prices and biogas production stability. --- ## 9. **Project Plan (Appendix)** ### **Planned vs. Actual Table** | Task | Planned | Actual | Why (deviation) | |------------------|-----------|-----------|-------------------------------| | Data gathering | 2 weeks | 3 weeks | Data access delay | | TEA calculation | 1 week | 1 week | As planned | | Sensitivity anal.| 1 week | 2 weeks | Additional scenarios analyzed | --- ## **Summary Table (Profitability & Impact)** | Item | Baseline | Optimised (CHP) | |---------------|--------------|-----------------| | NPV (10 years)| €100,000 | €150,000 | | Payback | 6 years | 5 years | | CO₂ avoided | t/y | 200 t/y | | IRR | 7% | 10% | --- ## **Key Learnings** - CHP increases both profit and sustainability. - Most sensitive to electricity price and biogas yield. - Practical: Requires upfront investment, but payback in 5 years. --- **This structure covers all required steps for your project report. Adjust numbers and details based on your plant data!**