LIFE CYCLE ASSESSMENT OF WHEAT STRAW AS A FUEL INPUT FOR DISTRICT HEAT PRODUCTION

Parajuli, Ranjan

4. Term

Urban, Energy and Environmental Planning, Master

2013

2013-05-28

95

Dette studie undersøger miljøpåvirkningerne ved at producere fjernvarme i et halmfyret kraftvarmeværk (CHP) og sammenligner dem med alternativerne naturgas og importerede træpiller. Analysen er en livscyklusvurdering (LCA) med fokus på disse påvirkningskategorier: forbrug af ikke‑fornybar energi (NRE), globalt opvarmningspotentiale over 100 år (GWP), forsuringspotentiale (AP) samt eutrofieringspotentiale (EP) for både vandmiljø (akvatisk) og land (terrestrisk). Resultaterne angives per 1 MJ leveret varme. Under antagelsen om, at den samtidige elproduktion fra det halmfyrede kraftvarmeværk fortrænger el fra et kulfyret kraftværk (marginal el‑substitution), findes: GWP på -86.54 g CO2‑ækv./MJ varme og NRE‑forbrug på -1.23 MJ‑primær/MJ varme. Med samme antagelse er AP 0.008 m2 UES/MJ varme, akvatisk EP 0.125 g NO3‑ækv./MJ varme og terrestrisk EP 0.006 m2 UES/MJ varme. De negative GWP‑ og NRE‑værdier betyder netto­reduktioner, fordi den producerede el fortrænger kulbaseret el. Sammenlignet med naturgas og importerede træpiller klarer halm sig bedre på klimaaftryk (GWP) og forbrug af ikke‑fornybar energi, men dårligere på forsuring og eutrofiering.

This study examines the environmental impacts of producing district heating in a straw‑fired combined heat and power (CHP) plant and compares them with natural gas and imported wood pellets. The analysis uses a life cycle assessment (LCA) focusing on these impact categories: non‑renewable energy (NRE) use; 100‑year global warming potential (GWP); acidification potential (AP); and eutrophication potential (EP) for both water (aquatic) and land (terrestrial) environments. Results are reported per 1 MJ of heat delivered. Assuming the electricity co‑generated by the straw CHP displaces electricity from a coal‑fired power plant (marginal electricity substitution), the study finds: GWP of -86.54 g CO2‑eq/MJ heat and NRE use of -1.23 MJ‑primary/MJ heat. Under the same assumption, AP is 0.008 m2 UES/MJ heat, aquatic EP is 0.125 g NO3‑eq/MJ heat, and terrestrial EP is 0.006 m2 UES/MJ heat. The negative GWP and NRE values indicate net reductions because the electricity produced displaces coal‑based power. Compared with natural gas and imported wood pellets, straw performs better on climate impact and non‑renewable energy use, but worse on acidification and eutrophication.

[This abstract was generated with the help of AI]

District heat ; Straw ; Wood pellets ; Natural gas ; LCA ; Marginal electricity ; substitution of fossil fuel

Download
View record in AAU Student Projects