Regulated Emissions of Biogas Engines—On Site Experimental Measurements and Damage Assessment on Human Health

Abstract

Despite biogas renewability, it is mandatory to experimentally assess its combustion products in order to measure their pollutants content. To this purpose, the Authors selected six in-operation biogas plants fed by different substrates and perform an on-site experimental campaign for measuring both biogas and engines exhausts composition. Firstly, biogas measured compositions are compared among them and with data available in literature. Then, biogas engines’ exhaust compositions are compared among them, with data available in literature and with measurements obtained from an engine characterised by the same design power but fuelled with natural gas. Finally, the Health Impact Assessment analysis is used to estimate the damage on human health caused by both biogas and natural gas engines emissions. Results show that biogas causes a damage on human health three times higher than the natural gas one. But, this approach does not consider biogas renewability. So, to include this important aspect, also an analysis which considers Global Warming categories is carried out. Results highlight that natural gas is twice harmful than biogas.

A Human Health Toxicity Assessment of Biogas Engines Regulated and Unregulated Emissions

“…In Kristensen et al's investigation, biogas is mainly derived from agricultural wastes (manure), but they also included emissions analysis where biogas is produced at waste deposit sites and waste-water treatment plants. The general composition of biogas is: 65% methane and 35% CO 2 ; a very different content compared with those measured in this experimental campaign [35].…”

“…A detailed description of the Italian legislation is given in [33][34][35] while a comparison between German and Italian regulatory frameworks is presented in Appendix A.1.…”

“…Italy, with 1352 MW, ranks in second place after Germany in the European scoreboard and it is considered one of the most advanced countries in the world for biogas technology (see, e.g., [33][34][35]).…”

“…By looking deeper at the world biogas growth rates and established support policies (see, e.g., [34,35]), it is clear that the European Union (EU) considers biogas as a key renewable energy source (RES) that can help to reduce energy related CO 2 emissions and to reinforce energy security.…”

Life Cycle Assessment of a Commercially Available Organic Rankine Cycle Unit Coupled with a Biomass Boiler

“…Concerning electricity generation using biomass, several technologies are available according to the biomass type. As an example, liquid biofuels or biogas can be burnt in an Internal Combustion Engine (ICE) or in a Gas Turbine (GT) to generate electricity only or electricity and heat in Combined Heat and Power (CHP) units (see, e.g., [19][20][21][22][23][24][25]). In these cases, plant arrangements are really simple because the ICE and/or the GT, being their shaft mechanically coupled with the electric generator, directly produce electricity while heat is extracted from ICE coolant and lube oil or from the GT exhaust gases.…”