4.3. Mechanical extraction
Mechanical extraction can be used to produce oil from the seeds of solid waste. Rapeseed oil can be processed further by
reacting it with alcohol, a process known as esterification, to obtain biodiesel. The type of energy produced from biogas
depends directly on the buyer's needs. These needs can be broken down into three categories: electricity generation, heat
and steam generation, and transportation of fuel.
4.3.1. Electricity generation
The most common form of energy production today is through well-designed facilities and are as follows:
Combined heat and power (CHP) generation, also known as cogeneration, is an efficient, clean, and reliable approach to
generating both power and thermal energy from solid waste. When a CHP system designed to meet the thermal and
electrical base loads is installed, it can greatly increase a facility's operational efficiency while decreasing its energy costs,
and CHP can also reduce greenhouse gasses, which contribute to global climate change [12–15, 17].
The conversion of biogas to electricity via fuel cell technology offers significant increases in efficiency and, hence, is
highly sought after technology. Several biogas installations utilize molten carbonate fuel cell technology. However, solid
oxide fuel cell technology is thought to be the most promising technology due to its higher power density and its
applicability to a wide range of scales [18,19].
Biogas can be used as a motive power for the production of electricity using engines. A biogas-fueled engine generator
will typically convert between 18% and 25% of biogas to electricity. Biogas engine depends on engine design and load
factor.