Landfill Biomass Energy Solutions

Waste to energy power considerations for landfill

Most landfill sites do not utilise the heat generated by waste to energy power equipment, it’s wasted. Landfill cogen systems are more often than not run for straight power generation, the heat could be used but often it is not.

As most landfill sites use only the power generated, the electrical efficiency of the generator is critical. A more efficient generator makes more electricity for the biogas available, resulting in a higher income for the investor.

Landfill sites normally minimise investment in buildings, sheds  – so generators are installed outside. So they must be:

• Weather proof
• Secure
• Quiet

High percentage uptime availability

The generator needs to run very reliably, with a minimum of downtime due to faults or breakdowns, waiting for parts, or servicing and maintenance, etc. A generator with a long service interval ensures that there is a maximum of running hours between service visits.

The power generation system also needs to be able to cope with biogas which changes as the landfill cell ages. The system must also deal with biogas contaminants, such as water, siloxanes, and H2S (hydrogen sulfide) without adding to maintenance costs or being unpredictable. 

Most rubbish dump sites receive an income by selling the power they generate, so they need absolute confidence in maintenance costs. Generator maintenance costs need to be low AND predictable.

Starting the generator without grid power

Often waste to power generators must start up without the aid of grid power. This is referred to as a Black Start. 

Starting a generator engine on weak gas is not easy, however, there is more to the problem than just starting. Power is needed to start the blowers that suck the biogas from the landfill and boost the pressure for the generator to run on BEFORE the generator even starts up.

A common solution to this issue is to install a diesel generator that starts, then powers up the site so that the biogas generator can start. Another approach is to set the biogas generator up with two fuels (dual fuel generator), biogas and LPG. A tank of LPG is then used to start the generator and once the generator is running, and the site powered up, the generator is switched over to biogas (hoping the engine doesn’t stall). 

Both of these options add operating costs of an added fuel and the complexity of extra fuels to the site. 

Landfill gas to electricity generation

To set up the biomass-based power generator to feed electricity back to the grid the generator must be approved for connection and parallel operation with the power distribution system and then up to date with thorough compliance requirements.

• Generator Certification to Australian Electrical Standards and power stability studies.
• Generator Certification to Australian and state gas standards and individual inspections.

Landfill gas to electricity generation sell’s a commodity, power, back into the grid at relatively low costs. For this reason the investment cost needs to be low to achieve a bankable return on investment. The margins in the electricity market are pretty skinny, so there is a downward cost on everything.

Inoplex biomass electricity generation plant

If you read and consider all these requirements, this sounds like an application for large generators, and it is. Engines with 70 + L volumes, not our relatively tiny 4L. This leaves smaller sites that do not have sufficient gas to run a MW scale generator at a serious disadvantage. 

This is where the Inoplex inverter generator can make a great contribution.

• Inverter generators can black start by using their own battery power to start ancillary equipment such as blowers, etc. 
• They can run on a much broader variety of gas qualities, enabling them to produce power from gas that is often just wasted by flaring.
• The low cost of generator maintenance enables the system to produce power at rates lower than the ‘big boys’.
• The Inoplex generators are locally manufactured, so if heat is not required, the generator design can be adjusted.
• The variable speed engines provide a large turndown capacity, so generators are most easily able to follow the site’s, often variable, gas supply. 
• Forward asset planning is much simpler using the Inoplex biogas generator.
• A generator can be installed when a cell is producing a small amount of gas, and the generator produces more and more power as the cell produces more gas. As the site matures and the gas flow slows, the generator can slow down and follow the gas availability until the cell is no longer viably producing gas. The generator can then be deployed at another, newer site.