Understanding Biogas Plant Costs – Biogas Plant Types
Biogas design, or in other words, the design of biogas production plants, varies greatly and any discussion about biogas plant costs must take the types of biogas plants into account as the cost of each varies substantially.
Here is a list of some of the most common types of biogas plant designs which have been conceived and built, and some of them in large numbers, numbering in the tens of thousands:-
1. Household sewer and soil biogas plant designs (developing nations): Low cost, low maintenance gravity fed concrete tanks below ground close to the dwelling with a lead off pipe from the top of the digester vessel which provides biogas to the kitchen where it fuels a hob.
2. On-farm biogas design which is simple and automated, but restricted to the developed nations and an order of magnitude more high-tech than the household plant just described. These may use purpose grown biofuel crops, or they may use animal slurry. They do have basic automation and usually run as a continuous process which reduces biogas plant costs.
3. Sewage treatment biogas plant designs. The truth is that these in the past were probably designed first and foremost as a method of taking sewage sludge and rendering it pathogen free an safe for use as a fertiliser and soil conditioner for farmland and nurseries. These are quite large plants but until recently they would supply no more than the power to run the sewage works and maybe some would use the biogas directly to run site owner’s vehicles.
4. A biogas design option emerging in the last 10 years has been that of the community biogas plant, providing both a convenient waste disposal route for organic wastes ad a source of income to farmers and residents alike within the community. Such plants will accept a wide range of feed materials from food waste from local residents to farm animal waste slurries, and where food processing takes place probably also food waste processing. These can be highly cost-effective investments where there are no biogas plant costs for the provision of feedstock materials.
5. All the foregoing options are water based so called “wet” digestion processes, but anaerobic digestion can be carried out on solids, with the exclusion of air. Mixing is more difficult and many examples of this technique therefore operate on a batch rather than a continuous production basis. Rather than a tank a batch type dry digester comprises a tunnel filled and emptied by a wheeled front end loader or similar. Simple dry digester systems may be low cost and help reduce biogas plant costs.
6. Many further options have been developed for larger digester plant designs and plants using municipal solid waste (MSW), and specialist technology provider companies have patented many of these. They first is where the biogas designer adds pre-processing variations on the feed materials to ensure the best percentage of organic matter is digested while in the reactor. The most common is to reduce the particle size for quicker digestion. Another pre-digestion stage method is to add hydrolysis which again improves the conversion rate of biomass into biogas, however adding such additional sophistication can easily increase initial biogas plant costs during construction.
Opinions About Biogas Plant Costs for a Variety of Biogas Plant Types
With the above biogas digester types in mind we have collected some articles which discuss biogas plant costs, as follows:
Although the construction cost is estimated at $5.4 million, the benefits of the biogas plant will be worth the cost. The 500-kilowatt plant will provide enough electricity to power over 250 households. In addition, it will reduce greenhouse gas emissions by 12,000 tonnes (the equivalent of removing 2,100 cars off the road).
Jackson offered the owners a Siemens integrated solution that included a VFD to control a large fan in the anaerobic digestion process. The VFD would yield an energy savings of 54%, a considerable savings given the large power requirements for the fan.
Additionally, the solution featured an in-feed automation system that would control a mixture of agriculture waste and animal manure to increase the methane output by 30%. This would open the opportunity for the developer to sell process gas to the grid.
Ultimately, Jackson showed the developers that considerable cost and time could be saved through the design and engineering phases by specifying the mechanical and electrical drive components as a single, horizontally integrated drive system.
A growing number of large food vendors in the US. “Universities and even sports teams are beginning to embrace biogas production as a means of reducing waste and greenhouse gas (GHG) emissions while creating renewable energy”, but costs are an issue, as the follwing article reveals:
But, they handle biogas plant costs effectively in East Africa by having a pay-as-you-go biogas business model:
The scarcity of wood fuel and high cost of kerosene may no longer be a concern for many rural households in Central Kenya, thanks to a patent pending pay-as-you-go biogas business model that delivers a user friendly and …
The technology provides an affordable alternative, compared to traditional biogas systems. Farmers pay a small fee to install the system; they then pay for the biogas as they use it. This saves the farmers upfront cost (an average of $1,700) for purchasing the biogas system.
Others say that Biogas plants can be extremely cost-effective when you control biogas plant costs:
Human society is facing changing climates and eroding landscapes, after centuries of exploiting non-renewable resources biogas is the emerging alternative, and for good reason. Moreover, biogas is extremely cost-effective …