Homebiogas is an Israeli company that has designed small domestic methanizers that enable individuals to turn their fermentable waste into biogas and digestate.
What is methanization?
Anaerobic digestion is the biological process whereby organic matter is broken down by micro-organisms in the absence of oxygen. This degradation produces a mixture of gases, mainly methane (CH4) and carbon dioxide (CO2), known as biogas. The materials used for methanization generally come from agricultural waste, food waste, sewage sludge or green waste.
The process takes place in several stages: During these stages, micro-organisms gradually break down complex organic matter into simpler compounds, eventually producing methane. Methanization comprises four key stages: hydrolysis, acidogenesis, acetogenesis and methanogenesis:
- Hydrolysis breaks down complex organic molecules into simpler elements.
- Acidogenesis converts these elements into volatile fatty acids and alcohols.
- Acetogenesis transforms these products into acetate, CO2 and H2.
- Finally, methanogenesis produces methane from acetate, CO2 and H2.
The Homebiogas domestic methanizer
Homebiogas offers a kind of mini domestic methanizer, just over a metre high and wide, for installation in the garden. An opening lets you put in fermentable household waste such as vegetable peelings mixed with water to aid hydrolysis. The gas produced is filtered by an activated carbon filter. The device can store pressures of up to 10 bar.
The company offers 3 digester formats: the smallest costs €1,200 and can produce 700L of biogas / day, which would be enough for 2h of combustion (?) and the largest costs €2,400 and can produce 2,500 L / day. It also produces a nutrient-rich liquid, ideal for fertilizing plants (digestate): from 6 to 20L for the smallest and up to 120L for the largest. The biogas is piped to a gas stove, supplied with the device. The system would be totally enclosed and odorless. They are also proposing a system combined with a toilet, sending the result directly into the digester.
The anaerobic anaerobic digestion process differs from conventional aerobic composting (with oxygen, in the open air) in a number of ways:
- the result is not the same (compost on one side, biogas and digestate on the other),
- anaerobic digestion does not attract insects, unlike compost
- meat and fish waste cannot be composted
Questions that arise
As is often the case with highly original products, a few questions arise. For example, what happens if you don’t use the biogas produced on a regular basis (e.g., if you go on vacation)? Is there a risk of explosion? We also note that you need to be able to connect the methanizer to the kitchen or the area where you’re going to use the gas, which isn’t easy.
Is the Homebiogas methanizer environmentally friendly?
On the face of it, the system does seem virtuous: it’s reasonable to assume that there are no leaks (to be confirmed), so the energy produced is CO2-neutral: the CO2 produced by combustion corresponds in principle to the CO2 absorbed by the organic matter used as a base. Ditto for the CO2 produced directly by methanization and mixed with CH4.
Then you have to ask yourself: what use is being replaced? For example, many people don’t use gas, but electricity, with electric ovens or induction hobs. For these people, this device offers little or no ecological advantage. We could ask the same question for countries that don’t have decarbonized energy, but the problem lies with electricity production.
Finally, we need to compare the effort and investment required with other alternatives. Wouldn’t it make more sense not to cook with gas? You could also compare it to installing a heat pump, for example. The basic module (which seems pretty big to me already) costs €1,200, or just under 10% of the price of an aerothermal heat pump. Which is more viable? So the final answer is, as in so many areas, “it depends”.
Note that, in rural African areas where there is no electricity, this product is clearly interesting. In fact, the company has set up a subsidiary in Kenya to serve farmers.
History, development and financing of Homebiogaz
HomeBioGaz is an Israeli company created by Yair Teller, Erez Lancer and Oshik Efrati in 2012. They developed the first prototypes between 2014 and 2016. The company was listed on the Tel Aviv Stock Exchange in February 2021 at a valuation of €79 million (TASE: HMGS).
According to the business report for 2021, published in June 2022:
- They would have sold over 15,000 systems in more than 100 countries in total in 2021 (a priori this should correspond to €20-35M in cumulative sales?).
- Sales would be $2,482,000.
- The company has 93 employees.
- They have set up a subsidiary in Kenya for farmers.
In France, it seems to be marketed by ATENEA Environnement and its website www.biogazmaison.com/.