Biomethane production and anaerobic digestion gas to grid is a development which is of great interest and show just what improved technology can do. (The grid we refer to is the natural gas grid (i.e. the national natural gas pipeline system.) It's a ...
Biomethane production and anaerobic digestion gas to grid is a development which is of great interest and show just what improved technology can do. (The grid we refer to is the natural gas grid (i.e. the national natural gas pipeline system.)
It's a mature technology now, with about 100 active plants in Germany alone.
For those farms and business seeking to get started in the UK, CHP and gas to grid is probably close to a minimum 18 month project from inception to completion and new gas-to-grid plant RHI applications are only good until early 2020.
3 Advantages of Biomethane Gas to Grid AD Plants
The difference between a “gas to grid” biogas plant and a normal anaerobic digestion plant is that rather than use the biogas produced to make electricity, we take it a step further.
We clean up, the raw biogas from the digester in a process that we call “upgrading”.
The specification of upgraded biogas is for a product gas which is suitable to be injected into the natural gas grid.
1. Environmental Benefits
The integration of enriched biomethane into the national gas grid has several key environmental benefits.
On a full lifecycle basis Bio-CNG provides a 72% reduction in CO2 emissions as well as being exceptionally clean, with ultra-low particulate emissions and ultra-low NOx emissions.
2. Financial Benefit for the Transport Company/ User – CNG Fuel Costs Less
In fact CNG users commonly report about a 30% reduction in fuel costs.
3. The Biomethane Producer Makes a Profit
They get two sources of income:
First, there are UK Renewable Heat Incentive (RHI) payments.
Second, they are paid by the grid Company for the biomethane gas produced.
Those are just a few of the benefits of gas to grid AD plants.
This is our version of the basic information on buried Chinese home biogas plant designs, as provided very expertly on the Eco Tipping website.
Why Eco Tipping? We assume this was features on the Eco Tipping website because if everyone was to adopt home biogas as an energy source the fate of planet earth would be tipped toward being sustainable. The following is the part of the original article which we have used to make the above video: The basic biogas system involves an anaerobic digester (usually underground) with an inlet pipe, an outlet pipe, and a tube for the biogas. The feedstock is a combination of plant and animal wastes, plus water. Crop residues as well as tree litter and weeds are suitable, as are manure from pigs, cows, chickens, and humans. It ferments in the digester tank to produce biogas, which contains 60-70% methane (CH4). The energy content is 22 gigajoules (GJ=1 billion joules) per m3, about the same as 0.5 liter of kerosene. The basic chemical reaction is: 2 C + 2 H2O » CH4 + CO2. The process occurs with the aid of bacteria, and is temperature sensitive (range is 8-60° C). Under ideal conditions, a 10 m3 digester can supply enough gas for cooking and lighting for a family of five. Biogas can also be used for fueling farm machinery and for power generation. Both the liquid sludge from the outlet pipe and the sediment at the bottom of the tank are very good fertilizers. via EcoTipping
The following are our views on Home Biogas Plants:
Home biogas is widely produced in developing regions of the world. It has been used in the greatest numbers in rural China where exceeding 30 million of thse plants ahve been built.
Unfortunately, the design relies entirely on the skill of local builders to make these plants gas-tight. Doign that is not easy, and leaks may occur after backfilling the tanks when repairs would be very difficult.
There is also no way to test this design of home biogas plant before it is filled with digestate. Many of thse plants lie unused due to such difficulties.
Thta's why designs using purpose built tanks above ground are much better, as long as they are ewll insulated from cold climates, and can be kept warm for efficient biogas production.
Israeli startup Home Biogas has developed a relatively affordable home-sized biogas unit that allows people to convert their own waste into fuel.
In Israel, where temperatures get quite hot in summer but where winter lows have included snowfall, the start-up company Eco-gas Home Biogas has launched commercial biodigesters for the home and small institution.
Many people say that to make your own home energy the alternative method of usign solar panels is better. We do not agree. Solar panels are expensive and the high initial costs takes perhaps 10 year to repay in energy cost savings. The initial cost of a home biogas plant is lower than a solar array. In addition to the lower upfront cost, home biogas does not require a grid-tie or any type of energy storage, as energy is stored in gas form and used on-demand when needed.
Visit the Anaerobic Digestion Community web site, for the growing buzz around biogas digesters.
There is no doubt that until recently there was a powerful concern that in nations such as the US, parts of South America, and the EU (especially in Germany), renewable biofuel production would reduce food available to eat.
The result would be rising food prices for us all.
For a while, governments were so keen to encourage renewable fuels, to reduce climate-changing emissions that they seemed to forget that people must come first when food is needed.
Some were saying things like:
"Crops Used for AD raise the price of food", and that "People could go hungry as a result".
But, this was not primarily aimed at biogas production.
The technology used for the original diesel-fuel-replacement biofuels, which were widely subsidized was, and still is, the chemical conversion of vegetable oils into bio-diesel.
This is a diesel fuel replacement which is added to the fuel bought at filling stations, and lots of it is still produced.
The production of biogas using the anaerobic digestion process is a completely different process.
AD processes once received subsidies for crops such as maize and beet as well as agricultural biomass waste and, in parts of the EU.
As a result of the spin-off from the main biodiesel "Food-for-Fuel" debate, such subsidies have all-but ceased. They are now historical and are no longer granted.
Unfortunately, anaerobic digestion and biogas has become erroneously tarred with the same "Food versus Fuel" brush. This is wrong in our opinion.
When crops are grown for AD, this is usually done as part of a traditional agricultural rotation, helping farmers to improve food crop yields and soil quality, or these are grown on marginal land not suitable for food crops.
The amount of land used for growing crops for energy generation in England is less than 1%. This figure is even lower across the devolved nations of the UK. More land is used for golf courses.
The ADBA analysis also shows that the growing of these crops has had no discernible impact on food supply for humans or livestock.
The following are just some of the reasons to support the agricultural production of biogas fuel, when based upon using crop and other waste.
AD has a vital role to play in recycling wastes, reducing greenhouse gas emissions, and producing the renewable energy, clean transport fuel, and soil-restoring biofertiliser that the UK desperately needs.
Source: AD and Bioresources News Issue 41, Autumn 2018
Biofertilizer is a product of fermentation of organic material in water which contains living microorganisms which, when applied to seeds, plant surfaces, or soil, enriches plants with foods to create a healthy biology, and supplies minerals for biological processes to digest.
Through the use of biofertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil.
Since the microorganisms play several roles, a preferred scientific term for the beneficial bacteria in biofertilizers is "plant-growth promoting rhizobacteria".
Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances.
Biofertilizer can be made in a variety of ways, but biogas plants are the main producers, and the anaerobic digestion and biogas industry calls it 'digestate".
All biogas plants (also known as "Anaerobic Digestion Plants" or "Methane Digesters") produce digestate (renewable biofertilizer) as a by-product when making biogas.
Some Anaerobic Digestion Plants produce a digestate that is not suitable for use as a biofertiliser. In most of these cases, the digestate is usually suitable after pasteurization, in accordance with the Animal By-products Regulations.
Many digestate biofertilizer users have reported that not only is crop growth increased by correctly applied digestate, they also witness a biocide effect where a number of plant diseases are reduced.
Home Biogas: New home biogas products are gaining great reviews suggesting that you don’t have to be poor or living off-grid to find it useful to make your own worthwhile biogas cooking fuel.
In the following article, Samuel Alexander a Research fellow, at the Melbourne Sustainable Society Institute, University of Melbourne describes his experience of one such system:
Home biogas: turning food waste into renewable energy
Samuel Alexander, University of Melbourne Last night I cooked my family a delicious pasta dinner using biogas energy. This morning we all had eggs cooked on biogas. I’m not sure what’s for dinner tonight, but I know what will provide the energy for cooking: biogas. And not just any biogas – it’s home biogas, produced in our suburban backyard, as part of my ongoing “action research” into sustainable energy practices. Read more: Biogas: smells like a solution to our energy and waste problems In an age of worrying climate change and looming fossil energy decline, the benefits of biogas are obvious. It is a renewable energy source with zero net greenhouse emissions. And yet its potential has largely gone untapped, at least in the developed world. Based on my research and experience, I contend that home-produced biogas is an extremely promising technology whose time has come. In fact, I believe it could provoke a domestic green energy revolution, if only we let it.
What is biogas?
Biogas is produced when organic matter biodegrades under anaerobic conditions (that is, in the absence of oxygen). This process produces a mixture of gases – primarily methane, some carbon dioxide and tiny portions of other gases such as hydrogen sulfide. When the biogas is filtered to remove the hydrogen sulfide, the resulting mixture can be burned as an energy source for cooking, lighting, or heating water or space. When compressed it can be used as fuel for vehicles. On a commercial scale biogas can be used to generate electricity or even refined and fed into the gas grid. The types of organic matter used to produce biogas include food waste, animal manure and agricultural byproducts. Some commercial systems use sewage to produce and capture biogas.
The primary benefit of biogas is that it is renewable. Whereas the production of oil and other fossil fuels will eventually peak and decline, we will always be able to make biogas as long as the sun is shining and plants can grow. Biogas has zero net greenhouse emissions because the CO₂ that is released into the atmosphere when it burns is no more than what was drawn down from the atmosphere when the organic matter was first grown. As already noted, when organic matter biodegrades under anaerobic conditions, methane is produced. It has been estimated that each year between 590 million and 800 million tones of methane is released into the atmosphere. This is bad news for the climate – pound for pound, methane is a far more potent greenhouse gas than CO₂. But in a biogas system this methane is captured and ultimately converted to CO₂ when the fuel is burned. Because that CO₂ was going to end up in the atmosphere anyway through natural degradation, biogas has zero net emissions. There are other benefits too. The organic matter used in biogas digesters is typically a waste product. By using biogas we can reduce the amount of food waste and other organic materials being sent to landfill. Furthermore, biogas systems produce a nutrient-rich sludge that can be watered down into a fertiliser for gardens or farms. All of this can help to develop increased energy independence, build resilience and save money.
My biogas experiment
In the spirit of scientific research, I installed one of the few home biogas systems currently available, at a cost of just over A$1,000 delivered, and have been impressed by its ease and functionality. (Please note that I have no affiliation, commercial or otherwise, with the manufacturer.) In practical terms, I put in about 2kg of food waste each day and so far I have had enough gas to cook with, sometimes twice a day. If I ever needed more gas, I could put in more organic matter. I will continue to monitor the system as part of my research and will publish updates in due course. If interested, watch this space. My personal motivation to explore biogas (related to my research) arises primarily from a desire to decarbonise my household’s energy use. So far, so good. We have disconnected from the conventional gas grid and now have more money to spend on projects such as expanding our solar array. Given the alarming levels of food waste in Australia, I also like the idea of turning this waste into green energy. My neighbours kindly donate their organic matter to supplement our own inputs, increasing community engagement. When necessary I cycle to my local vegetable market and enthusiastically jump into their large food waste bin to take what I need, with permission. They think I’m mad. But, then, I think using fossil fuels is mad.
Hurdles and hopes
Home biogas is widely produced in developing regions of the world. The World Bank and the United Nations actively encourage its use as a cheap, clean energy source. China has 27 million biogas plants. But developed regions, including Australia, have been slow to exploit this vast potential. Given that Australia is one of the most carbon-intensive countries on Earth, this is unfortunate. The failure to embrace home biogas is partly due to a lack of clear regulations about its use. Where is the Home Biogas Act? Almost every Australian backyard has an independent gas bottle to power the ubiquitous barbecue, so clearly storing gas in the backyard is not a problem. My biogas system came with robust safety certificates, warranties and insurance, and these systems do not feature high-pressure gas pipes. Read more: Capturing the true wealth of Australia’s waste Home biogas production is unusual. But I believe that state governments should draw up legislation to accommodate it, and that local councils should offer advice and assistance to householders who are interested in taking it up. Hoping for progress in this regard, I recently made a submission to the Victorian government as part of its Waste to Energy consultations. My own carefully managed experiment demonstrates how home biogas can be used safely and successfully. Nevertheless, biogas is a combustible fuel and needs to be filtered for poisonous hydrogen sulfide. Like any fuel, it should be respected and used responsibly. But biogas need not be feared. Fossil gas is far more dangerous anyway. Samuel Alexander, Research fellow, Melbourne Sustainable Society Institute, University of Melbourne This article is republished from The Conversation under a Creative Commons license. Read the original article.
Please give us your comments on your experiences with home biogas systems, in the comments section blow this article..
Visit the Anaerobic Digestion Community web site, for the growing buzz around biogas digesters.