If I had the ear of policy-makers, one of the many suggestions I would whisper..would be to look at the potential for AD to solve at least some of our problems, especially with regard to waste and energy.
AD stands for Anaerobic Digestion. It is a very simple biological process, where bacteria that exist in oxygen-free conditions, break down organic matter and convert it into a mix of CO2 and CH4.. methane. This energy-rich gas can be directly substituted for propane and used in stoves, vehicles, boilers..any appliance that normally runs on conventional gas, with no modification.
This low-tech form of energy has been utilised for millenia in eastern cultures. The Chinese have been building basic Anaerobic Digesters, usually a brick-lined pit with a brick-dome top, to process their organic waste, including their animal’s manure [and their own] into a readily usable cooking gas. Even more valuable to them was the residual organic matter, which is called the “digestate”, and is beyond compare as a fertiliser. Any dangerous pathogens are destroyed in the digestion process. So toxic substances such as raw manure can be reduced to inert, rich fertiliser and a potent source of energy.
India has also been tapping this source of energy and soil-conditioner since the time of Siddarta. In their more recent past, around the time of the so-called “green revolution”, they implemented a nation-wide program of installing community-sized digesters, run on a co-operative basis, much like the Chinese model. So why hasn’t this simple technology been implemented in every corner of the planet?
Well in recent decades, it has been realised as a very clever way to turn a problem into a solution in forward-thinking countries.. guess.. you got it.. Scandanavia, Germany, The Netherlands, and more recently the UK. It is surprising that our so-called developed society were so late in adopting this simple solution to waste and energy headaches in one neat step. What is even more surprising is the fact that Ireland has almost no evidence of following their lead.
When you consider that we produce more animal manures per capita than most countries, with our diary and meat industry.. not to mention the steady stream coming from the mouths of certain politicians.. then we have another huge quantity of organic waste from the rest of the food industry. You can add to this the mountains of food waste from the shelves of our supermarkets and kitchens. Don’t forget all the raw energy being flushed down the toilet every day. Our neighbours are beginning to capture these waste streams and convert them into energy and soil, using age-old techniques, while we drown in our own ignorance. As we try to persuade the short-sighted leaders not to allow exploitative multinationals to use dangerous, perhaps deadly methods of gas extraction in one of the most environmentally-pristine regions of our country, it seems ironic that we have a potentially enormous resource of clean gas on tap, with no limit in supply. [see “hydraulic-fracturing” or “fracking” for more detail].
The laws relating to Anaerobic Digestion of food waste in this country are the chief obstacle blocking the progress of this financially-lucrative and common-sense approach. Almost every other member of the EU has recognised the need for modification in their legislation. But this doesn’t explain the non-existent use of AD to deal with the problem of animal wastes. In this wet and grassy land, we have a long tradition of spreading raw slurry on the fields in the drier parts of the year. Recent Nitrates Directives from Brussels have limited this window drastically, resulting in the need for farmers to store this slurry for almost twice as long, something like from October to April. This new measure, brought in to rescue the water table from over-nitrification [resulting in fish/wildlife death and algae-bloom], meant that farmers needed to double their storage capacity. They couldn’t afford the expense of building slurry-pits, so they were subsidised.. a subsidy that could have been used to build biogas digesters, which could be shared between a handful of farms and run co-operatively. There are less than a handful of these digesters in the country, one built by then president of the Bio-Energy Association of Ireland. It was constructed to demonstrate the potential of community-based digesters, strategically situated in areas close to farms with livestock.
Another was built at the Camphill Community in Wexford. It is an unusual horizontal design which consists of a big auger screw, moving the feedstock slowly along a cylindrical vessel, when the material reaches the end of the line, it comes out as digestate, having released the equally valuable methane along the way.
The SEAI [Sustainable Energy Association of Ireland] did introduce an offer of grant-funding for industrial-scale models. There was plans by Greenstar to avail of this 50% grant with a new plant in Cork, but as far as I know it never saw fruition, probably due to planning issues. This scheme was well out of the reach of most private interests and farmers, which is exactly where it should have been targeting.
There was another plant due to be built in Westmeath, but objections from a local NIMBY [not-in-my-back-yard] dropped the axe on that project. This attitude seems to be prevalent. People assume that a facility like this is going to be unpleasant in aesthetic and odour, with tractor-trailers full of slurry coming and going constantly, but that does not have to be the case. The digester itself is quite innocent-looking and can be mistaken for a normal holding-tank, the gas itself is the only thing that has an odour, and it is captured and contained at all times. The manures and other feedstock could be collected weekly from farms and processing plants by nondescript oil-tanker type vehicles with minimal disturbance to local residents. One such facility in Shropshire, UK, built and managed by Greenfinch Engineering, takes in feedstock from farms, supermarkets and households in the area, charging a gate-fee to businesses disposing of “waste”, but colloecting from households without charge. The methane is used to drive a combined heat and power plant [CHP], which is a highly-efficient generator, recovering heat discharge and diverting it to a disrict-heating system and local swimming pool. The electricity is fed into the grid, providing a second income stream, and the digestate is sold as a fertiliser, providing a third income stream.
Greenfinch have already got several of these facilities on the drawing board, as local authorities in the UK realise their potential. These same bodies have already begun using AD to process raw sewage into safe organic fertiliser in many sewage-treatment plants around the UK.
In conclusion, I would like to tag on a quote from a FIE [Friends of the Irish Environment] newsletter, which landed in my in-box this morning and co-incidentally criticises the non-existence of an anaerobic digestion policy in successive government administrations.
“The group [FIE] points out that ‘in an EU LIFE supported project, Silver Hill Foods have installed a converter to deal with the slurry of 3 million ducks – 70,000 tons per annum. T’he unit extracts dry pellets for fertiliser while capturing the methane gas to power the operation and no slurry spreading is necessary. This is a model for Irish farmers.”
I haven’t researched this case yet, but I’m guessing it’s in the UK, worth googling.
The entire article can be read here:
How’s that for sychronicity? The universe is trying to tell us something..