A project which began in lockdown in 2020 has spawned a small business with big ideas of becoming a model sustainable food system in Dublin.
'Revolution Farm & Kitchen', set up by urban farmers Paddy Arnold and James Egan, operates out of a retrofitted 45ft container at University College Dublin (UCD).
The pair collect spent coffee grounds from the cafés around campus and use them to grow fresh oyster mushrooms.
Once harvested, the mushrooms are used to make a range of sauces which are on sale in cafés and other retailers around Dublin and Kildare.
Co-founder and chef Paddy Arnold said: "We collect about 150 kilos of coffee grounds a week. But there is a lot more. We don't even collect from every café here in UCD. Coffee grounds work for mushroom production because you need a neutral base so the mushrooms can take over quite quickly. But they're also a form of nitrogen.
"We are producing about 20 to 30 kilos of oyster mushrooms a week. So, it can produce a lot of sauces but it can also produce a lot of food for the small scale of it".
Co-founder James Egan added: "Coffee grounds are a great substrate for mushroom production because as the steam passes through the coffee grounds, making your cup of coffee, it sterilises the coffee grounds. A lot of mushroom farms will sterilise or pasteurise the entire substrate. The problem with that pasteurisation or sterilisation is that it's labour-intensive and energy-intensive".
The pair designed their urban farm with energy-efficiency and sustainability in mind.
Jame Egan explained: "We have two rain water collection surfaces on the roof of the container and they both feed into this 750-litre tank so we actually have more than enough water for all the farm's needs.
"A lot of mushroom farms are using layflat tubing which is a single-use plastic. So, we had a bit of an issue with that and tried to use different reusable plastics. We decided on wheelie bins. What we do is we get an ESB pipe and we drill a load of holes into it. We stick that in the centre.
"And then by drilling holes in the outside of the bin at four-inch centres, we're able to get airflow to penetrate from the outside-in and from the inside-out. After incubation, and then into fruiting, the mushrooms start to come out the holes after a period of about four weeks".
The project recently partnered with the UCD Innovation Academy as part of their sustainable initiative on campus with many students from the academy working at the farm.
The academy's Education Innovation Lead Maurice Knightly said: "It's important for all of us to be involved in whatever way we can in sustainability. It would be great if we could all concentrate a bit more on small circular businesses within our own environment, whether it's towns and villages or indeed campuses. UCD, if all its population were here, it would be one of the largest towns in Ireland so we think it's a good model of a community where we can have that circular economy actually happening".
Revolution Farm & Kitchen's next aim is to bring things full circle by getting their vegan sauces on the menu in UCD's canteens.
Paddy Arnold explained: "Oyster mushrooms have a great texture and taste. They are quite meat-like. Sometimes they are scary looking but they have a really great taste. We decided to put them in a familiar meal so we have a vegan bolognese sauce and also a chilli con carne".
Paddy and James hope their circular project shows it's both possible and accessible to successfully farm sustainably in a urban setting.
"This idea that we just throw away everything is crazy and it's really energy-intensive when often the solutions are already there".
In our 'Climate Heroes' series of reports, we shine a light on the people who are stepping up to protect the environment and tackle climate change. While these people come from all walks of life, they share a common purpose to improve the world around us.