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Food waste is becoming an increasingly serious issue. Various solutions are being explored, such as restaurants turning food scraps into innovative dishes and delivery services bringing ‘imperfect’ produce, once disregarded by supermarkets, right to your doorstep. However, we still generate personal food waste, and often the compost heap is the perfect solution for it.
As compost breaks down, it generates significant heat, reaching temperatures between 66–82 degrees Celsius (150–180 °F). From culinary experiments to renewable energy efforts, people have found creative ways to make the most of the heat generated by their compost heaps.
Compost is well-known for enhancing the soil, but it can also improve many other aspects of our lives. So relax, maybe brew a cup of compost tea (just kidding), and take in the creativity of those pioneering the compost movement.
10. Craft Your Own Dairy Products
In 1980, Jim McClarin had an epiphany that led to the birth of compost cookery. Writing for Mother Earth News, McClarin recounted how he placed his yogurt container in his compost pile to keep it warm. The next morning, he was surprised to find that the compost’s heat had exceeded expectations, and instead of yogurt, a cheese curd had formed.
Cheese and compost share a unique connection in their aromatic characteristics. Unfortunately, McClarin did not elaborate further on the process of compost-based cheese making. Instead, he continued experimenting with temperature variations at different depths within his compost pile, eventually finding the ideal temperature for compost yogurt, which became a regular staple in his diet.
9. Boiling Eggs with Compost Heat
According to the ‘half-remembered thought’ of compost cookery pioneer Jim McClarin, cooking eggs in compost could be an ancient Chinese tradition. However, this method remains unverified enough to raise safety concerns, so we advise against attempting it. But if you still wish to try it, be sure to wrap your food securely and eat with caution, as this is cooking amidst a mix of decaying plant matter, food scraps, and possibly manure.
Unlike the precision of kitchen cooking, preparing an egg in compost is a slow and unpredictable process. Those who have attempted it report cooking times ranging from 1 to 24 hours. McClarin recommends placing your eggs in the compost before bed, so they’ll be ready by morning. The outcome, however, is dependent on the fluctuating temperature of the heap, which varies based on its contents and timing. Compost cooking may be energy-efficient, but it’s a long game.
While McClarin wrapped his egg in a plastic bag, others have placed the egg directly in the compost. Based on personal experience, an egg wrapped in one layer of foil and sealed in a sandwich bag isn’t quite enough. My egg came out looking lovely, with a silky texture and a rich golden yolk, but the smell was unbearable. In the end, all I had to show for it was a nice photo.
8. Cook a Cake
A group of homeschooled children in Massachusetts managed to bake a lava cake in a compost heap. It took about a day. As we explore the growing possibilities of compost-based cooking, this success gives us hope for the future.
To be fair to the kids involved, it's important to note that they had access to a 6-meter (20 ft) compost pile. The cake was buried about 0.6 meters (2 ft) deep within it. A 6-meter (20 ft) mound of compost is naturally going to generate and retain far more heat than the typical compost pile most of us have access to.
7. Fine Dining in Compost
For years, the team at the Highfields Center for Composting had cautiously tested heating cans of soup in their compost piles. But it took professional chef Suzanne Podhaizer, formerly of Salt restaurant, to elevate the concept.
Podhaizer successfully compost-cooked a dish featuring branzino and scallops, served atop a bed of well-cooked, albeit slightly squashed, rice. The meal was described as ‘perfectly cooked, earthy, and satisfying.’
Podhaizer utilized the center’s compost pile—or “worm parlor”—where the restaurant regularly sent its food scraps. The compost was also used to nourish the plants in their kitchen garden. The brilliance of Podhaizer’s dish lies in its cooking process: it was prepared using energy partially derived from Salt’s own leftovers, and then the leftovers from her scallop dish were returned to the compost system.
Once again, McClarin’s influence is evident. As his compost cooking methods evolved, he was able to prepare complete roast beef meals, along with duck served in an orange and apricot sauce, accompanied by a red wine and wild plum reduction. However, despite his successes, he never managed to cook soft pinto beans successfully.
6. A Gourmet Compost Dining Experience
New York has been delving into a variety of food waste initiatives, spearheading what some are calling a composting ‘revolution.’ The city's sanitation department has rolled out several composting sites near subway stations and is exploring the possibility of requiring all restaurants and businesses to compost their food waste.
In 2013, according to Bon Appetit, a prominent New York restaurant took the concept a step further by planning to cook its dishes using the heat generated by composting. It’s unclear whether the restaurant was successful in this endeavor. Due to legal concerns, likely related to selling food cooked in compost, the restaurant’s identity was not revealed.
While it seems the upscale compost-powered restaurant never became a reality, Bon Appetit noted that the temperature at the core of a compost heap can surpass that of a sous vide bath. Although the methods differ—comparing a countertop water bath to a compost heap—this concept holds fascinating potential for sustainable fine dining.
5. Showers Powered by Compost
Though it may not be ideal to have your shower near your compost pile, many have successfully designed shower systems that utilize the energy from compost.
Some methods are as simple as coiling a length of hosepipe inside the compost heap and attaching a showerhead and stand at the other end. However, the effort required to maintain the compost heap often outweighed the benefits of the warm shower it provided. Solar panels were found to be far more efficient while still being eco-friendly.
Permaculture expert Darren Doherty had much greater success. By burying a 2-meter (7 ft) by 2-meter (7 ft) heating system within his compost and combining it with a solar heating setup, he was able to produce up to 150 liters (40 gal) of hot water at once. On average, this was sufficient for over 20 minutes of showering or two relaxing hot baths.
4. Methane Harvesting
You may not find direct contact with your compost appealing, but fortunately, heat isn’t the only by-product of the composting process. When managed properly, compost also emits methane gas. Achieving this requires a balance between acid-producing bacteria and the methane-producing bacteria that feed on it.
Methane is frequently captured from landfills, where the gas produced is sufficient to power around 8,500 local homes in some cases. Additionally, farms such as Green Mountain Dairy in Vermont have found success in generating electricity for the grid from the methane produced by manure.
On a smaller scale, the Urban Farming Guys have constructed a system they refer to as a "methane biodigester." This setup consists of a compost cylinder with a smaller one placed upside down on top. This design captures the methane released and pressurizes it. A pipe connects the methane chamber to a stove or generator, enabling a steady supply of methane for 7–8 weeks.
This method seems to offer the best of both worlds: cooking using the by-products of your compost while avoiding the inaccuracies and lingering smells that come with burying food. Naturally, you could also combine both methods for even greater efficiency.
3. A Sustainable Energy Source
Inspired by Jean Pain’s groundbreaking work, several groups have begun to investigate the broader potential of compost’s by-products as a renewable energy source.
The University of Edinburgh's School of Engineering created a compost heat exchange system capable of producing water at a temperature of 60 degrees Celsius (140°F). When compared with other solar and ground source heating systems, the compost-based system proved to be the most reliable in terms of consistent supply.
Additionally, there is the Compost Power Network, a non-profit organization focused on compost heat recovery. They have partnered with several universities to further research in this area. Their ongoing projects aim to refine Jean Pain's methods and develop safe, compost-based energy systems that provide renewable energy while also benefiting the land.
2. Heat Your Pool
If we were to rethink Maslow’s hierarchy of needs in the context of compost, we’re now nearing the top tier with this idea. Building on Jean Pain’s domestic successes, we enter the realm of life's luxuries. After enjoying a compost-heated shower and a meal of scallops from your steaming compost heap, what’s next?
In his recent book, The Compost-Powered Water Heater, Gaelan Brown provides a practical guide for building DIY compost heating systems. Among his ideas is the possibility of using compost heat to warm your swimming pool for free. Imagine relaxing by a perfectly warm pool on a hot summer day, without the stench of compost. Brown notes that this system can also help eliminate unpleasant odors.
While having a compost-powered hot tub may not be a feasible option, a heated pool certainly remains a luxurious alternative.
1. Power Your Car
In the 1970s, French innovator Jean Pain found several ways to power much of his home using the energy from his compost pile. He used the organic waste generated from maintaining his woodlands to fertilize gardens that flourished abundantly. Pain also created a compost-powered water heating system, which was capable of heating a 93-square-meter (1,000 ft) house.
Additionally, Pain developed his own air heating system. He buried heat ducts within one of his compost piles, with pipes running directly into his home for ventilation.
Pain’s creativity extended further. He also devised a methane-harvesting tank and wrapped it with water-cooling pipes to maintain its temperature. This system allowed him to heat water for his home while efficiently collecting methane from his compost pile.
The system produced 1.4 cubic meters (50 ft) of gas daily. The methane generated powered the household appliances and fueled the Pain family's Citroen 2CV truck, enabling it to travel up to 100 kilometers (62 mi).
