Waste food prevention

About

Overview

A report released by WWF-UK and Tesco in 2021 found that global food waste on farms amounted to 1.2 billion tons per year, approximately 15.3% of the food produced globally. This measures up to USD$370 million of food wasted on farms. 4.4 million square kilometers of land is used to grow food, which is then wasted on farms per year, larger than the entire Indian subcontinent. When these statistics are viewed alongside with the recent findings reported by the Food Waste Index, which reported that 17% of food is wasted from retail to consumer stages of the supply chain, it suggests that significantly more than one third of the total food produce is wasted, possibly up to 40%. Food that was unharvested due to reasons such as the inability of farmers to fund harvesting laborers or market-based specifications not being included in these estimations, result in an underestimate of the true amounts of food waste on farms.

Estimates predict that 3.6 million tons, or 7.2% of all food harvested, is wasted before it leaves UK farms every year. If this wasted food had been sold at market value, it would have fetched £1.2 billion. The main reasons for the losses are unpredictable ripening patterns and environmental factors, like weather, pests, and diseases. Poor technology and infrastructure are another direct contributor of food waste due to reasons such as inadequate storage for harvested produce, poor harvesting technology, lack of temperature management of produce at harvest, and inappropriate fishing gear and lack of chilling of landed catch. Without adequate storage of perishable produce, farmers are forced to sell regardless of market prices, or risk they waste. However, through technological, financial, and educational investment, food waste from these factors can be effectively reduced.

Avoiding waste food by utilizing low carbon ripening chambers and cooling rooms

Fruit ripening is the set of processes that occur from the later stages of growth and development until the fruit is ready to be consumed. Ripening chambers work by stimulating or controlling the natural ripening process by controlling the temperature, humidity, and supply of fresh air in the chamber as well as the levels of ethylene, CO2, and nitrogen that get released from the produce during the ripening process. This process is applicable to climacteric fruits, fruits that can be harvested at an early stage after achieving minimum maturity. After harvesting, the fruits are stored in ripening chambers where they ripen to maturity for consumption. The most common examples of climacteric fruit are: apples, pears, tomato, custard apple, avocado, banana, mango, papaya, kiwi. To ensure that all fruits ripen evenly and there is no harmful accumulation of CO2 in the ripening chamber, a uniform air circulation and fresh air supply must also be ensured. By utilizing a ripening chamber for example, farmers can harvest bananas at an earlier stage (young bananas that are not ready to be eaten) and then control the ripening process during transportation in order to speed up the ripening process or, conversely, bananas can be picked closer to maturity and then have the ripening process slowed down in a ripening chamber.

Bananas, for example, typically reach maturity for eating within 4 to 8 days in ripening chambers. For this, they require temperatures between 18 °C and 25 °C and a high humidity of >90 % RH. In contrast, banana cold rooms are designed to keep bananas at temperatures between 13-15°C (55-59°F) to slow down the ripening process and extend shelf life. Processing warehouses maintain temperatures of 12-16°C (53-60°F), but adjustments and operations should be made by staff members according to changes in ripeness.

One of the main fruits consumed in the UK are bananas, we eat over 5 billion bananas a year (on average, that’s 100 bananas per person), and Tesco is one of the largest importers in the UK. In terms of ripening, Chiquita and Fyffes together have around 90% of the ripening capacity in the country.

Not only for the banana market, but ripening chambers and cold storages are also utilized in many fruits and vegetables production worldwide, becoming an important sector receive innovations to avoid food waste and to be decarbonized.

As the ripening chamber system needs cooling and heating systems to complete the fruit production and reduce waste on the farm level, Sunamp becomes a source of thermal storage for those systems.

Sunamp technology

In modernized systems, the fruits are placed in a gas-tight, closed chamber. Continuous measurement of the gas concentrations of oxygen (O2), carbon dioxide (CO2) and ethylene (C2H4) in the chamber is used to determine the plant physiological condition of the fruit via the respiratory activity (change in values). This "communication" allows dynamic calculation and adjustment of optimal fruit ripening conditions (air temperature, O2, CO2 and C2H4 concentration). The fruit itself determines the required state of the atmosphere and by automatically setting the optimal parameters it is able to ripen ideally "stress-free".

It’s important to constantly monitor the temperature of fruit during the ripening process because temperature plays a critical role in both controlling the process and determining the speed at which fruit ripens. Ripening rooms must have adequate refrigeration capacity to remove the heat that climacteric fruits generate as they ripen. It is important not to control the ripening process and to maintain the correct temperatures for the various phases of ripening, avoiding over ripening and waste.

The room must have properly sized fans that facilitate adequate airflow. If the ripening chamber uses a forced-air cooling system, the composition of the internal room must allow for air circulation even in the interior of boxes, so the pulp temperature is maintained.

Sunamp offer a low carbon solution that can reduce operational cost of cooling and heating systems by running equipment during off-peak time to store energy to be used during on peak time, increasing resilience by not fully depending on the grid operation, or increasing the usage of existing renewable energy that can be stored during periods of excess production.

Sunamp thermal battery differs from the other types of storage by being based on a phase change material. This material stores thermal energy instead of electrical energy, which means that it stores the temperature needed for cooling and heating the chambers, when needed. Phase change materials are temperature specific, requiring two batteries, one for heating and one for cooling, allowing the implementation of a central system with multiple chambers and parallel usage of the battery in different phases of the ripening process of each chamber. The phase change material also comes from sustainable supply chain, is non-flammable, recyclable and is designed and tested to operate at least 25 years with a minimum maintenance required. A whole solution that can be on the field for a long time.

The key innovation of the solution is the Sunamp thermal batteries that use phase change materials (PCM) to store energy for domestic hot water, heating, steam, and cooling applications. Giving more technical information about the technology, melting, and freezing a PCM can stores 3-4 times as much energy in latent heat as the sensible heat of water in a typical thermal storage (i.e., thermal buffering) applications.

The generic construction of the battery includes the PCM, and the heat exchanger housed in a sealed enclosure (The Cell). Although the Cell is sealed against ingress of moisture and air, the pressure inside the Cell is around the ambient atmospheric pressure and is fitted with an expansion relief valve. The Cell is insulated using vacuum insulation panels. The outer case and hydraulic connections are designed so that multiple batteries can either be stacked or positioned side by side and then connected either in series or parallel. The polypropylene container containing the heater exchanger is filled with the appropriate phase change material that is prepared in a mixing tank. Sensors and wiring are connected to the controller that sits within the overall casing.

Compared with conventional PCM and water based thermal stores, the Sunamp thermal battery technology has the following advantages:

a)   High flow rates and power ratings (heat exchanger immersed in PCM)

b)   Additive to PCM and internal design of heat battery eliminates sub-cooling

c)    PCM Raw materials: Made from by-products of widely deployed industrial processes, non-toxic, and based on inorganic salts, which are non-flammable and with low stable commodity pricing.

d)   PCM costs < $0.5/kg; complete heat batteries cost under $65/kWh.

e)   Strong focus on corrosion and permeability (water/ oxygen ingress), resulting in confidence in long lifetime. Over 95% capacity remains after 40,000 accelerated cycles.

f)     Very low water content, lower water treatment costs, and additional expansion vessels not required. (90 kWh battery has only 70 Liters of water inside).

g)   Unlike a hot water thermal store, the aspect ratios of Sunamp Heat Battery can be changed without compromising, storage capacity, utilization efficiency and stratification.

h)   Over 80% of thermal energy is stored in the PCM and the PCM enclosure is at near atmospheric pressure and therefore safety devices associated with pressurized hot water stores will not be required.

i)     Two independent hydronic circuits, which can be combined where separate and/or simultaneous charging and discharging is not required.

Compared with conventional commercial electrical storage, Sunamp have the following advantages:

a)      Lifespan tested for over 40.000 cycles (50 years when cycled 2 times/day).

b)     Sunamp batteries can be charged from multiple thermal sources including boilers, heat pumps, waste heat, electricity (grid or embedded), steam, glycol/water, thermal solar panels and recovered heat.

c)      At least 2.5 times cheaper than an electric battery.

d)     Non-flammable substances in the PCM composition.

e)     Non-toxic substances in the PCM composition.

f)       Derived from sustainable supply chains.