Green Coffee Grinds Feedstock

Gothenburg September 29, 2012

There is not an industry more focussed on being green than the Coffeehouse business right now. On the high street its all about green credibility. There is much debate about in store waste and renewable coffee cups, not to mention what to do with the spent beans or “grinds” as they are called in the trade. When the SOLIDEA Group EVE® team were asked to look at how renewable energy might best impact the Coffee business we came up with a few surprises.

The SOLIDEA EVE® [Energy Value Engineering] team review business premises and industry segments to introduce renewable energy solutions to save energy, save money and add value. SOLIDEA’s clients want to be the World’s first Zero Net Energy Coffee House Operators.

For the Coffee house the big bang for the buck is energy savings “Midstream” at the Coffee Roaster says SOLIDEA’s Steve Walker there is little we can do Upstream as according “the bean cycle” green coffee beans are imported. What gets wasted Downstream needs sending back up Midstream for process if we are to go beyond Zero Net Energy Downstream.

Midstream Operations

Midstream the coffee industry stores imported green coffee beans in insulated ambient warehouse facilities in sacks. The Midstream operation stores and processes the coffee in coffee roasters, it also redistributes disposable cups, paper goods, plastic utensils and various other disposable and food items. Midstream operation is the supply hub for branded supplies for Downstream Coffee Houses on the high street in retail galleries, in shopping centres and elsewhere.

The Midstream operation is headquartered in a combined sales and distribution centre of approximately 10,000m2 industrial unit of which less than 7% of the area accommodates the sales team management and operational offices. The premises are operated all year round and for 24 hours per day

Operational Energy Requirements

Working through EVE® we establish new consumption benchmarks and breaking the energy requirements down differentiating the core electrical and heating needs. After process heat recirculation and a little EVE® the warehouse and office electrical operation is serviceable at below 100kWh/m2/yr. So 10,000m2 now consumes less than 1,000,000kWh per year which is less than 114kWe.

Process Energy Requirements

The Coffee roasting process requires heat and the full operation consumes the equivalent of 15kWe of electrical energy and 260kWth of heat. Coffee roasting output is over 200 kilos per hour and the roasting process delivers an average of more than 4.8 tons of roasted coffee beans per day.

The solution

The PowerCan® 200 lives in the car park in its own 20ft container it consumes <4 tons per day of feedstock and produces 200kWe of electrical energy and 260kWth of heat. The combination of electricity and heat is ideal for the Midstream operation as one unit provides more energy than all of the operational and process energy combined.

The gasification process works very well with coffee grinds says SOLIDEA’s Steve Walker and having a consistent feedstock produces excellent results. PowerCan® 200 Gasification produces synthesis gas in a vacuum and the process has no gaseous emissions in the extinction process.

Coffee roasting is not entirely emission free explains Dr Janusz Przeorek SOLIDEA’s President however we are able to recirculate those emissions through the  PowerCan® 200 gas scrubbers to clean up unlikely NOx and VOC’s. Once the synthesis gas is exhausted through the converted Perkins Diesel CHP unit any final emissions are environmentally value added; on balance  PowerCan® 200 actually cleans up the emissions from the Coffee roasting process.

Coffee Grinds Feedstock

Although almost 20% of the coffee ground in the field will be lost still more than 80% is recovered [and because of the higher moisture content as grinds] the grinds are returned Midstream in the dry paper container they were supplied in as beans. Four tons per day of coffee grinds feedstock are returned Midstream and with an average moisture content of just under 25% in most weather conditions. During the extinction process less than one ton of slightly acidic water will be ejected from the system each day and the ashes recovered including the dry paper containers will be reduced to less than 3% of the original weight.

4 tons of coffee grinds produces sufficient energy to operate the entire Midstream operation and with over 71kWe of electrical energy over Zero Net Energy which is income producing. Less than 3% of the original feedstock is ejected as ash, this is very pure it represents the minerals in the coffee beans and what is left of its wrapper and as such it is an excellent fertilizer. The grey water evacuated from  PowerCan® 200 is easily recycled it reduces the local Midstream footprint to zero save imported drinking water.

More Feedstock Downstream

Downstream in the coffee shop MSW is created in the many stores, the stores operate sorting of metal, glass and other wastes by the consumer, at least one sink is provided in every store to ensure waste remains reasonably dry. Glass and metal containers are becoming scarce in retail environments and metal fasteners are no longer used in cartons or banding. Everything that is not sorted can be feedstock into a second  PowerCan® 200 system located Midstream or elsewhere where the heat generated as well as the electricity can be put to best use.

Each store produces its own waste, packaging, cartons and of course coffee grounds. All the waste is compacted to minimum 5:1 on site it is wrapped to keep it food safe and clean, it is returned to the Midstream distribution warehouse by the same method as it first arrived. Processing MSW from Coffee Houses in a PowerCan® 200 elsewhere can offset many Coffee House operations creating a Zero Net Energy network off site.

Costs

The  PowerCan® 200 can be installed and commissioned with an automated feed loader and simple shredder for less than 400,000 Euro. Whilst the black rate of electricity in the EU, and West Africa is still under 0.21c kWh many EU countries offer incentives through PPA’s. With a combined output of 200kWe and 280kWth the PowerCan® 200 demonstrate a rapid payback for electricity, heat and landfill tipping savings and in most countries a period of less than 36 months is the norm.

Lessons Learned Knowledge Gained

An holistic approach to energy and waste can add great value to many business segments. Innovative new technology introduces new revenue streams and reduces environmental impact. There seems little point embedding more CO2 in recycling coffee house, restaurant and convenience store plastic and paper when it can be reused and recycled locally as energy and fertilizer.

 

 

 

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