CENTRALIZED SYSTEM FOR GASIFICATION

FOR ENERGY AND ASH RECOVERY

 

Garth W. Boyd, Ph.D

Director, Environmental Technology

Smithfield Foods, Inc.

277 Faison McGowan Road

Kenansville, NC  28349

 

Smithfield Foods has joined forces with two Australian companies (QED Corporation and Renewable Energy Corporation) to build and operate several on-farm wastewater treatment systems and a single, centralized biomass energy pilot plant. The business venture is called BEST Solutions; BEST is an acronym for Biomass Energy Sustainable Technology.  This project is estimated to cost ~ $4 million dollars and is partially funded by money ($800,000) from the Smithfield Foods/ Attorney General agreement and will be officially evaluated by NCSU scientists as many other projects will.

The BEST solution involves primary treatment of the pig manure stream using proven dual solid separation technologies at the farm level.  The core technology involves mechanical solids separation via a reliable and efficient screw press separator manufactured by FAN Separator of Oelde, Germany.

Treatment of the residual water from the FAN Separator is accomplished by using a QED Corporation patented Tangential Flow Separation System (QTFS). This second step enhances solids removal and nutrient recovery.  Separation of the solids should result in a minimum 50% decrease in BOD.  Treated water will be discharged to the lagoon for “polishing” and storage.  The separated solids at 30% dry matter (DM) will be collected from several farms and transported in dump trailers to a centralized biomass energy plant.  At the plant, the pig manure solids, along with the required volume of turkey and poultry litter, will be used as biomass feedstock for an innovative gasification/combustion unit manufactured by the Renewable Energy Corporation.  Poultry litter as received averages 4000-5000 Btu/lb as does pig manure solids at 70% DM.  The unit converts biomass into highly combustible gases and then very efficiently combusts the gases at extremely high temperatures (2150^o F) resulting in heat energy, pathogen free nutrient rich ash and clean and odorless atmospheric emissions similar to clean burning natural gas.

Currently, there are several litter-fired power plants being planned or built in the U.S.  For example, Fibrominn, a biomass energy plant provider from the U.K. and Minnesota energy provider Xcel Energy signed an energy purchase agreement in September 2000 to build a 50 megawatt biomass plant.  A similar plant has been built in Virginia with Renewable Energy  supplying the gasification and combustion unit.  Other similar plants are being planned in the U.S. using Renewable Energy equipment.

Part of the heat energy from the unit will be used to pre-dry the pig manure solids from 30% DM to 70% DM.  The excess heat will be efficiently transformed into steam energy through a simple one-step process using a boiler.  The steam energy can be converted to electricity using a steam turbine generator.  Electricity is an easily traded and transferred renewable energy commodity.  However, changes in state and power company energy policy removing disincentives to “green” or renewable energy production will be required to make the business plan for electricity generation economically viable.

Duke and CP&L have both agreed to implement a voluntary green tariff program in 2002.  Consumers in North Carolina served by these utilities will have the option of buying blocks (100-150 kwh) of green energy for a rate of about $2-$4.  Participation rates in other states with a voluntary program have averaged 0.1-3%.  This voluntary program will generate money, which will then be used to help fund green energy generators whether it comes from solar, wind, hydro or agricultural waste like manure. However, it is doubtful that enough money will be generated to attract significant investment in green energy generation.

Some other states have recently embraced biomass fueled electricity generation.  For example, statelaw inMinnesota requires Xcel Energy to purchase 150 megawatts per year of “green” power.  Thus the rate paid for biomass power is an attractive7.0 cents/kwh.  Presently in NorthCarolina, power companies pay only an “avoidance” rate for biomass power or any other supplemental power and that is 2.2-2.6 cents/kwh.  This low rate does not attract capital investment because of negative returns. The fact is that green power costs significantly more to generate than coal, nuclear or natural gas derived power.

Gasifier/Combustor ash is an odor and pathogen free concentrated  nutrient source with 20-25% phosphorus and 12-16% potassium.  The ash is approximately 15% of the weight of the manure and today has significant market value between $70-$100/ton as a commodity component of fertilizer or feed. Ash can  easily be transported in bulk to existing fertilizer plant infrastructure in North Carolina and other southern states that currently require phosphorus and potassium as key ingredients. 

 

Specifically the BEST Solution pilot project will involve:

 

·        Dual solids separation at three (3) finishing farms

·        Construction of a 2 ton/hr gasifier/combustor, using pig manure and poultry litter as a fuel source generating electricity for plant use and sale

·        Manufacture of granulated fertilizer grades

·        Implementation of all related activities, as required, for success

 

This latter will include all necessary due diligence required for contracting the required tonnage of chicken litter/turkey litter/other organics, negotiating energy and ash sales, and the transportation logistics for solids and ash for the manufacturing of fertilizers or feed.

In summary, the BEST project may prove to be a viable integrated solution because:

 

·        It is a realistic, environmentally sound solution based on known, proven patented technologies that have been put together in a unique process.

·        The energy and nutrient content of pig and poultry manure is economically and practically harvested, combusted and recycled as opposed to land applied or treated as waste and destroyed. This plan takes advantage of the density of animal operations, impending regulations on poultry producers and the high volume of nutrient rich, combustible biomass feedstock available by integrating manure from the poultry industry.  Additionally, other organic streams, such as Coastal Bermuda hay, the primary crop of lagoon irrigation and litter applications fields, can serve as another excellent source of biomass feedstock should a higher market value not be found.  This option further reduces nutrient loading of the land.

·        The phosphorus loading problem is solved that both the pig and poultry industries may soon face due to impending regulations that may reduce manure application rates because plant phosphorus uptake is lower than nitrogen uptake.

·        It achieves affordable, simple, practical and low labor primary treatment of pig manure. Farms will remain land based and utilize existing manure management infrastructure to manage residual nutrients in the supernatant.  However, with the transport of solids off farm and greatly reduced organic loading of the lagoon, this system will achieve compliance with the AG’s agreement performance standards for environmentally superior technology.

·        It achieves environmentally beneficial recycling of the key fertilizer elements in a closed loop from the farms back to the grain growers.

 

If this pilot plant proves to be environmentally superior and economically feasible, there exists the potential for widespread adoption by larger farms.