Making Silk Purses from Sows Ears: Converting Waste Into Energy and Biofuels, Pt 1

by Tim Sklar
Special to The Digest

The Problem

Most regular readers of Biofuels Digest would certainly agree that over the last several years, there has been a plethora of reports on “promising” biofuels technologies. And most would agree that these reports tend to focus on “claims” used to explain to why the particular technology or process is “promising” or why it offers significant advantages over those that had been previously announced.

Many of these articles contain compelling arguments supporting the claims being made, others do not. But in all cases, the over-riding objective is to make the case that the technology and/or process being touted, promises to be better than others that have previously been announced. In other words the claim most often made is that biofuels technology being developed is a “better mousetrap”.

Unfortunately, the historical record indicates that very few of the “promising” biofuels technologies that have been announced, end up being used in projects that are commercially viable. Granted, that a number of these announced technologies have been attractive enough to obtain first-round financing, but only a few of these companies seem to able to attain commercial scale and fewer yet, have become economically viable.

The reasons for this lack of success are not limited to the most common causes of failure that plague start-ups enterprises that rely on new technology. It seems that many of the companies providing new biofuels technologies do not fully understanding the competitive environment that they must navigate. As a consequence they fail to develop strategies that will allow the company to successfully compete, as they try to have their technology widely used in a number of projects.

Finding a Solution

If biofuels are to become a meaningful part of the clean energy spectrum any time soon, it is important for those active in biofuels project development to better understand why successful commercial-scale development of biofuels projects has lagged, and to be willing to make changes in their project development strategies that are needed. In order to better assure widespread commercialization of promising technology it makes sense for providers of the technology and project developers agree on a plausible plan before they commence commercial-scale development. This is the focus of this article.

The Attraction of Making High Value Biofuels From Wastes

From the outset, the development of biofuels has been driven by the desire to replace fossil fuels that release carbon into the atmosphere when combusted, with carbon-neutral fuels, namely those that are made from substances that contain carbon that has been recaptured from the atmosphere.

The first generation of biofuels produced on a commercial scale was sugar and corn based ethanol. Second-generation bio-ethanol and other biofuels are now being produced using cellulosic crops such as wood chips, wood waste, sorghum, switch grass, miscanthus and agricultural wastes.

As the technology advanced, it is now possible to make biofuels from municipal solid wastes and other combustible wastes that have low cost, no cost or a negative cost. This waste can then be converted into electric power or it can be converted into a biofuel.

The attraction in making a “silk purse from a sow’s ear” in this way, is that in addition to Waste-to-Energy (“WTE”) plants providing a carbon neutral power source and Waste-to-High Value Product (“WTHVP”) plants providing carbon neutral fuels, the electricity and biofuel produced is marketable and enough value is added to provide an adequate return on WTE or WTHVP plant investment. whereas disposing of waste through operating landfills or waste incinerators produce no marketable power or fuel.

The Evolution of the Waste to Value Pathway

For some time, promising developments have been taking place in technologies and processes that can be used to convert waste into power and into high value products. Unfortunately, up until recently the technologies available and the processes being used by WTV plants, have proved to be too costly unless they are scaled up to produce large quantities of power or biofuels.

For example, one such successful developer of Waste-to-Ethanol plants that are producing 10,000 gallons of ethanol per year from MSW reported that they each cost ~$150 million to build. As a consequence, this developer has decided not to build additional Waste-to-Ethanol plants unless they can produce 20,000 gallons per year, as the added output is expected to cost only $25 million more.

However, these larger plants are expected to require 200,000 dtpy of wastes, and this waste requirement threshold could make it difficult for many less populated jurisdictions to support the larger plants, if the amount of MSW they generate is significantly less than this threshold. But there now be a way around this impediment. A promising technology provider, Sierra Energy, now claims to have developed a cost effective small-scale gasifier that will be able to convert wastes of all types into syngas.

The Need For Critical Analysis of Promising Claims Being Made

Rationale for Using a Case Study

In this article, a “Case Study” is used to illustrate how to apply “critical analysis”“ and perform “strategic thinking” to increase the prospects for successful roll-out of promising technologies and processes that have developed. The illustrations presented have been developed primarily through re-examining claims made by Sierra Energy in an article that appeared in Biofuels Digest on February 6, 2014. This article was titled ”Pathfinder: Sierra Energy heads for a world beyond garbage, traditional power, fuel”.

Sierra Energy and Its Scaleable WTV Process

This Biofuels Digest article suggests that that Sierra Energy’s chances for success appear to be outstanding, given the fact that Sierra has already developed “a commercially feasible technology for converting municipal waste into useful power and fuel, (and that they are coming) closer and closer (to attaining commercial viability)”.

The reason for using Sierra Energy as a case study is that although they already have a contract for a commercial scale use if their technology, some of the claims being made, as to how they plan to roll-out their technology need to be challenged, based on the realities of the markets in which they plan to compete. And if some of the expectations they have prove to be false, alternative strategies may then have to be developed.

It should be noted that the critical analyses that are presented as part of this case are in no way to be considered as a criticism of Sierra Energy, as they may in fact be aware of them, addressed them and made the strategic decisions they believe need to be taken. It should also be noted that the number of alternative strategies offered are included to illustrate some the obstacles that Sierra Energy may encounter can be avoided. They are in no way to be construed as being the recommended plausible plan for Sierra Energy to follow.

Company Overview

Sierra Energy is a young California based gasification technology provider. It has recently announced significant progress of delivering small-scale gasifiers of their own design to the US Department of Defense. The first such gasifier that is about to be being commissioned to operate on a commercial scale is to be used to convert wastes generated at a base in California into syngas that will then be used to generate electricity.

A Description of Sierra Energy’s FastOx Gasifier and “FastOx Pathfinder” Systems

Sierra Energy believes that there is a large potential market for small-scale waste-to-value plants among the one-third of our nation’s counties who are populous enough to provide the waste streams that such plants will need. Accordingly, Sierra Energy has focused on designing small-scale modular waste-to-high value systems to service this target market.

Sierra Energy has already developed a pilot FastOxum gasified in that has been described as being a small “blast furnace”” that is “about the size of a shower stall”. Sierra Energy describes the gasification process used in FastOxTM gasifiers as “a conversion of materials into a syngas, without combustion, (but) with (injection of) a controlled and limited amount of oxygen and steam (to) aid in breaking down remaining solids…”.

Sierra Energy’s has named its small-scale waste gasifier “FastOx, as it is a high-temperature, energy-efficient unit capable of gasifying a wide variety of mixed waste streams. It has since designed larger FastOx gasifiers to be used in commercial applications.

Sierra Energy has also designed the modules needed to convert syngas produced from small-scale FastOx gasifiers into based a mix of high value products such as methanol, olefin intermediates, ethanol and advanced liquid fuels and chemicals. Sierra Energy plans to offer this package of small scale waste-to-value modular systems under the trade name, “FastOx Pathfinder”.

Sierra’s Answers to FAQ’s on Their FastOx Gasification Technology

A number of claims Sierra Energy has made related to its FastOx technology were compiled from answers given by Sierra Energy to its list of Frequently Asked Questions (“FAQ’s”). Other claims were compiled from information contained on their web site, and information contained in recent articles that appeared in The New York Times and Biofuels Digest. These claims have been included under relevant topic headings along with a summary of explanations.

Sizing

Sierra Energy pilot FastOx gasifier can process a waste stream of 5 tpd. Sierra Energy is in the process of having in commercial operation, a FastOxTM gasifier with a waste processing capacity of 25 tpd. They claim that it will be easy to increase the capacity of the FastOx gasifier to 250 tpd and suggest that scaling of a gasifier using FastOx technology to process 1,000 tpd of waste is possible.

The CEO of Sierra Energy had recently said that this scalability is possible because the only design change needed to the gasifier is the height and diameter of the unit. In the FAQ’s they suggest that because consumption of wastes is related to gasifier volume, small increases in the gasifier diameter “will significantly increase waste capacity and thermal efficiency”. However, Sierra Energy made it clear that when sizing the gasifier, sizing modifications will also have to be made to the modules that are needed for waste handling, gas conditioning and cleanup, energy generation as well as those that are used in intermediate and end product generation, suggesting that these modifications may not be simple and could become costly.

Wastes Used

Sierra Energy stated that in processing mixed wastes streams “in some instances it may be practical and financially viable to include drying, sorting, or shredding, whereas in other instances elaborate pre-processing may not be necessary.
But Sierra Energy’s FastOx gasifier offers more “flexibility” as it does open up more opportunities to process un-separated MSW stream as well as tires, biomass, forestry wastes, C&D wastes, medical waste, shredder waste, and other hydrocarbons such as coals, petroleum coke, charcoal, oil shale. It can also handle materials such as sludge’s that have up to 65% moisture content by weight, without pre-drying.

Sierra Energy explained that its FastOx gasifier uses “an updraft configuration” that allows volatiles and moisture to be driven off,” before gasifying and melting reactions take place. Sierra points out that most other gasifiers can only accept wastes that have moisture contents of between 10% and 15% by weight. And, although Sierra’s 5-tpd pilot unit requires the feedstock to be sized to 2” to 3”, they expect that wastes that are shredded or ground to larger sizes could be used in larger sized FastOx gasifiers.

The FastOx Gasifier Process Description

Wastes that are conveyor fed into the top of a FastOx gasifier are “charged into the furnace in alternating layers” along with injected oxygen. A “fixed carbon to waste ratio” is maintained by maximize process output, and the residence time in the gasifier is controlled by varying the supply of oxygen injected.

All organic materials in the waste stream are volatized, which are marketable as by-products. The FastOx gasifier produces a syngas that in turn is “cleaned” to remove and recover sulphur, salt and nitrates. Glass, metals and other inorganic materials melt and form slag. The slag may contain some heavy metals that are non-leaching and are therefore saleable as a by-product. Unlike many other WTE processes, the FastOx gasifier produces no ash and nothing needs to be taken to a landfill.

The FastOx Gasifier Process Output

Primary Product

The clean syngas produced, can then be used in gas turbine generators to produce electricity at an average rate of 1,500 kWh per ton of waste.

Alternatively, the clean syngas produced can be reformed in a F-T process module into High Value Products (HVPs) such as methanol, olefin intermediates, and ethanol. The expected yield of these HVPs is 100 gallons per ton of dry waste.

By-Products
The sulphur, salt and nitrates recovered from syngas cleaning are marketable as by-products.

When cooled the slag is sold as a construction material often used in manufacture of cement clinker or as a road base ingredient.

Environmental Concerns
Sierra Energy claims that FastOx technology gasifiers are clean. They describe their FastOx gasification process as “a thermo-chemical conversion process that operates at the 3,000oF to 4,000oF range”. They explain that this process causes the feedstock to break down at the molecular level and converts the wastes used as feedstock into liquid metal, inert stone and energy dense syngas.

Sierra Energy then claims that the emissions from their gasifiers are “close to zero” as the system to clean the syngas operates as a closed loop. They also explain that there is not enough O2 used in this process for the feedstock to burn. They attribute this to the fact that “because no combustion takes place”, and at the high temperatures that are attained, emissions such as CO2, SOx and NOx. are not generated. They also claim that little if any ash is produced. Sierra Energy also points out that although process modules that are “downstream” from the gasifier, such a F-T unit, may emit a small amount of CO2 ,these are offset by reduced fossil fuel use and methane emissions associated with operating landfills, which they claim are 21 times worse.

Major Claims Made for Using FastOx Gasifier Technology

The following is a list of ten claims that are believed to be the most significant. These claims have either been directly expressed by Sierra Energy in materials used in this case study, or they have been implied.

1 FastOxTM gasifiers can be sized to match the waste streams now being collected by waste management authorities serving smaller communities. And the life of existing landfills could probably be extended if wastes are diverted to WTE and WTHVP plants using FastOxTM gasifiers. By implication, this offers the possibly of reducing or eliminating costs associated with landfill operations.

2 Based on what is being implied by Sierra as to capital costs of FastOxTM gasifiers, overall capital costs of WTE plants using FastOxTM gasifiers are expected to be lower than competing WTE systems.

3 FastOxTM gasifiers may be able to process mixed waste streams without pre-processing, and at the same or less cost as when using landfills.

4 WTE and WTHVP plants using FastOxTM gasifiers could probably be used to convert waste already in landfills thereby adding capacity and reducing the need and cost for additional landfill development.

5 Diverting wastes now being disposed of in landfills to WTE and WTHVP plants using FastOxTM gasifiers offers plant owners and by implication, waste management authorities, the potential for obtaining revenues for providing cheap power to the grid and/or from sale of high value products.

6 WTE and HVP plants using FastOxTM gasifiers produce biofuels cheaply, as feedstock costs are expected to be minimal, being derived for MSW and other combustible wastes.

7 The market prices for ethanol and other high value products a WTHVP plant can produce, appear to offer WTHVP plant owners unusually high margins.

8 Likewise power generated from syngas produced using FastOxTM gasifiers is expected to be competitive even if low feed-in-tariffs are obtained.

9 All by-products produced by WTE Plants and WT HVP plants using FastOxTM gasifiers are marketable.

10 WTE Plants and WT HVP plants using FastOxTM gasifiers are environmentally friendly, which will facilitate obtaining locations for them and little if any process waste is generated that has to be disposed of.

In tomorrow’s concluding installment, we look at the claims in detail in our case study.

Tim Sklar is a longtime Digest contributor on biocoal and torrefection topics. He can be reached here.