A Quantum Leap for Waste and BECCS with B-VM Power Plant

Abstract

This chapter details the development of a so-called B-VM power plant from a patented bioenergy process B-V. The objective is the valorization of municipal waste and the implementation of an upstream waste system for the B-V to process the delivered waste. Intermediate products of the B-VM process are storable pyrolysis coke, pyrolysis oil and synthesis gas which generate electrical and thermal energy. A portion of this energy is used to extract carbon dioxide from the process emissions for realizing BECCS (Bioenergy with Carbon Capture and Storage). Compared to the combustion of waste or biomass, the following ecological and economic benefits and innovations are achieved: Optimal valorization of residual waste and biomass; decoupling of thermal and electrical energy production; doubling of the net electric efficiency of the power plant; potential to achieve negative emissions through BECCS; capable for base and peak load and also very strong grid balancing.

1. Introduction

1.1 The global problems of carbon dioxide (= CO₂) and waste

In addition to the widely recognized worldwide problem of CO₂ and its associated impact on the climate, waste pollution is also a significant global challenge. The issue of CO₂ is increasingly highlighted by the media and politicians as a global problem and is becoming more apparent due to the resulting restrictions, while waste primarily affects the local environment. However, the volume of waste continues to rise and appears increasingly threatening, as the data in the World Bank’s “What a Waste” study [1] shows.

There are no quick solutions for reducing CO₂ emissions and significant investments and restrictions are required. In contrast, waste issues might be promisingly addressed through stringent management and the combustion or similar treatment of waste. The volume of global waste is expected to increase from 2016 by 1.7 times to approximately 3.4 billion tons annually in 2050. This escalation adversely affects populations and environments and leads to a widespread scarcity of land. An alternative and far superior method of waste disposal is undoubtedly thermal waste treatment. However, the waste incineration technologies available in the market are profoundly imperfect. These technologies are ineffective, inefficient, pollute the environment and almost invariably provoke societal controversies.

To combat the worsening waste problems and reduce the concentration of CO₂ in the atmosphere, a new process has been developed for power plants based on waste. Through this, the high proportion of biomass in the waste can also be used via BECCS. This innovative power plant concept has significantly better ecological and economic parameters than any waste incineration. The innovative approach and main difference to conventional waste incineration plants is that the underlying process uses pyrolysis instead of incineration, which determines the entire subsequent process, including a very special but world-renowned diesel engine.

As a result, improvements and new applications for waste management and BECCS can be realized, which may certainly be considered a quantum leap. It is noteworthy that almost all essential facts and circumstances have been long known and utilized, yet they had not been rethought or linked to a new solution until now.

1.2 Given project circumstances

The newly developed power plant for biomass and waste utilizes the so-called KSW Process® for biomass [2, 3, 4], which was developed and patented in Germany approximately 10 years ago (hereafter referred to as the B-V bioenergy process). Power plants employing this process harness the pyrolysis of the input for thermal valorization and produce storable energy sources in the form of pyrolysis coke and pyrolysis oil as intermediate products. These intermediates are utilized as synthesis gas and pyrolysis oil in slow-running, two-stroke, dual-fuel large diesel engines, with generator capacities ranging from 3 to 80 MW. This concept leads to optimal ecological and economic performance metrics and offers numerous advantages. On this basis, a power plant with a 14 MW engine was designed, utilizing biomass and meeting the requirements of Germany’s Renewable Energy Sources Act (EEG). The author of this chapter was involved in the economic assessment, the business plan and several technical variants.

These circumstances led to the idea of using municipal solid waste (in the broadest sense and almost always with very high biomass content) instead of pure biomass and implementing this as a separate project through a consortium in Poland. The primary decision was to employ the pyrolysis process to decompose plastics in the waste along with organic biomass. This includes plastics that would otherwise not be recycled and whose complete separation from waste and its fractions is either not feasible or only possible with great effort. This means, among other things, that the extraction of plastic fractions from the delivered waste can be realized at any time, provided there is an economic rationale or legal mandate.

Municipal solid waste requires appropriate processing as an optimal basis for the B-V pyrolysis, along with various adaptations within the existing B-V process. Figure 1 illustrates the simplified process of a B-V with an upstream waste treatment, here referred to as B-VM.

Figure 1.

New developed power plant for biomass and residual waste. From author’s BMC Sp.z o.o. working group B-VM.

Based on this, the five innovations mentioned in the abstract are presented in the following Sections 2–6 and summarized in a brief conclusion in Section 7.

2. Optimal residual waste utilization and pyrolysis

The high flexibility of pyrolysis in rotary kilns concerning operational parameters and tolerance to varying properties of feedstock is proving to be essential. This adaptability facilitates the processing of nearly all thermally degradable wastes or residues with minimal issues. A high carbon content of the input has a positive effect on the process with regard to profitability. Moreover, it is fundamentally important to understand the interactions between the input and the output of the pyrolysis to direct the output into desired fractions through targeted modifications of the input, thus optimizing the effectiveness and purposefulness of the process. The pyrolysis input must be prepared according to the required, optimal process conditions, ensuring that:

• the particle size is ≤20 mm,

• the residual moisture content is ≤10% and

• (nearly) all inert and valuable substances are extracted.

The use of B-V with more or less pure biomass leads to drying and crushing and possibly a system against metals and stones or similar. The entire processing is straightforward and therefore fully integrated into B-V.

However, when using municipal solid waste, waste processing becomes a distinct area before B-V and with the great variety of globally produced municipal waste, the systems required for the waste treatment are determined. All necessary technologies are well known and are being developed continuously. B-VM has several own patents in preparation. Sorted materials can be recycled, further processed, or secured. This enables optimal and sustainable implementation of locally and legally prescribed waste processing worldwide and, if necessary, later adaptation.

Typically, this range results in an output where, excluding the ≤10% residual moisture and ≥10% ash (also containing remaining inert substances), about 70–80% biomass (always +/− contaminated in waste) plus 30–20% non-recyclable plastics are fed into the process. This is based on dry material and the additional use of some regional biomass increases the corresponding share of biomass, ensuring better efficiency for BECCS.

2.1 The worldwide waste structures

It is evident that waste treatment before B-V can be very complex and costly, but it can meet all requirements for environmentally friendly use and processing. The additional effort required is offset by the advantages associated with B-VM and there is no other system with this process and these capabilities.

The waste structure to be processed with its different fractions is crucial for the feasibility of using B-V worldwide. Global waste structures are similar when broken down to regionally determining compositions. This is particularly true after the locally necessary processing and even more so with the output from pyrolysis. In this context, the global waste composition and that from 17 representative cities in China, as well as in Germany, were closely examined.

Figure 2 [1] displays the structure of global waste. It is evident that at least about 3/4 consists of biomass and plastic; increasing to 4/5 if 50% of “Other” is covered by biomass and plastic. Figure 3 [5] shows the municipal solid waste in 17 representative cities in China, displaying a very similar structure to Figure 2 but with own water fraction (the whole German/Chinese study in [5]).

Figure 2.

Global waste with fractions. Based on figure 2.8 in [1]. This is an adaptation of an original work by The World Bank. Views and opinions expressed in the adaptation are the sole responsibility of the author of the adaptation and are not endorsed by The World Bank.

Figure 3.

Physical composition of MSW in typical cities of China (Yang Na, 2014; Yang et al., 2015): given as figure 5.5 in [5].

In Germany, the problem is that between 2000 and 2024, waste incineration has quadrupled, but biomass must be legally separated. This results in an annual amount of about 16 million tons biomass, but besides and in addition, up to 40 % of household waste is still biomass and is therefore incinerated with household waste. The separated biomass is going to biomass processing plants to be burned, composted, or gasified. However, burning and gasification are inefficient and composting and gasification involve more or less contamination. The fact is that Germany and ultimately the EU cannot really handle the biomass they produce sustainably. It should be realized that at least all biomass collected from the households will inevitably always contain more or less foreign substances and also plastics. The data for Germany, regarding the composition of residual waste in 2002, show that biomass and plastics make up over 4/5 of the mass (Figure 4 [6]) and this value is assumed to be realistic also for the present overall.

Figure 4.

Material composition of German residual waste processed to TROCKENSTABILAT®. Given in German as figure 7.4 in [6].

2.2 HERHOF’s DRY STABILAT® as the basis for the pyrolysis input

Figure 4 illustrates the structure of the HERHOF DRY STABILAT® as a development that tries to modify the traditional incineration of waste. In Germany, there are extensive studies on waste processing and valorization through incineration, gasification and pyrolysis. This implies that some of the structures and pyrolysis data investigated there can be directly applied to the B-VM process, requiring minimal effort for additional proprietary and new research.

Currently, waste data from the HERHOF DRY STABILAT process (hereinafter referred to as HTS) are used in the B-VM concept. The HTS data are adapted as much as possible to the waste structures required for B-VM or can be converted. There are several scientific studies on HTS between approximately 1995 and 2015 (key references are [6, 7, 8]), including aspects related to pyrolysis. Most of the waste data required for B-VM are derived from these studies; this is particularly true for the pyrolysis input and the output, including data on heavy metals and pollutants. In the case of local waste, independent tests could be conducted for safety.

Contrary to widespread expectations in Germany, the waste recycling system developed by HERHOF proved to be practicable in the entire environment. However, the subsequent incineration and possibly the gasification of the produced STABILAT have not been convincingly implemented on a large scale. Importantly, systematic and EU-funded trials based on STABILAT with its low residual moisture content of ≤20% were conducted using a specially built pilot plant for several additional processing steps. Among other objectives, these trials aimed to produce clean biomass from STABILAT [9] and use it as environmentally friendly material. But the technical processing possibilities and their economic viability demonstrated in the “LIFE+ Project MARSS” (Material Advanced Recovery Sustainable Systems) are also crucial for the B-VM pyrolysis. It is essential that the demonstrated systems offer the new possibility to extract most of the inert material down to a few millimeters in size. If it is sensible to go further, it will be necessary to install specialized wet or air-based technologies.

2.3 Pyrolysis input data and output fractions

Based on data from China and Germany and with detailed further parameters for each fraction from Figure 3, initial general processing for the upstream system to B-VM was developed. Among other things a direct correlation between waste mass and engine power was established, indicating a requirement of about 10,000 t/a (wet and defined waste) per MW of engine power. For an actual plant, the locally given current waste structures must be considered. An example shows data from table in [8] with STABILAT material and proximate and ultimate analysis (both % weight and dry-base) including: moisture = 22.1; volatiles = 66.3; fixed carbon = 10.2; ash = 23.5; C = 42.1; H = 5.8; N = 1.3; S = 0.5; Cl = 1.1; O = 25.7 by difference; HHV = 18.42 kJ/kg, dry base). This structure is incorporated into the mass and energy balance we have developed for the B-VM and is shown in Section 4.4.

Figure 5 [6] displays the output fractions after the rotary kiln for STABILAT as weight percentages across rising temperatures (the B-VM operates in the range of approximately 450–600°C normally); the water content and the very high ash content of B-VM (including inert material) are important.

Figure 5.

STABILAT product fractions in the output of the rotary kiln with increasing pyrolysis temperature. Translated from figure 7.8 in [6] but without the scattered measurement results.

3. Decoupling thermal and electrical output

Based on Figure 1, the pyrolysis in the rotary kiln results in outputs of pyrolysis coke and pyrolysis gas (= “fluids”). The fuel for the large diesel engine comprises pyrolysis oil (on a new, large, commercial scale) and synthesis gas. The oil is derived by quenching from the pyrolysis gas and the synthesis gas is produced by gasifying the pyrolysis coke. Oil and coke thus serve as storable energy sources and can be used as a basis for motor fuel and/or for fluidized bed combustion (or similar) to generate thermal energy. With oversized storage units for coke and oil, it is possible to decouple the generation of thermal and electrical energy, achieving otherwise unattainable flexibility in the utilization of thermal energy in such motor systems.

The storage tanks for pyrolysis coke and oil are typically designed only in terms of capacity to compensate for predictable smaller fluctuations in the process before and after them inclusive of contracted normal change in power on demand for grid balancing. Expanding the storage tanks beyond this measure means that the entire system upstream and downstream of the storage tanks is more or less decoupled, with the interface lying downstream of the storage tanks. In extreme cases, the two areas thus created could also be physically separated and then connected through the transport of pyrolysis coke and oil. The upstream storage area must be designed for the expected delivery volume, fill the storage and be optimally utilized throughout the year. This also applies to the mass and energy ratio between pyrolysis coke and pyrolysis oil. The area downstream of the storage tanks must be designed in terms of the expected electrical and thermal energy to be generated in time, where it is important that the ratio between pyrolysis oil and synthesis gas as fuel for the diesel engine is very flexible.

The potential decoupling of thermal and electrical energy represents a completely new development and will have significant impacts. This is particularly true for the resulting capability of short-term and substantial network balancing, as shown in item 5. Similarly, the adaptation to the changing demand for thermal energy over longer periods means stored energy in the tanks can be accessed at any time as needed and by this even months later after production and also with large jumps in output.

One of the major issues in a conventional combined heat and power plant, for example, is the almost non-existent demand for thermal energy in the summer and the high-energy demand in winter. The necessary seasonal balancing can be easily achieved by adjusting the storage capacities for pyrolysis coke and oil. The upstream capacities for filling the storage tanks and the downstream capacities for combustion must then be determined accordingly.

4. Doubling net electrical efficiency of the power plant

The potential net electrical efficiency of the newly developed power plant is approximately doubled by employing a special large diesel engine instead of a steam turbine. Steam turbines used in waste incineration typically operate with an efficiency of ≤25%. In contrast, the diesel engine achieves an efficiency of nearly 55% and also has the best other parameters, besides other things boasting a guaranteed lifespan as the longest of any reciprocating combustion engine.

The comparison begins with a comparative presentation of parameters for waste incineration and the utilization of our B-V bioenergy process with upstream waste treatment, substantiating the data used as a foundation for combustion and our system. The basis for this is the actual net electrical efficiency achieved in waste incineration. Reliable empirical data are available for this value, which can also be calculated from existing data on waste and plant configuration. The efficiency of steam turbines is the determining factor for this value. The power plant’s efficiency is only slightly lower due to minor losses through the aggregates used. In global waste incineration, capacity ranges are approximately per line with 20,000–380,000 t/a and about 4–40 MW per steam turbine. The relatively low turbine output is primarily due to the maximum possible steam temperatures and associated pressures resulting from the flue gases in waste incineration. The maximum turbine efficiency under these conditions is slightly above 30% (the highest known efficiency is realized in Amsterdam waste incineration plant with ≈ 30% net). However, with turbines specified in this way the German incineration plants for waste and for Refuse-Derived Fuel (RDF) only achieve net electrical efficiencies of about 11–15%. These for years 2012–2016 representative values were published by the German Federal Environment Agency (UBA) in 2018 [10] and can also be confirmed by calculations of 12–14% through corresponding mass and energy balances. It is important to note that the waste incinerated in Germany has a residual moisture content of about 25%. Globally, higher moisture content values reduce efficiency.

Compared to the steam turbine, the efficiency of the engine used in B-VM is the determining factor for the overall plant performance. The entire plant incurs greater efficiency losses due to its design and the systems and units used. The actual achievable net electrical efficiency can only be more accurately determined in advance through mass and energy balances, including all parts of the process.

4.1 Drive unit by slow-running, two-stroke diesel engine

The drive unit utilizing B-VM necessitates a much higher efficiency than that of a steam turbine. The following Figure 6 [11] illustrates the application of some of the most commonly used power generation technologies along with their respective performance ranges in megawatts (MW) and the achievable efficiencies. Although this diagram of 2016 is relatively up-to-date and accurate, it is missing, as in nearly all similar figures and the associated discussions and evaluations, the inclusion of the slow-running, two-stroke large diesel engine, which is produced with generator outputs ranging from 3 to 80 MW and achieves efficiencies of up to approximately 55% (see Figure 7 [12]). Figure 6 alone by its additions underscores the crucial objective of replacing the turbine with two-stroke diesel engine.

Figure 6.

Technologies for generating electricity with their power and efficiency ranges. Basis given in German by ASUE in [11].

Figure 7.

Increase of efficiency, MAN low-speed, two-stroke diesel engine with turbo compound system (TCS) in [12].

The slow-running, two-stroke large diesel engines are evidently capable of surpassing the current application range of steam turbines for waste combustion in every respect and by a considerable margin. These large diesel engines operate with undisputedly the highest availability, efficiency, reliability, and lifespan (guaranteed up to 25 years at 8000 hours per year). These have been deployed for decades in the largest ships and in stationary power plants, especially in island operations and achieve the highest fuel efficiency in propulsion systems. Only the use of pyrolysis oil on a large commercial scale would represent an innovation. Initial tests for this were conducted in 1994 and have been confirmed to this day by the two engine developers who have made respective proposals. Due to the severe consequential damage in the event of a failure or extended repair times, the engines were designed to achieve the highest MTBF (Mean Time Between Failure = “Reliability”) and the lowest MTTR (Mean Time To Repair; where then the following applies: “Availability” = MTBF/(MTBF + MTTR)) and this even at peak continuous output. At the same time, for economic reasons, a long lifespan (for optimal ownership costs) and low fuel consumption are required. This would also lead to environmental benefits over decades.

4.2 Pyrolysis by rotary kiln

The externally heated rotary kiln, essential for pyrolysis, in conjunction with the two-stroke large diesel engine, constitutes the most important unit in the B-VM system and is responsible for the production of the necessary fuel. A highly comprehensive study published at the beginning of 2022, titled “Pyrolysis-based Municipal Waste in Poland - SWOT Analysis” [13], asserts that… “Pyrolysis is an economically attractive alternative to incineration, with a significantly lower environmental impact, allowing efficient waste management and the use of pyrolysis by-products ….”

In Germany, there are extensive and reliable experiences with some industrial waste pyrolysis plants (MPA), but further developments and utilizations are lacking. Nonetheless, these systems clearly demonstrate at least the feasibility of rotary kilns in waste management operations. The MPA in Burgau/Bavaria was operational from around 1985–2015, handling up to 35,000 tons each year and serving the waste disposal needs of approximately 120,000 residents and industries, including sewage sludge. The pyrolysis coke was landfilled and the landfill gas produced was combusted along with the pyrolysis gas from the rotary kilns in a combustion chamber at approximately 1200°C to generate steam. Two rotary kilns, each with a diameter of 2.2 m and a heated length of 21 m, were employed. The CONTHERM MPA was used as an upstream unit for a coal-fired power plant for about 10 years. The two rotary kilns, 20 m in length and 2.8 m in diameter, processed up to 100,000 tons each year of RDF (Refuse-Derived Fuel).

Besides the influence on the distribution of the output fractions (Figure 5 [6]), the pyrolysis temperature also has an effect on the pH value of the pyrolysis oil. The residence time of the input and the formed pyrolysis gases in the rotary kiln, as well as the heating rate, play significant roles and can be manipulated to control the output from the rotary kiln. Produced pyrolysis coke, in combination with hot pyrolysis gas and appropriate process control through catalytic effects, can ultimately lead to higher-value output in pyrolysis oil and provide an advantage for engines (see “TCR” process with its thermo-catalytic reforming [14]). The “Co-pyrolysis of Biomass and Plastics from Municipal Wastes” (search these keywords) generally yields a more advantageous pyrolysis output than individual fractions and there is a vast array of procedures, scientific experiments and various material combinations available. The suitability of different waste components for pyrolytic conversion has been demonstrated through small-scale experiments, which also showed that the varied composition of waste does not play a decisive role and can generally be compared well with international data [15].

4.3 Further crucial units

Most important are quenching of pyrolysis gas, gasification of pyrolysis coke and handling of thermal energy. The methods for implementing these can be covered with a large number of well-known variants and decades of experience. All technologies used in B-V and B-VM are designed for comparatively safe and long-term use align with the current state of the art and largely comply with the use of sustainable input and operational materials in the process.

In the quenching zone, the hot gases produced by pyrolysis are rapidly cooled, halting all ongoing reactions and directly converting the gases into a permanent gas fraction and a pyrolysis oil fraction. When the hot gases enter the quencher, the pyrolysis gas still contains a considerable amount of dust and water, thus requiring appropriate treatment. The permanent gas serves as a heating base for the rotary kiln. The produced pyrolysis oil depends among other things on the conditions during quenching and may need further processing for buffering in the tank system and subsequent use in the engine (similar to the use of heavy oil or ORIMULSION for this engine type).

For the gasification of pyrolysis coke into the required synthesis gas, we generally use fluidized bed gasifiers. It is crucial that gasification of coke, theoretically devoid of volatile components, produces almost tar-free synthesis gas. All our previous approaches have been based on Auto Thermal fluidized bed gasification, where the necessary thermal energy is generated by burning part of the coke within the system. Water and almost pure oxygen are used as gasifying agents. In the future, the use of a Dual Fluidized Bed (DFB) will be explored. This will be the case in particular if the fundamental possibility of using gas engines instead of diesel engines is utilized. Among other things, the combustion of part of the coke and the use of oxygen will be eliminated and the entire process could probably be made more efficient and effective. But on the other hand, gas engines do not achieve the high performance and efficiency of the two-stroke diesel engine (see Figures 6 and 7 [11, 12]). In this context, the entire mass and energy balance of B-VM needs to be redesigned and the use of a quencher also reviewed.

For thermal handling, a significant area arises from the mass and energy flows, linked with the blue flows as shown in Figure 1. In this depiction, all areas of thermal energy have been simplified for clarity. The aim is to comprehensively capture and optimally utilize individual items of generated and required thermal energy. The underlying mass and energy balances are complex and extensive, ultimately utilizing thermal oil. The waste heat from the heating system at the rotary kiln can be considered as a base. This is primarily combined with waste heat from engine exhausts and the heat of the fluidized bed exchanger. Merged, this thermal energy is then directed either to internal or external consumers or used in a separate power generation engine, particularly in the form of an ORC turbine or a steam engine, both of which exhibit excellent performance in the required partial load range.

4.4 Resulting mass and energy balance MEB

A detailed MEB for the process shown in Figure 1 can be used to derive CAPEX and OPEX and demonstrate a self-contained and resilient system. The feasible profitability calculation allows the creation of the necessary business plan and with the appropriate engineering a pilot plant can be designed.

Based on the B-V, a business plan for biomass and a 14 MW engine was developed, implementing the Renewable Energy Sources Act (EEG) in Germany. The net electrical efficiency was thus represented with the Mass and Energy Balance (MEB) at 36%. Approximately 600 items of the MEB were evaluated and results in a CAPEX of about 100 million Euros (excluding BECCS). The Return on Investment (ROI) is 11% and the Internal Rate of Return (IRR) reaches nearly 20%. The entire concept and calculation have a “Study Estimate Level” with an accuracy of +/−20% to +/−30%. On this basis, a similar B-VM concept for Poland and for the Czech Republic determines a net electrical efficiency of about 30% and a CAPEX of about 120 million Euros (including BECCS; approximately 3.8% of the total net electrical efficiency of 33.8% is allocated for the upstream waste processing). Figure 8 shows an excerpt from this structure of the MEB (excluding BECCS and excluding waste processing). The waste fees and revenues from all extracts (including CO₂) then lead to significantly improved economic conditions compared to the B-V.

Figure 8.

Simplified mass and energy balance for STABILAT and slow running, two-stroke, dual-fuel 14 MW diesel engine. From author’s BMC Sp.z o.o. Working Group B-VM.

Due to the stipulations of the German EEG, it is not possible to directly transfer the data to other countries. However, CAPEX and OPEX can be adjusted country-specifically and then work with the respective location-specific fees for waste and the compensation for electricity and heat (plus the revenues from the extracts, including CO₂). The decision to develop the B-VM derived from the B-V was, among other things, based on an analysis of the structure and CAPEX of waste incineration. It was found that only cost-effective providers from China could compete regarding the CAPEX of the B-VM.

In addition to clear ecological advantages over waste incineration, the significantly higher net electrical efficiency and the possible thermal decoupling lead to a strong global unique selling proposition (USP). The possible use of BECCS increases this advantage. Investors and plant operators benefit from the previously unattainable performance and environmental friendliness compared to waste incineration.

5. Possibility to realize negative emissions through BECCS

The utilization of BECCS is facilitated by the high biomass content in waste and the high efficiency of electricity generation, as well as the decoupling from thermal energy. Additionally, locally available biomass can be used in the decentralized facilities. Biomass in the B-VM is climate-neutral and the use of BECCS can enable the achievement of negative CO₂ emissions. This also allows for a balance with the CO₂ from the plastic content in the waste, thereby realizing more or less negative CO₂ emissions. BECCS with the B-VM presents an opportunity to implement Negative Emission Technologies (NETs) for CO₂ on a large scale. There are significant objections to BECCS globally due to its associated consumption of agricultural land, water, and fertilizer etc. However, these do not apply to the B-VM for our technology is scalable and the required biomass is based on waste.

Preliminary calculations suggest that up to 1 billion tons of CO₂ per year could be extracted from the exhaust gases of a 50% portion of the globally possible B-VMs. This corresponds to about 20% of the 5 billion tons per year of negative emissions postulated by the IPCC (Intergovernmental Panel on Climate Change) and NAS (National Academy of Sciences) for BECCS.

Further rough calculations indicate that the additional revenue from power generation could at least cover the expenses for CO₂ extraction. The effort for further utilization of CO₂ then depends on the respective local conditions. Economically the B-VM process, with its very high net electrical efficiency and variable thermal energy and the expected CO₂ compensations, advocates because using BECCS in the B-VM as the best complementary investment to enable better amortization.

The output of CO₂ by the HTS as STABILAT with 10% water and a 14 MW diesel engine was roughly calculated and shows:

The collection of a waste input of about 133,000 t/a results in 66,400 t/a entering the pyrolysis process and water-free per hour: C = 3145 kg; O = 1920 kg; H = 433 kg; N = 97 kg; Cl = 82 kg, S = 37 kg; ash = 1755 kg.

1. Flue gas with 26 t/h contains 3.6 t/h CO₂, at 125°C

2. Engine exhaust gas with 115 t/h contains 3.5 t/h CO₂, at 124°C

With 8000 operating hours per year, this amounts to approximately 57,000 tons of CO₂, of which at least could be extracted an estimated 50,000 t/a. If these figures are linearly scaled up to the largest diesel engine of 80 MW, a corresponding facility would emit about 326,000 t/a CO₂, of which could be extracted annually nearly 290,000 tons.

The extraction of CO₂ from exhaust gases is already known for a long time and the development of more efficient processes is ongoing worldwide. For the B-VM, we consider working with the Chilled Ammonia Process (CAP) and are monitoring developments such as the Metal-Organic Framework (MOF). Local conditions are always crucial for the realization of storage or utilization of CO₂ and several options are currently available and new ones under development.

6. Base and peak load and very strong energy balancing

The B-VM facilities are decentralized in their establishment and are broadly distributed according to the given concentration of population and economic activity. This configuration evidently allows these plants, due to their complete independence from external influences, to serve as ideal compensators for regional grid fluctuations and also to absorb extreme outages, for example, from wind power and, above all, photovoltaic sources.

Based on the size of the buffer storage tanks, the system can cover peak performances and thus be utilized in the normal area of “balancing energy” to compensate for electricity network fluctuations. This is applicable both for the use of the large diesel engine and for the steam-powered units. Particularly, an Organic Rankine Cycle (ORC) system is capable of responding very quickly and with its full capacity. In the case of the large diesel engine, a significant portion of its output can be utilized with minimal efficiency losses according to its characteristics curve (Figure 7 [12]), though with time constraints in the overload range.

If necessary, this capability can be enhanced by a significant enlargement of the buffers for pyrolysis coke and pyrolysis oil and consequently serve to split the overall facility into two systems. Including the two buffers, the plant can be designed for optimal use with its annual input of 8000 hours, thereby continuously filling both buffers. Concurrently, however, based on the two buffers, a system for extraction for the delivery of electricity and thermal energy is established, whereby the annual usage time is more or less reduced. In return, the system performance is increased. For instance, with an operational time of 4000 hours per year, it would be possible to double the engine power during the night (using a 28 MW engine instead of a 14 MW engine) and thus provide an optimal compensation example for the loss of photovoltaic power at night.

Assuming a waste capacity of 25 million tons in Germany and other regionally available biomass of the same amount, it would be feasible to provide about 50% of the power currently generated by photovoltaics during the day also at night with approximately 410 systems and 28 MW engines.

7. Conclusion

The importance of the work lies above all in showing that there is a safe thermal process for recycling waste which is far superior to incineration in ecological and economic terms and which can then be used to take real and successful action against the worldwide increase in waste. It is worth noting that this process enables the global use of BECCS for the first time due to its decentralized high proportion of biomass in the waste and the best electrical efficiency and the possibility of decoupling from thermal energy. This is particularly the case if the respective location offers the possibility of simply processing or storing the extracted CO₂.

The B-VM power plant has the potential to solve the existing problems associated with waste and its incineration and also offers new and best opportunities. This applies not only to the approximately 20% of waste incinerated worldwide today, but to almost the whole waste worldwide. Notably, the predominant current handling of biomass could become an obsolete method, facilitating the elimination of composting which invariably releases pollutants into the environment to varying degrees. Additionally, the incineration of materials such as plastics, in cement kilns, with its associated ecological problems, becomes unnecessary. Furthermore, the environmentally very harmful open production of methane from the fermentation of free biomass would at least be reduced. With Figure 1, there also exists a fundamental opportunity to utilize the intermediate product, synthesis gas, for producing alternative fuels such as DME (Dimethyl Ether) and OME (Oxymethylene Dimethyl Ether) or similar through appropriate processes.

The B-VM process offers the possibility to utilize existing systems and units with many years of successful use and an assessment as state-of-the-art technology; only their configuration and the use of pyrolysis oil are new. This means besides other things that all the necessary data is known and can be found in existing systems. Precise and detailed explanations and verifications exist for the process and its evaluation based on the planned project for B-V according to the Renewable Energy Sources Act (EEG) in Germany and the derived B-VM projects in Poland and the Czech Republic. The prototype was designed as fictional large-scale pilot plant with a comprehensive and detailed mass and energy balance. Therefore, the remaining tasks include developing a location, adjusting all the capacities, conducting detailed engineering and realizing a first pilot power plant with profitability calculation.

The opportunity to utilize BECCS arises from the high proportion of biomass in waste and the very high efficiency of electricity generation, along with the straightforward decoupling from thermal energy. All the disadvantages typically associated with BECCS up to date, such as significant loss of agricultural land and consumption of fertilizers and water, as well as logistics costs, is avoided.

Given the potential for rapid and consistent implementation of BECCS, the usual governmental responsibility associated with waste proves advantageous. Since BECCS can be assessed as an extension investment in waste recovery, the current problems of waste disposal and the achievement of CO₂ reductions can be linked and implemented by the state.

In this regard, it would be sensible to employ large and global capacities in engineering and production for realizing the B-VM without delay and in this aspect some companies have a great and unique alternative opportunity with the growing elimination of fossil fuel projects.