Very recently InnoEnergy commissioned a study to BVG Associates to evaluate how innovation would impact the electricity generating cost, in Europe and till 2025, from new gas CHP (combined heat and power) plants and retrofitted coal plants.
The study  outlines that for a 500 kW gas CHP plant, the levelized cost of energy (LCOE) shall drop by about 17% between 2016 (the baseline) and 2025, while for a 225 MWe solid fuel power plant (coal retrofitted) such decrease is estimated to be about 27%.
For the solid fuel plant, according to the authors  and as evidenced in Fig. 1, over half of the LCOE savings arise from innovations in the modification, pre-treatment and combustion of new fuels.The identified major innovations for the solid fuel plant are reported in the following :
- Topic 1 – Improvements in fuels through modification, switching; hybrid fuels (-10% LCOE). The use of low quality fuels is limited by operational challenges (e.g. slagging and fouling). Today, fuel additives are still limited to basic minerals (e.g. kaolinite) to reduce slagging and fouling and fuel blending is still limited to fuels that are not classified as waste. The use of advanced mineral or artificial additives to reduce ash challenges and influence emissions and the blending of low quality fuels/wastes shall be increased. According to the study, 80% of the benefit of these innovations is already realisable in 2016, with 100% realisable by 2020 onwards, however with an implementation limited to 40% of plants in 2025 because of local policy and regulations limitations.
- Topic 2 –Introduction of thermal pre-treatment of solid fuels (-7% LCOE). As an example, torrefaction, by upgrading the properties of biomass and waste fuels, could reduce fuel transportation and handling costs (but might increase processing costs). According to the study, 40% of such benefit is already realisable in 2016, with 100% realisable by 2025 onwards, with an implementation limited to 30% of plants in 2025 because of local policy and regulations limitations.
- Topic 3 –Improvements in preventive maintenance, power plant start-up system and boiler flexibility (-5% LCOE). Innovations cover advanced burners to reply heavy oil start up burners with liquid biofuel waste (70% of the benefit of these innovations is realisable in 2016) and the increase in boiler’s flexibility to enable plant operation at below 40% of maximum output (e.g. improving electronic/digital control and using high temperature heat accumulation systems). Moreover, modern preventative maintenance algorithms, based on real operations, could provide information about failure in advance (e.g. material failures due to corrosion, especially when using biomass).
- Among other 10 innovations (-5% LCOE): improvements in treatment of solid fuel combustion byproducts (today used by the cement industry, tomorrow to produce artificial zeolites, geopolymers and cenospheres, or vitrified), improvements in steam circuit design (optimal turbine blades, valves and condenser designs), introduction of superconducting technology in transformers/cables, integration of the main three pollution control systems (NOx, SOx, dust emissions), today in series, by using single sorbents and oxidisers in single wet scrubbers.
As a summary, reduced fuel OPEX in solid fuel plants by 2025 is achieved through innovations that enable the use of lower cost fuel and waste products (Topic 1), with thermal pre-treatment (Topic 2) and additives. Improvements in operations (Topic 3) also deliver significant savings, with preventative maintenance, operational flexibility and treatment of the byproducts of solid fuel combustion.
Topic 1 is addressed by many research projects (e.g. ) and now also with an operational, available tool called BIOFACT (BIOmass Fuel Advisory Characterization Tool) which wants to disclose a tool to characterize solid biomass for its utilization as a fuel in existing and new units, by estimating the impact of its utilization in terms of operational problems. In fact, fuel characterization tools are supposed to unlock the 8% reduction of the solid fuels generation costs already realisable today, with the final objective of providing flexible back-up plants for wind and solar energy technologies as well as renewable heat production.
 InnoEnergy, “Future Energy Costs: Coal and Gas Technologies“, BVG Associates, 2016, (accessed 21/02/2017).
 European Union’s Horizon 2020 research project: Biofficiency. Developing the next generation of CHP plants, (accessed 21/02/2017).
By Lucio De Fusco, InnoEnergy PhD School Fellow
According to the recent book by Dr. D. Thrän, “Smart Bioenergy: technologies and concepts for a more flexible bioenergy provision in future energy systems” (2015), the currently developing energy system (in Germany, but more generally, in Europe) based on renewable energy sources, could be built on the following pillars:
- solar and wind energy (heat and/or electricity);
- balancing/residual power load, e.g. from biomass and waste;
- upgrading/storage of excess energy with heat, gases/accumulators (batteries);
- rely on system control solutions, e.g. grid stabilization and security;
- bio-refineries for the production of refined fuels, for specific applications (i.e. heavy duty vehicles, ships and aviation) as a synergy with electric mobility, and for feedstock conversion to materials;
- (renewable) heat provision (e.g. standalone CHPC units, co-generating heat, power and cold) for households, public buildings and industry.
Among the contribution to such regional, distributed and interconnected energy system, solid biomass could play a significant role: for residual power balancing (e.g. flexible electricity generation from thermal conversion technologies) and heat/cold production in standalone applications.
For the development of such framework, a strategic question which arises is: “Which solid feedstock is suitable for which conversion technology?” If matching feedstock type and conversion technology with a simplified (and didactic) approach, the following scheme could be considered (r.t. reaction time; own elaboration).
As indicated in the proposed scheme, high hydrogen (H), oxygen (O) and nitrogen (N) to carbon contents in the fuel, identify the biological conversion technologies (with respect to thermochemical) as better suited options for the fuel conversion. Yet, the answer to this question is far from being comprehensive and it is rapidly evolving as the technological options develop. However, it seems clear the strategic interest of coupling the specific feedstock with the suitable technology, in order to efficiently valorise solid fuels in the modern, renewable based, energy system.
Fuelsim is a useful mass, volume and energy balance Excel tool, by Dr. Øyvind Skreiberg, for computations related to biomass combustion processes. It might be useful for preliminary simulations to compute heat output, adiabatic combustion temperature and system efficiencies. Report here, tool download here.