Energy Return On Investment Research Articles

Thermodynamic and environmental assessment of different scenarios for the insertion of pyrolysis technology in palm oil biorefineries

The large quantities of residual biomass produced in the palm oil industry have become one of the main environmental and financial concerns of this industry. For this reason, biorefineries are gaining strength in recent years, since through their production model the residual biomass can be used as raw material to produce bioenergetics (biofuels and bio-products), hence contributing to the reduction of greenhouse gases emissions. Therefore, the main objective of this work is to compare and evaluate alternatives to convert a conventional palm oil mill into a biorefinery considering energy and environmental sustainability indicators. In this context, this work presents a study of three scenarios: the first (I), the base case, consists of a traditional palm oil mill; the second (II) considers a palm oil mill working under the biorefinery concept that uses the fast pyrolysis process for the production of bio-oil and biochar; and the third (III) considers a biorefinery that, besides incorporating the pyrolysis process, has an extraction/transesterification stage for the production of biodiesel and glycerin in the palm oil mill. The surplus electricity index was calculated for the three scenarios, and scenario III was the most favorable, achieving 110.23 kW per ton of fresh fruit bunch with an overall efficiency of 82.69%. The environmental assessment carried out for scenario III indicates that environmental impacts of bio-oil production are 32.5% lower than the ones to produce electricity (climate change category) and 14.2% lower than environmental impacts to produce biodiesel (resources category), demonstrating that the production of bio-oil using fast pyrolysis result in lower environmental impacts compared with the other products obtained in the biorefinery. Finally, the Net Energy Ratio was calculated for the scenario with the best thermodynamic performance (scenario III: 21.17) and compared with previously published studies, resulting in a gain of total energy flow of up to 17.77.

Bio-combustion of petroleum coke: The process integration with photobioreactors. Part II – Sustainability metrics and bioeconomy

In this study, we evaluated the sustainability metrics and bioeconomy of the integrated bio-combustion system. Based on previous experiments, inventory data were standardized for a functional unit of 1 kg of mass, 1 MJ of energy, 1 m3 of water, and a stream factor of 0.90. The impact categories resulted in a net energy ratio of 0.71, greenhouse gas emissions of 0.70 kgGHG/kgfuel, global warming potential of 12,523.60 kgCO2eq/yr, water footprint of 56.40 m3/m3/yr, acidification potential of 33 kgSO2eq/yr, eutrophication potential of 4.42 × 10−3 kgNeq/yr, and ozone depletion potential of 2.15 × 10−8 kgCFC-11 eq/yr. Regarding the utilities, fuel consumption cost was reduced close to 40%, and the oxygen and volatile organic compounds productions were responsible for the majority revenue generation. Besides, both avoided and captured carbons obtained potential revenues through carbon credits. The current contribution of the integrated process has shown improved environmental performance and is a promising approach towards circular bioeconomy.

The Changing Meaning of Energy Return on Investment and the Implications for the Prospects of Post-fossil Civilization

Energy return on investment (EROI) is a useful physical metric to compare the utility of energy production processes and their development over time. The concept has been extended from its physical, process-based origin to one that describes the societal metabolism. As such, EROI has been used to speculate about the prospects of humanity in a late-fossil and post-fossil civilization. Often, the narrative to emerge around EROI is that in the (near) future, prosperity will be compromised. Here, we take a fresh look at EROI, with a distinction between a physical EROI, which is useful at energy project level, and a societal, or economic, EROI—appropriate at the level of the whole economy. This distinction leads us to conclude that a renewable future is possible. Such a future is essentially unconstrained by the physical EROI and will have an acceptable economic EROI—not much different from that of the past century.

When is EROI Not EROI?

This paper outlines some very real issues with the use of energy returnon investment (EROI) for comparing different energy delivery pathways, particularlywhen directly comparing EROI calculated at the scale of a single energy facility (asa ratio of full lifetime energy transfers) with that calculated at the scale of ageographical region or industry (as a ratio of annual energy flows). While these tworatios may converge, it is only under a very specific set of circumstances. The aimof this paper is to outline this issue in detail and provide some specific examplesof the difference between these two ratios for the global wind and photovoltaicsindustries.

Energy Saving Potential using Elite Jatropha Curcas Hybrid for Biodiesel Production in Malaysia

The world continues to search for renewable energy resources, due to the devastating effect of global warming and the dwindling resources of fossil fuels. Without needing much modifications to the existing diesel engines, biodiesel is regarded as one of the most promising ways to treat these two issues simultaneously. However, the production of biodiesel is always associated with a higher cost compared to its counterpart; the petroleum-derived diesel. In addition, the type of feedstock used in the production of biodiesel also has also become a big concern due to the never-ending fuel vs food debate. Jatropha curcas is a second generation feedstock which can be specifically grown to avoid the usage of edible oils as feedstock to produce fuel. In this paper, the energy saving potential of using elite Jatropha curcas hybrid for biodiesel production in Malaysia are evaluated by conducting a full chain energy analysis. It was found that the new hybrid consumed 25.32 MJ of energy in order to produce 1kg of biodiesel. The net energy balance (NEB) and net energy ratio (NER) when by-products are not utilized are found to be 15.89 MJ/kg and 1.63, respectively. However, the NEB and NER increase to 26.72 MJ/kg and 2.84 when the by-products are used in the biodiesel conversion process. Hence, this new hybrid of Jatropha curcas has a huge potential to be used for the production of biodiesel.

Capacity Expansion of Electricity Sector Using Multiple Sustainability Indicators

The fast-paced growth in electricity demand across the globe raises the question of availability and sustainability of the electricity sector. This paper considers five different sustainability indicators: the risk to human lives, carbon footprint, water footprint, land footprint, and energy return on energy investment (EROI), for planning the capacity expansion of different power plants to fulfil the electricity demand sustainably and cost-effectively. A method is developed for the capacity expansion planning of power sector using Pinch Analysis approach. Different sustainability indicators are combined into an aggregated sustainability indicator by using different methods: p-norms (grid norm, Euclidean norm, and infinity norm) and Analytic Hierarchy Process (AHP). The prioritisation for commissioning of new power plants, to assure the future electricity demand, is accomplished using the concepts of prioritised cost. It is shown in this paper that the aggregate sustainability indicator and the prioritising sequence of different power plants help in achieving sustainable electricity demand in a cost-effective (both capital cost and overall annualised cost) way. Physical insights of Pinch Analysis help in explaining the optimisation results and optimal energy mix. The proposed method, developed for capacity expansion, is demonstrated in this paper through a case study of the Indian electricity sector.

Is hydrothermal treatment coupled with carbon capture and storage an energy-producing negative emissions technology?

This paper evaluates the feasibility of hydrothermal treatment (HTT) with carbon capture and storage (CCS) as an energy producing negative emissions technology (NET) and compares such system with a conventional bioenergy with carbon capture and sequestration (BECCS) system. Machine learning models were developed to predict product yields and characteristics from HTT of various feedstocks. The model results were then integrated into a life cycle assessment (LCA) model to compute two metrics: energy return on investment (EROI) and net global warming potential (GWP). Results showed random forest models had better prediction accuracy than regression tree and multiple linear regression to model HTT of feedstocks (e.g., microalgae, crops/forest residues, energy crops, and biodegradable organic wastes) and predicted the mass yields of multiple products (biocrude, hydrochar, gas, and aqueous co product) as well as the energy and carbon contents of biocrude and hydrochar. LCA results revealed that the proposed HTT-CCS system constituted a net-energy producing NET for some combinations of feedstock characteristics and reaction conditions. Best overall energy and GWP performance was achieved for HTT-CCS of lignocellulosic biomass at low temperature. Compared with the conventional BECCS system, HTT-CCS generally exhibited higher EROI but higher net GWP, depending on processing conditions and the feedstock types.

Production potential, economics and energetics of rice (Oryza sativa) genotypes as influenced by varying levels of nitrogen

Performance of eight rice (Oryza sativa L.) genotypes (IR 83383–B–B–129–4, IR 83387–B–B–27–4, IR88867– 9–1–1–4, IR88964–24–2–1–4, IR88964–11–2–2–4, IR88966–39–1–4–4, Rajendra Sweta and Rajendra Bhagwati) were evaluated in different levels of nitrogen (N) application, i.e. control, 50% RDN (60 kg N/ha), 100% RDN (120 kg N/ha) and 150% RDN (180 kg N/ha) during the rainy season of 2016–17 in lowland transplanted condition of Patna, Bihar. Significantly higher grain yields (5.19 t/ha) and net returns (` 52260/ha) were recorded with application of 180 kg N/ha. Grain yields and net returns were noted higher with IR 83383–B–B–129–4 (4.27 t/ha and ` 38181/ ha). Carbohydrate equivalent yield (4.06 t/ha) and carbon output (6.42 t CE/ha) were also higher with 150% RDN. IR83383–B–B–129–4 had significantly higher carbohydrate equivalent yield (3.34 t/ha) and carbon output (5.23 t CE/ ha). Gross energy output, net energy return, energy use efficiency, energy profitability, energy productivity, energy intensity in economic terms and energy output efficiency were markedly higher with 180 kg N/ha. These attributes were higher with IR83383–B–B–129–4 but being on a par with IR83387–B–B–27–4. Therefore, growing of IR 83383–B–B–129–4 along with application of 180 kg N/ha is an ideal approach to achieve the higher productivity, profitability and energetics in lowland transplanted condition of Bihar.

Crop-diversification and organic management increase the energy efficiency of cacao plantations

The increasing global demand for chocolate and related products has intensified their production systems by both replacing traditional agroforestry systems with monocultures and increasing the use of synthetic external inputs and machinery. High dependence on non-renewable energy is a clear symptom of unsustainability in food production systems. Consequently, more sustainable agricultural practices should be promoted. With a special focus on non-renewable energy, this work compares: i) the cumulate energy demand (CED), ii) energy return on investment (EROI), and iii) energy return on labour of four different cacao production systems: two agroforestry systems and two monocultures under organic and conventional management. Cacao and subproduct yields and the use of labour and external inputs were recorded during the first five years after the establishment of the trial in Bolivia. Results show that CED per hectare was almost 2-fold higher in monocultures than in agroforestry systems. With regard to the kilograms of cacao produced, the higher number of inputs used in monocultures was compensated by a higher cacao output. However, when subproducts were also taken into account, non-renewable CED was 7.4times higher in monocultures, and non-renewable EROI increased up to 4.8times in agroforestry systems compared to monocultures. Under organic management, less than 10% of CED was from non-renewable sources, while it reached 75% in conventional systems. Non-renewable EROI was higher under organic management, both when only cacao was considered and when subproducts were also included. Productivity per hour worked and per energy unit of labour invested were both higher in agroforestry systems than in monocultures. In conclusion, diversification of production and organic management are crucial to increase EROI and diminish dependence on non-renewable energy sources of cacao plantations.

Life cycle and economic assessments of biogas production from microalgae biomass with hydrothermal pretreatment via anaerobic digestion

Biogas production from microalgae biomass via anaerobic digestion can be enhanced by hydrothermal pretreatment. The process of hydrothermal pretreatment has a significant impact on the energy gain, greenhouse gas emissions, and levelized cost of energy in biogas production from microalgae biomass, which has not been reported until now. In this study, life cycle and economic assessments of biogas production from microalgae biomass with hydrothermal pretreatment and with solar-driven hydrothermal pretreatment were conducted. The results showed that both types of pretreatment methods improved the biogas yield, promoted the energy gain, and reduced the levelized cost of energy. In biogas production through hydrothermal pretreatment, the net energy ratio (Energy input/Energy output), greenhouse gas emissions, and levelized cost of energy were 0.54, −129.94 g CO2-eq/(kWh biogas), and 0.22 $/m3, respectively, whereas in biogas production through solar-driven hydrothermal pretreatment, the corresponding values were 0.69, −166.13 g CO2-eq/(kWh biogas), and 0.17 $/m3, respectively. The biogas yield had the maximum effect on the net energy ratio and economic benefit. The efficiency in nitrogen recovery from the biogas residual had the maximum effect on greenhouse gas emissions. This work provides a theoretical guide to promote the environmental and economic benefits of biogas production from microalgae biomass.

Are Higher Input Levels to Triticale Growing Technologies Effective in Biofuel Production System?

Energy use in agricultural production has been increasing faster than in many other sectors of the world economy. Owing to high energy consumption during the production of agricultural inputs, with mineral nitrogen fertilizers in particular, it is often questioned as to whether agricultural production is still energy efficient. The objective of this research was to evaluate the energy efficiency of different intensity systems for the production of semi-dwarf winter triticale cultivar ”Twingo”. Cultivar “Twingo” entered the Polish National List in 2012 as one of the best yielding. For this reason, it was used in this experiment to examine its response to basic agrotechnical factors. The field experiment was conducted in the Agricultural Experiment Station in Tomaszkowo in 2013–2015. Low-input, medium-input and high-input production systems were evaluated. The compared systems differed in nitrogen fertilization rates and the level of fungicide protection. The highest output/input ratio was noticed growing winter triticale in low-input production system. The most energy-consuming operation during winter triticale production in the compared systems was mineral fertilization. The high-input production system was significantly lower energy efficiency than the other systems (6.21, medium-input 5.95, low-input 8.19). The energy return on investment (EROI) ratio was low, but above 1, in all the analyzed technologies (low-input 1.30, medium-input 1.14, high-input 1.15). The energy value of the bioethanol produced was higher than the energy inputs into the production of raw material and its processing. The conversion of winter triticale grain to bioethanol proved that the EROI reached the most favorable value for the low-input production system.

Evaluating energy and greenhouse gas emission footprints of thermal energy storage systems for concentrated solar power applications

Abstract Greenhouse gas emissions from the power generation sector contribute significantly to climate change. The use of thermal energy storage systems can reduce the sector's impact depending on factors such as plant energy performance and environmental friendliness. In this study, an Excel-based model was developed to evaluate the greenhouse gas emissions and net energy ratio for thermal energy storage technologies used in concentrated solar power applications. Five thermal energy storage systems were considered: two-tank indirect sensible heat storage, two-tank direct sensible heat storage, one-tank direct sensible heat storage, latent heat storage, and thermochemical storage. To capture the uncertainties in the results for each type of storage, a Monte Carlo simulation was performed by varying key operational and model parameters. With uncertainty taken into consideration, it was determined that the mean greenhouse gas emission values for two-tank direct sensible heat storage and one-tank direct sensible heat storage are 15 gCO2-eq/kWh and 11 gCO2-eq/kWh, respectively. The two systems offer higher energy performances and lower emissions than the other storage systems and thus the potential to be implemented commercially for concentrated solar power applications.

Evaluation of the onshore wind energy potential in mainland China—Based on GIS modeling and EROI analysis

Due to the advantages of relatively mature technologies and low greenhouse gas pollution, wind energy represents a vital energy alternative for electricity generation. Using onshore wind power has become increasingly important in China. Currently, wind energy faces energy return on investment (EROI) and geographical constraints, which both have significant impacts on net wind energy potential. This study combines GIS modeling, wind turbine performance, and the wind speed distribution with a large daily dataset to estimate onshore technical and net wind energy potential in China and to visualize the available wind energy potential. In this study, more detailed local topographic effects (changing air density, surface roughness, air density, array placement efficiency) were considered despite the complexity of applying them at a country level. The results show that the technical potential of China’s onshore wind energy could reach 2560 TW h/yr in a 0% agriculture land scenario and 3501 TW h/yr in a 70% agriculture land scenario, and the net energy potential could reach 2335 TW h/yr and 3194 TW h/yr when EROI = 11.4:1 (when averaging performance of turbines across geographic areas) in these two different scenarios.

Life cycle assessment, energy balance and sensitivity analysis of bioethanol production from microalgae in a tropical country

Overuse of petroleum and ongoing carbon-di-oxide (CO2) rise in the air of Brunei Darussalam has been emerged as a major environmental concern in this country. To resolve this issue, a comprehensive life cycle assessment (LCA) of alternative biofuel, bioethanol production from microalgae was demanded for realistic implementation. Therefore, LCA of bioethanol production from microalgae in terms of CO2 emission and energy balance was investigated based on the scenario of industrial-scale in Brunei Darussalam. This study demonstrated that 220 tons microalgae biomass was cultivated on 6 ha offshore lands for commercial bioethanol generation. The annual outcome of this commercial bioethanol plant has revealed net CO2 balance 218.86 ton. From the energy perspective, this study manifested itself as favourable with net energy ratio, 0.45 and net energy balance, −2749.6 GJ y−1. Apart from CO2 balance and energy generation aspect, the project demanded low water and land footprints. For photobioreactor cultivation, water and land footprints were 2 m3 GJ−1 and 2 m2 GJ−1, respectively as well as for open pond approach, they were 87 m3 GJ−1 and 13 m2 GJ−1, respectively. The project also presented microalgae growth supplements (phosphorus and nitrogen) accumulation possibilities from wastewater of manure and industries which is another positive aspect for benign environment. Overall, the commercial plant presented low CO2 emission, low land and water demand for microalgae cultivation, alternative eco-friendly and cheaper nutrients sources, quite high energy generation with main product and by-products. Thus, this study projected positive impact on energy and environmental aspects of microalgae-to-bioethanol conversion.

An Improved Model for Marine Energy Price and Efficiency Assessment

Li, Z. and Liu, Y., 2019. An improved model for marine energy price and efficiency assessment. In: Gong, D.; Zhu, H., and Liu, R. (eds.), Selected Topics in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 94, pp. 640–647. Coconut Creek (Florida), ISSN 0749-0208.It's generally known that ocean stores abundant energy resources for the development and growth of human beings. Nowadays, the sustainable development of marine economy calls for precisely speculation of marine energy prices and efficiency. However, the traditional methods of measuring energy price and efficiency, for instance, the EROI (energy return on investment) model unable to define system boundaries and to calculate labor and physical costs, be it tidal energy or marine biomass energy. Thus, these methods may ignore as much as 50% of input energy consumption. Energy efficiency could be calculated by the ratio of average energy input cost to the average useable energy output cost while energy price could be measured by the ratio of the monetary input to the output. The principle above could be viewed as a check for energy return on investment as well as an elimination for a redundant process analysis. The results give us a chance to innovate traditional energy efficiency model by social and environmental factors which could be depicted through monetary terms. The precise estimation of marine energy efficiency could also help us make appropriate policies to combat global warming.

Dynamic Energy Return on Energy Investment (EROI) and material requirements in scenarios of global transition to renewable energies

A novel methodology is developed to dynamically assess the energy and material investments required over time to achieve the transition from fossil fuels to renewable energy sources in the electricity sector. The obtained results indicate that a fast transition achieving a 100% renewable electric system globally by 2060 consistent with the Green Growth narrative could decrease the EROI of the energy system from current ~12:1 to ~3:1 by the mid-century, stabilizing thereafter at ~5:1. These EROI levels are well below the thresholds identified in the literature required to sustain industrial complex societies. Moreover, this transition could drive a substantial re-materialization of the economy, exacerbating risk availability in the future for some minerals. Hence, the results obtained put into question the consistence and viability of the Green Growth narrative.

Predicting nutrient digestibility and energy value for broilers.

Digestibility coefficients of nutrients, metabolizable energy (ME), net energy (NE) and the ratio of NE to ME (NE/ME) of 20 diets were measured in broiler chickens (1 to 21 d). Dietary nutrients were formulated to keep similar ME/nutrient ratios, except for dietary protein, fat, and fiber using corn, soybean meal, animal protein blend, barley, poultry oil and an enzyme mixture of xylanase, glucanase, and phytase. Digestibility coefficients of nutrients and ME were measured in battery cages under free-access of feed, while NE was measured in floor pens feeding 75% of recommended ME intake each day. NE for maintenance was calculated on basis of mean metabolic weight using a coefficient from a previous study and NE for gain was calculated by body protein and fat gains using dual-energy x-ray absorptiometry. Digestibility coefficients of protein and neutral detergent fiber (NDF) were curvilinearly related to dietary protein and NDF, respectively, while digestibility coefficients of fat and starch were linearly correlated to dietary fat and starch, respectively. The inclusion of enzymes increased the digestion coefficient of NDF to predict the digestibility of protein, NDF, fat, and starch. MEn/gross energy ratio averaged 72.5% and was correlated to protein, fat, NDF, and starch. ME values were accurately predicted from chemical characteristics, where best equations were obtained from digestible nutrients. Energetic efficiencies of ME were 72% (NE/MEn) and 68% (NE/ME) and varied by about 20 and 18%, respectively. Ratios of energetic efficiency were 68% for digestible carbohydrates; 86% for digestible fat; and 76% (NE/MEn) and 59% (NE/ME) for digestible protein. According to the lowest residual standard deviation the best nutrient components to predict energy were digestible nutrients for predicting ME values (41kcal/kg); digestible protein intake, fecal organic matter, and body fat and protein for predicting heat increment values (111kcal/kg); and combination of ME and crude nutrient for predicting NE values (140kcal/kg).

Effects of crop rotation on energy use efficiency of irrigated potato with cereals, canola, and alfalfa over a 14-year period in Manitoba, Canada

Crop rotations can be used to optimize energy use efficiency (EUE) by preserving or enhancing optimal fertility and chemical use and reducing greenhouse gas (GHG) emissions. A field experiment consisting of six rotations of potato (Solanum tuberosum L.) with canola (Brassica napus L.) (P-C), wheat (Triticum aestivum L.) (P-W), canola-wheat (P-C-W), oat (Avena sativa L.)-wheat (P-O-W), wheat-canola-wheat (P-W -C-W), and canola underseeded to alfalfa (Medicago sativa L.)-alfalfa-alfalfa (P-C(A)-A-A) was conducted on a clay loam soil in Manitoba, Canada for 14 years to assess the relative energy use performance of potato and all crops in each rotation. The potato phase in the P-C(A)-A-A rotation had the largest average annual net energy (93.5 GJ ha−1), the largest output/input energy ratio (3.65), the highest potato yields harvested per GJ input (1013 kg GJ−1) and the lowest cost per tonne of carbon retained ($912 t−1) in comparison with potato in the other rotations. The net energy, energy ratio, and potato yield harvested per GJ input used for potato in P-C(A)-A-A was, respectively, 11%, 10%, and 9.5% higher than 2-yr P-W or P-C rotations. Similarly, cost per tonne of carbon retained for potato in the 2-yr rotations was 8% higher than for potato in the P-C(A)-A-A rotation. The 2-yr rotations performed well in terms of EUE and economics in early cycles of the study but became less efficient as the study progressed due to buildup of plant diseases and decreased yields. The EUE indicators of entire rotations were different; however, the overall results suggested that the longer P-C-W or P-C(A)-A-A rotations are beneficial in that P-C-W provided better economic and EUE outcomes overall while P-C(A)-A-A provided the best potato yield and environmental indicators. These findings suggest that potato growers should include a legume in their crop rotation systems to enhance energy use efficiency while maintaining crop productivity.

Evaluating the Environmental Impacts and Energy Performance of a Wind Farm System Utilizing the Life-Cycle Assessment Method: A Practical Case Study

The ever-increasing popularity of finding alternative forms of renewable energy has seen an increased interest and utilization of wind energy. The objective of this research therefore, is to evaluate the environmental impacts and energy performance of wind farms. This study was operationalized in Jordan using a life-cycle assessment (LCA) method. The environmental impact is evaluated through lifecycle emissions that include all emissions during various phases of the project. The energy performance is illustrated by the energy indicators. The latter is the energy payback ratio (EPR) and the energy payback time (EPT). This study was conducted on a 38 Vestas V112 3-MW wind turbine located in the southern region of Tafilah in Jordan that is host to the country’s first wind farm. SimaPro 7.1 software was used as the modeling platform. Data for this study were collated from various sources, including, manufacturers, the wind turbine farm, and local subcontractors. A software database was used for the modeling process, and the data obtained modeled in accordance with ISO 14040 standards. The findings of this study indicate that the impacts of the transportation and installation phases were moderate, with the largest negative environmental impact deriving from the manufacturing phase. To remedy some of the negative impacts in these phases, green cement was used for the turbine foundation to limit the environmental impacts to be had during the installation phase, while the transportation phase saw the utilization of locally-manufactured turbines. Furthermore, an evaluation of the study’s results revealed that the energy payback period of the wind farm is approximately 0.69 year (8 months), while the payback ratio is 29, and the annual CO2 saving estimated to be at 2.23 × 108 kg, 3.02 × 108 kg, 3.10 × 108 kg for an annual generated power of 371, 501, and 515 GWh/year.

Economic and environmental impact assessments of a stand-alone napier grass-fired combined heat and power generation system in the southeastern US

Napier grass, one of the high yield perennial energy crops can be grown on marginal lands with minimal inputs, but with increased soil carbon sequestration in the southeastern US. The sustainable use of Napier grass for bioenergy applications such as combined heat and power at low cost to mitigate greenhouse gas emissions needs to be investigated. In this study, an integrated life cycle assessment and techno-economic analysis approach were used to estimate the energy use, environmental emissions, and minimum selling price (MSP) of electricity and thermal heat produced from Napier grass and compared with a coal or natural gas-fired combined heat and power generation plant. The use of Napier grass as a feedstock decreased the global warming potential (GWP) of the medium-sized CHP (i.e., 13 MWe) plant by 73–92 % compared to that of a coal and natural gas-fired CHP plants. Other environmental impacts were also reduced by 24–100 %. Eutrophication was the only impact comparable to that of the coal-fired CHP plant. The energy return on investment (EROI) was around 5:1. The minimum selling price of electricity generated from the CHP plant was US$0.05–0.4 MJe−1 (US$0.13–0.18 kWh−1) considering the credits for steam production, renewable electricity production tax credit (PTC), and carbon footprint from the fossil fuel-based electricity generation. Although the pelleting of Napier grass for the CHP plant increased the cost and GHG emissions by 38% and 55% over the non-pelleted system, the pelleting process can ensure consistent quality and uninterrupted supply of the feedstock for heat and power generation.