Continued population growth could lead to protein deficiency in the human diet. To counteract this risk, attempts are being made to identify new edible sources of protein. The aim of this paper was to review the existing literature and to analyse the current state of yellow mealworm (Tenebrio molitor) rearing for food and feed, especially in Europe. The yellow mealworm is the most widely bred and traded insect species in Europe that has high feed conversion ratio; 3.4 to 6.1 kg of feed ingested per kg of harvested larvae. Mealworms could compete with livestock due to their high protein and fat content and low environmental impact. Mealworms have been extensively researched as a source of feed for animals, including poultry, fish, pets and birds. Its nutrient content depends on the processing method, where thermal processing is least desirable. Mealworms are characterised by a high and variable microbial load which has to be reduced before consumption. The antibiotics, pesticides and other substances should also be analysed to ensure that mealworms are a safe protein source for human consumption. The nutritional benefits of mealworms have to be communicated to European consumers who are generally averse to eating insects.

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Silphium perfoliatum is a perennial crop native to North America that has been the subject of increased scientific interest in recent years, especially in Europe. It is drought- and frost-resistant, which makes it suitable for cultivation in Europe on marginal lands that are not used for growing other crops. This review analyzed the distribution and purposes of the cultivation of Silphium perfoliatum worldwide, as well as its biomass yields and characteristics as a feedstock for biogas production and other purposes. A total of 121 scientific publications on Silphium perfoliatum were identified, with the highest number (20 papers) published in 2019. It was found that higher biomass yields can be obtained at higher precipitation levels, with the use of fertilizers and an adequate type of plantation. The mean dry matter yield of Silphium perfoliatum was 13.3 Mg ha−1 DM (dry matter), and it ranged from 2 to over 32 Mg ha−1 DM. In some countries, Silphium is used as a forage crop mainly due to its high crude protein content (from 4.9% to 15% DM), depending on the vegetation phase. Silphium perfoliatum is a promising perennial crop in terms of energy and other benefits for biodiversity, soil quality and applications in medicine and pharmacology.

Since the world’s population will continue to grow in the next decades, the problem of providing people with food will deepen. One-third of the food production volume is wasted while nearly one in ten people in the world suffer from hunger. To reduce the negative impact of human activity on the environment and meet the needs of the population, alternative sources of protein are proposed. Yellow mealworm larvae can be used as a source of food and animal feed. Therefore, this study aimed to compare the growth performance, feed conversion ratio (FCR) and efficiency of ingested feed (ECI) by yellow mealworm larvae fed 13 different diets containing chicken feed (CF), rapeseed meal (RM), wheat bran (WB) and willowleaf sunflower (WS) residues after the process of supercritical CO2 extraction. The mean dry individual bodyweight for all diets used in the experiment was 31.44 mg dry matter (d.m.) Mealworms fed diet mixes that contained WB demonstrated the highest dry individual larval weight (from 40.9 to 47.9 mg d.m.). A significantly lower dry individual larval weight was found for mealworms fed solely WS residues (3.9 mg d.m.). The FCR ranged from 1.57 to 2.08, for pure CF and pure WS diet, respectively. The ECI of yellow mealworm larvae varied significantly (mean value 20.1%) and depended on the diet. Moreover, the ECI of mealworm was significantly the lowest and amounted to 5.9% for the pure WS diet. The industrial residues investigated in this study can be successfully used for mealworm farming, excluding pure willowleaf sunflower residues.

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Renewable energy is becoming a widely discussed topic in the European Union (EU), due to a desire to reduce the negative effects of fossil fuels on climate change and biodiversity. About 60% of the total renewable energy produced in the EU is derived from biomass. Anaerobic digestion (AD) is an important pathway to convert biomass into biogas and then into bioenergy. Helianthus salicifolius is a perennial plant, whose biomass can serve as a co-substrate in biogas plants. Biomass composition, in addition to the biomethane and biogas potential, were investigated in raw green biomass and silage obtained from Helianthus salicifolius plants grown under different types (mineral and organic) and doses (0, 85, 170 kg N ha−1) of nitrogen fertilization. The biomethane production efficiency from Helianthus salicifolius was recorded for 25 days and found to range on average between 169.4 NL kg−1 VS for raw biomass and 193.2 NL kg−1 VS for silage. It follows from the current study that ensiling increases substrate digestibility and has a positive impact on methane concentration, but the biomethane and biogas production outputs from those substrates did not differ significantly at the end of the process.

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Biogas production is one of the solutions for replacing fossil fuels, which promotes the widespread use of green energy. The aim of this study was to determine the potential of Silphium perfoliatum as an energy crop for biogas production, as well as the effect of different fertilization doses (0, 85 and 170 kg N ha−1) on the production potential (NL CH4 kg−1 VS) of Silphium perfoliatum. The study investigated the use of different feedstocks, such as raw and ensiled Silphium perfoliatum biomass. The methane production ranged between 193.59 and 243.61 NL CH4 kg−1 VS. The highest biogas production potential was achieved with the biomasses which were cultivated with the highest fertilization dose (170 kg N ha−1), both for raw and ensiled crop biomasses, although the difference from the other fertilization doses was not significant. The feedstock (biomass and silage) and digestate parameters were investigated as well. The use of Silphium perfoliatum for biogas production seems very promising since its methane production potential was found to be similar to that of the most common energy crop, such as maize, indicating that Silphium perfoliatum can compete in the future with maize.