Microalgae-utilizing biorefinery concept for pulp and paper industry: Converting secondary streams into value-added products

Traditional pulp and paper industry is in transition due to increased competition and changes in consumption habits. Advanced biorefining is seen as one option to create new business opportunities. This article presents a microalgae-utilizing biorefinery which is integrated into a traditional pulp and paper mill and which produces high-value algal products, fertilizer and biogas from secondary process streams. Presented biorefinery process is validated with mass balances, employing initial data from a Scandinavian pulp and paper mill. Results indicate that the proposed process is technically viable. Production potential is sensitive to light and nutrient availability in algae cultivation, and seasonal changes in irradiance result in significant output variation. The biorefinery process can be generalized to other process industry and wastewater treatment plants that have similar output flows.Peer reviewe

Energiatehokkuuden mittarit ja potentiaalit

The first objective of the research ‘Energy Efficiency Metrics and Improvement Potentials’ was to study how energy efficiency is measured in different sectors. The second objective was to study how energy efficiency improvement potential could be evaluated on a sectoral basis, and more comprehensively in society as a whole. The research covered five sectors: communities, buildings, transportation and logistics, (process) industry and energy production. According to the Energy Service Directive 2006/32/EC (EC, 2006), energy efficiency is defined as “a ratio between an output of performance, service, goods or energy, and an input of energy”. The output of performance, service, goods or energy covers a wide range of subjects. This results in a variety of energy efficiency metrics. Sometimes it is useful to provide a broader perspective on energy efficiency measurement(e.g. kWh/m3, kWh/m2, etc. in the construction and real estate sector). Sometimes explanatory metrics are also needed, e.g. ‘the capacity utilisation rate’ in the process industry sector. In the analysis of efficiency, one must make decisions about how to set the balance boundary and how to take the life-cycle aspects into account. It is worthwhile to compare only objects which have been defined in a similar way. Energy is used in different forms: as fuel, electricity and heat. Different forms of energy should not be aggregated until they have been transformed into a comparable form. This is made using so-called primary energy factors. There are varying practices in the use of primary energy factors, and the ways in which they are calculated is not well established. Energy efficiency and energy efficiency potential should be studied primarily using energy units. Carbon dioxide (or greenhouse gas) efficiency can be used as a supporting and complementary evaluation criterion. Energy efficiency improvement potential means a difference in energy consumption between the current situation and the reference situation. Defining the reference situation, i.e. the target state, is one of the challenges in calculating the potential. Such a target state can be the best known reference (such as BAT), or ideal performance. No common method exists to define the target state, so practices vary between the sectors. For example, the concept ‘ideal state’ is not even suitable in communities and logistics. A case study was carried out during the late part of the research to calculate the energy efficiency potential of an example area. The study was made in the Kalasatama district near the city centre of Helsinki. The case study verified for example, that metrics from different sectors can be combined in a single study. Based on the study it can be said that the methods being used are still undeveloped, and much research is needed in this area. In practical work, emphasis should be put on reaching agreements concerning the standardisation of energy efficiency calculation methods.Energiatehokkuuden mittarit ja potentiaalit (EPO) – tutkimushankkeen ensimmäinen tavoite oli selvittää, miten energiatehokkuutta mitataan eri sektoreilla. Toinen tavoite oli selvittää, miten energiatehokkuuden parannuspotentiaalia arvioidaan sektorikohtaisesti ja myös kattavammin koko yhteiskunnassa. Tutkimuksessa mukana olleet sektorit olivat: yhdyskunnat, rakennukset, (prosessi-) teollisuus, liikenne ja logistiikka sekä energiantuotanto. Energiapalveludirektiivin 2006/32/EY mukaan (EU, 2006):”Energiatehokkuus on suoritteen, palvelun, tavaran tai energian tuotoksen ja energiapanoksen välinen suhde”. Tämä suorite, palvelu, tavara tai energian tuotos on laaja joukko erilaisia asioita. Näin ollen myös energiatehokkuuslukuja on erilaisia. Energiankulutusta on usein tarkasteltava useammasta näkökulmasta kattavan kokonaiskäsityksen saamiseksi (esim. rakennussektorilla kWh/m3, kWh/m2, jne.). Energiankulutusluvun tukena on usein ilmaistava myös selittäviä tekijöitä, kuten teollisuudessa kapasiteetin käyttöaste. Laskelmia tehdessä on tehtävä rajauksia koskien kokonaisuuden laajuutta ja sitä miten huomioidaan elinkaarivaikutukset. Vain samalla tavalla rajattuja kohteita on mielekästä vertailla toisiinsa. Energiaa käytetään eri muodoissa: polttoaineina, sähkönä ja lämpönä. Erilaisia jakeita ei tulisi laskea yhteen ennen niiden muuttamista keskenään vertailukelpoiseen muotoon. Tähän käytetään ns. primäärienergiakertoimia. Kertoimien käytössä on vaihtelevia käytäntöjä eikä laskenta ole vakiintunut. Energiatehokkuutta kuten sen tehostamispotentiaalia tulee ensisijaisesti tarkastella energiayksiköiden avulla. Hiilidioksidi- tai kasvihuonekaasutehokkuutta voi käyttää tukevana ja täydentävänä arviointikriteerinä. Energiatehokkuuden parannuspotentiaali on ero energiankulutuksessa nykytilanteen ja vertailutilanteen välillä. Potentiaalin laskennan haaste kulminoituu tavoitetilan eli vertailutilanteen määrittämiseen. Vertailutilanteena voidaan käyttää parasta nykykäytäntöä (esim. BAT) tai ideaalitilannetta. Vertailutilan määrittämiseen tai laskemiseen ei millään tutkituista viidestä sektorista ole olemassa yleisesti hyväksyttyä, käytössä olevaa menettelytapaa ja siksi käytännöt vaihtelevat. Esimerkiksi yhdyskuntien ja logistiikan sektoreille käsite "ideaalitilanne" ei edes sovellu hyvin. Tutkimuksen aikana suoritettiin kokeilulaskenta yhdessä yhteisessä kohteessa, joka oli Helsingin Kalasatama. Case laskenta osoitti mm., että eri sektoreiden mittareita voidaan käyttää samanaikaisesti valitun kohteen energiatehokkuuden tarkastelussa. Mittareiden käyttö eri laskentatapausten vertailussa mahdollistaa energiatehokkuuden potentiaalin arvioimisen. Tutkimuksen perusteella voidaan sanoa, että menetelmät energiatehokkuuden mittaamiseksi ja potentiaalien laskemiseksi ovat vielä varsin kehittymättömiä siihen, että ne toimisivat käytännön työn ohjaajina. Aihealueella on edelleen perustutkimustarve. Käytännön työssä tulisi edistää sopimuksia liittyen laskennan pelisääntöihin

Optimisation model for integration of cooling and heating systems in large industrial plants

Large industrial plants have often hundreds of heating and cooling heat exchangers. A common situation is that cooling demands of the processes are satisfied without any deeper analysis of the overall impact of the cooling systems on the plant’s economy or the environment. If cooling water is available it is used as much as needed and then pumped back to the river, some degrees warmer. An optimisation model was developed for integration of cooling and heating systems to tackle the problem. An industrial cooling system is a complex energy system comprising different options of producing cooling, distribution pipelines for cold media and cooling storages. Integration of power generation and heating systems to the cooling systems was included in the model. An illustrative example is presented in the paper. 10 process streams with cooling demand and 10 streams with heating demand were chosen, situated at different locations at the plant site. The optimal matches between the streams were found together with the sizes of the heat exchangers and the demands of hot and cold utilities. The costs of pipelines and the pumping costs of the streams are included in the model. The model can be used in the design of greenfield and retrofit investments and in versatile what-if analyses of the plant design or operation

Business angel investment decision-making criteria

OBJECTIVES OF THE STUDY: The purpose of the thesis is to provide new evidence and address the partially lacking understanding of business angel decision-making. This thesis studies the issue by investigating both the investment criteria and the rejection criteria business angels use to decide whether an opportunity should advance beyond the initial screening stage to the due diligence. The study focuses on the pitch meetings, in which entrepreneurs try to sell their ideas and equity to business angels in exchange for capital. DATA: The unique hand-coded data on business angels is sourced from a TV show called the Dragons' Den. By analysing the latest two UK production seasons, I was able to observe the decision-making process of seven business angels, of which three were female. The total number of observed pitch meetings amounts to 129, which consists of 27 successful pitches and 102 declined ones. The empirical evidence of business angel rejection criteria is based on 241 rejection reason provided by the investors. The above-average sample size is considered to be reasonable in the area of studying business angel decision-making. RESULTS: The results suggest that business angels invest primarily in early stage or start-up companies seeking for expansion financing. In their investment decision-making, business angels place emphasis on the entrepreneur, product and financials and intend to add value by taking hands-on roles. On the other hand, the partially contradictory findings to prior literature suggest, that the most important rejection criteria are related to financials, product and market. My findings also suggest that the investor fit criteria and investors' gender is affecting the decision-making of business angels

Determination of the Real Loss of Power for a Condensing and a Backpressure Turbine by Means of Second Law Analysis

All real processes generate entropy and the power/exergy loss is usually determined by means of the Gouy-Stodola law. If the system only exchanges heat at the environmental temperature, the Gouy-Stodola law gives the correct loss of power. However, most industrial processes exchange heat at higher or lower temperatures than the actual environmental temperature. When calculating the real loss of power in these cases, the Gouy-Stodola law does not give the correct loss if the actual environmental temperature is used. The first aim of this paper is to show through simple steam turbine examples that the previous statement is true. The second aim of the paper is to define the effective temperature to calculate the real power loss of the system with the Gouy-Stodola law, and to apply it to turbine examples. Example calculations also show that the correct power loss can be defined if the effective temperature is used instead of the real environmental temperature