torsdag 27. juni 2013

Geothermal energy for the future!

Av Henrik Holmberg, stipendiat ved Fakultet for ingeniørvitenskap og teknologi, Institutt for energi- og prosessteknikk, NTNU

Geothermal energy has received increasingly international interest during the recent years. One example of this is the yearly geothermal conference at Stanford University in USA where both the number of publications and participating countries has increased rapidly during the last 5 years. Geothermal energy is commonly used both for heating demands and for electricity production and the theoretical potential is enormous. In a MIT-rapport from 2006 it is estimated that the resource can contribute with up to 100.000 MW electricity in USA within the next 50 years [1].
Geothermal energy referrer to the thermal energy that is produces in earth’s crust through breakdown of radioactive isotopes and the heat that is transported outwards from earth’s interior.  The concept geothermal energy includes both deep geothermal energy systems where heat is mined from depths of several kilometers and shallow geothermal systems where wells with depths of a few hundred meters are used in ground source heat pump (GSHP) systems. While shallow geothermal energy is indeed an important part of the geothermal sector, deep geothermal energy is the focus for this text.
Deep geothermal energy has long been tightly associated with the geographically constricted and naturally occurring hydrothermal systems in volcanic active regions, see figure 1. In recent years it has been pointed out that engineered geothermal systems (EGS) can provide a way for geothermal energy to grow outside its geographical constraints and thereby to reach a significant share of its huge global potential. 

Figure 1. Manifestation of hydrothermal system in Iceland.

onsdag 19. juni 2013

Noreg - ein framtidig biogassnasjon?

Av Kristian Fjørtoft, stipendiat ved Institutt for matematiske realfag og teknologi (IMT), Universitet for Miljø og Biovitenskap (UMB)

Svar: Nei!

Det er lite truleg at biogass , i overskodeleg framtid, vil utgjere ein betydeleg del av BNP i Noreg. Like  vel kan biogass utgjere ein særs verdifull del av det framtidige biletet der fornybar energi skal dekkje ein stadig større del av Noreg sitt energibehov.

I arbeidet mitt her ved UMB har eg mellom anna sett på sett på forbehandling av halm og samrotning av storfegjødsel med ulike tilleggssubstrat. Det er eigentleg ganske utruleg at mikroorganismar dannar høgverdig kjemisk energi frå avfall og gjødsel. I følgje Raadal (2008) kan avfall og biprodukt på landsbasis gje seks TWh i året i form av biogass. Etter utrotninga vil substratet ved eit gardsbiogassanlegg verte nytta til gjødsel på åker til ny fôr- og matproduksjon. Næringsemna har gjennom prosessen ikkje berre vorte bevart men også gjort meir plantetilgjengeleg. Såleis styrker ein grunnlaget for matproduksjon for komande generasjonar samstundes som ein hentar ut fornybar energi.

tirsdag 11. juni 2013

Believe in the unbelievable!

by Ida Fuchs, Higher Executive Officer, SFFE - Centre For Renewable Energy, NTNU

Happy renewable times

We live in the happy situation to observe an enormous growth of renewable energies. Some of you might say that it is still not enough, while others think it is too much, but really, personally, I am proud of every brain who contributed with a part to the big puzzle. When I read the news and found that in Germany, my home country, sun and wind covered half of the power capacity demand in April 2013, I felt simply happy and really proud of my fellow engineers, scientists, economists and also politicians. The latter provided really great programmes to give renewable technologies the necessary push into the business. A great example is the 100.000 Roofs Programme, a subvention programme for photovoltaic installations.

World’s Firsts
A lot of exciting things happen in the renewable energy field and you can find many “World’s Firsts”. I was the lucky master student who got the possibility to write a master thesis about the world’s first autonomous wind and hydrogen system and it is located here in Norway on the small island Utsira. And not far away from there the world’s first floating wind turbine was set into the sea. Lately, I came across the incredible promising Sahara Forest Project where they grow food in the desert by using a smart process to condence fresh water out of the sea. And another incredible project is the Omega System where the growth of algae cleans wastewater, captures carbon dioxide and ultimately produces biofuel without competing with agriculture for water, fertilizer or land. 

tirsdag 4. juni 2013

Say nano for better solar cells?

by Hanne Kauko, PhD Candidate at Department of Physics, NTNU

Solar energy is undoubtedly one of the main candidates for our future renewable energy providers. The sun is essentially inexhaustible, and a very abundant source of energy: the rate of solar irradiation incident on the earth is 10 000 times greater than the rate at which people use energy [1]. Solar cell technology - that is, technology for direct conversion of sunlight into electricity – is currently one of the fastest emerging technologies.

There is a wide variety of possible solar cell technologies, the most common still being a simple planar silicon (Si) solar cell based on the junction between p- and n-doped silicon – even though already in the 1970s it was thought that Si would eventually give way to other technologies with higher efficiency and less energy-demanding production. The drastic price reduction of the raw material for Si solar cells, and the entry of Chinese solar-cell manufacturers into the market, has however brought the price of Si solar panels rapidly down. This has been the death strike for most Norwegian solar cell producers – but it has of course been very positive for increasing the usage of solar panels on roof tops world wide. Nevertheless, a Si solar cell is far from being optimal, and better alternatives are constantly searched for.