Bioenergy

Bioenergy means energy utilization of biomass as wood, wood chips, pellet, organic waste, straw, algaes etc. The most common utilization of bioenergy is combustion for heat production. It is also possible to produce electricity, biofuels, biogas and hydrogen from biomass.

Bioenergy is a flexible fuel that is possible to utilize in everything from small ovens for heat production in private houses to big combustion units at several hundred MW.

Increased use of bioenergy is an expressed goal both internationally and for the Norwegian energy supply. In Norway biomass will play a considerable role in achieving the goal of increasing the use of renewable heat energy.

Technology
There is a lot of different technologies related to utilization of bioenergy, where the most common one is small scale heat stoves for house heating, at least in Norway. Boilers with sizes between 0,2 and 5 MW is also quite common. The boilers are then connected to a district heating system, distributing the heat by water.

Boilers larger than 20 MW are usually producing electricity in addition to heat. It is becoming more and more widespread to add biomass, as woodchips and straw, to the combustion chamber in CO2-fired power plants to reduce the emissions of CO2.

Gasification is a technology that involves heating of the biomass to 700-1000 degrees without sufficient oxygen for combustion. The solid biomass is then converted to an energy rich gas consisting of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2) and methane (CH4). This gas is usable for a lot of different purposes as power prdouction in motors or turbines. The gas is also convertible to liquid biodiesel through a Fischer-Tropsch reactor.

The heating of biomass above 430 degrees in the absence of oxygen is a technology calledpyrolysis, a process that produces charcoal, tar and the gases methane and hydrogen.

Biofuels
Liquid bioenergy, biofuels, has the advantage that it has a high energy density, easy to store and transport. It is also relatively easy to replace fossil based gasoline and diesel with biofuels.

Biofuel is normally divided into two kind of fuels; alcolhols (bioethanol) and vegetable oils (biodiesel). Ethanol and methanol is the two most common alcohols that is used as fuel. Ethanol is produced from plants as sugar cane, corn, potatoes and all kind of fruits. The highest volume of pure alcohol is produced through fermentation of biproducts from sugar cane harvesting. The global production of bioethanol is four times higher than the total production of biodiesel, and USA and Brazil is responsible for 88 percent of the total production.

It is possible to mix until 5 percent bioethanol in regular gasoline without experiencing car engine problems. The gasoline named E85, consisting of 85 percent bioethanol, is possible to use in cars designed to handle this fuel.

Biogas
As wet organic material is degraded, it produces biogas, consisting mainly of methane and karbondioxide. Methane is an energy rich gas (natural gas) that is possible to utilize for heat production or in a gas motor, producing both heat and electricity.

Research at NTNU, SINTEF and IFE
NTNU and SINTEF are in front, both national and international, in research on utilization of bioenergy. This includes combustion of all kind of biomass, from waste to pellet, in small heat producing units as well as big units for production of heat and electricity.

Bioenergy projects at NTNU and SINTEF include; utilisation of energy by gasification of waste, distributed energy from biomass and residual waste, development of clean burning fire places, BIOSOFC (Gasification of biomass combined with fuel cells for the production of highly efficient electrical power) and environment and process control.

Chief engineer Morten Grønli shows different forms of bioenergy from wood. Photo: SFFE

SINTEF Fisheries and Aquaculture are doing reserach on the production of sea tangle with the intention of producing biofuels. NTNU Environmental Biotechnology and Microbial Ecology are looking at the possibilities for producing biofuel from algeas and other biological substances, as well as the production of biogass.

Both SINTEF and NTNU participate in the Bioenergy Innovation Centre.

More information
Bioenergy Innovation Centre (CenBio)
Bioenergy, SINTEF Energy Research and SINTEF Materials and Chemistry
Biorefinery, SINTEF Materials and Chemistry
NextGenBioWaste web site
IEA Bioenergy
PyNe – The Biomass Pyrolysis Network

Contacts
Lars Sørum, SINTEF Energy Research
Morten Grønli, NTNU, Department of Energy and Process Engineering
Kjetill Østgaard, NTNU, Institute for biotechnology
Jorunn Skjermo, SINTEF Fishery and Aquaculture