Featured Research

from universities, journals, and other organizations

Hydrothermal liquefaction: The most promising path to sustainable bio-oil production

Date:
February 6, 2013
Source:
Aarhus University
Summary:
A new generation of the HTL process can convert all kinds of biomasses to crude bio-oil, which is sufficiently similar to fossil crude oil that a simple thermal upgrade and existing refinery technology can be employed to subsequently obtain all the liquid fuels we know today. What is more, the HTL process only consumes approximately 10-15 percent of the energy in the feedstock biomass, yielding an energy efficiency of 85-90 percent.

The graphs show the contents of oxygen, hydrogen and carbon in HTL-oil before and after upgrading, compared to other fuel types.
Credit: Mørup et al., Energy & Fuels, 2012, 26 (9), 5944-5953

A new generation of the HTL process can convert all kinds of biomasses to crude bio-oil, which is sufficiently similar to fossil crude oil that a simple thermal upgrade and existing refinery technology can be employed to subsequently obtain all the liquid fuels we know today. What is more, the HTL process only consumes approximately 10-15 percent of the energy in the feedstock biomass, yielding an energy efficiency of 85-90 percent.

Related Articles


To emphasize, the HTL process accepts all biomasses from modern society -- sewage sludge, manure, wood, compost and plant material along with waste from households, meat factories, dairy production and similar industries.

It is by far the most feedstock flexible of any liquid fuel producing process, including pyrolysis, bio-ethanol, gasification with Fischer-Tropsch or catalytic upgrading of different vegetable or agro-industrial residual oils, and does not carry higher costs than these.

Hydrothermal liquefaction is basically pressure cooking, but instead of cooking the biomass in batches, one pot-full at a time, this new generation of HTL is based on flow production, where the biomass is injected into a 400 °C pre-heated reactor, "cooked" under high pressure for ~15 minutes and then quickly cooled down to 70°C.

At 400°C and high pressure the water is in a supercritical state, neither liquid nor gas, at which it easily decomposes the biomass. The process is environmentally friendly, since no harmful solvents are involved, and the energy efficiency is very high: The HTL process only consumes approximately 10-15% of the energy in the feedstock biomass, because the heat energy is recycled between the heating and cooling of the process medium.

The wet medium means that HTL readily accepts moist or wet biomasses, such as those mentioned above. Wet biomasses are in vast majority on Earth. All other known processes for liquid bio-fuel production either require expensive drying or only make use of a limited proportion of the biomass, e.g. the carbohydrate content.

The water phase emanating from the HTL process has low carbon contents and can either be recycled into the process or ultimately be purified to attain drinking water quality, which is the long-term goal. As such HTL replaces the burden of disposal with the benefit of recycling.

The HTL process has the following benefits:

  • Crude HTL oil has high heating values of approximately 35-39 MJ/kg on a dry ash free basis
  • The HTL process only consumes approximately 10-15% of the energy in the feedstock biomass, yielding an energy efficiency of 85-90%
  • Crude HTL oil has very low oxygen, sulphur and water content (compared to e.g. pyrolysis oil which typically contains approx. 50% water)
  • HTL oil recovers more than 70% of the feedstock carbon content (single pass)
  • HTL oil is storage stable, and has comparatively low upgrading requirements, due in part to a high fraction of middle distillates in the crude oil. It is much less upgrading intensive than e.g. pyrolysis oil, which needs immediate upgrading in order not to deteriorate.

The bio-oil from HTL can be used as-produced in heavy engines or it can be hydrogenated or thermally upgraded to obtain diesel-, gasoline- or jet-fuels by existing refinery technology. In this sense, HTL bio-oil is directly comparable to fossil crude oil. This is unique among liquid bio-fuels and means that it can directly enter the existing fuel distribution network for automotive transportation in any concentration, giving it full drop-in properties.

In Denmark, Aarhus University and Aalborg University are in partnership on HTL research at all levels. In Aarhus, Dept. of Chemistry focuses on fundamental understanding of the process and quick surveys of the effects of different feedstocks and catalysts along with subsequent upgrading. Dept. of Agro-Ecology develops energy crops while Dept. of Engineering works on pilot-scale HTL. The latter is pursued even more vigorously at Aalborg University (Dept. of Energy Technology), which focuses strongly on pilot-scale production and process efficiency, as well as upgrading of HTL bio-oil along with end user testing of oils and upgraded distillates in engines and turbines. The Dept. of Biotechnology, Chemistry and Environmental Engineering, AAU Esbjerg, directs its activities towards extracting value not only from the oil, but also from the effluents.

The combined efforts and unique results already obtained hold promise of another energy technology endeavor in Denmark comparable only to the breakthrough of the windmill-industry in the 1980's.


Story Source:

The above story is based on materials provided by Aarhus University. Note: Materials may be edited for content and length.


Cite This Page:

Aarhus University. "Hydrothermal liquefaction: The most promising path to sustainable bio-oil production." ScienceDaily. ScienceDaily, 6 February 2013. <www.sciencedaily.com/releases/2013/02/130206162229.htm>.
Aarhus University. (2013, February 6). Hydrothermal liquefaction: The most promising path to sustainable bio-oil production. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2013/02/130206162229.htm
Aarhus University. "Hydrothermal liquefaction: The most promising path to sustainable bio-oil production." ScienceDaily. www.sciencedaily.com/releases/2013/02/130206162229.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) — The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
NY Gov. on Flood Prep: 'prepared for the Worst'

NY Gov. on Flood Prep: 'prepared for the Worst'

AP (Nov. 23, 2014) — First came the big storm. Now comes the big melt for residents of flood-prone areas around Buffalo. New York's governor says officials are preparing for the worst as the temperature is expected to rise and potentially melt several feet of snow. (Nov. 23) Video provided by AP
Powered by NewsLook.com
Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) — For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Raw: Buffalo Residents Digging Out, Helping out

Raw: Buffalo Residents Digging Out, Helping out

AP (Nov. 22, 2014) — Hundreds of volunteers joined a 'shovel brigade' in Buffalo, New York on Saturday, as the city was living up to its nickname, "The City of Good Neighbors." Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins