Final Report: Pyrolysis of Algal Biomass in a Solar Furnace Reactor

EPA Grant Number: SU836018
Title: Pyrolysis of Algal Biomass in a Solar Furnace Reactor
Investigators: Deng, S. , Dailey, Peter , Garcia, Chris , Herrera, Edward , Muppaneni, Tapaswy , Willis, Adam , Wise, Christopher
Institution: New Mexico State University - Main Campus
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Agriculture , P3 Challenge Area - Energy , P3 Awards , Sustainability

Objective:

Algal biofuels are some of the most promising renewable-energy resources that could potentially replace part of the fossil fuels for driving tomorrow’s economy. A large quantity of lipid extracted algal biomasses will be produced if an algae-based economy is to occur. The success of the algae-based economy not only depends on the main liquid fuel products, but also critically depends on the optimal utilization of algal biomass residue. The New Mexico State University team has proposed a solar-driven pyrolysis process for converting whole algae into solid, liquid and gaseous fuels to enhance the energy recovery from the algal biomasses. This project strongly supports our on-going algal biofuels research activities by utilizing a unique solar furnace that can provide a maximum of 4.2 kW of solar thermal energy at 1600 degrees Celsius.

The main objective of this research was to show, on a lab scale, the feasibility of using a solar furnace in the pyrolysis of algae. This objective strongly supports the ideals of the EPA P3 competition. Algae biofuels is a carbon neutral alternative to petroleum-based fuels, making it extremely environmentally friendly for our planet. When an economically competitive alternative fuel is introduced as an alternative to petroleum fuels, the supply in the market will rise, and thus the price of all fuels will decrease. A decrease of any magnitude in the price of petroleum makes all consumers of energy wealthier, and thus prosperous from the newfound wealth.

Summary/Accomplishments (Outputs/Outcomes):

We went through many different designs of the lab-scale pyrolysis reactor powered by a solar furnace to convert algal biomass into liquid and gaseous products at controlled conditions. The temperature and pressure achieved in the reactor from the solar furnace was measured to provide accurate control for the pyrolysis reaction. We pyrolyzed the algae sample in a high pressure pyrolyser, where temperature and pressure can be maintained to do the pyrolysis. The feedstock and pyrolysis reaction products were analyzed by FT-IR (fourier transform infrared spectroscopy), GC-MS (gas chromatography mass spectrometry), and TGA (thermo gravimetric analysis). These methods can be used to determine the energy content and composition of the feedstock and pyrolyzed algae liquids, gasses, and solids.

The major project activities included: Design and manufacturing of the reaction vessel, running of the solar furnace, running the commercial pyrolyser, characterization of the feedstock and pyrolyzed algae, design of the gas capture system, and running of the conventional furnace. The main findings of this project are:

  1. A maximum of about 535 degrees Celsius (1000F) was achieved inside the reaction vessel.
  2. The main constituents of the pyrolyzed algae from t

Conclusions:

  1. Solar furnaces are able to generate a lot of heat in a small area and in a very small amount of time.
  2. Weather is a major impediment to using a solar furnace. When there is no sun or it is too windy to safely use the solar furnace, tests cannot be run. These problems would have to be addressed before an industrial sized plant could become feasible.
  3. Most of the cost of algae is in the cultivation and drying stages, not the conversion from algae to fuel.
  4. Because of the high temperatures experienced in the reactor, heat resistant materials must be used. This creates an increase in cost.
  5. In order to keep reaction times low and to minimize the degradation of the reactor, a clear window is used to direct sunlight directly onto the algae sample. Quartz glass worked very well for this.

Supplemental Keywords:

Algae, biodiesel, biofuels, green, energy, pyrolysis, solar, furnace, gasification, methane, GC-MS, FT-IR, TGA, New Mexico State University, reactor, biomass, gas capture, carboxylic acids, silicates, solid, liquid, oil