Resource and By-products

 Algae: Fast-growing algae absorb energy from sunlight, and are some of the most efficient organisms on the planet to produce biomass. It has been estimated that the yield of algae can reach to 100 tons per acre per year. Up to 60% of the biomass can be converted into bio-fuel with the HTL technology.
Algae can be produced 365 days per year, and have a harvesting cycle of 1-10 days. They can be cultivated on lands, in wastewater, and under conditions that are not suitable for other established crops, and thus do not compete with food crops. Algae can be classified into macroalgae and microalgae. Macroalgae, called seaweed sometimes, are abundant in the world and have been used as feedstock for producing bio-fuels in some researches. But it is microalgae that have attracted people's much more research interests for the mass-production of bio-fuel. Microalgae are unicellular photosynthetic organisms less than 0.4 mm in diameter, and grow fast. Their less complex structure also makes the oil conversion easier. Wastewater from the treatment of sewage, agricultural, or flood plain run-off, and the post HTL process provides nutrient for algae growing. Algae will remove most of pollutants in the wastewater, and the wastewater will become cleaner.
Both high-lipid algae and lower-lipid algae can be directly converted into biocrude oil without any extra drying via HTL. Combining HTL of biowastes with algae production can provide algae with their primary nutrients and purifies the post-HTL wastewater at the same time. For more information about growing algae in waste water, please see

 Agricultural residues: Agricultural residues include those parts of arable crops not to be used for the primary purpose of producing food, feed or fiber, used animal bedding and feathers, such as straw and corn stover. Many agricultural crops and processes yield residues, and it is estimated that the annual production of agricultural residues in the United States is between 140 and 350 million tons.
It has been reported that the oil yields from agricultural residues with HTL technology range from 21% to 36%, depending on the species and parts of feedstock. We have achieved about 50% conversion of corn fiber with HTL. Although there is no need to reduce the moisture content in agricultural residues before the conversion, a pretreatment to reduce agricultural residue sizes to sub-millimeters is needed to enhance the conversion efficiency of the feedstock. In addition, because of the high cost of transportation and the large space requirements of storage, agricultural residues should be ground in rural areas, near the farms that supply the residues.

 Animal waste: Animal waste includes animal manure and related animal waste (such as bedding and feed), dead animals, and waste from slaughter and meat processing. Almost 900 million tons of animal waste is generated per year in the United States, including over 335 million tons of livestock manure dry matter. Land application is the primary and oldest treatment method for livestock manures. But sufficient agricultural land is not available within the vicinity of animal operations to safely use all the manure produced. If not utilized and treated properly, animal wastes could cause adverse environmental problems. Disposal of these wastes cost billions of dollars. HTL can be applied to convert animal waste into bio-crude oil, and provides a possible promising solution for solving both environmental and energy problems. Originally, the HTL, then named as hydrothermal processing, was used to convert swine manure into crude oil as a cost effective approach for reducing the animal waste on swine farm and simultaneously increasing farmer's income by generating value-added product. In the HTL process, the solid materials in swine manure rapidly decompose in a closed system with volatile organic solids being converted to gas and liquid products at high temperature and high pressure. Among those resultants derived from swine manure, a major value-added product is the tarry oil, which looks like residual oil from petroleum and could be further upgraded to transportation fuel such as gasoline and diesel through various well-developed processes. Up to 70% of raw oil yields have been achieved from the HTL conversion of swine manure.

 Food waste: Food wastes are the organic residues generated by the handling, storage, sale, preparation, cooking, and serving of foods. The United States spends about 1 billion dollars a year for disposal of food waste. The HTL technology can be used to convert food wastes into biocrude oil and thus, to greatly reduce the amount of waste being dumped in landfills and the disposal cost.

 Municipal waste: Hundreds of millions of tons of solid and liquid municipal waste per year are created in the United States. Although municipal solid waste, commonly known as garbage, can be used to generate energy with the HTL technology, it is municipal liquid waste, commonly known as sewage sludge, that can play an important role in an E2-Energy system. Sewage sludge contains recoverable energy and nutrient for algae growing. A demonstration plant with HTL technology has converted 48% (maf-moisture and ash free) of the organic materials in sewage sludge into heavy oil. Sewage sludge can also been used to provide nutrients for growing algae. The produced algae biomass could provide a huge amount of biofuel feedstock in the E2-Energy system.

 Chemicals: Bio-crude oil produced from HTL can be upgraded to produce different organic chemicals. The oil samples are usually very sticky and highly viscous. These characterizations are very similar to the properties of conventional asphalt therefore can be used as an alternative source for road construction to replace petroleum-based asphalt. The solid byproducts from different feedstocks can also be used for different purposes. For example, solid product from cellulosic and/or ligneous feedstock is a good absorbent because of its high porosity and hydrophobicity. Residues from diatoms conversion contain a considerable amount of silicon, which has the potential to be utilized as construction materials.

 Biochar and fertilizer: The HTL post-processed solid residue can be further compounded into biochar, and the HTL post-processed water will be used as "green" fertilizers for algae growing. Biochar can be spread on agricultural fields and incorporated into the top layer of soil as soil enhancers. It will increase crop yields, boost food security, prevent fertilizer runoff and leeching, retain moisture, and sequester historical carbon emissions.