EnviroWonk writer Samantha Hulkower can now enjoy her weekend after three days of blogging from WIREC

The Washington International Renewable Energy Conference ended yesterday, and we couldn't be more thankful. Not that the conference wasn't interesting, but we didn't have the energy (pun not intended) to spend another day wandering around the windowless D.C. Convention Center, looking for decent free food and avoiding eye contact with people who wanted to exchange business cards.

We weren't alone, as the Trade Show floor was practically a ghost town yesterday compared to the hustle and bustle of the previous two days. From what we saw, the side events and business forums had far fewer attendees, and the whole thing closed up by 4 p.m.

All week there were side events at the Convention Center, covering topics such as "Clean Cities and Energy Independence," "Sustainability Criteria for Biomass," and more esoteric topics like "African Rift Valley Geothermal Initiative." From what we heard, these events were hit-or-miss in terms of their usefulness and entertainment value, so we waited until the last day to check one out.

We tried to find some sessions worth sitting in on, but passed on rooms that were less than half full or had more than 3 audience members dozing off. Needless to say, it was slim pickings.

We did sit in on a talk about "alternative" renewable energies. We braced ourselves for a discussion about nuclear power, but were pleasantly surprised to hear stuff about emerging renewable energies. There is pig and dairy cow manure that can be used to make energy from biomass, and what we found to be an excellent and surprisingly underutilized source of energy -- waste heat. A steel plant in Illinois produced 95MW of electricity just from capturing the heat radiating off the coke that was previously left to radiate out into the atmosphere.

Silicon chip production is another heat-intensive process, and a plant in West Virginia managed to produce 50MW of electricity from recycling waste heat -- allowing the plant to save money on energy costs, and invest those savings into further energy-efficient upgrades to the facility.

See, everyone wins when you recycle.