Switchgrass

The Chariton Valley (IA) Project generated electricity from switchgrass for three months in 2006. It resulted in an output of 1.25MWh/Dry-Ton. A typical Ohio home uses about 1 Mwh/month. So a year’s electricity for a home could be supplied from about ten tons, which would cost around $200-300 for fuel. A home using 1 Mwh/month would have a $100 electricity bill (this seems high).

I posted a query about home biomass generators on Yahoo! Answers and got this anonymous reply:

“I can't give you a direct answer, but I'm going to venture that operating such a system would be a full time job. It would consist of either a gasifier or wood burner system, then some sort of generator.

“A gasifier system would likely be simpler on the downstream end, syn-gas would be fed to a retro-fit ICE and used to direct drive a generator. A burner system would require a boiler and a let down turbine, condensate handling system, etc etc. It'd be a trade off, operating the wood-burner would be easy, the boiler and turbine pretty complicated, where in the other scenario, the gasifier would be difficult to operate whereas the ICE would be very simple. In one system the front end is easy, the back end difficult, in the other system, the opposite.

“Supplying enough biomass to support any level of generation would be a chore in itself also. You're not going to get enough grass clippings or yard waste for free to run your house. Assuming GREAT efficiency, you'd be looking at burning about a pound of bone dry wood every hour to power the average American household. Feeding 25lbs per day doesn't seem like much, but you'd have to feed it continuously, all day every day. You'll probably pay around $80-100/ton for biomass supply (more with shipping), which will be at least 20% moisture. So you'll at a MINIMUM be spending $600 per year on feedstock, I'd guess around half what you're paying for electricity now. Factor in the compounding efficiencies of EITHER system so you'll end up buying around TWICE the mass of wet biomass as your actual energy load requires, so your $600 becomes $1200, bringing you pretty close to on par with your current bills, PLUS the additional cost of paying for the equipment up front, then the maintenance and operational costs of the system.

“Bottom line, it's not hugely economical for home use.
“Source(s):
“I'm a renewable energy engineer.”

I’m not convinced that his cost is right, but the message is that the technology for a home system is not here yet.

Fuel Costs for Cars

In Sept. 2007, Popular Mechanics estimated the fuel costs to go from coast to coast using various fuels. The results for the leading contenders were:

Petrol = $212.70 ($2.34/gal - about today's price)
E85 = 425
Electricity = 60

Compressed natural gas, though not a contender for cars, cost $110. Fuel cell, which seems to have lost its glow, was exorbitant = $804.

Electricity Supplied

To calculate the number of homes powered by one MW of capacity, I used the following formula:

E = 730fP ----- (1)

where E is electricity provided (MWh) in a 730-hour month, f fraction of rated power actually delivered, and P is rated power (MW). Assuming the average home in Ohio uses 1 MWh = 1,000 kWh per month, Eq. (1) becomes:

H = 730fP ----- (2)

where H is the number of homes supplied.

I used the data of www.nrel.gov/analysis/costs.html
for my estimates.


----------------------------------------------- Construction-- Construction
Power Source ------------------ f --- H/P---- Cost, $/kW --- Cost, $/Home

Coal ----------------------------- 0.86 - 630 -------- 2800 -- 4450
Geothermal --------------------- 0.84 - 615 -------- 3200 -- 5200
Natural Gas (Combined Cycle) -- 0.80 - 585 -------- 3100 -- 5300
Wind ---------------------------- 0.39 - 285 -------- 1700 -- 5965
Biomass ------------------------- 0.69 - 505 -------- 3200 -- 6335
Hydro --------------------------- 0.45 - 330 -------- 2300 -- 6970
Nuclear ------------------------- 0.90 - 655 -------- 4900 -- 7480
Solar Thermal ------------------- 0.32 - 235 -------- 4600 -- 19,570
Solar PV ------------------------- 0.20 - 145 -------- 5600 -- 38,620


where f = capacity factor
H/P = Homes per MW