HomeMy WebLinkAboutThorne Bay cord wood info.Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-18 T R Miles
4.3.3 Heating System Costs: Cordwood
Table 4-9 summarizes cost estimates for four cordwood systems. The total cost is
often two to three times the cost of the boiler.
Table 4-9. Cost Estimates for Cordwood Systems.
Facility Thorne Bay
School
Craig
Community
Center
Thorne Bay
Shop +
Duplexes
Thorne Bay
Solid
Waste
Fuel Oil, gallons per year 11,501 6,605 3,050 2,000
Calculated required capacity* 347,000 207,000 90,000 60,000
Wood Boiler, Btuh 425,000 350,000 350,000 100,000
Building and Equipment Costs
Building $ 21,600 $ 14,500 $ 6,500 $ 1,900
Boilers $ 19,500 $ 15,540 $ 15,540 $ 9,200
Piping $ 38,300 $ 3,500 $ 8,000 $ 3,200
Installation $ 3,500 $ 1,200 $ 1,300 $ 2,100
Total Direct Costs $ 81,700 $ 34,700 $ 31,340 $ 16,400
Engineering +Contingency** $ 22,000 $ 2,000 $ 560 $ 600
Total $ 104,300 $ 37,000 $ 31,900 $ 17,000
Notes:
* Table 4-6 Estimate of heat required in Coldest 24 Hr period.
** This larger project may require more allowance for indirect costs such as
engineering, approvals, etc.
Building and piping are the most significant costs besides the boiler. Building
costs deserve more site specific investigation. A variety of prefabricated buildings were
considered to enclose the boiler and wood supply. A quote was obtained from one
supplier to deliver a pre-assembled boiler in a shipping container. Since the boiler
enclosure had to meet special codes the cost of a containerized boiler was higher than in a
separate building.
Piping from the wood-fired boiler is another area of potential cost saving. The
impact of piping costs can be seen in the costs estimates for Craig Community Center
compared with the Thorne Bay school. Long piping runs and additional heat exchanger
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-19 T R Miles
substantially increase project costs. The hard pipe normally used in Alaska costs
$70/foot. If plastic or PEX piping is used the cost is reduced to about $40/foot.
Allowance for indirect costs such as engineering and contingency are most
important for larger systems that involve extensive permitting and budget approval by
public agencies. This can increase the cost of a project by 25% to 50%.
Figure 4-7 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 425,000 Btuh cordwood system to replace 11,500 gallons of fuel oil per year at
different terms of cost recovery. This is the reported use at the Thorne Bay School. A
70% efficient boiler system would be used at a full load equivalent of 3,175 hours per
year or about 36% capacity. The cost to recover a $104,300 investment would be about
$13.23/MMBtu for 5 years, $7.57/MMBtu for 10 years or $4.86 for 20 years. Boilers in
this example have been in use for more than 20 years. No labor is included in this
calculation since most sites indicated that stoking the wood boilers would be included in
responsibilities of existing personnel.
0.00
5.00
10.00
15.00
20.00
25.00
20000 40000 60000 80000 100000 120000
Capital Cost ($/425 kBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-7. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 11,500 gpy Fuel Oil. Does not include wood cost.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-20 T R Miles
Figure 4-8 illustrates the effect of capital and non-fuel costs on the cost of heat for
a 425,000 Btuh cordwood system to replace 6,605 gallons of fuel oil per year at different
terms of cost recovery. This is the reported use at the Craig Community Center. A 70%
efficient boiler system would be used at a full load equivalent of 1,823 hours per year or
about 21% capacity. The cost to recover a $40,000 investment would be about
$8.84/MMBtu for 5 years, $5.06/MMBtu for 10 years or $3.25 for 20 years. Boilers in
this example have been in use for more than 20 years. No labor is included in this
calculation since most sites indicated that stoking the wood boilers would be included in
responsibilities of existing personnel.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
20000 40000 60000 80000 100000 120000
Capital Cost ($/425 kBtuh)Cost Hot Water($/MMBtu)20 years 10 years
5 years Oil 2.50/gal
Figure 4-8. Impact of Capital and Non Fuel Cost on Cost of Heat for a 425,000 Btuh
Cordwood Boiler to Replace 6,600 gpy Fuel Oil. Does not include wood cost.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-21 T R Miles
Figure 4-9 shows the total cost of heat including the wood and capital cost for a
425,000 Btuh system saving 11,501 gallons of fuel oil per year at 20 year capital cost
recovery with an interest rate of 6% and an annual maintenance cost of 3% ($1,200).
Operating and maintenance costs do not include labor since each institution indicated that
fuel handling would be included in the normal duties of maintenance personnel. From
this figure $160/cord would be the maximum price for fuel when fuel oil is $2.50/gallon
($21.31/MMBtu). This example would fit a single boiler at Thorne Bay school to recover
all of the fuel oil consumed.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
40000 50000 60000 70000 80000 90000 100000 110000
Capital Cost ($/425 kBtuh HW)Cost of Hot Water ($/MMBtuOil $4.00 $75.00 $100.00
$125.00 $150.00 $175.00
Oil $3.50 Oil $3.00 Oil $2.50
20 Year CR 6%
Figure 4-9. Total Cost of Heat to Replace 11,500 gpy Fuel Oil At Various Wood Costs
($/Cord).
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-22 T R Miles
Figure 4-10 shows the total cost of heat including the wood and capital cost for a
425,000 Btuh system saving 6,605 gallons of fuel oil per year at 20 year capital cost
recovery with an interest rate of 6% and an annual maintenance cost of 3%. Operating
and maintenance costs do not include labor since each institution indicated that fuel
handling would be included in the normal duties of maintenance personnel. From this
figure $160/cord would be the maximum price for fuel when fuel oil is $2.50/gallon
($21.31/MMBtu). This example would fit the Craig Community Center. If the $66,000
Dot Lake system were built again today it could afford to pay about $140/cord to be
equal to oil at $2.50/gal.
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
20000 30000 40000 50000 60000 70000 80000
Capital Cost ($/425 kBtuh HW)Cost of Hot Water ($/MMBtuOil $4.00 $75.00 $100.00
$125.00 $150.00 $175.00
Oil $3.50 Oil $3.00 Oil $2.50
20 Year CR 6%
Figure 4-10. Total Cost of Heat to replace 6,605 gal Fuel Oil at Various Wood Costs
($/Cord).
4.3.4 Conclusions:
! This analysis suggests that a chip system would be feasible at Delta Greely
Schools but a low cost system ($300,000) would be necessary for the
Thorne Bay School.
! Cordwood systems may be appropriate at Thorne Bay School and Craig
Community Center or similar applications saving 6,600 to 11,500 gpy fuel
oil.
Alaska Wood Energy Development Task Group
Feasibility Assessment for Wood Heating 4.0 Fuels and Heating Systems Overview
10 August 2006 4-23 T R Miles
! Chip fuel cost has a low impact on wood boiler systems at a high level of
oil replacement (102,000 gpy).
! Capital costs have a high impact at low levels of oil replacement (11,500
gpy).
! Cordwood fuel costs have a high impact on small and large systems.
! Capital costs have a high impact at low levels of oil replacement.
! Building and piping or integration costs must be kept low for wood boilers
to be feasible.