SOLAR THERMAL- WOOD BOILER COMBI SYSTEMS

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1 SOLAR THERMAL- WOOD BOILER COMBI SYSTEMS Reducing Pollution, Increasing Efficiency, Economically Advantageous Thank you to the University of Minnesota Central Region Sustainable Development Partnership for supporting this study

2 SOLAR TAXONOMY RECIRCULATING (GLAZED) TRANSPIRED Solar Air Heat ACTIVE SYSTEMS GLAZED FLAT PLATE UNGLAZED EVACUATED TUBES Solar Water Heat Building Design PASSIVE SYSTEMS SOLAR ELECTRICITY (PV) Makes usable energy from the sun in the form of electricity SOLAR THERMAL Makes usable energy from the sun in the form of heat

3 SOLAR TAXONOMY GLAZED FLAT PLATE ACTIVE SYSTEMS EVACUATED TUBES Solar Water Heat SOLAR ELECTRICITY (PV) Makes usable energy from the sun in the form of electricity SOLAR THERMAL Makes usable energy from the sun in the form of heat

4 SOLAR THERMAL WATER HEAT A hydronic heating system harnessing solar energy to heat fluid in the system, which can then be transferred to building heat loads. Wikipedia

5 OUTDOOR WOOD BOILER A method of wood-based hydronic heating adapted for set-up outdoors, and transferring the heat generated to building interiors. Wikipedia

6 SOLAR THERMAL WATER HEAT- OUTDOOR WOOD BOILER COMBI A wood and solar thermal energy combination hydronic heating system harnessing solar energy and biomass energy, and transferring the heat generated to building heat loads.

7 THE PROBLEM Outdoor wood boilers INEFFICIENT (averaging 30-40% annual efficiency) YEAR ROUND OPERATION (summer use for DWH only) - super inefficient burns CYCLIC OPERATION Increases toxic and PM emissions SHORT STACK HEIGHTS Smoke does not disperse OVERSIZED FIREBOX Simple for users to combust inappropriate material WOOD CONSUMPTION INCREASING MPCA 2012 study showed over half (53%) of MN households burned wood; 9% of the Nation s space heating energy needs come from wood

8 THE PROBLEM Burning wood emits highest amount of carbon dioxide per unit energy Source: Renewable Energy Systems Soot is second-greatest contributor to climate change Source: Black Carbon Second only to CO 2 in climate change Soot ranks behind carbon dioxide but ahead of methane gas as a cause of climate change Source: Black Carbon Second only to CO 2 in climate change US social cost of carbon dioxide = $40 per ton

9 Alaska New York Ohio OUTDOOR WOOD BOILER POLLUTION Minnesota

10 OUTDOOR WOOD BOILER POLLUTION Emissions from ONE Outdoor Wood Boiler equivalent to: 22 EPA certified wood stoves 205 oil furnaces 8,000 natural gas furnaces Relative Emissions of Fine Particulate Matter Source: NESCAUM, 2006

11 THE QUESTIONS Costs/Benefits of solar OWB combi system? Pollution reductions? Fuel consumption saved? Add l. Details? THE METHOD Models (flat plate & evacuated tube) Case Studies (flat plate & evacuated tube)

12 THE MODEL Base case Residential Base case Commercial Larger Commercial Case # persons in HH 2.61 (Census) Building size (sq ft) 2169 (Census) 5000 (US DOE) Wood Cost per mmbtus (EIA) $12.72 $6.56 $6.56 Annual Wood boiler efficiency est. 40% 30% 40% 30% 40% 30% mmbtus input required based on annual delivered wood boiler efficiency (NASCAUM) Total annual cost wood $ 3, $ 4, $ 2, $ 3, $ 8, $ 11, Solar System Design Solar Fraction (% of load) 25% 40% 25% 40% 25% 40% 25% 40% 25% 40% 25% 40% mmbtu Annual theoretical potential mmbtu wood savings, adjusted for boiler efficiency Cord equivalent annual hardwood savings Annual cost savings $ 862 $ 1,379 $ 1,149 $ 1,838 $ 735 $ 1,176 $ 980 $ 1,568 $ 2,206 $ 3,529 $ 2,941 $ 4,705 Social benefits of carbon pollution avoided - annual savings $ 341 $ 546 $ 455 $ 728 $ 565 $ 904 $ 753 $ 1,205 $ 1,695 $ 2,711 $ 2,259 $ 3,615 Fine PM emissions reduction - annual minimum kg Flat Plate System - Solar Skies System 1 System 2 System 1 System 2 System 3 System 4 System 3 System 4 System 5 System 6 System 5 System 6 Size - collector sq ft Total Cost est. $ 9,838 $ 17,968 $ 9,838 $ 17,968 $ 13,019 $ 23,778 $ 13,019 $ 23,778 $ 39,057 $ 71,335 $ 39,057 $ 71,335 MN State Rebate (through 2024) $ (2,459) $ (2,500) $ (2,459) $ (2,500) $ (3,255) $ (5,945) $ (3,255) $ (5,945) $ (9,764) $ (17,834) $ (9,764) $ (17,834) Federal tax credit (after rebate) $ (3,689) $ (6,140) $ (3,689) $ (6,140) $ (4,882) $ (8,917) $ (4,882) $ (8,917) $ (14,647) $ (26,751) $ (14,647) $ (26,751) Federal accelerated depreciation 5-yr schedule 5-yr schedule Total system cost after incentives $ 3,689 $ 9,327 $ 3,689 $ 9,327 $ 4,882 $ 8,917 $ 4,882 $ 8,917 $ 14,647 $ 26,751 $ 14,647 $ 26,751 Total O&M (5% every 5 years, est 30 year lifespan)(usda) $ 2,951 $ 5,390 $ 2,951 $ 5,390 $ 3,906 $ 7,133 $ 3,906 $ 7,133 $ 11,717 $ 21,400 $ 11,717 $ 21,400 Simple payback after incentives (years) Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) Evacuated Tube System - Thermomax System 1 System 2 System 1 System 2 System 3 System 4 System 3 System 4 System 5 System 6 System 5 System 6 Size - collector sq ft Total Cost est. $ 9,909 $ 18,098 $ 9,909 $ 18,098 $ 17,020 $ 31,086 $ 17,020 $ 31,086 $ 46,975 $ 85,796 $ 46,975 $ 85,796 MN State Rebate (through 2024) $ (2,477) $ (2,500) $ (2,477) $ (2,500) $ (4,255) $ (7,771) $ (4,255) $ (7,771) $ (11,744) $ (21,449) $ (11,744) $ (21,449) Federal tax credit (after rebate) $ (3,716) $ (6,179) $ (3,716) $ (6,179) $ (6,382) $ (11,657) $ (6,382) $ (11,657) $ (17,616) $ (32,174) $ (17,616) $ (32,174) Federal accelerated depreciation N/A N/A N/A N/A 5-yr schedule 5-yr schedule Total system cost after incentives $ 3,716 $ 9,419 $ 3,716 $ 9,419 $ 6,382 $ 11,657 $ 6,382 $ 11,657 $ 17,616 $ 32,174 $ 17,616 $ 32,174 Total O&M (5% every 5 years, est 30 year lifespan)(usda) $ 2,973 $ 5,429 $ 2,973 $ 5,429 $ 5,106 $ 9,326 $ 5,106 $ 9,326 $ 14,093 $ 25,739 $ 14,093 $ 25,739 Simple payback after incentives (years) Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years)

13 THE MODEL Base case Residential Base case Commercial Larger Commercial Case Solar System Design Solar Fraction (% of load) 25% 40% 25% 40% 25% 40% mmbtu Annual theoretical potential Cord equivalent annual hardwood savings Annual cost savings $ 1,149 $ 1,838 $ 980 $ 1,568 $ 2,941 $ 4,705 Fine PM emissions reduction - annual minimum kg Flat Plate System - Solar Skies System 1 System 2 System 3 System 4 System 5 System 6 Size - collector sq ft Simple payback after incentives (years) Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) Evacuated Tube System - Thermomax System 1 System 2 System 3 System 4 System 5 System 6 Size - collector sq ft Simple payback after incentives (years) Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years)

14 CASE STUDIES RESIDENTIAL I - NY

15 CASE STUDIES RESIDENTIAL II - MN

16 CASE STUDIES COMMERCIAL I - MN

17 CASE STUDIES COMMERCIAL II - NY

18 CASE STUDIES COMMERCIAL/RES - MN

19 CASE STUDIES

20 THE SOLUTION Solar-Wood Boilers Combi Systems PAYBACK in less than 10 years REDUCE PM EMISSIONS by 1,000 kg annually ELIMINATE OWB SUMMERTIME OPERATION

21 THE SOLUTION Deep Portage Solar-Wood Boiler Combi System

22 FIND OUT MORE CLEANENERGYRESOURCETEAMS.ORG LOOK FOR THE REPORT: COSTS AND BENEFITS OF SOLAR THERMAL AND WOOD BOILER COMBI SYSTEMS Thank you to the University of Minnesota Central Region Sustainable Development Partnership for supporting this study