SOLAR THERMAL- WOOD COMBI SYSTEMS

Reducing Pollution, Increasing Efficiency, Economically Advantageous

Thank you to the University of Minnesota Central Region Sustainable Development Partnership for supporting this study SOLAR – TAXONOMY RECIRCULATING (GLAZED) GLAZED FLAT PLATE UNGLAZED TRANSPIRED EVACUATED TUBES Solar Air Heat Solar Water Heat

ACTIVE SYSTEMS Building Design PASSIVE SYSTEMS

SOLAR ELECTRICITY (PV) SOLAR THERMAL

 Makes usable energy from  Makes usable energy the sun in the form of from the sun in the form electricity of heat SOLAR – TAXONOMY GLAZED FLAT PLATE

EVACUATED TUBES Solar Water Heat ACTIVE SYSTEMS

SOLAR ELECTRICITY (PV) SOLAR THERMAL

 Makes usable energy from  Makes usable energy the sun in the form of from the sun in the form electricity of heat SOLAR THERMAL WATER HEAT

“A hydronic harnessing solar energy to heat fluid in the system, which can then be transferred to building heat loads.” Wikipedia OUTDOOR WOOD BOILER

“A method of wood-based hydronic heating adapted for set-up outdoors, and transferring the heat generated to building interiors.” Wikipedia SOLAR THERMAL WATER HEAT- OUTDOOR WOOD BOILER COMBI A wood and combination hydronic heating system harnessing solar energy and biomass energy, and transferring the heat generated to building heat loads. THE PROBLEM

Outdoor wood …

 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 THE PROBLEM

 Burning wood emits highest amount of carbon dioxide per unit energy Source: Systems  Soot is second-greatest contributor to climate change

Source: Black Carbon Second only to CO2 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 CO2 in climate change  US social cost of carbon dioxide = $40 per ton New York Alaska

OUTDOOR WOOD Ohio BOILER POLLUTION Minnesota OUTDOOR WOOD BOILER POLLUTION

Emissions from ONE Outdoor Wood Boiler equivalent to:

22 EPA certified wood stoves 205 oil 8,000 natural gas furnaces

Relative Emissions of Fine Particulate Matter

Source: NESCAUM, 2006 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) 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) 15000 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) 271 361 448 598 1345 1793

Total annual cost wood $ 3,447.12 $ 4,596.16 $ 2,940.85 $ 3,921.13 $ 8,822.54 $ 11,763.39 Solar System Design Solar Fraction (% of load) 25% 40% 25% 40% 25% 40% 25% 40% 25% 40% 25% 40%

mmBtu Annual theoretical potential 27.1 43.36 27.1 43.36 44.83 71.728 44.83 71.728 134.5 215.184 134.5 215.184

mmBtu wood savings, adjusted for boiler efficiency 67.8 108.4 90.3 144.5 112.1 179.32 149.4 239.1 336.2 538.0 448.3 717.3

Cord equivalent annual hardwood savings 1.4 2.2 1.8 2.9 2.3 3.6 3.0 4.8 6.8 10.9 9.1 14.5

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 584.8 935.7 779.8 1247.6 967.4 1547.9 1289.9 2063.9 2902.3 4643.7 3869.7 6191.6 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 78.7 143.7 78.7 143.7 130.2 237.8 130.2 237.8 390.6 713.3 390.6 713.3

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) 7.7 10.7 5.8 8.0 12.0 13.6 9.0 10.2 12.0 13.6 9.0 10.2

Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) 5.5 7.6 4.1 5.7 6.8 7.7 5.1 5.8 6.8 7.7 5.1 5.8 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 66.1 120.7 66.1 120.7 136.2 248.7 136.2 248.7 408.5 746.1 408.5 746.1

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) 7.8 10.8 5.8 8.1 15.6 17.8 11.7 13.4 14.4 16.4 10.8 12.3

Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) 5.6 7.7 4.2 5.8 8.8 10.1 6.6 7.6 8.1 9.3 6.1 7.0 THE MODEL Base case Base case Larger Residential Commercial Commercial Case Solar System Design Solar Fraction (% of load) 25% 40% 25% 40% 25% 40% mmBtu Annual theoretical potential 27.1 43.36 44.83 71.728 134.5 215.184 Cord equivalent annual hardwood savings 1.8 2.9 3.0 4.8 9.1 14.5 $ $ $ $ $ $ Annual cost savings 1,149 1,838 980 1,568 2,941 4,705 Fine PM emissions reduction - annual minimum kg 779.8 1247.6 1289.9 2063.9 3869.7 6191.6 Flat Plate System - Solar Skies System 1 System 2 System 3 System 4 System 5 System 6 Size - collector sq ft 78.7 143.7 130.2 237.8 390.6 713.3 Simple payback after incentives (years) 5.8 8.0 9.0 10.2 9.0 10.2 Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) 4.1 5.7 5.1 5.8 5.1 5.8 Evacuated Tube System - Thermomax System 1 System 2 System 3 System 4 System 5 System 6 Size - collector sq ft 66.1 120.7 136.2 248.7 408.5 746.1 Simple payback after incentives (years) 5.8 8.1 11.7 13.4 10.8 12.3 Weighted payback including Annual Savings from Avoided Carbon Pollution and Incentives (years) 4.2 5.8 6.6 7.6 6.1 7.0 CASE STUDIES – RESIDENTIAL I - NY CASE STUDIES – RESIDENTIAL II - MN CASE STUDIES – COMMERCIAL I - MN CASE STUDIES – COMMERCIAL II - NY CASE STUDIES – COMMERCIAL/RES - MN CASE STUDIES 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 THE SOLUTION

Deep Portage Solar-Wood Boiler Combi System 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