Popular Mechanics - USA (2019-05)

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@PopularMechanics _ May 2019 73

IFTEEN YEARS AGO, motivated by the primal appeal of wood-

fueled fire (and a little by my peculiar compulsion for chopping

firewood), my wife and I replaced the gas range in our Vermont

farmhouse with a wood-burning cookstove. Every day since, I

rise before dawn, lay a bed of newspaper and dry scrap wood, and kindle

the day’s fire. This is a necessity, considering that the stove heats our home

and our water, but it has also become a comforting ritual. As the fire takes,

I tamp grounds into my little stovetop espresso maker, which sits on the

cast-iron cooktop in the exact spot I’ve found to heat up the fastest. If it’s

winter, I open the door to the firebox—in violation of every fire-safety code

known to humankind—and warm myself while my coffee percolates and

the early light filters through the windows. If it’s summer, I head outside

to tend to our chickens and cattle, which takes exactly as much time as the

coffee needs to brew.

The stove is our kitchen’s centerpiece. It’s our heater, our cooking range,

and our boot dryer. But it’s also a reminder. I’ve found that living with our

stove—tending the fire, cutting and splitting the five cords of wood we feed

it annually—has meant forming a close relationship with the source of my

well-being. It’s a rare, front-row view of the transformation of raw and under-

appreciated resource into fundamental necessity.

DEEP-CYCLE BATTERIES are central to every off-grid solar, wind,

or hydroelectric system because they store the excess energy cre-

ated by your renewable resource and make it available when you

need it. Your storage capacity needs depend on two key factors:

the amount of energy your system can generate and your home’s

average energy load. (Ideally, you want to always have three to

five days’ worth of power saved.) In terms of space requirements,

these systems range in size from a narrow bookcase-size space

for a modular system up to a laundry closet or small attic space

for a bank of wired cells. —J.K.

THREE GREAT BATTERY-STORAGE SYSTEMS

Once you know how you’re going to generate electricity, you need a way to store any excess.

SEALED MODULAR

Sealed modular systems use recharge-

able lithium-ion batteries. The Tesla

Powerwall’s batteries each have 13.5 kilo-

watt-hours of capacity and can be linked

with up to nine other units. This option can

be used as a stand-alone energy-storage

system or as a backup power supply. The

Powerwall also includes electronics for

managing the charging and discharging of

cells, as well as an inverter for converting

DC to the AC power more common in resi-

dential use. This all-in-one prepackaged

solution will make it easy to retrofit your

grid-connected system.

EXAMPLE: You guessed it: Tesla

Powerwall

LEAD-ACID BATTERIES

Invented in 1859, this is the oldest and most

common type of rechargeable battery in

use today. They are larger, heavier, and

less energy-dense than newer technolo-

gies—and therefore less expensive. (They

offer the highest watt-hour capacity per

dollar spent over the short term.) Most of

the renewable-energy equipment on the

market today will work within their volt-

age range. To maximize their life span,

they should only be discharged to about 65

percent of their capacity and be protected

from the elements and direct sunlight. Many

of them are also 100 percent recyclable.

EXAMPLE: Tro j a n l e a d - a c i d b a t te r y

(6 -volt)

LITHIUM-ION (OR LITHIUM-IRON-

PHOSPHATE) BATTERIES

Thanks to recent intense interest in elec-

tric vehicles (EV), a lot of progress has

been made with this category. Relatively

maintenance free, more compact, and

highly efficient, these batteries offer up to

10,000 charge cycles within their life span

and are at least 2.5 times more energy

dense than lead acid. They can be drawn

down further than lead-acid batteries

without affecting their performance. The

DIYer can use lithium-ion cells to create a

storage solution comparable to a packaged

modular system, but for a lot less money.

EXAMPLE: Relion high-performance LFP

battery (12-volt)

Take care of it, and it takes care of you.

BY BEN HEWITT

AN APPRECIATION

THE WOODSTOVE