POWER February 2020 - 39

BIOMASS POWER
" A significant amount of power is pro1.
Using innovative technology, Ameresco
processes raw biogas generated at the
91st Avenue Wastewater Treatment Plant
in Phoenix, Arizona, into renewable natural
gas suitable for injection into the nation's
high-pressure natural gas pipeline. Courtesy:
Ameresco
veto came up four votes short.
Cox also cited the example of the Nacogdoches
biomass facility in East Texas.
That plant-originally owned by Southern
Power-sold its generation under a
power purchase agreement (PPA) with
Austin Energy. " It opened in 2012 and is
the largest biomass facility in the U.S.,
so it is very efficient and is in a very attractive
wood basket, " explained Cox.
" Unfortunately, because of low gas prices,
and cheap wind and solar, the plant
rarely dispatched in the ERCOT [Electric
Reliability Council of Texas] market. Even
though the plant did not dispatch, the
terms of the PPA required Austin Energy
to make capacity and O&M payments
that would essentially keep the owner
whole. Austin Energy recently purchased
the plant from Southern to avoid continuing
to pay out on the PPA. "
Biomass and Waste Still Viable and
Promising in Some Applications
Slow expansion, however, does not
mean it, or other fuel sources like it, are
dead and gone. Opportunity exists, not
just in biomass, but also as the EIA statistics
point out, with waste products.
Ameresco's 91st Avenue Wastewater
Treatment Plant (Figure 1) in Phoenix,
Arizona, is purifying organic waste materials
into biomethane, or renewable
natural gas (RNG). The RNG is then used
as a fuel source for renewable electric
power generation.
RNG is an ultra-clean and ultra-lowcarbon
natural gas alternative. As organic
waste breaks down, it emits methane
gas that would otherwise be released
into the atmosphere. Now, it may be purified
and used as an alternative renewable
energy source.
February 2020 | POWER
duced by biomethane power generation, "
explained Michael T. Bakas, executive
vice president, Distributed Energy Systems,
with Framingham, Massachusettsbased
Ameresco. The firm partnered
with the City of Phoenix to establish the
biomethane plant. " Biomethane that is
used at power plants makes up 20% to
25% of the biomethane in North America.
The RNG generated at the 91st Avenue
Wastewater Treatment Plant was
a wasted resource that represented an
opportunity for the City of Phoenix to not
only make a powerful statement about
its commitment to the environment and
sustainability, but to also reap significant
financial benefits, " said Bakas.
In other applications, biomass as
an energy source may help solve two
challenges: it mitigates environmental
problems and can be burned with very
low oxygen to produce biochar. Farmers
use biochar to enhance and improve soil
quality. Furthermore, the biochar captures
carbon and is a promising source
of carbon sequestration.
That's the case with Lake Tana, in
Shea Gomengie, Ethiopia. The lake is the
largest lake in Ethiopia (52 miles long by
42 miles wide), supplies nearly half the
nation's fresh water, and it's full of serene
green water hyacinths with pretty
lavender-colored blooms. In spite of such
beauty, the plants are a menacing vegetation
and a dangerous weed.
" It deprives fish and plants of nutrients
and poisons the atmosphere with
methane, " said
German-based Char2Cool, operating in
Ethiopia. " It brings hydroelectric plants
and the drinking water supply to a halt. "
Char2Cool has found a solution. It uses
large waterborne machinery to harvest the
water hyacinths (Figure 2) and turn the unwanted
vegetation into treasure: biochar.
By cultivating the biomass, it's producing
a CO2
-negative fuel. " Now, it becomes a
major opportunity, " Thierley said.
Opportunity Remains
If, as baseball legend Yogi Berra said,
" It ain't over, 'til it's over, " then biomass
still remains as a workable fuel source
for sustainable power in many ways. It
remains as a fuel source and biomass
plants still operate. In order for it to regain
a second wind, though, it will need
to continually overcome challenges.
" From an environmental perspective,
biomass energy faces greater challenges
than other renewable resources due to
the ongoing controversy surrounding the
www.powermag.com
Olivia Thierley of the
2. Water hyacinth is a big problem at Lake
Tana in Ethiopia. However, the invasive vegetation
can be harvested and biochar made
through pyrolysis, which is the thermal decomposition,
in
a
limited-oxygen environment,
of biomass into a carbon-rich solid
residue (char), gases, and liquids. Courtesy:
Char2Cool
question of whether CO2
emitted from
combusting biomass is-or always is-
'carbon neutral,' " said McGuffey. " [The
U.S. Environmental Protection Agency]
has made several attempts to craft a
policy regarding the carbon-neutral nature
of biomass without success, but a
new proposal is expected in March 2020.
Despite these challenges, several companies
remain active in biomass energy,
and there are many utility-scale biomass
energy facilities in operation throughout
the U.S. "
While the biomass bonanza from
plants like Covanta's in California may
be dead, byproducts such as biomethane,
and other applications such as
the utilization of biomass vegetation
to create biochar-as in the harvest
of water hyacinths from Lake Tana in
Ethiopia-do show promise in more
selective operations. It is also used for
smaller-scale, off-grid applications, such
as a farm in Canada that cultivates willow
trees and growth around a wetlands
area, converting it into a fuel to be used
for farm property use.
Biomass awaits new opportunities,
new exploitation, and new ventures to
serve world sustainable energy markets
for today and tomorrow. As the futurist,
Buckminster Fuller, who lived nearly nine
decades and saw America expand from
an agricultural to an industrial nation,
said, " Pollution is nothing but resources
we're not harvesting. We allow them to
disperse because we've been ignorant
of their value. " ■
-Jim Romeo (www.JimRomeo.net) is a
technology writer and speaker.
39
http://www.JimRomeo.net http://www.powermag.com
POWER February 2020

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