U.S. power grid

 

In 2022/2023, solar and wind are expected to add more than 60% of the utility-scale generating capacity to the U.S. power grid (46% from solar, 17% from wind). The United States is a resource-rich country with abundant renewable energy resources.

Renewables are on track to generate more power than coal in the United States this year. But the question is whether they can grow fast enough to meet the country’s climate goals.

Supply chain constraints and trade disputes have slowed wind and solar installations, raising questions about the United States' ability to meet the emission reductions sought by the Inflation Reduction Act. The Biden administration is banking on the landmark climate law cutting emissions by 40 percent below 2005 levels by 2030.

Many analysts think the United States will ultimately shake off the slowdown thanks to the Inflation Reduction Act's $369 billion in clean energy investments. But it may take time for the law’s impact to be felt. Tax guidance needs to be finalized before developers begin plunking down money on new facilities, and companies now face headwinds in the form of higher interest rates and the looming threat of a recession.

The Inflation Reduction Act's emission reductions hinge on the country’s ability to at least double the rate of renewable installations over the record levels observed in 2020 and 2021.

Assuming intermediate efficiency, solar photovoltaic (PV) modules covering 0.6% of the U.S. land area could meet national electricity demand. PV module prices have declined to an average of $0.27/watt. The U.S. manufactured 1% of PV cells and 3% of PV modules globally in 2020. In 2021, a new record high of over 23.6 GW of solar photovoltaic capacity was added in the U.S., raising the total installed capacity to over 121 GW. Solar accounted for 46% of the new generating capacity in 2021.

Hydrothermal resources, i.e., steam and hot water, are available primarily in the western U.S., Alaska, and Hawaii, yet geothermal heat pumps can be used almost anywhere to extract heat from the shallow ground, which stays at relatively constant temperatures year-round. Electricity generated from geothermal power plants is projected to increase from 15.9 billion kWh in 2021 to 47.4 billion kWh in 2050. Geothermal electricity generation has the potential to exceed 500 GW, which is half of the current U.S. capacity.

U.S. onshore wind resources have a potential capacity of almost 11,000 GW and a current installed capacity of 132.7 GW. Offshore wind resources are potentially 4,200 GW, the current capacity is 42 MW, and the development pipeline contained over 28 GW of projects in 2019. Over 16 GW of wind capacity was installed in the U.S. in 2020, an 85% increase from 2019. The federal production tax credit (PTC) significantly influences wind development, but cycles of enactment and expiration lead to year-to-year changes in investment. In 2020, the PTC was extended to allow wind projects beginning construction in 2020 or 2021 a PTC at 1.5¢/kWh for 10 years of electricity output. Based on the average U.S. electricity fuel mix, a 1.82 MW wind turbine (U.S. average in 2019) can displace 3,679 metric tons of CO2 emissions per year. By 2050, 404 GW of wind capacity would meet an estimated 35% of U.S. electricity demand and result in 12.3 gigatonnes of avoided CO2 emissions, a 14% reduction when compared to 2013.

In the U.S., net electricity generation from conventional hydropower peaked in 1997 at 356 TWh/yr. Currently, the U.S. gets about 260 TWh/yr of electricity from hydropower. While electricity generated from hydropower is virtually emission-free, significant levels of methane and CO2 may be emitted through the decomposition of vegetation in the reservoir. Other environmental concerns include fish injury and mortality, habitat degradation, and water quality impairment. “Fish-friendly” turbines and smaller dams help mitigate some of these problems.

Wood—mostly as pulp, paper, and paperboard industry waste products—accounts for 43% of total biomass energy consumption. Waste—municipal solid waste, landfill gas, sludge, tires, and agricultural by-products—accounts for an additional 9%. Biomass has low net CO2 emissions compared to fossil fuels. At combustion, it releases CO2 previously removed from the atmosphere. Further emissions are associated with the processing and growth of biomass, which can require large areas of land. Willow biomass requires 121 acres of land to generate one GWh of electricity per year, more land than other renewable sources.

For now, U.S. renewable output is edging higher. Wind and solar output are up 18 percent through Nov. 20 compared to the same time last year and have grown 58 percent compared to 2019, according to the U.S. Energy Information Administration. The government energy tracker predicts that wind, solar and hydro will generate 22 percent of U.S. electricity by the end of this year. That is more than coal at 20 percent and nuclear at 19 percent.

Renewable output also exceeded coal in 2020, though that year saw a decrease in energy generation across the board due to the economic lockdowns associated with the Covid-19 pandemic.

Wind and solar growth have to continue at a blistering pace to meet the United States' climate targets. Researchers at Princeton University estimate the country needs to install about 50 gigawatts of wind and solar annually between 2022 and 2024, or roughly double the 25 GW that the United States installed annually in 2020 and 2021.

Agrošumarstvo u sklopu Hrvatskog Centra Obnovljivih Izvora Energije (HCOIE)

  

Croatian Center of Renewable Energy Sources (CCRES) is a non-governmental organization registered and working in Croatia in the field of renewable energy, agroforestry, reforestation, and sustainable land uses. The organization started working at the CCRES Research facility in the year 2013 and has been involved with giving farmers free seeds, training farmers and the community at large on more about agroforestry techniques, and environmental conservation awareness. CCRES has been able to facilitate the planting of trees in forest lands, community farms, schools, waterlines, and private lands. Some of the benefits the farmers have been able to acquire from the organization include; free seeds, free training manuals in agroforestry, workshops in agroforestry, and sustainable land uses. 

Agroforestry takes advantage of the interactive benefits of combining trees and shrubs with crops and/or livestock.

Several types of agroforestry:

*Forest Farming: the intentional cultivation of non-timber forest crops underneath the established canopy of an existing forest.

*Forest Gardening: mimicking the structure and function of forests in the way we garden, or using the forest as a model for the way we garden.

*Silvopasture: grazing animals under a forest canopy of about 50% cover, so that grasses can persist

*Riparian Buffers: tree crop systems in waterways like streams, rivers, wetlands, etc.

*Windbreaks: tree crop systems to buffer effects of wind

*Alley Cropping: rows of trees in between conventional crops, like Black Walnuts in-between rows of corn or soybeans

Agrošumarstvo se uglavnom sastoji od miješanja sadnje stabala sa sadnjom usjeva i/ili uzgojem stoke. To omogućuje bolju iskorištenost resursa, pomaže povećanju bioraznolikosti i može povećati prinose.

U sklopu Hrvatskog Centra Obnovljivih Izvora Energije (HCOIE), objavili smo svoje nove planove za razvoj ekološki održivih šumarskih praksi diljem Hrvatske. Ovi projekti imaju za cilj smanjiti negativan utjecaj na okoliš te integrirati prakse upravljanja šumama u agroekologiju.

Agrošumarstvo se uglavnom sastoji od miješanja sadnje stabala sa sadnjom usjeva i/ili uzgojem stoke. To omogućuje bolju iskorištenost resursa, pomaže povećanju bioraznolikosti i u konačnici povećava prinose. Studija HCOIE pokazala je da parcela od 100 ha pod agrošumarskim praksama daje ekvivalent od 136 ha pod standardnim principima korištenja, dajući tako potencijalni ekonomski rast za proizvođače koje takve prakse usvoje.

Koncept ima velik broj prednosti po pitanjima uzgoja usjeva i zaštite okoliša. U principu, drveće kroz svoje korijenje stvara uvjete u tlu koji potiču bolju apsorpciju vode i minerala usjevima na površini. Agrošumarske tehnike potiču strateško pozicioniranje stabala kako bi se maksimiziralo povećanje prinosa. Dodatno, stabla pomažu u diverzifikaciji proizvodnje, ograničenju gubitaka nitrata iz tla te onečišćenju podzemnih voda.

Plodnost tla također se poboljšava padom jesenskog lišća i njegovom razgradnjom na tlu, stvarajući tako važan izvor prirodnog komposta i gnojiva okolnim kulturama. Drveće i živice na poljima povećavaju bioraznolikost, što je pogodno kukcima za oprašivanje. Konačno, stabla igraju važnu ulogu u apsorpciji CO2 i spremanju ugljika tijekom faze rasta, smanjujući tako učinak klimatskih promjena.

Agrošumarstvo tako postaje ključni igrač u agroekološkom planu HCOIE. Zbog svih ovih prednosti, promocija i širenje korištenja agrošumarstva postali su nam jedan od glavnih ciljeva u borbi protiv klimatskih promjena. Plan otkriva naše konkretne prijedloge za njegovu promociju u širokim kategorijama s brojnim specifičnim aktivnostima u svakoj od njih.

Kategorije uspostavljaju sustav za istraživanje i praćenje različitih oblika agrošumarstva koji se provode u Hrvatskoj, te uspostavljaju mreže za razmjenu informacija između različitih sudionika u agrošumarstvu. Povećanje informacija o tome što se radi u agrošumarstvu omogućit će širenje inovativnih ideja koje su u budućnosti primjenjive.

Još jedan veliki prostor na koji se odnosi plan jest poboljšanje regulatornog, pravnog i financijskog okvira koji okružuje agrošumarstvo. Neke od specifičnih aktivnosti uključuju osnaživanje financijske potpore za agrošumarstvo, poboljšanje dostupnosti alata za različite sudionike na regionalnom nivou te favoriziranje razvoja agrošumarstva kroz financijske alate.

Obrazovanje je još jedna važna komponenta plana, kako u poljoprivrednim školama, tako i u pružanju obuke već postojećim poljoprivrednicima o prednostima agrošumarstva i kako prijeći na njega. Dodatno, plan postavlja sustav pomoći kako bi se podigla vrijednost proizvedenih kultura koristeći agrošumarstvo te strategiju promocije agrošumarstva na međunarodnoj razini.

Široko korištenje agrošumarstva moglo bi imati veliku ulogu u prelasku na održive okolišne prakse u dugoročnom razdoblju, a također bi pomoglo i proizvođačima na ekonomskom nivou u povećanju prinosa, te korištenje biomase drveta, kroz malčiranje, kao prirodno gnojivo za usjeve. Predstavljeni plan trebao bi svoju primjenu naći na nacionalnom, ali i na međunarodnom nivou.

Field windbreaks

Wind protection is a long-standing indigenous practice in traditional agriculture of many regions. In attempts to improve or establish wind protection schemes with trees, it makes sense to study the link which can be observed between traditional and relatively recent but promising agroforestry practices. And it makes sense as well to try to quantify phenomena taking place in such traditional and promising practices alike.

In the case study in Croatia reported here, the farmer requested CCRES to assist in providing the agrometeorological input into the set-up of experiments under conditions in farmers' fields, with a system of wind barriers with trees, in irrigated crops in Lika Region.

The choice to use multiple tree breaks appears justified by the increase in roughness over a larger area in addition to separate windbreak effects, and by the multipurpose use of trees and their products which is economically possible. In larger-scale agriculture, where irrigated cash and food crops have to be protected against very strong winds, relatively narrow rows of trees are to be preferred above wider belts as an intercrop or scattered trees or bushes.

As mentioned earlier, where mechanical damage from strong winds is the primary limiting factor, the agronomist member of the team should pay primary attention to phenology, growth and yield parameters, and visual or even microscopic observations of actual mechanical damage. This will make it possible to observe differences between unprotected crops and protected ones at different distances from belts.

Whether in strip cropping, in using narrow tree rows, or in mixed experiments, cost/benefit ratio determinations are absolutely necessary to understand the proper gain from the multipurpose role of trees and from yield (quality) increases due to the trees or crops applied for protection from wind.

Zeljko Serdar, Croatian Center of Renewable Energy Sources (CCRES)